Clinical findings:
(1) onset during fifth decade or later
(2) onset insidious
(3) gradually progressive course (course is not step-like) eventually becoming severe
(4) duration >= 3 years
(5) spastic paresis with findings limited to those of corticospinal dysfunction (spinobulbar spasticity):
(5a) spastic quadriparesis
(5b) pseudobulbar palsy
(5c) spastic dysarthria
(5d) hyper-reflexia
(5e) bilateral Babinski sign
(6) symmetrical distribution
(7) persevered bladder function
Imaging findings:
(1) focal atrophy of precentral gyrus on MRI scan
(2) decreased glucose uptake in the pericentral region on PET scan
EMG testing - both of the following:
(1) absent or very prolonged latency on cortical motor evoked responses
(2) normal peripheral stimulus evoked maximum compound muscle action potentials
Exclusions:
(1) absence of a family history
(2) normal laboratory testing, including vitamin B12 concentrations
(3) negative serologic tests for syphilis, Lyme disease and HTLV-1
(4) absence of high signal lesions on MRI as seen in multiple sclerosis
(5) normal CSF findings with absence of oligoclonal bands
(6) absence of denervation potentials on EMG (or occasional minor fibrillation and increased insertional activity)
(7) absence of compressive lesions on cervical spine or foramen magnum
