a case of oro-facio-bulbar weakness
Post on 12-Nov-2014
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DR.MAHESH KUMAR’S UNIT.
Case historySikkandar ,70 yrs male,retd from TNEB3 months ago,initially had fever /URI/ear block
which lasted for 5 days,subsided with RX.Later noticed insidious onset of diplopia&difficulty
in eye closurenasal speechdifficulty in chewing/swallowing&nasal regurgitation.
No h/o difficulty in smell perception. disturbances in color vision. altered sensory perception over face .
No h/o
HOH/tinnitus/vertigo
difficulty in turning from side to side/shoulder shrug
motor weakness of the arms & legs
sensory deficit/positive/negative sensory phenomena
involuntary movements
seizures/headache/vomiting/head injury
previous similar episodes
Not a known TB/DM/HT patient;no high risk behaviour.
o/e no neurocutaneous markers ht neck ratio normal vitals stable.Examination of CNS:HF:normal,MMSE:28/30
Cranial nerves Rt Lt
1.Smell perception Normal Normal
2.Visual acuity field of vision color vision fundus
Normal Normal
3,4,6 palpebral fissure pupil size&reacn EOM
ptosis +3 mm,reacn normalFull
Ptosis+3 mm ,reacn normalFull
5.Sensory perception muscles of mastication jaw jerk
Normal Weak Not exaggerated
Normal Weak Not exaggerated
7.Raising eyebrows eye closure pursing &whistling taste over ant 2/3
Weak Not completeNot possibleNormal
Weak Not completeNot possibleNormal
8. Rinne ‘ s test weber ‘s test
Positive Not lateralized
Positive Not lateralized
9&10Palatal reflex gag reflex
diminished diminished
11. Power of SCM shoulder shrug
Normal Normal
12. Size wasting strength fasciculations
Normal No Decreased No
Normal No Decreased No
Motor system: no muscle wasting/weakness supercial &deep tendon reflexes normalGait normalSensory system:normalNo cerebellar signsSpine &cranium normalOther systems:no abnormality detected.
orofaciobulbar weakness
DD?
DD of orofaciobulbar weakness1.Neurasthenia /depression2.Progressive external ophthalmoplegia3.Polymyositis /inclusion body myositis4.Congenital myasthenic states5.Progressive bulbar palsy6.Multiple sclerosis7.Stroke 8.GBS variants –Miller-fisher variant9.Initial stages of botulism
DD -contd..MCNP syndromes: Intracranial –extramedullary or extracranial
processes1.Neoplastic meningitis2.Nasopharyngeal carcinoma3.Osteopetrosis4.Vertebro-basilar dolichoectasia5.Neurosarcoidosis 6.Polyneuritis cranialis(GBS variant)7.Bannwarth ‘s syndrome(lyme disease)
Investigations done CBC:Hb :11 g% TC:8000 DC:P65L33E2 ESR:2/5RFT: Sugar:110 urea:22 creatinine:0.7ECG:NSR,WNLCXR:WNLMRI BRAIN:No significant abnormalityRNS:Done at 2 HZ,recording from the orbicularis
oculi,nasalis,deltoid.Normal amplitudes obtained with significant
decremental response in the nasalis,deltoid&orbicularis;consistent with MG.s
Sr AchR abs:18.98(neg <0.25;positive>0.40)CT thorax:No significant abnormalityTFT:normalRhematoid factor:negativeCRP:negativeANA:1:10 dilution &1:40 dilution
positive;speckledECHO:normal Lv systolic function;no RWMA
Treatment givenStarted on ,T.Pyridostigmine 60 mg qidT.Prednisolone 5 mg 2 od
MYASTHENIA GRAVIS
Myasthenia gravisA neuromuscular disorder,Characterised by, 1.weakness &fatiguability of skeletal
muscles 2.decrease in no of AchR at the NMJ due
to an antibody mediated autoimmune
attack.
PathophysiologyDecrease in the no of AchR at the post-synaptic
membrane;flattening of post-synaptic folds.Even with normal release of Ach end-plate
potentials are smallfailure to trigger MAP.Neuromuscular abnormalities d/t AchR abs.The abs are IgG and T cell dependent.The thymus plays a role in this process.?Myoid cells with AchR on surface-autoantigen
Clinical featuresAll age groups, women in 20-40 yrs&men in
50-60 yrs.Weakness increases with repeated use,may
improve following rest.Course variable with remissions and
exacerbations.Remissions rarely complete.
