abstracts of poster and platform presentations

ABSTRACTS OF POSTER AND PLATFORM PRESENTATIONS: FOURTH INTERNATIONAL CONFERENCE ON COMPUTERIZED AND QUANTITATIVE EMG Mainz, Germany, September 13- 15, 1990

DUGNO : TE F

A. Vila, M.D.', F. Reymond, M.D.', V. Rialle, Ph.D.2

( Lpboralcuc dElsuomyographie, Cenllc Hospitalicr el Universilaue'. DCpartemenl de

mtMmafiqm. smtistiqnes el mfmnatique rn6dicales. Fxulle de MedSins2, Gnmblc. France)

Computuized methods of automatic quantitative elcmomyography &MG) had been widely studied, and resulted in different EMG signal analysis profedures. Their clinical value in routine practice may now he estimated owing to the new EMG integrated systems.

We have used various automatic quantitative EMG methods as a routine since 1986: integrated surface EMG; specrral analysis; interference pattern analysis; mcasuremcnt of single motor unit potentials during weak contraction. We compared the parametas provided by those methods: mean rectified voltage, rout mean square and N m s per second of the integrated EMG mean and median frequency from the spectral analysis; turns per second, amplitude per turn and the ratio between these two parameters of the interference pattern analysis; the number of polyphasic. the mean duration and the amplitude of motor unit potentials. We compared the results statistically from Tibialis Anterior, Biceps Brachii and Abductor Pollicis Brevis in muscles with definitely normal, neurogenic or myogenic patterns, as well as unspecified ones.

The results are discussed to define the interest of such automatic quantitative EMG methods as routine diagnostic tools.

N OF CONDUCTION VFlOClN D ISTRlBUTlON ANAL YSlS TO TH E N OF THE &RBUE&E IN THF CARPAL

IYkJMEL SchoReld IS. M.B. B.S. Fawall P.R.W FRCP KennBtt R.P M.D.

(Regional Neuroloplcal Center Newcaslleupon-lyne England).

Conventional nerve conduction techniques estimate the near- maximum amdudion

velocily and can be normal 1 oniy a portion of the nerve is wmpmmised. This study of the

application of wndudlon velocity distribution (CVD) analysis has tm, aims:-

1. TO improve the single response CVD method of Kovacs

el. a1.(1879) for routine studles.

2. To determine lhe wndudion velocity dlstribution m patients wilh a mild carpal tunnel

syndrome.

A good eslimate of a single nerve fibre adion potential (SFAP) is essential in each

sub@ for the sing* response CVD method. A prcgrammable stimulator has been

designed to perform sequential recruitment sludies allowing the divkion of lhe compound nerve adion potential (CAP) into a number of subpopulatiins. from which a 'best' estimate

of the SFAP can ba obtained. The PCAP CCV method of Cummins el. al. (1978) was used

for wmparath purposes wilh modMcalions.

Gaod estimates of a SFAP were obtained from a wnlrol group but inRial studies of a

patient group indicated that inadequate responses may be found when lhe compression

was signficanl. A 3cm. platinum strip electrode has been used to reduce the effects of

rewrdlng geOmetW allowing a 'standard SFAP to be used in all cases.

S.F'ientka1, J.Willamowski1, D.Ziebelin.Ph.D.1, A.VilaM.D.2. F.Reymond,M.D.Z. L.Abaoub,M.D.2

(UNwnie & Savorc, LabomtoLC dlntclligencc AruTiielle. Chamb5y'.

Lzboraroire d'Elecuomyographie. C u m Hospitalier el UnivCrPilak, Grenoble 2, F m )

The specialized environment approach enables the newphysiologist to m a t e his own expert system through introduction of his own knowledge. This approach falls between

an almost inflexible expm system and a shell system that is not really appropriate for the needs of the neurophysiologist. It was chosen as a result of much experience whilst developing expert systems at the EMG laboratory of CHU Grenoble: including MYOSYS (1982-86) which aid to represent the entire EMG knowledge in PROLOG and NEUROP (1987-90) in which a shell was used to represent knowledge only about neuropathies. These projects revealed certain problems. In MYOSYS t h m were maintenance and validation problems and in NEUROP general problems inherent to a shell. i.e. resmctive knowledge representation and no flexible user interface

The discussed environment is based on a deep model that explicitly represents the expert's knowledge. This suppons coherence of the knowledge base, the generation of adequate explanations and an user adapted howledge acquisition interface. The EMG examination is an interactive process that analyses clinical symptoms, suggests and evaluates hypotheses of dysfunctions, proposes suitable protocols and makes conclusions at different levels of absuaction. This reasoning process may be expressed in different smtegies which have to be adapted to the state of the patient's examination and to general circumstances such as limiting factors e.g. medical tnamxnts. To achieve the required flexibility for our system we chose a blackbaard architecmrc for the internal representation. This architecture provides a problem solving mechanism for reasoning simultaneously on several levels of abstraction.

ANALYSIS OF MOTOR UNIT POTENTIAL ACTIVITY USING FOUR-CHANNEL INTWSCULAR RECORDING

Tapani Salmi, M.D and Markku I( Nieminen, M.D. (Lab Clin Neurophysiology, Helsinki University Hospital, Helsinki, Finland)

We have constructed a recording system with four simultaneous intramuacular recording sites to analyze the location of the motor unit potential

system consists of two needle electrodes located 5 mm from each other and supplied with two recording sites situated 5 mm from each other. Thus recording sites are situated in the corners of a tetrahedron.

The signals f r m the four electrodes are digitized by an IBM PC computer and the peaks of the MUPs are identified. In our model the decay of the MUP amplitude is presumed to be exponential and equal to both X and Y directions. Using this exponential model and the area of the simultaneous peaks of MUPs on the four channels, the relative distances of the generators from each corner and thereafter the location of Mups are calculated on the recording plane. Because both the distance and the amplitude of MUP is now known, the relative size (correlating to the nunbar of fibers) of the generator can be calculated. The generators of equal size appearing repeatedly in same location are presented graphically as a map of activated MUPs. This graph simulates the common muscle biopsy.

The quantitative parameters calculated are independent on the diatance between the electrode and MUP. In the recording of normal subjects (tibialis anterior muscle) using the present method we are capable to analyze an area of 10 x 15 nun of muscle tissue.

(MUP) activity within the muscle. The recarding

972 Abstracts: Computerized and Quantitative EMG MUSCLE & NERVE October 1990

PREFERENTIAL GENERATION OF RECURRNT RESPONSES BY GROUPS OF MOTORHEURONES (MNS) IN MAN. CONVENTIONAL F-WAVE (FW) AND SINGLE UNIT F STUDIES.

H Modarres-Sadeghi MD. RJ Guiloff MD (Westminster Hospital, London. UK).

The distribution of conduction velocities (CVs) of 1692 Fw.recorded over

the adductor digiti minimi of 33 normal subjects, with 60 supramaximal stimuli

at the wrist. was shifted towards faster values than expected from the

distribution of CVs in single peripheral nerves.

81 single unit F, recorded with a bipolar needle electrode (BNE) and threshold

stimulation, in 8 subjects. was similarly shifted. F frequency during 200

stimuli correlated with the CV of these units (~0.35, p-0.002). furthet

Supporting preferential generation of F by larger me. The latencies of the

fastest surface single unit M and F potentials associated to the BNE recorded

motor unit6 (MUa), identified in 6 subjects, were similar to those of the

compound muscle action potential and fastest Fw, validating the estimation

of CVs made for hr.

similar to that of voluntary Mus recorded with a spike triggered averaging

technique in a further 8 subjects. Two methods gave a mean of 2.8tad2 MUs per

F wave.

The dietribution Of CVS of

The mean surface F amplitude of BNE recorded MUs was

The higher than expected mean 10% of repeater (rep) Fw shapes. and the

presence of distinct peaks in the distribution of intervals between rep of the

same 6hape. suggest special and heteregeneous functional end anatomical

arrangements for the MNs generating them. The amplitude and area of rep. but

not their CV and duration, were significantly greater than those of "on-rep

(e<O.OOl). suggesting a larger number of component MUs.

