laboratory neuro

8/13/2019 Laboratory Neuro

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Diagnostic and Laboratory Test

Reference in Neurology

An up to date, essential reference

that allows easy access toclinically relevant laboratory and

diagnostic test.


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Computed Tomography of the BRAINComputed Tomography of the BRAIN

(CT scan of the Brain)(CT scan of the Brain)

Type of Test: X-RAY WT! "#$TRA%T &Y'

"o(puteri)ed analysis of (ultiple

to(ographic *-ray fil(s ta+en of the braintissue at successive layers, providing a threedi(ensional view of the cranial contents. Thei(age is placed on a television screen andphotographed. The final result is a series ofactual anato(ic pictures of coronal sectionsof the brain.


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sed in the differential diagnosis of intracranialneoplas(, cerebral infarctions, ventriculardisplace(ent or enlarge(ent, cortical atrophy,

cerebral aneurys(s, intracranial he(orrhage andhe(ato(a, and arteriovenous A/(alfor(ation. 0ultiple sclerosis and otherdegenerative abnor(alities can be identified

also.isuali)ation of a neoplas(, previous infarction,

or any pathologic process that destroys, theblood-brain barrier (ay be enhanced by in1ection of an iodinated contrast dye.


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CNTRAINDICATIN!"

2atients who are allergic to iodinateddye or shellfish

2atients who are claustrophobic2atients who are pregnant, unless the

benefits outweigh the ris+s

2atients whose vital signs are unstable2atients who are very obese, usually

(ore than 344 lbs.


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#otential Complications

Allergic reaction to iodinated dye

Acute renal failure fro( dye infusion

!ypoglyce(ia or acidosis (ay occur in

patients who are ta+ing glucophage and

receive iodine dye

Apnea if *enon is used because it is an

anesthetic gas


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#rocedure and #atient Care

Explain the procedure to the patient. The patients cooperation isnecessary, because he or she must lie still during the procedure.

Obtained informed consent if required by the institution

Show the patient a picture of CTScan machine and encourage the

patient to erbali!e his or her concerns because some patientsmay hae claustrophobic can be scanned after appropriatepremedication with antianxiety drugs.

"eep the patient on #$O for % hours before the study, if oralcontrast is to be used.

&nstruct the patient that wigs, hairpin, clips or partial dental plates

cannot be worn, during the procedure because they hamperisuali!ation of the brain.

'ssess the patient for allergies to iodinated dye or shellfish

Tell the patient that he or she may hear a (clic)ing* noise as thescanning machine moes around the head.


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'ncourage the patient to drin+ fluids,

because dye is e*creted by the +idneys

and causes diuresis.Appropriate interventions concerning

care of patients with iodine allergy.


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$agnetic Resonance Imaging

Type of Test: 0agnetic 5ield %tudy

$oninvasive diagnostic scanning techni6ue

that provides valuable infor(ation about thebody7s anato(y by placing the patient in a(agnetic field. 0R is based on howhydrogen ato(s behave when they areplaced in a (agnetic field and then disturbedby radiofre6uency signals.The uni6ue featureabout 0R is that is does not re6uiree*posure to ioni)ing radiation.


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$RI has se%eral ad%antages o%er computedtomography scanning& including the follo'ing"

0R provides better contrast between nor(al tissueand pathologic tissue.

#bscuring bone artifacts that occur in "T %canning

do not occur in 0R %canning. 8ecause rapidly flowing blood appears dar+, which

results fro( its 6uic+ (otion, (any blood vesselsappear as dar+ lu(ens. This provides a naturalcontrast fro( other tissues to the blood vessel whenusing 0R.

8ecause spatial infor(ation depends only on how the(agnetic fields are varied in space, it is possible toi(age the transverse, sagittal and coronal directly

with 0R.


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Although the full usefulness of $RI is yet to bedetermined& it sho's promise in the e%aluation of the

follo'ing areas"

!ead and surrounding structures9

%pinal cord and surrounding structures9

5ace and surrounding structures9$ec+, 0ediastinu(9

!eart and reat essels, ;iver9


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Contraindications

2atients who are e*tre(ely obese (ore than 344 lbs/ 2atients who are confused or agitated

2atients who are claustrophobic if an enclosed scanneris used

2atients who are unstable and re6uire continuous life-support e6uip(ent

2atients with i(plantable (etal ob1ects such as

pace(a+ers, infusion pu(p, aneurys( clips, inneri(plants.