Muscle weakness-distributionCranial muscles: 1.lids &EOM are often the first affected. 2.facial weakness/ weakness in chewing. 3.nasal timbre to speech(palate)/dysarthric(tongue) 4.difficulty in swallowing/regurgitation. 5.bulbar weakness-esp with anti MUSK abLimb muscles 1.weakness generalizes in 80% 2.often proximal and asymmetric.
Others axial muscles. diaphragm/abdominal ms/intercostals. even the external sphincter of
bladder&bowel.Preserved DTR despite muscle weakness
Osserman’s grading Grade Weaknes
sProgress Crises Drug
responseIncidence
I Ocular ? No satisfactory
15-20%
II A Mild generalized
slow No satisfactory
30%
II B Moderately Severegeneralized
Slow No Less than satisfactory
25%
III Acute Fulminant
Rapid yes Poor 15%
IV Late severe
Steady Progression over 2 yrs
yes poor 10%
Diagnosis history/physical examinationLab 1.anti AchR radioimmunoassay 85% positive in generalized MG,50% in
ocular MG 40% of negative pts have antiMUSK abs. 2.repetitive nerve stimulation 3.single fiber EMG 4.tensilon test
Repetitive nerve stimulationAchEmedication stopped 6-24 hrs beforeBest to test weak/proximal musclesRepetitive stimulation of the nerve at 3/secDecremental response (decrease in muscle
CMAP)of atleast 10-15%Edrophonium can prevent this response.
Single fiber EMGMore sensitive than RNS.Identification of APs from single muscle
fibersInconstancy of the normally invariant interval
between firing of fibers connected to same motor unit(jitter)/blocking of successive discharges.
NCV &distal latencies are normal
Tensilon (AchE)testReserved for pts with neg abs/EDS.Edrophonium;onset:30 s,DOA:5 minAn objective endpoint selectedGiven in two divided doses(2+8 mg) to avoid
sideeffectAtropine should be kept ready.False +: ALS,placebo reactors
Disorders a/w MG1.Thymus Thymoma,hyperplasia2.Thyroid3.Autoimmune RA,SLE,sjogren’s and others4.Exacerbation of MG Hypo/hyperthyroidism,occult infn,stress etc5.Interference with therapy TB,DM,GIB,HT,BA,osteoporosis,obesity etc
lab testsCT/MRI of mediastinumANA/RF/anti thyroid absPPD skin testCXRFBS/HbA1cPFTBone densitometry in older pts.
Treatment Anticholinesterase drugsThymectomyImmunosuppressive agentsPlasmapheresis &IVIg
Pyridostigmine most widely used.Action begins in 15-30 min,lasts for 3-4 hrs.Rx started with 30-60 mg tds to qid.Tailored to individual requirements.Max useful dose rarely exceeds 120 mg every
3-6 hr.Over dosage may increased weakness.Muscarinic side effects in a few.Atropine/diphenoxylate can be used.
ThymectomyAdvantages :85% experience remission,drug-free remission in 35%Improvement typically delayed for months to yrs.Definite: All pts between puberty&55 yrs.Those with thymoma.Doubtful :Children & those >55 yrs.Ocular MG,MUSK ab positivity.
Immunosuppression Immediate improvement : IVIg Plasmapheresis Intermediate term: 1-3 months Glucocorticoids Cyclosporine Tacrolimus Long term: Mycophenolate mofetil /Azathioprine
Glucocorticoid therapy: Given in a single dose. Low initial dose(15-25 mg/d),increased stepwise. Until marked improvement/50-60 mg/d reached. Gradually modified to an alternate day regimen.Most common errors with steroid RX in MG: 1.Insufficient persistence 2.Too early/rapid/excessive dose tapering. 3. Lack of attention to side effects.
Myasthenic crisisExacerbation of weakness usually with respiratory
failure caused by diaphragm&intercostal muscle weakness.
Rarely occurs in properly managed persons.Anticholinesterases temporarily stopped.RX:antibiotics ,supportive measuresPlasmapheresis:usually 5 exchanges over a 10-14
day period.IVIg:usually 2 g/kg given over 5 daysBoth have intermittent benefit& are costly
Immunosuppresive drugsMycophenolate mofetil:1-1.5 g bd relative lack of side effects,high costAzathioprine :2-3 mg/kg ,beneficial effect takes 3 -6 months to
beginShould never be given AllopurinolCyclosporine/Tacrolimus:4-5mg/kg &0.1 mg/kg/d resply;nephrotoxicCyclophosphamide :reserved for refractory cases
DRUGS & MGDrugs that may exacerbate MGAntibiotics :aminoglycosides,quinolones,macrolid
esNondepolarising muscle relaxants(curare)Beta blockersLocal anaesthetics &related agentsQuinine derivativesMagnesiumPenicillamine Botulinum toxins
THANK YOU
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