PROGNOSIS IN NEURALGIC AMYOTROPHY: A CLINICAL AND NEUROPHYSIOLOGICAL

FOLLOW-UP

Perini M. MD,Mazzalovo E. MD,Zarcane D. MD (Neurological Department,

Gallarate Hospital. I . 1

Neuralgic amyotrophy is a well-defined disorder: pain, weakness and

wasting in rapid progression, localized an the shoulder girdle. maih-

ly an one side.

Clinical prognosis is good with remission within Weeks or months.

Etiology is unknown; clinical findings seem to suggest a viral infection.

The Authors describe Your cases of neuialgic amyotrophy exsmined

clinically and neuraphysiologically ( EMG-SEP ) at the Onset of sym-

ptoms and after one year.

In one patient there was also an asymptomatic pericarditis of suspected

viral etiology.

The EMG at the Onset showed e moderate decrease in motor nerve conduc-

tion and severe denervation of the affected shoulder. The SEP examina-

tion showed altered responses in Erb's derivation (increase in latency

or anomalous morphology).

After one year clinical recovery was excellent with only moderate was-

ting an the affected shoulder. The EMG showed e reinnervation picture

while an anomalous morphology in Erb's derivation persisted.

The discrepancy between clinical end neurophysiologioal findings could

explain some relapses of the disease.

FASCICULATIONS AND VOLLINTARILY ACTIVATED MOTOR UNITS IN MOTOR NEURON DISEASE. A MACRO EMG STUDY.

W Guiloff HD, H Modarres-Sadeghi MU (Westminster Hospital, London, UK)

Each of 22 faaeiculatians (FUe) had a Macro EMG (MAC) potential of similar

amplitude, area and shape to that of a voluntarily activated motor unit (W).

These homologous paire

and muscle penetrations. in 9/10 brachial biceps, out of 200 W s and 211 FUs

sampled in 10 patients.

(VFUs) were always recorded at the same electrode sites

All pus, and PUS not activated voluntarily (n-189), had e higher mean

number of s p i k e s in their triggering single fibre (SF) potential# (p<O.001) but

similar median, and distribution o f . MAC amplitude and area when compared to

all Ws. and to "pure" W s (n-178) and VFUB. respectively. A positive

correlation between fibre density and MAC median amplitude in individuals

(n-10. r-0.79, p-0.01). and between the number of SF spikes and MAC parameters

in the pooled data (n-189, r -0 .34 , p<O.OOI), was found for FUs and FUs not

activated voluntarily respectively. but not for VUs nor "pure" Ws.

vpus in MND may originate near or above the point of axonel branching.

Some FUs that are not activated voluntarily may have a higher number of smaller

muscle fibres, or more closely packed fibres of similar or greater size, than

Ws.

may underlie ectopic impulse generation.

Differences in the peripheral microanatomy of a number of "pure" PUS

IS NOT

Robert W. shields Jr., M.D. (Cleveland Clinic, Cleveland, OH, USA)

A 3 4 year old woman is reported vho developed new symptoms of exercise-induced fatigue and pain in muscles previously weakened by a congenital obstetrical brachial plexus injury. Neurological examination revealed atrophy and partial weakness of all muscle groups in the right upper extremity. Tendon reflexes were absent but sensory function was only mildly impaired. Nerve conduction studies (NCS) disclosed low amplitude median, ulnar, radial, medial antebrachial cutaneous and lateral antebrachial cutaneous sensory responses and low amplitude radial and muaculocutaneous motor responses: median, ulnar and axillary motor NCS were normal. Needle electrode examination revealed decreased interference patterns and increased duration, high amplitude, polyphasic motor unit potentials without fibrillation pOtentialS in all muscles examined. These findings indicate a remote, inactive axonal loss lesion of the brachial plexus. Single fiber ZMG of the extensor digitorurn comunis revealed an increased fiber density of 2.50 (normal <1.65), increased mean jitter of 48.3 uaec MCD (normal <34) , and 30% of potential pairs with increased jitter and/or blocking. The clinical and electrodiagnostic features in this patient are similar to those seen in the post polio syndrome (PPS). This suggests that decompensation of chronically reinnervated motor units may bo a common pathophysiologic mechanism not unique to PPS.

Abstracts: Computerized and Quantitative EMG MUSCLE & NERVE October 1990 973

RELIABILITY OF DIFFERENT TURNS ALGORITHMS FOR M O M R UNIT ACTION POTENTIAL

(MAP) AUALYSIS.

0 . Pfeiffer MU, K. Runze I(D (Department of Neurology. University of Uamburg

FRO).

Turns and phase counts are sensitive 8easurements of the MUAP

co8plexity. Different turns algorithns are used by current computer

programs. We tested their retest-reliability and error possibilities to

decide, which one to use for a multivariate MUAP parameter analysis. The al-

gorith8s were applied to double registrations (VIKING ANOVA) of 420 MAPS

f r m patients with neurogenic and myopathic disorders. Their retest-

reliability was tested by regression analysis. It was best for the Willison

algorith8 (R Square 0.85) with 25 micro V linit as collpared to algorithms

based on limits of a8plitude differences between successive peaks (R-Square

0.77 or 0.71 if succeeding peaks had to be of different polarity) and it was

superior to phase count measures (R-square 0 . 1 8 ) . The absolute turns value

was clearly influenced by the algorithm used (slope of the regression line

up to 1.2; different fro8 1 with p<O,Ol). The different turns 8easures cor-

related well with each other (R-square between 0.88 and 0.91) but the corre-

lation with the phase count was lor (R-square 0.60). The Ilillison turn count

with an amplitude limit of 25 microv and the phase count are entered into a

multivariate analysis as reliable and partly uncorrelated MAP parameters.

AN EMG EXPERT SYSTEV (luwoID) TESTED AT DIFFERENT EMG LABORATORIES.

A. FuglsBng-FTedeTikSen'. S. Vingtoft**, J. RBnager', J. Petrera (Denmark), P. Fawcett, I. Scoufield, R.G. willison, J.A. Jarratt (United Kingdom), G. Otte, G. Sieben (Belgium), A. Vila (France), 8. Stigsby (Saudi Arabia). (*Department of clinical neurophysiology, Hvidovre Hospital. University of Copenhagen and '*CRI. BirkerLd, Denmarkl.

The rule-based Expert System W I D is a knowledge-baaed assistant for

neuromuscular disorder aiagnosing, which performs an iterative plan-test-diag-

nose cycle during the EMG examination. A version implemented on a PC in prolog

has been tested by nine clinical neurophysiologists at seven laboratories in

five countries; none were involved in the development. In all 157 patients in-

cluding 1177 test structures were examined. In average 28% of the time for a

patient examination was used for handling of KANDID. Using the examiners own

scores of agreement with KANDID on individual patient cases the clinical neu-

rophysiologists agreed (score 4 and 5 out of 51 with the KANDID diagnose in

53% of 143 patients. Diagnostic agreement was highest for entrapments and

lowest for anterior horn cell disorders. Many of the cases with disagreement

between examiner and KANDID were patients with multiple disorders. There was

an interesting variation from country to country in diagnostic agreement from

30%-50% in United Kingdom to 60%-77% in Denmark and Belgium. This variation

probably reflects differences in planning Strategy and control material. User

editors for adaption of the knowledge-base can increase the agreement. The

evaluation proved that an EMG Expert system implemented on a PC can be used

at different EMG laboratories. Eight experts felt that KANDID would also prove

to be a valuable teaching tool.

SAMPLING FREQUENCY mR TURNS-AMPLITUDE ANALYSIS.

A. Rlglsang-Frederiksen, S.A. JBrgensen. T. Bbge-Rasmus=en.(Department of clinical neurophysiology, Hvidovre Hospital, University of Copenhagen).