$T'R5'R$ 5A"T#R%: 0#'0'$T &R$T!' %"A$ 0AY "A%' ART5A"T% #$ 0R


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#rocedure and #atient Care"

'*plain the procedure to the patient.

nfor( the patient that there is no e*posure to radiation.

#btain infor(ed consent if re6uired by the institution.

Tell the patient that he or she can drive without assistance afterthe procedure.

Tell parents of young patients that they (ay read or tal+ to achild in the scanning roo( during the procedure.

Assess the patient for any contraindications for testing.

nstruct the patient to re(ove all (etal ob1ects, because theywill create artifacts on the scan.

nfor( the patient that he or she will be re6uired to re(ain(otionless during the study.

nfor( the patient that no fluid or food restrictions are necessarybefore 0R.


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Interfering actors"

!igh glucose levels in diabetics (ay confound 2'Tscans using 5& as the radionuclide9

Recent use within >? hours/ of caffeine, alcohol, or

tobacco (ay affect test results9 '*cessive an*iety (ay affect brain function

evaluation 9

'*cessive e*ercise within the preceding 3 days can

cause factitious update of the contrast (aterial in the(usculature.

&rugs that (ay influence results include tran6uili)ersand sedatives.


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o '*plain the procedure to the patient

#btain infor(ed consent if re6uired by the institution

nfor( patient that he or she should abstain fro( heavy e*ercise for 3days prior to testing

nfor( the patient that he or she (ay need to restrict food or fluids for ?to @ hours on the day of the test. The patient should refrain fro(alcohol, caffeine, and tobacco for >? hours before the test.

Tell the patient that no sedatives or tran6uili)er should be ta+enbecause she or he (ay need to perfor( certain (ental activities duringthe test.

The radioactive (aterial can be infused through an line or inhaled asa radioactive gas.

f the brain is being scanned, the patient (ay be as+ed to perfor(different cognitive activities e.g. reciting / to (easure changes in thebrain activity during reasoning or re(e(bering.


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Cont*"#T !can

'*traneous auditory and visual sti(uli are

(ini(i)ed by a blindfold and ear plugs.

nstruct the patient to change position slowlyfro( lying to standing to avoid postural

hypotension.

'ncourage the patient to drin+ fluids and

urinate fre6uently to aid re(oval of the

radioisotopes fro( the bladder.


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$+L,RA#-+ ($yelogram)

Type of Test: X-ray with contrast dye

8y placing radiopa6ue dye into the

subarachnoid space of the spinal canal, thecontents of the canal can be radiographically

outlined. "ord tu(ors, (eningeal tu(ors,

(etstatic spinal tu(ors, herniated

intravertebral dis+s, and arthritic bone spurscan be readily detected by this study.


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Contraindications"

2atient with (ultiple sceloris, e*acerbation(ay be precipitated by (yelography

2atients with increased intracranial pressure,because ;2 (ay cause herniation of thebrain

2atients with infection near the ;2 site,

because this (ay precipitate bacterial(eningitis.

2atients who are allergic to shellfish oriodinated dye.


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'*plain the procedure to the patient. 'nsure that the physician has obtained written

and infor(ed consent for this procedure.

Assess the patient for allergies to iodinatedcontrast dye or shellfish.

Ascertain whether the patient has recently ta+enphenothia)ines, tricyclic antidepressants, "$%sti(ulants or A(pheta(ines if (etri)a(ide willbe used. These (edications should be avoided,because they could decrease the sei)urethreshold.


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Cont*" #atient Care

!ave the patient e(pty the bladder and bowel before(yelography if possible.

nfor( the patient that he or she will be tilted into an up and

down position on the table so that the dye can properly fill thespinal and provide ade6uate visuali)ation in the desired area.

A lu(bar puncture is perfor(ed.

5ifteen (illiliters of cerebrospinal fluid "%5/ is withdrawn, andB (l or (ore of radiopa6ue dye is in1ected into the spinalcanal. 8ecause the specific gravity of the dye is greater than

that of the "%5, the direction of dye flow will depend on the tilt ofthe table and the patient7s position.

with the needle in place, the patient is placed in the proneposition on the tilt table with the head tilted down. A foot supportand shoulder brace or harness will +eep the patient fro( sliding.


