Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fluctuating stiffness and paroxysmal spasms of the trunk and legs are the primary features of stiff-man syndrome and it's variants, progressive encephalomyelopathy with rigidity and myoclonus (PERM) and stiff-leg syndrome. The spasms characterized by hyperextension of the back and legs are both spontaneous as well as stimulus-sensitive. They can be excruciatingly painful and are frequently accompanied by symptoms of autonomic dysregulation. Hyperreflexia may be the only pathological finding on the neurological examination. Most patients show psychiatric disturbances suggestive of psychogenic movement disorder and this may cause delays in adequate pharmacotherapy. The disease progresses over the span of months to years rendering many patients wheelchair-bound or bedridden. GABA-mimetics are most effective in treating symptoms, but tolerance and life-threatening withdrawal symptoms are common drawbacks. For therapy-refractory patients, intrathecal baclofen represents a good alternative. The diagnosis is based on clinical, biochemical and electrophysiological findings. Spasmodic reflex myoclonus is observed in nearly all SMS patients. It consists of well-reproduced reflex EMG-activity commencing 50-80 ms after medial or tibial nerve stimulation and lasting several seconds thereafter. The activity is first myoclonic then spasmodic in nature, and commonly begins in the muscles most severely affected before spreading bidirectionally along the neuraxis. Spasmodic reflex myoclonus and the high incidence of antibodies against GAD are suggestive of an autoimmune disorder affecting GABAergic neurons in the spinal cord, but the precise locus of dysfunction remains to be elucidated.
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PMID:Stiff-man syndrome: an overview. 957 75

The head retraction reflex (HRR) is a vestigial withdrawal reflex of the face and is suppressed in healthy subjects. We investigated the prevalence and electrophysiological patterns of the HRR in patients suffering from stiff-man syndrome (SMS, n = 28) and related disorders, stiff-limb syndrome (SLS, n = 2), and progressive encephalomyelitis with rigidity and myoclonus (PERM, n = 20). In patients with a positive HRR, the electromyographic (EMG) pattern was analyzed with surface recordings from the orbicularis oculi, sternocleidomastoid, trapezius, and the paraspinal extensor muscles at midthoracic and lumbar levels. On clinical testing, 17 of 28 SMS patients, 10 of 20 PERM patients, and 0 of 2 SLS patients had a positive HRR, ranging from a brief contraction of the neck extensors to violent retropulsion of the upper body. In all muscles, EMG reflex patterns elicited by gentle taps to the face or by electrical stimulation of the trigeminal nerve branches consisted of two components: an early, synchronous, brief burst with the shortest latency in trapezius (12.5-20.0 msec) and a late, asynchronous, longer response with latencies between 44 and 70 msec. We conclude that the HRR is an abnormal cutaneomuscular brainstem reflex that occurs in a considerable proportion of patients with SMS and related disorders. Although neither specific nor particularly sensitive for SMS, presence of the HRR in a setting with otherwise unexplained stiffness and spasms might help to avoid the otherwise frequent misdiagnosis of a psychogenic motor disturbance in patients with SMS.
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PMID:Head retraction reflex in stiff-man syndrome and related disorders. 1288 80