For the turns-amplitude analysis of the interference EMG pattern a too

low sampling frequency may result in a decrease in the number of turns. We have

examined the influence of the sampling frequency from 6 kHz to 200 kHe on the

turns-amplitude analysis in ten sites of the brachial biceps muscle in each of

five control subjects, five patients with myopathy and five patients with neu-

rogenic disorders. Sampling frequencies down to 17 kHz gives proper reproduce-

bility of turns, mean amplitude and ratio of turns to mean amplitude but requi-

res comparison to normal values specific for the sampling frequency. The syste-

matic errors were less than 2% down to a sampling frequency of 26 kHz which is

negligible compared to the variation from site to site within the muscle. The

results are therefore comparable to normal material obtained at or above 26 kHz.

For time intervals between turns (not studied here) a higher sampling frequency

is probably required.

In a pilot Study analysis time from 50 msec to 1000 msec and l o w pass fil-

ters from one kHz to 10 kHz of the turns-amplitude analysis were examined in

one site in each of five control, five myopathic and five neurogenic muscles.

The results suggested that reproduceable values may be obtained with an analy-

sis time down to 100-200 msec and with a low pass filter down to approximately

3 kHz.

SINGLE FIBER EMG IN HEMIPLEGIA

P.Girlandd MD, C.Nimlosi MD. C.Venuto MD, R.Mangiapane MD, C.Messina MD

(Institute of neurological and neurosurgical sciences - University of Messina Italy)

Pathogenesis of muscle atrophy in hemiplegia remain6 unclear.

We performed SFEMG in patients suffering from after-stroke hemiparesis.

No subject showed clinical signs of peripheral neumpathy or was affected by

disease that could induce damage of peripheral nervous system as diabetes,

uremia or collageno-vascular diseases. The dwation of hemiparesis ranged

from 1 month to 6 years. SFEMG investigation was carried out usually on

extensor digitorum cownunis (EDC) muscle of both paretic and unaffected

sides. In each examination 20 pairs of single fiber potentials were recorded

to calculate the mean jitter value and'the percentage of recordings with

abnormally increased jitter. Fiber density was also evaluated.

In patients with short-lived hemiparesis no significant difference in

SFEMG parameters between paretic and unaffected sides was present. In

patients with longer-lasting hemiparesis a significant increase of jitter and

fiber density occurred on the paretic side. Jitter resulted above normal

liMits also in recordings from patients who had underwent stroke 1 year

previously.

Data aveilable at this moment suggest that a denervation-reinnervation

process occurs in hemiparetic muscle. Further knowledge mainly about the

timing of this phenomenon would arise from the follow-up study in single

patients.


eXTRACELUlURRECORDINGSeEELECTRTCALmmDWERVATEDBhTMISELES

Willeiien Wallinga, F'hD, Ab Evenhuis, MS, Johan Put, Vet.D.. Bcnno van Veen,

MS (BioMedical Engineering Division, Department of Electrical Engineering.

University of Tvente. P.O. BOX 217, 7500 AE Enschhade, NL)

In fibres of skeletal muscles of animals the resting membrane potential

shifts towards less negative values (shift about 15 mV) within seven days

(e .g . Kotsiao and Muchnik, 1987). Intracdlula= action potentlds appear to be

slower than normal (same ref.). There are no extracellular recordings of

activity with needle or wire electrodes in animal research available in

contrast with a lot of data in clinical practice. We aim to study quantita-

tively extracellular activity (both spontaneous end intracellularly evoked) in

relation with the time of denervation.

In 7 and 10 days denervated m. EDL in the hindleg of the rat we found

elear changes in the single fibre action potentials recorded with 25 #m

isolated wires with a blank tip with respect to the normally innervated

situation. In the dsnervetsd muscles, the amplitudes of the SFAP's tend to be

lower; the time between the first positive peak end the second negative peak

is longer up t o II factor two in the 7 days denervatad muscles; the change in

this time is lass pronounced in ten days danervaced muaclas.

B.A. Kotsias and S . Muchnik, Mechanical and electrical properties of

denervated rat skeletal miscle, Exp. Neural. 9 7 . 1987. 516-528.

REPETITIVE NERVE STIMULATION OF THE ANCONEUS MUSCLE

Kennett R.P. M), Fawcett P.R.W. FRCP (Newcastle General Hospital,

Newcastle upon Tyne, UK).

Repetitive nerve stirnuletion (RNS) studies have an established role in

the investigation of patients with disorders of neuromuscdlar transmission.

Proximal muscles are more sensitive than distal, but sre subject to

technical artefact. To overcome these difficulties we have performed RNS

on the radially innervated enconeus muscle. In controls, the anconeus

compound action ,.ritential has a mean amplitude of 14.5 * 5.ZmV; during 3Hr

trains, the mean 5th/lst response was 102.7 t 2.0% and inmediately

following 20s activation the mean amplitude of the 1st response / 1st at

rest was 104.6 t 8 8 . G .

In patients with generalised myasthenia gravis (MG) a eignificant

decrement ( > 10%) in anconeus was seen in 561, the mean decrement for ~ l l

patients being 25.2 t 33.3%. The decrement in anconeus was similar to that

in deltoid but significantly greater than in abductor digiti minimi.

Compared with single fibre EMG jitter in extensor digitorum comunis,

about 20% o f pairs may show blocking and OD% show increased jitter before a

significant decrement occurs in anconeus. SF EHG jitter measurement is

therefore more sensitive, but RNS on anconeus is a useful and technically

reliable screening test for defective neuromuscular transmission.

-L SFEMG STUDIES IN POST-F€IUO SYND ROME

V. Bril. MD'. R Goldstein, MD, P. L v n h MD. T. Dolmaae, J. Tokar. MD. KIN 'versitv of Toronto, Toronto, C anadal

Electromyographic abnormalities are known to persist long after acute

poliomyelitis. Although these patients often complain of progressive

weakness, fatigue and disability, objective investigation usually fails to

demonstrate significant change in either clinical or electromyographic status.

We used serial single fiber eleammyography (SFEMG) in 79 subjects with

remote poliomyelitis in an effort to document electrophysiological

deterioraton corresponding to clinical complaints. Thirty-four men and 45

women were tested in either the extensor digitorum cummunis (EDC), or the

tibialis anterior CCA) muscle. Forty-two patients complained of progression

(mean 45.8Y), whereas 9 were stable. The mean age was 51.3Y with a polio age

of 10.4Y, and a post-polio interval of 35.6Y. Examination of 30 E X ' S and 49

TAs was done at 0,12 and 2411.

The fiber density decreased in both EDC and TA in progressive patients, but

remained stable in non-progressive subjects. The jitter remained stable in

both groups. The progressive group tended to have a higher mean jitter than

non-progressive patients in the EDC . This difference was not observed in the

TA. In conclusion, patients with symptomatic progression following remote

polio show SFEMG differences from those who are dinidly stable.

EFFECT OF FREQUENCY ON AXONAL STIMULATION JITTER VALUES IN MYASTHENIC

DISORMRS

Kennett R.P. M), Fswcett P.R.W. FRCP, (Newcastle General Hospital,

Newcastle upon Tyne, UrC)

The axonal stimulation method has been used to assess rate dependancy

of jitter at single neuromuscular junctions in various myasthenic

conditions.

Studies were performed on extensor digitorum comunis using a

monopolar stimulatinq electrode inserted near the motor end-plate zone and

recordings were made with a SFEMG electrode situated 1-2 cm distally.

Single muscle fibre action potentials were identified st a stimulatmn rate

of 3Hz and jitter was measured both 'on ' and 'off-line' after storage on

magnetic tape. Stimulation rates of 1, 3, 5, 10 and 2OHz were employed.

In controls, jitter did not change significantly over this range of

frequencies. In patients with ganeralised myasthenia gravis, jitter values

w e r ~ lowest at 1 and ZOHz, with higher vnlues at intermediate frequencies.

In Lambert-Eston myasthenic syndrome, potentials often could only be

obtained at rstes of 1OHz and above. In two patients with congenital

myasthenia jitter WBB lowest at 1 and 20Hz (similar to MG) while in another

case, potentials either followed the pettern of MG or of LEHS.

findings were interprcted aa showing both prs and post-synaptic

abnormalities in this patient.