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Cont*"#atient Care

The lights are turned off, and the colu(n of dye is followed in acephalad direction with flouroscopy.

#bstruction to the flow of the dye are evident, and the level of

the lesion is easily detected. After (yelography is perfor(ed, the needle is re(oved and a

dressing is applied.

sually place the patient on bed rest with the head slightlyelevated for several hours afterward as indicated. 2osition thepatient specifically ordered by the physician in consultation with

the radiologist. #bserve the patient for signs and sy(pto(s of (eningeal

irritation e.g. fever, stiff nec+, occipital headache. 2hotophobia/

'ncourage the patient to drin+ fluids to enhance e*cretion ofthe dye and to hasten replace(ent of "%5.


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L.$BAR #.NCT.R and

CRBR!#INAL L.IDTY2' #5 T'%T: 5luid Analysis

$or(al 5indings:

2ressure: less than >4 c( Water

"olor: "lear and "olorless

8lood: $one

"ells: W8": $eonate 4 -34 cellsCul

- B years 4 - >4 cellsCul

@ - D years 4 - 4 cellsCul

adult 4 - B cellsCul


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Cont*" C!

"ulture E %ensitivity: no organis(

lucose: B4 - FB (gCdl or @4 -F4G

"hloride: F44 -FB4 (gCdl;actate &ehydrogenase: H ?4 units

;actic Acid: 4 - >B (gCdl

"ytology: no (alignant cells%erology for %yphilis: negative

luta(ine: @ - B (gCdl


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#atient Care for Lumbar

#uncture"This study is a sterile procedure that can be easily

perfor(ed at the bedside. The patient is usually placed inthe lateral decubitus fetal/ position.

The patient is instructed to clasp the hands on the +neesto (aintain this position. %o(eone usually helps thepatient (aintain this position.

Three sterile test tubes are filled with B - 4 (l of "%5.

Apply digital pressure and an adhesive dressing to the

puncture site. 2lace the patient in the prone position with a pillow under

the abdo(en to increase the pressure in the tissuessurrounding the spinal cord. This retard continued "%5flow fro( the spinal canal.


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Cont*" Lumbar #uncture

'ncourage the patient to drin+ increased a(ounts offluid with a straw to replace "%5 re(oved during thelu(bar puncture. &rin+ing with a straw will enable the

patient to +eep the head flat. sually +eep the patient in a reclining position for

hour or up to several hours to avoid the disco(fort ofpotential postpuncture spinal headache. nstruct thepatient to turn fro( side to side as long as the head is

not raised. Assess the patient for nu(bness, tingling, and

(ove(ent of the e*tre(ities, pain at the in1ection site9drainage of blood or "%5 at the in1ection site9 and theability to void. $otify the physician of any unusual

findings.


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/.C0N!TDT1!T0+

T!Tf bloc+age in "%5 circulation in the spinal

subarachnoid space is suspected, a Iuec+enstedt-%too+ey Test (ay be perfor(ed. 5or this test the

1ugular vein is occluded either (anually by digitalpressure or by a (ediu(-si)ed blood pressure cuffinflated to appro*i(ately >4 ((!g. Within 4seconds after 1ugular occlusion, "%5 pressure shouldincrease fro( B - ?4 c( Water and then pro(ptly

return to nor(al within 4 seconds after release ofthe pressure. A sluggish rise or fall of "%5 pressuresuggest partials bloc+age of "%5 circulation. $o riseafter 4 seconds suggest a co(plete obstruction

within the spinal canal.


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LCTRNC#-AL,RA#-+

TY2' #5 T'%T: 'lectrodiagnostic The '' is a graphic recording of the electrical

activity of the brain. '' electrodes are placedon the scalp over (ultiple areas of the brain todetect and record electrical i(pulses within thebrain. t can be used to evaluate trau(a and druginto*ication and to deter(ine cerebral death in

co(atose patients. The '' can be used forearly detection of cerebral tissue ische(ia, whichwould indicate that continued carotid occlusionwill result in a cerebrovascular accident stro+e/syndro(e.


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#rocedure and #atient Care

'*plain the procedure to the patient. Assure the patient that this test cannot read the (ind or detect

senility.

