Course: chronic, typically with long-term survival
Cause: autoimmune, idiopathic, possibly paraneoplastic (unlikely in a chronic survivor)
Clnical features:
(1) absence of generalized myoclonus
(2) rigidity and painful spasms of affected limbs, especially distally
(3) no or mild brainstem signs
(4) relative or total sparing of the trunk
(5) absence of long track signs
(6) not usually associated with diabetes mellitus
(7) associated with impaired mobility, often resulting in the patient becoming wheelchair bound
The legs are most often affected but the arms may also be involved.
Laboratory features: Some patients have anti-GAD antibodies. Rheumatoid factor is common.
The EMG may show a segmented appearance which is not seen in the stiff man syndrome. This is causes by a synchronous discharge of motor units.