The


R EMG EV- O F CENTRAL

Joe F. Jabre, M.D. and James Rainville, M.D., Boston University VAMC Boston, MA

Using single fiber EMG studies of the H-Reflex and M-Wave in the Flexor Carpi Radialis muscle, we were able to study the central monosynaptic transmission between a I s fiber and an anterior horn cell. The Jitter of the H-Reflex and that of the M-Wave are obtained and their difference calculated. This difference gives an estimate of central monosynaptic transmission. Our study was performed in 15 subjects aged 19-41 years in the Flexor Carpi Radialis muscle using the technique described by Jabre and Stdlberg in 1980. The central Jitter is a combination of the variability in central monosynaptic transmission and that of the anterior horn cell depolarization threshold, itself a function of the excitatory and inhibitory actions of the intemeusons with synaptic connections to that anterior horn cell. The study of central monosynaptic transmission provides an avenue for the investigation of the action of certain drugs used in the treatment of spasticity as well as in the study of disorders involving descending or ascending spinal pathways which affect the depolarization threshold of the anterior horn cell.

NERVE CONDUCTION STUDIES I N JAPANESE AND SWEDISH SUBJECTS

Kimiyoshi Arimura, M.D.' , E r i k S t s l b e r g , M.D., Yumiko Arimura,

M.D., Shunnichi Sakoda, M.D., Shuugo Suwazono, M . D . , Hidehi to

Imamura, M.D. (Kagoshima Univers i ty ' , Kagoshima, Japan)

Nerve conduction s t u d i e s have been established a s a n

important examination f o r d i a g n o s i s of neuromuscular d i s o r d e r s .

Unfortunately t h e methods of nerve conduction s t u d i e s and t h e

a lgor i thms f o r measurement of parameters a r e not i d e n t i c a l among

t h e d i f f e r e n t l a b o r a t o r i e s . For t h e s e reasons , t h e r e a r e no

reports about t h e d i f f e r e n c e s of t h e nerve conduction s t u d i e s

among t h e d i f f e r e n t races . We performed t h e nerve conduction

s t u d i e s i n Japanese s u b j e c t s wi thout neuro logica l symptoms by t h e

same method ( K U S I N method) which is a t p r e s e n t be ing used a t

Uppsala Univers i ty . Measurements w e r e performed w i t h t h e SES

program which has been developed a t Uppsala Univers i ty . The

c o l l e c t i o n s of normative d a t a a r e compared wi th t h e d a t a

c o l l e c t e d a t Uppsala Univers i ty us ing t h e same method and

algorithm. The d i f f e r e n c e i n nerve conduction s t u d i e s between

both r a c e s w i l l be presented .

IHE USE OF (MRV) TO EXPEES

Joe F. labre, M.D. and Luke Sato, M.D., Boston University VAMC Boston. MA

In Nerve Conduction Studies, Normal Values are usually expressed in ranges of minimum and maximum. Results which fall within this range are considered normal. We report a I<,chnique :v!iich t-\;rrq-t'. IhL, rc.iultc electrophysiological data as they relate to the Mean and Standard Deviation of the Normal Values. Implicit in this is that the distribution and coefficient of variance of these Normal Values are taken into account and statistically treated if necessary before determining this Mean. The result is a Mean Related Value (MRV) expression of the electrophysiological data calculated by subtracting the raw value from the Mean and dividing the difference by the Standard Deviation as follows. MRV= (x - M)/SD. The technique was developed using a Macintosh SE personal computer and Hypercard software, both from Apple Computer, and a commercially available Spreadsheet (Microsoft Excel"9. The computer allows for immediate generation of the MRVs as well as for the plotting and further data manipulation as needed by the electromyographer. The expression of data as MRV offers several advantages: It eliminates the need to report normal values; It enhances diagnostic sensitivity; It makes it easier to compare with follow-up studies; It permits the generation of '"profiles" of neurophysiological disorders and makes it possible to "grade" degrees of severity

RULE BASED EXPERT SYSTEM I N CLINICAL NEVROPHYSIOLOGY

Kimiyoshi Arimura, M . D . l , E r i k S t a l b e r g , 1.0.. Mats Melander Eng,

Hi roaki Otose, M.D. (Kagoshima Univers i ty ' , Kagoshima, Japan)

C l i n i c a l neurophysiology lends i t s e l f w e l l a s a test bench

€or e x p e r t s y s t e m s . The d i a g n o s t i c r u l e s of i n t e r p r e t a t i o n about

v a r i o u s neurophys io logica l i n v e s t i g a t i o n s a r e r e l a t i v e l y

s tandard ized . We have a p p l i e d a system c a l l e d SMR (Simulation of

Medical Reasoning) , which was developed a t Uppsala Univers i ty ,

BMSA, a s a genera l purpose s h e l l f o r t h e e x p e r t system. This

system n o t on ly enables one t o draw f i n a l conclus ions b u t may

a l s o provide informat ion about t h e r u l e s and f u r t h e r examinations

t h a t can be appl ied . I n t h e p r e s e n t s tudy , w e have chosen a

r e s t r i c t e d a r e a of c l i n i c a l neurophysiology, t h e most common

d i a g n o s i s i n an EMG, c a r p a l t u n n e l syndrome(CTS) and added a

number of other diagnosed t h a t may be p o s s i b l e a l t e r n a t i v e s i n

p a t i e n t s r e f e r r e d for CTS. We compared t h e r e s u l t s between t h e

neurophys io logica l d i a g n o s i s by EMG e x p e r t s and SMR d iagnos is i n

f i f t y c a s e s f o r de te rmining t h e u s e f u l n e s s of t h i s system.

Furthermore w e made another A 1 program cons t ruc ted by t h e Baysian

theorem. T h e d i f f e r e n c e s of e f f i c a c y between these two systems

w i l l be d iscussed .


TEMPERATURE EFFECTS ON MOTOR NERVE CONDUCTION STUDIES

Ken Sonoda, M.D.' , Teruto Rashiguchi, M.D., Asutsuqu Kurono, M.D.,

Riroshi Komura, PhD, Koichiro Yonemitsu, PhD, Shinichi Kawada,

PhD, Kimiyoshi Arimura, M.D., Erik Stblberq, M.D.

(Kaqoshima Medical Association Hospital', Kaqoshima, Japan)

The effects of the temperature on nerve conduction

velocities have been discussed by many authors, however, there

are few reports concerning the effects of temperature on compound

muscle action potential (CMAP). We studied the correlations

between the temperature and CV, DL, CMAP measured by surface

electrodes simultaneously. The temperatures of the surface and

deep tissue (lcm depth1 were measured by a deep-body thermometer.

The principle results of our study are as follows.

1) MCVs are positively correlated with temperatures. 2 ) DLs are

negatively correlated with temperatures. 3 ) Durations and areas

of the negative component of CMAP are increased with decreasing

temperatures. 4) Amplitudes of the negative component of CMAP

are slightly increased with decreasing temperatures. 5 ) These

results are more correlated with deep temperatures than surface

temperatures.

Our results suqgest that the effects of the temperature on

nerve conduction studies are important for standardization of

measurement of CMAP.

QUANTITATIVE ANALYSIS OF THE MOTOR UNIT ACTION POTENTIAL CIIMEXITY

Zalewska Ewa PhO, Hausnanowa-Petrusewicz Irma H),prof. (Neurmscular hit

Pol. Ac. Sci., Oepartnent of Neurology Md. School, Warsaw, Poland)

The mtor unit action potential (MAP) recorded by a needle electrode is

a result of teworal and spatial sunmation of action potentials of muscle

fibers. The WAP wave form depends on the motor unit architecture. Disease

p m s S e 9 change the spatial distribution and activity of muscle fibers. This

is manifested as changes of the WAP wave form. Particularly, the wave form

may becm w l e x i.e. it contains sure separate conponents.

In rcutine analysis the carplexity of signal can be described only by

one paraneter - the nwnber of satellites. This parmter is insufficient hence

w) try ta elaborate a mthod suitable for quantitative analysis. In this

nethod the following parameters are considered: duration of interaignal,

duration of signal, maxinun arplitude P-p. signal power, nulnber of phases in

each signal ccmcment.