Assure the patient that the flow of electrical activity is fro( thepatient. !e will not feel anything during the test.

nstruct the patient to wash the hair or sha(poo his or her hair

the night before the test. $o spray, no oil or gel should be used.

nstruct the patient if sleeping ti(e should be shortened the

night before the test. Adults (ay not be allowed to sleep (orethan ? to B hours. And children not (ore than B to F hours if a

sleep '' is to be done.


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&o not ad(inister any sedatives or hypnotics before the test

because they will cause abnor(al waves on the ''.

nfor( the patient not to past before the test, because

hypoglyce(ia (ay alter test results. nstruct the patient not to drin+ tea, coffee, cocoa, or cola on

the (orning of the test because of their sti(ulating effects.

Tell the patient that he or she needs to re(ain still during the

test. Any (ove(ent during the test, including opening the eye,

will create interference and alter the '' recording. $ote that this study is perfor(ed by an '' technician in

appro*i(ately ?B (inutes to > hours.

Tell the patient that no disco(fort is associated with this study.


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!IN,L #-TN $I!!IN

C$#.TD T$,RA#-+Three di(ensional i(aging techni6ue using

nuclear (edicine procedures that e(ploy

radionuclides and instru(ents that e(it anddetect respectively single photon.

a((a photons are e(itted fro( a

radiophar(aceutical agent ad(inistered to

the patient and are detected by a rotatingga((a ca(era or ca(eras9 the i(age are

sent to a (icroco(puter.


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%2'"T is useful in detecting the e*tent andlocation of abnor(ally perfused areas of the

brain, thus allowing detection, locali)ation,and si)ing of stro+e before it is visible by

"T%can/, locali)ation of sei)ure foci in

epilepsy, and evaluation of perfusion before

and after neurosurgical procedures.2regnancy and 8reastfeeding are

contraindications to %2'"T.


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LCTR$+,RA#-+

An 'lectro(yography '0/ is obtained byintroducing needle electrodes into the s+eletal

(uscles to (easure changes in the electricalpotential of the (uscles and the nerves

leading to the(.

The electrical potentials are shown on an

oscilloscope and a(plified by a loudspea+erso that both the sound and appearance of the

waves can be analy)ed and co(pared

si(ultaneously.


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'07s are useful in deter(ining the

presence of a neuro(uscular disorder

and (yopathies. They helpdistinguished wea+ness due to

neuropathy functional or pathologic

changes in the peripheral nervoussyste(./ fro( wea+ness due to other

causes.


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$o special patient preparation is

re6uired. The patient is infor(ed that he

will e*perience a si(ilar sensation tothat of an intra(uscular in1ection as the

needle is inserted into the (uscle. The

(uscles e*a(ined (ay ache for a shortti(e after the procedure.


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Cerebral Angiography

(Arteriography)With the in1ection of radiopa6ue contrast

(aterial into arteries blood vessels can be

visuali)ed to deter(ine arterial anato(y,vascular disease, or neoplas(s. With the

catheter usually placed through the fe(oral

artery and into the desired artery, radiopa6ue

(aterial is rapidly in1ected while *-ray fil(sare obtained.


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CNTRAINDICATIN!

2atient with allergies to shellfish or iodinated dye. 2atient who are uncooperative or agitated.

2atient who are pregnant unless the benefits outweigh the

ris+s.

2atient with renal disorders because iodinated contrast is

nephroto*ic.

2atients with a bleeding propensity.

2atient with unstable cardiac disorders. 2atient who are dehydrated because they are especially

susceptible to dye-induced renal failure.


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'*plain the procedure to the patient. Allay any fear

and allow the patient to verbali)e concerns.

'nsure that written and infor(ed consent for this

procedure is in the patient7s chart.

Assess the possibility of allergies to iodinated dye.

to D hours before testing.

f the patient is suspected of having

pheochro(ocyto(a ad(inister propanolol and

pheno*yben)a(ine as ordered to prevent potentially

fatal hypertensive episode.


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X-ray studies are co(pleted, the catheter isre(oved and a pressure dressing is applied to the

puncture site.

2erfor( neurologic assess(ent for any signs of

catheter induced e(bolic stro+e syndro(e if cerebral

arteriography is perfor(ed.

0aintain pressure at the puncture site with a J > lb

sandbag or an bag.

laboratory neuro

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