Features that suggest the presence of a Stiff Man Plus Syndrome:
(1) rigidity and abnormal posturing involving one or more distal limbs, with variable trunk involvement
(2) myoclonus involving all four limbs
(3) involvement of:
(3a) brainstem
(3b) long track
(3c) lower motor neurons
(4) memory impairment and/or other cognitive changes
(5) autonomic failure or dysfunction
(6) sphincter involvement
(7) pleocytosis in the CSF
(8) suboptimal response to diazepam or baclofen
(9) suboptimal therapeutic response
(10) worse prognosis
(11) histologic evidence of a polioencephalitis
The Stiff Man Plus Syndrome is comprised of 3 conditions:
(1) progressive encephalomyelitis with rigidity (subacute)
(2) jerking stiff man syndrome (brain-stem myoclonus, chronic)
(3) stiff limb syndrome (chronic)