These paramters are calculated in absolute values and relative to

the whole signal and its main cmwonent. Such parmters scaled by

appropriate weights determine a coefficient describing the carplexity of

signal. The dependame of this coefficient on various types of potentials in

various neuro-nuscular disorders is discussed.

Effi-LAB COMPUTER SYSTEM

J. Kopeb, P. Kalinowska, A. Wawco, R. Wyszmirski

Oepartmt of Neurology Medical School, 02-097 Warsaw, Poland

System EMG-LAB is unique canbination of hardware and software enables powerful and user-friendly automatic analysis of cwlex EM3

examinations. The system consists of IBM PC mode AT equipped with special interface of 2-chnmel AN Mnverters. It allows the use of different Effi equipnants, for acquisition and analysis functions with simultanaws color graphics display. Malysis software imludes 2-main programs (Main Menu) divided into 10-vmrking program (Subnenus). In hard disk memory. normal values will be stored and used for proper classification of obtained results. Dccwnentation is printed as graphs and numericals tables in two documents. One short with final cmlusion for clinical use, and second as cmlite sets of data for evidence and father statistical analysis.

h . EMG-divided into I-programs based on our own (ANOPS) analysis. 6. Nerve conduction - divided into 7 different program.

Main Menu

C.S. Pattichis, MSc., C.N. Schizas, Ph.D., K. Lazarou, L.T. Middleton. M.D., and W.F. Fincham, Ph.D. (MDRTC Neuromuccular Unit, Mokcuios HospdaI, Nicosia, Cypw)

Recent advances in quantitative electromycgraphy (EMG) have demonstrated the Importance of quantification in the neurophysiological diagnosis of neuromuscular diseases. Mificial neural networks (ANN) constructed to resemble some simple organisational principles of the human brain were considered as possible candidates for handling the processing and classification of EMG data.

Learning in ANN models is accomplished through systematic training with known data. ANN learning is classified into Supervised and UnSUpeNiSed. In supervised learning the training data is supplied at the input and the generatad output is compared with the desired output; the error diference is used for modifying the ANN connections until learning is accomplished. For supervised learning the back-propagation training algorihm was implemented (Rumelhan et al. 1986).

in unsupervised learning. data is presented sequentially at the input without specifying the desired output. These models are capable of self organisation; thus, topologically close output nodes become sensitive to physically similar inputs. Self-orgenised feature maps (Kohonen, 1984) have been used for unsupervised learning.

Resub from the above two types of ANNs have been compared and will be discussed.


ELECTRICAL AND MECHANICAL PROPERTIES OF REINNERVATED MOTOR UNIT IN ANTERIOR HORN CELL DISEASES AND PERIPHERAL NERVE LESIONS:

Thomas Vogt, M.D. Bernd Pfe ifer, M.D. and Wilfred A. Nix, M.D.

(Dept. of Neurology, University Clinics, Malnz, Germany)

18 Patients w i t h anterior horn cell diseases (ALS, SMA) and radicular or ulnar lesions were examined w i t h a combination of MACRO EMG and Spike Triggered Averaging. Amplitude and area of macro potentials and their corresponding twitchforce and contraction speed were measured. Normal values, that had been established w i t h thls method recently demonstrated that w i t h Increasing threshold, the force of single units enlarged exponentially compared t o their emg. ( 1 )

The correlation of electrical activity and twitch force Is disturbed in reinnervating processes, where anterior horn cell diseases and peripheral nerve lesions show different behavior. In ulnar lesions, the

increase of force is larger compared to the emg. in ALS. large emg signals are often associated with small twitch forces. Different sprouting capacity and reorganisation pattern as wel l as increased interstitiell fibrosis in ALS patients may explain this disso- ciation of muscle force and electrical activity.

Vogt et. al: Relationship between electrical and mechanical properties of single motor units in man. J Neurol Neurosurg Psychiatr 1990

In Press

JllTER IN THE NEURAPWIC MOTOR UNIT

Adnan J. Khuraibet. DSc (Ibn Sina Hospital, Kuwait) and Jote V. Trontelj, D.Sc. (University Institute of Clinical Neurophysiology.

University Medical Centre of Ljubljana, Yugoslavia)

Axonal microstimulation was used to study jitter in paralyzed orbicularis oculi

muscle of 13 patients with Bell’s palsy 620 days after the onset. A total of 296 motor

end-plates were compared to 517 motor end-plates from normal subjects. The jitter

values did not differ significantly between both groups (mean MCD was 13.0 and 12.4

ps, respectively) although a small proportion of neurapraxic end-plates showed clearly

abnormal jitter, Some with blocking (4.7% compared to 1 .% in the normal material). On

the other hand, some patients tended to have an unusually high proportion of end-

plates with small Jmer between 4 and 8ps (over one-half in three patients).

Nineteen orbicularis ocuii motor end-plates of two patients with Bell’s palsy as

well as 44 eXtenSor digitorum communis motor end-plates of two patients with Saturday

night palsy were studied over a range of stimulation frequencies. The rate-dependent

jitter changes were essentially similar to those in normal subjects. showing that

neurapraxic terminals are capable of tetanic potentiation. This also applies to the end-

plates with abnormally large per.

SiNW FIBER FO LLOW-UP S N O Y IN PATfENTSTREATEDNU M-T OXIN. ‘ T w INMWCLES DISTANTTO THE INJECTION S J E

CG Garner MD, A Svaube MD. ThN wnt MD. T Gasser MD. W Oertd MD (Deparlinent of Neurdcgy LudwiQ Maximlltans UnV6fdIy Munlch FRO)

In 1978 Schlller and Stalbwrg Rrsl shoed. that Increased litter and blccklng occur In human

botulism. Sanders B( al. found the same effecl In patlents treated v&h botullnum toxin (h]. Jmer was

Increased in musdes c l w to the Injecllon ske but also In dlstant muscles. lnvestlgatlons wncernlng

the time courss and the onset ol the Jmer In remole muscles are mbsing. We therefore lnvestlgated the

extensor dlgkorum communls muscle in nine pationts before and repeeledly aner (up to two month )

therapeutic bb: Injenion restrktod to the neck and head regions.

8 of the 9 patlents showed variable Increase of lmer and in some mses also of fiber density.

Mean MCD before Injection was 27.3 us (SD 3.04 us). aftof appllcatlon 55.2 u8 (SD 37 us). F I N densky

Increased from 1.37 upto 1.73 after lnjenkm of bb: In the 4 patlents studled for this parameter. In a11

patients m e @ the one mentioned above blocking of flbers In varylng degree could be obsewed. The

liiter became pathdcgic behueen day 3 and 14. There was no mnaletlon between dosage and increase

of jmer. However. there was a posklve cofroiallon t+tnwn the Increaw of Iltter and cllnlcsl effecl or the

occurrence of Me-eftects.

These results plnt toward a distant effect starting about 5 days after Injection of btx. which

may be e x p l a l d by collateral sprouting. The sensitivii of the patients 10 the toxin. howover, seems to

be lndlvklually determined.

THE JllTER OF STIMULATION SITE ON THE MOTOR AXON

Dr. J.V. Trontelj. Dr. M. Mihelin (University Institute of Clinical Neurophysiology. Ljubljana, Yugoslavia),

Dr. E. Stallberg (Univ. Dept. Clinical Neurophysiology, Uppsaia. Sweden). Dr. A.J. Khuraibet (Ibn Sina Hospital, Kuwait)

The j i e r of the motor end-plate is increasingly more often studied during axonal

micro-stimulation. This technique has the advantage of being often more accurate. as it

avoids errors due to interdischarge interval-dependent muscle fibre propagation

velocity changes. as well as unrecognized spM muscle fibres. There has however been

a concern whether jitter may also be generated at the stimulated site on the axon,

especially with liminal stimulus strength.

In this study, near-liminal stimulation resuited in a small additional jmer. less than

5 ps in the average, ranging between 0 and 13 ps. However. liminal stimulation with

intermittent false blocking tended to produce much larger additional jitter, 40 ps in the

average (range 2 to 175ps). The jitter increase in this case was strongly correlated to

response latency. It is considered to reflect changes in muscle fibre propagation

velocity due to disrupted rhythmicity of activation with intermittent false blocking, and

depends on the length of the muscle fibre segment between its motor end-plate and the

recording SFEMG electrode as well as on the strength of the velocity recovery function

of that fibre.


