Abstract Details

Title Can Triple Stimulation Technique Detect Proximal Conduction Block Improvement Following IVIg Therapy in MMN?

Topic Clinical Neurophysiology

Presentation(s) P07 - (-)

Poster/Presentation
Number 180

Objective

Background BACKGROUND: In MMN,muscle strength shows improvement following high dose IVIg.Changes in electrodiagnostic(EDX) parameters can be sometimes useful in tracking treatment response.In some patients with clinical features consistent with MMN,routine EDX cannot demonstrate the presence of CB.Proximal-CB can be present in such patients.Demonstration of proximal-CB is difficult using routine EDX.TST is sensitive tool for detecting proximal-CB.We describe a case-report using TST in MMN with proximal-CB before and after IVIg.

Design/Methods DESIGN/METHODS: The subject, a 38 year old right handed man,with bilateral arm weakness, starting in the left 1st and 2nd digits in 2000.Weakness subsequently involved left 4th & 5th digits.Hand and forearm muscles were wasted with cramps and twitching.On examination,MMST revealed weakness in left triceps,wrist flexion,wrist extension,extensor digitorum communis(EDC),flexor pollicis longus(FPL),flexor digitorum profundus index(FDI),pronator&abductor pollicis brevis(APB) and rightFDI.The reflexes were normal or absent.Sesnsory examination was normal.Nerve conduction studies showed diffuse neurogenic motor-nerve disorder with left ulnar neuropathy.No conduction block was identified.MR imaging of brain,brachial plexus and cervical spine revealed no abnormalities.TST confirmed a proximal-CB.

Results RESULTS: TST amplitude& area ratios before& after the infusions were compared. The results are expressed as a percentage change.TST area ratio showed a 43.45% increase in right median and 52.47% increase in left median following the infusion. Also, TST amplitude ratio had a71.41% increase in right median and 103.85% increase in left median; following the infusion.Right ulnar nerve with no conduction block showed similar(±10%) TST ratios before and after the infusion.

Conclusions CONCLUSIONS: Following IVIg,TST showed two nerves with atleast 25% improvement.All nerves with accompanying TST improvement of>20%also showed increased MEP amplitudes.We demonstrate TST as a potentially useful tool for the identification of proximal-CB & monitoring therapeutic effects of IVIg in MMN.

Authors/Disclosures
Rahul Remanan, MBBS (Nanoveda) PRESENTER	No disclosure on file
Mona Shahbazi (Hospital for Special Surgery)	No disclosure on file
	No disclosure on file
Dale J. Lange, MD, FAAN (Lange Neurology, PC)	No disclosure on file
	No disclosure on file

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