Abstract Details

Title Lance-Adams Syndrome Presenting as Orthostatic Myoclonus

Topic Movement Disorders

Presentation(s) P03 - (-)

Poster/Presentation
Number 060

Objective

Background BACKGROUND: LAS, a rare complication of hypoxic encephalopathy, usually occurs after resuscitation from cardiopulmonary arrest. The myoclonus appears a few days or weeks after resuscition, and usually manifests as action myoclonus. Myoclonic jerks in LAS are often triggered by action, startle and tactile stimulation, and occur without electroencephalography (EEG) correlate. LAS is thought to be due to a mixture of cortical and subcortical myoclonus. Orthostatic myoclonus consists of leg jerking on attaining the upright position, accompanied by short duration bursts in lower extremity surface electromyography (EMG) channels. It often contributes to gait dysfunction in the elderly. We describe a case of LAS presenting as orthostatic myoclonus.

Design/Methods DESIGN/METHODS: A 54-year-old man was resuscitated after a cardiac arrest. He complained of jerking in his legs when he stood up or tried to walk. A polymyographic study using surface EMG electrodes was performed to evaluate multiple cranially and spinally innervated muscles, including upper and lower extremities. EEG-EMG correlation was performed with back-averaging, performed after triggering by the right quadriceps muscle jerks on standing. The patient had brief duration EMG bursts only in the lower extremity channels, only while standing and attempting to walk, but not while sitting or reclining. These bursts were not accentuated by audiogenic or somatosensory reflexes and there was no ballistic overflow myoclonus.

Results RESULTS: The presence of EMG bursts on polymyography in the lower extremities only while standing or attempting to walk, and the absence of a time-locked cortical potential and Bereitschafspotential (slowly rising negative potential 1000-1500 msecs before the jerking movements) suggest that the orthostatic myoclonus is of subcortical origin.

Conclusions CONCLUSIONS: We believe this case of LAS presenting as orthostatic myoclonus is a novel observation.

Authors/Disclosures
Sumaiya Salim, MD PRESENTER	No disclosure on file
Norbert Goebels, MD (Heinrich-Heine-University)	Dr. Goebels has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Biogen. The institution of Dr. Goebels has received research support from Sanofi-Genzyme.
Sudhansu Chokroverty, MD, FAAN	No disclosure on file
Sushanth Bhat, MD	Dr. Bhat has nothing to disclose.
Philip Hanna, MD, FAAN (JFK Medical Center)	No disclosure on file
Rony Dekermenjian, MD	Dr. Dekermenjian has nothing to disclose.
Nancy Gadallah, DO (JFK Neuroscience Institute at JFK Medical Center)	Dr. Gadallah has nothing to disclose.

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