NONLINEAR SVW&%XON OF S V B S ~ I O U S OF nwscm TWITCUES IN NOW

AND PATIENTS WITS NYOTONI C DYSTROPRY

Dillmann Ulr ich , H . D . ; Wilfr ed A. Nix, H . D . ; Gunther Kramer,

M.D.: Hanns C. Hopf H.D. (Department of Neurology, University

C l i n i c s , na inz , Germany)

I sometr ic twi tches of t h e adductor p o l l i c i s muscle following supramaximal u l n a r nerve s t imula t ion were investigated i n normals and p a t i e n t s with myotonic dystrophy. S i n g l e s t i m u l i and stimulus p a i r s (2-180ms i n t e r v a l s ) were used. Addi t iona l ly , we r e g i s t e r e d t h e absolu te r e f r a c t o r y period of muscle t w i t c h e s us ing interstimuluq i n t e r v a l s (ISI) bdtween 0 . 4

and 3 ms. W e computed electromechanical delay, maximal c o n t r a c t i o n v e l o c i t y (nCV), time of HCV (TnCV), cont rac t ion time (CT) , CT-TWCV, h a l f re laxa t ion time, maximal re laxa t ion ve loc i ty (KRV) and time of MRV and maximal twi tch f o r c e (WF). Linear or nonl inear summation of t h e subsec t ions of t h e twi tch was c a l c u l a t e d by comparing the measured parameters with t h e parameters of a curve achieved by summation of two s i n g l e t w i t c h e s regarding t h e respec t ive s t imulus i n t e r v a l . Absolute r e f r a c t o r y period was shortened i n myotonic dystrophy. In normals, CT comprises two d i f f d r e n t subsec t ions : TMCV and CT- TMCV. nF sumes more than l i n e a r with a maximum a t 1 2 m s ISI, which co inc ides wi th t h a t of t h e more than l i n e a r summation O f

CT-TnCV, whereas TnCV sumes l e s s than l i n e a r . In myotonic dystrophy, t h e r e is a s i g n i f i c a n t higher p o t e n t i a t i o n of KF, whereas CT-TnCV is s i g n i f i c a n t l y s h o r t e r a s compared t o normals. No d i f f e r e n c e s v e r e found comparing TPICV.

ESTIKCTICN OF MOTOR UNITS I N THR EXTENSOR DIGITCRLM BBEVIS

Paul E. Barkhaus, M.D.. D a n a C. Daly, B.S. (Minneapolis Vaterana Administration Medical Canter. ~ inneapo l l s . NN)

Estimation of number of motor units (Fwu) wae performsd i n the

extensor d i g i t o m brevis muscle (EDB) of 24 healthy volunteer subjects

(age range 22-89 years, mean 51 years). The Fwu was derived by dividing

the peak-peak mplitud. of the evoked surface-recorded compound muscls

act ion potential (PPCHILP) by the man peak-peak amplitude of individual

surface-recorded motor unit action potentials (SRwAps).

individual motor units (MIS) were recorded by spike-triggered averaging

w i t h an Intramuscular electrode. In most cases at least 1 5 SRXUAPa were

recorded in each subject and anslyzed o f f - l i ne wing conputer-assisted

methob.

The S W A P S of

Increased age was strongly correlated with decreased P P W P

(r-0.75) and Fwu (r-0.75).

S W A P amplitude which probably reflects sampling technique. Hence

decreased Fwu w i t h increased age appears related t o lower amplitude

PPCUAF's rather than changes in mean S W A P amplitude. T%E mean ElRT

based on S W A P amplitude for a l l ages w a s 37 (sd-15.6); the mean fo r

ages <60 was 48 (sd-9.7, range 25-63) and for ages >59 the mean vas 23

(sd-9.1, range 5-37).

percent difference between repeat Fwu measursnents was 4.9: (sd-4.4).

Age was not correlated (r-0.09) w i t h mean

Repeat EHU was performed i n 6 studies. The mean

COMPUTER-AIDED MEASUREMENT OF MUSCLE COORDINATION AFTER NERVE REPAIR I N M I C E

A. Kreischer, MD, M. Wasserschaff Em D. Kleinebeckel, PhD ( I n s t i t u t fur Neurophysiologie, un i ve r i i t i i t zu Koln, 0-5000 Koln 41, FRG)

After peripheral nerve repai r loss of muscle coordination i s mainly a t t r ibuted

to reinnervation of muscle by inappropriate anter ior horn motoneurons (Wasser-

schaff, M., Brain Res., i n press, 1990). Subject of the present study was an

objective computer-aided measurement o f reestablished p s c l e coordination.

The r i g h t c0RIK)n peroneal nerve was sectioned i n 6 mice. 14 weeks l a te r

EMG a c t i v i t y was recorded from the reinnervated t i b i a l i s anterior (TA) and the

medial gastrocnemius muscle (MG) simultaneously during f ree running. The E R

patterns were d ig i t a l i zed and the TA signal was integrated by a PC, the area

serving as a ra te o f muscle ac t i v i t y . The quotient of the integrated areas

o f phase I o f TA a c t i v i t y (poor e lec t r i ca l a c t i v i t y i n normal mice) and

phase I 1 ( f u l l r ec ru i tmn t pattern o f TA i n normal mice) of several step

cycles was cal led coordination factor. The beginning and end of each phase

were determined by the antagonistic R ac t i v i t y .

The coordination factor varied from 0.1 t o 1.96 between the individuals,

ind icat ing great v a r i a b i l i t y o f antagonistic coactivation. I n contrast t o

these f indings values between 0.03 and 0.27 were found i n 5 normal mice.

The coordination factor can be used as an objective ind icator f o r the

degree o f muscle coordination and consequently for the amount of inappropriate

muscle innervation.

m~OMIJSCuL*R D B W E B S IN P A T ~ S wm S C O L I ~ I C DEPOUITY 03 THE SPINE.

'Patyana A. Yakovleva, P.D., ( Dept. of Dleurology

and Neuropbysiology, Chi ldren Orthopaedic I n s t i t u t e , €4-68 Par- kovsya a t r . , Pushkin, Leningrad, US=, 189620).

The s t u d y deals with problem of pathogenes is of biomechsni- cal a b n o r m a l i t i e s of the spine in p a t i e n t s w i t h i d e o p a t h i c s c o l i - osis and a c u t e r a d i c u l i t i e s . E lec t romiogrephic techniques of re- c o r d i n p mom EMS, nerve conduction v e l o s i t y , =-reflex, somato- s e n s o r y evoked p o t e n t i a l s , tonic v i b r a t o r y reflex were used.

of tendon reflex, H-reflex, depress ion of a f f e r e n t (P ) and spi- n a l (NI4) components of evoked p o t e n t i a l s , tonic v i b r a t o r y reflex was decreased and f r e q u e n t l y was a b s e n t on the a i d e of sphe

curvature. The main r o l e in pa thogenes is of p r o g r e s s i v e i d e o p a t i o a c o l i o s i s in children belong t o d i s f u u c t i o n of gamma-motoneurones. Zhe alteration of motoneusones exc i tement and s o o l i o t i c deformity are secondary processes.

It was found that patients w i t h a c u t e r a d i c u l i t i e s have apontaneously a c t i v i t y , w c r o had special groups of p o t e n t i - als. A11 components of evoked p o t e n t i a l s were modificated. but DOE e x p r e s s i v e a l t e r a t i o n had e a r l y components (P,N3,g) on the sSde of curva ture . S c o l i o t i c rad icu lopa thy deformity was accompa- n i e d by decreas ion of a f f e r e n t nerve conduction v e l o s i t y . aaymmet- r y of H-reflex, modi f ica t ion of s p i n a l braldng, t e s t i n g by H-reflex. Usualy t o n i c v i b b a t o r y reflex was without cmge. &pression of EMG a l t e r a t i o n was g r e a t e r t h a n c l i n i c a l d e f e c t s . CNS took pa^ in f o r n a t i o n of sensory d e f i c i t and or thopaedic deformity of t h e sp ine .

