Myoclonus jerks also affected walking and patients would tend to fall because of a lapse in contraction of anti-gravity muscles, especially hamstrings and quadriceps, producing a characteristic 'bouncing' gait pattern. In addition, if, while walking at a slow pace the patient would inadvertently strike an object, such as a chair or a carpet fold, 'the proximal trunk and limb muscles would suddenly contract and immediately there would follow one or more myoclonic jerks, and possibly a lapse of posture and a fall'.
The patients described by Lance and Adams were all found to have a mildly impaired ability to accurately control the range of muscle movement (dysmetria), mild difficulty in articulating words (dysarthria) and loss of the ability to coordinate muscular movement (ataxia). Although the patients would appear cognitively normal, formal neuropsychological testing would frequently reveal evidence of subtle disorders of attention, memory and executive function.
Post-anoxic myoclonus therapeutic interventions are still based mainly on 'trial and error' method. The standard anti-convulsants, such as phenytoin and phenobarbital, have not produced desirable control of symptoms. There are reports of L-5-hydroxytryptophan in conjunction with carbidopa being used effectively in a group of patients; however, its intolerable gastrointestinal side effects make it less usable. Levodopa in conjunction with Gaba and baclofen were described and Gabapentin was also described in animal studies as an affective agent controlling experimentally induced post-anoxic myoclonus. Therapy with valproic acid and clonazepam has also been described to result in significant clinical improvement but care should be taken as they can affect level of alertness and cognitive function.
Novel anti-epileptic medications such as levetriacetam and zonisamide have recently been described and are gaining popularity in control of myoclonus disorders, including Lance-Adams syndrome. Levetiracetam is an analogue of piracetam (also found to be effective in post-anoxic myoclonus).
Myoclonus may be a devastating complication after anoxic brain injury. Rehabilitation specialists should be aware of this condition's presentation, natural history and management. Even thought Lance- Adams syndrome may not be fully curable at this point, the interventions can significantly improve functional level and overall quality of life for patients with this disorder.
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