I n c h i l d r e n w i t h p r o g r e s s i v e s c o l i o s i e we r e v e a l e d asymnetqy

9


Wilfred A. Nix, H.D, Bernd Pfeifer, H.D. and Thomas Vow, M.D., (Dept. of Neurology, University Clinics, Mainz, Germany)

Motor paresis or plegia is often the sequel of cerebrovascular accidents. It is of interest to knom in h n far lacking or reduced volitional control affects individual motor units. Until recently S F W studiea depended On voluntary innervation. In paretic muscles S F W disclosed some neuronus- cular instability and reorganisation of the motor unit as seen by an increased fiber density.

We studied in muscles xith stroke induced pnresis or plegia motor unit function at various times after the vascular accident ( 4 weeks up to 6

years). The group studied bad no clinical or electrophysiologicel signs of peripheral nervous system disorder. Motor units under volitional control were studied for twitch time combined with Macro-WG and for jitter measurements with S w . In plegic muscle fibers sthulared SPBHG and the mean jitter value calculated from 20 endplates.

VBS used

Muscle fibers under volitional control had moderately increased jitters. fiber density and Macro-= values. Twitch t h e was normal. forces were decreased. Fibers lacking voluntary control only seldom showed neuronus- cullrr instability. Residual functioning motor units seem to undergo con- stant remodelling. Tranasylllptic degeneration at the spinal card level or inappropriate trophic demands of the enlarging motor unit may play a role.

TURNS-AMPLITUDE ANALYSIS WITHOUT FORCE MEASUREMENT : PEAK- RATIO , MEAN AMPLITUDE AND TIME INTERV ALS. R.Liguori, K.Dah an A.Fu? sang-Fre eri sen Ri shospitalet and Mvidovre Hospita:, U:iversi:y of Cop%haien,(DKy.

A previous study suggested the peak-ratio of the EMG interference oattern to be a sensitive Darameter in diae- nosing of nekomuscular disorders. The peak-ratio defined- as the highest value of the ratio of turns to mean amplitude can be obtained without force measurement by using the mean amplitude as an indication of the force. The electrical activity was sampled during an increase in force from zero to maximum in ten sites of each muscle. The peak-ratio, mean amplitude and time intervals between turns, at the peak-ratio, were analysed on line at the site of the examination. The highest mean amplitude contained in the interference pattern was also analysed on line. To evaluate the sensitivity of this technique the results were compared to manual analysis of individual motor unit potentials. Twentytwo patients with myopathy and 20 patients with neurogenic disorders were examined in the brachial biceps muscle. The peak-ratio was increased in 86% of patients with myopathy and decreased in 85% of patients wiFh neurogenic disorders. The mean amplitude was decreased in 41% of patients with myopathy and increased in ?5% of patients with neurogenic disorders. The number of time intervals between zero and 1,5 msec was increased in 86% of patients with myopathy and reduced in 60% of patients with neurogenic disorders. All patients were diagnosed correctly when the three findings were combined. Analysis of individual, motor unit potentials indicated the Forrect diagnosis in 68% of patients with myopathy and in all patients with neurogenic disorders.

Bernd Pfeifer, M.D., Wilfred A. Nix, M.D., Sabine Pischer, M.D. and Hans H. Goebel', M.D. (Dept of Neurology and Neuropathology, university Clinics, Hainz, Germany)

The macro-BMG potential represents the compound action potential of all muscle fibers contained in a motor unit. In chronic neurogenic processes motor unit size increases, but decreases in primary myopathies. Accordingly there is an increase or decrease in macro-MG potential size.

In 17 patients with different myopathic and neurogenic disorders and in two normal controls the biceps brachii muscle was investigated by macro-MG immediately followed by muscle biopsy. The histograms of the macro potential amplitudes and -areas were compared to the muscle fiber diameter histograms. In some cases small or large macro-potential values were well correlated with biopsy findings. This concerned mostly healthy and neurogenically altered muscles whereas in myopathic muscles this correlation was often lost. The possible reasons for a lacking correlation will be demonstrated.

During macro-mG recordings fiber density.was estimated. Increased values were nearly always correlated with general- ized or patchy pathological findings in the biopsy.

The aim of this study was to develop a method for decomposing EMG signals into their constituent MUPs. The electrical activity was sampled via a concentric needle electrode and transferred to a computer with a sampling frequency of 25 kHz.

into segments containing MUPs activity. The segments were identified by calculating the variance on two different time windows. The segments were clustered by a modified nearest-neighbour method. This analysis led to a partition consisting of clusters containing isolated MUPs and clusters composed of superimposed MUPs. The number of segments in a cluster was used to detect clusters containing potentials from only one motor unit. From each of these clusters a template was selected. The clusters containing superimposed MUPs were analysed by a recursive algorithm. The cross-correlation between superimposed MUPs and a template was computed and timeshifts with high correlation were detected. The template was subtracted for each of these timeshifts, and the residual segments were processed by a subsequent pass through the algorithm. Furthermore, to improve the ac- curacy of the timeshifts an optimization algorithm was implemented.

The output of the decomposition algorithm provided information about the recruitment and firing rate of individual MUPs.

In the first phase the EMG signal was separated


g New s t r a t e g i e s & EMG s ~ e c t r a l a n a l y s i s usine Discrete ~~ H i l b e r t T r a n s f o r m a t i o n

FIBER ACTION POTENTIALS Id I, B.K. van Veen, MS, W.L.C Rutten, PhD, W.Wallinga, PhD (Biomedical Engineering

Division, Department of Electrical Engineering, Twente Umversity, P.O. Box 217,

7500 AE Enrhede , N L ) U n T v e r s i t y , GOR-6900 J e n a )

W i t t e , H ! a n d Schumann,N.P . by> ( I n s t i t u t e o f P a t h o l o g i c a l P h y s i o l o g y , F r i e d r i c h S c h i l l e r

In model studies, single muscle fiber actian potentials (SFAP'B) are often simulated

mng a macroscopic approximation in which skeletal muscle tissue is described BS a

homogeneous anisotropic volume conductor. The model of Albers et al (Med & B i d . Eng.

& Comput., 26, 1988, 605-610) takes into account the microscopic tissue structure and the

microscopic electrical parameters and i t enables the study of the effect of parameter

variation on potential distributions and on shapes of SFAP's. However, model dimensions

were taken to be infinite and the active fiber had to be positioned in the center of the

model. In this study, we adapted this model so that the limited radial dimensions of the

muscle were taken into account. Furthermore, the position of the active fiber was varied

through the model.

In this way. we studied SFAP's recorded LU the neighbourhwd of the active fiber. I t

appeared, that the SFAP amplitude increased substantially by the presence of the muscle

boundary.

TIA-ANALYSIS I N HEALTHY WOMEN AND DMD-CARRIERS AT DIFFERENT LEVELS OF FORCE (ABSTRACT)

F i n s t e r e r J . M . D . Mamol i B . M . D .

( N e u r o l o g i s c h e s K r a n k e n h a u s R o s e n h U g e l , A-1130 Wien. V i e n n a )

I n t e r f e r e n c e p a t t e r n s f r o m t w e n t y d i f f e r e n t s i t es of t h e r i g h t

biceps brachii (BIC) and t h e r i g h t q u a d r i c e p s f e m o r i s (QUA) a t 20, 40 a n d 60% of i t s maximum f o r c e were r e c o r d e d w i t h C N - e l e c t r o d e s

f r o m 1 4 h e a l t h y women ICO, age 26-39), 10 p o s s i b l e DMD-carriers (PC, age 26-36] and 4 o b l i g a t e DMD-carriers IOC. a g e 30-39). They

w e r e a u t o m a t i c a l l y a n a l y s e d u s i n g t h e method of W i l l i s o n 1964 ( T I A - a n a l y s i s ) . I n both m u s c l e s the t u r n s per s e c o n d IT/Sl increased c o n t i n o u s l y f r o m CO t o OC [KO PC OCI w l t h o u t a s i g n i f i - c a n t d i f f e r e n c e of its means i e x c e p t KOIOC). The same t e n d e n c y c o u l d b e s e e n w i t h t h e a m p l i t u d e s p e r t u r n LAIT) of the B I C a n d p a r t l y t h e QUA. The T I S a n d the A/T w e r e h i g h e r i n t h e BIC t h a n i n t h e QUA ( e x c e p t AlT KO). T h e ra t lo A/T:T/S w a s i n a l l t h e g r o u p s a n d b o t h m u s c l e s l o w e s t a t 40% ( e x c e p t KO QUA) a n d h i g h e s t a t 20% ( e x c e p t PC a n d OC BIC) of its maximum f o r c e . The e q u i - v a l e n t v a l u e s o f t h e ra t io were h i g h e r i n t h e QUA t h a n i n t h e BIC. The means of t h e r a t i o a t 20% of t h e maximum f o r c e of b o t h m u s c l e s Were s i g n i f i c a n t l y higher i n CO t h a n i n PC a n d OC (except COIOC B I C I . U s i n g S t a l b e r g ' s m e t h o d t o e v a l u a t e t h e l i m i t s of n o r m a l v a l u e s f o r T I S a n d AlT n o n e of t h e DMD-cariiers showed p a t h o l o g i -

cal v a l u e s . E x c e p t t h e ra t io A/T:TIS a t low l e v e l s of maximum f o r c e T I A - a n a l y s i s seems to b e of l i t t l e h e l p t o d e t e c t DMD- carriers.

On t h e b a s i s o f Discrete H i l b e r t T r a n s f o r m a t i o n (DHT) s p e c t r a l p a r a m e t e r s f o r d y n a m i c EMG a n a l y s i s c a n b e i n t r o d u c e d . W i t h i n a n a l y s i s i n t e r v a l s w h i c h are u s e d i n t h e same manner a s i n S p e c t r a l a n a l y s i s , t h e i n s t a n t a n e o u s power of EMG f r e q u e n c y b a n d s c a n b e c o m p u t e d as tyrne series of t h e same i n t e r v a l d u r a t i o n . A c l o s e c o n n e c t i o n e x i s t s b e t w e e n i n s t a n t a n e o u s power a n d t h e c u r r e n t phenomenalogy o f power s p e c t r a l a n a l y s i s b e c a u s e t h e i n s t a n t a n e o u s power of a d e f i n e d f r e q u e n c y band c a n b e s e e n a s t h e e x a c t d y n a m i c e q u i v a l e n t of t h e c o r r e s p o n d i n g mean power v a l u e d e d u c e d f r o m t h e power s p e c t r u m . A m u l t i c h a n n e l EMG r e c o r d i n g [ I 6 c h a n n e l s ) makes t h e r e p r e s e n t a t i o n o f t h e t o p o g r a p h i c a l d i s t r i b u t i o n of t h e s p e c t r a l p a r a m e t e r by a c o l o u r e d map p o s s i b l e . A d d i t i o n a l l y , t h e i n s t a n t a n e o u s power c a n b e u s e d t o c a l c u l a t e map s e q u e n c e s . I n t h i s way, m o v e m e n t - r e l a t e d c h a n g e s o f EMG a c t i v i t y c a n b e q u a n t i f i e d by map s e q u e n c e s of a n a r b i t r a r y t i m e r e s o l u t i o n . By c a l c u l a t i o n o f i n s t a n t a n e o u s f r e q u e n c y v i a DHT an a r t e f a c t d e t e c t i o n s c h e m e f o r ECG i n t e r f e r e n c e c a n b e s u g g e s t e d . U s i n g t h i s c o n c e p t of EMG p r o c e s s i n g , a new a n d common m e t h o d i c a l b a s i s o f EMG power s p e c t r a l a n a l y s i s c a n b e i n t r o d u c e d . The p r o g r a m p a c k a g e MYOMAP w h i c h c o n t a i n s t h e s e f u n c t i o n s was d e v e l o p e d f o r NORAXON OY ( F i n l a n d ) . I t s c l i n i c a l u t i l i t y c a n be shown , e . g . i n r e h a b i I i t a t i o n , o r t h o p a e d i c s , p h y s i c a l t h e r a p y as w e l l as s p o r t s m e d i c i n e .

1-T Middletiin. M.D., C.S. Pattichis, M.Sc.. C.N. Schms, Ph.D., K. h z a r o u . and M. Christophidnu, M.D.

(MDRTC Neuromusculor Unit, Mukrriio.~ Hospitul, ivicusru, Cyprw),

Motor Unit Action Potentials (MUAPs) were recorded from the biceps brachii

muscle of normal subjects and patients suffering of motor neuron d isease (MND) and

myopath ies T h e latter g r o u p included patients with muscular dystrophy

polymyositis and mitochondria1 disease

The numerical panern recognition (NPR) algorlthm based on the MUAP features

h a s been used to identihi and SeleCI MUAPs The parameters measured were

amplitude phases duration area spike duration and spike area These parameters

have been applied to Aflificial Neural Net (ANN) models trained to diagnose normals MND and myopathic patients Supervised a n d unsupervised learning algorithms

were utilised to train the neural net models investigated

Analysis of the data w a s carried out using 12 input models where the mean value

and the standard deviation of the 6 parameters of all MUAPs collected from each

subject formed the input vector, and 120 input models, where the values of the

individual parameters for e a c h MUAP formed the input vector In born tha 12 and the

120 input models a maximum diagnostic yield of 80% w a s obtained

The hndings of this study and individual borderline cases will be discussed


MACRO- EDLE IN S T 1 < TING P ITS I NT WI NEUROGENIC DISORDERS

L. Kasatkina, 8 . Gacht, MD (Institute of General Pathology and Pathophysiology of the Hedical Academy,Moscm,USSR).

The study demonstrates the value of results obtained with

different methods of motor unit investigation and to es-

timate their significance for the diagnosis of peripheral

neurogenic disorders. Tibia1 muscles of 145 patients were ex-

dried with various EHG methods, including fiber density (PD)

and jitter.

The results demonstrate that there is a correlation be-

tween MUP durations and Macro peak-to-peak amplitudes

(R-0.48). Macro-ms and FD (R=0.37). There is no correlation

between MUPs duration and FD. The difference between maximal

sizes of w p s and Macro-ms is more pronounced in

neuronopathy than in neuropathy. The mean M~cM-MUP amplitude

value is increased 2-5 times depending on typs of the disease,

degree of involvement and muscle strength. The highest values

of jitter (with blockings) were seen in neuronopathic muscles

with low strength and atrophies.

The combination of all techniques contributes information

on the capacity of motor neurone to form compensatory innerva-

tion and to create neuromuscular contacts

982 Abstracts: Computerized and Quantitative EMG

A NFW CDNSTRUCT FOR E.M& - C.Otte, M.D.', G.Sieben, M.D.0, L.Vercauteren, Ir.*, M.Praet, M.D.., L.Boullart, Ir.*, J.Brouns, M.D.', J.D.Guieu, M.D.**

(*Ghent State University-Belgium ** Universite de Li l le -France)

Many E.M.G. Expert systems are inference machines that desi with uncertainty in a probabilistic or categorical way.

Recently, b t i f i c i a i Neural Networks (A") have been successfully employed In several expert systems.

The Topological Mapplng technique (Kohonen) Is an ANN- paradigm (modeled after the laminate and columnar architecture of the sensory neocortex) that in its unsupervised learning mode adeptlveiy self-organires and "maps" the inherent perceptual reiationshlp of the pattern data and its statistlcei texture es a ZD-projection from the signal space to the feature space. Thls important dimensionality reduction property of the mapping process is further enhanced by application of a ilnear vector quantification algorithm.

In its learning phase (implemented in Occam I1 on INMOS T-800 transputers) the E.M.G. patterns were presented to the system as a set of multidimensional vectors. The neuron- and parametermaps were ported to the appllcatlon platform (a '386 PC Turbo-Pascal envlronment) in a user-friendly expert system configuratlon.

The results on E.M.G.- signsis are reported and experience with this paradigm is commented.

MUSCLE & NERVE October 1990

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