THE CHARACTERISTIC ELECTRODIAGNOSTIC FEATURES OF KENNEDYS DISEASE

To define the electrodiagnostic (EDX) features of Kennedy's disease, t heir distribution, their clinical correlation, and to determine whethe r they are unique to this disorder, we retrospectively evaluated the E DX and clinical features of 19 patients with Kennedy's disease and fou nd that: (1) the percentage with sensory nerve action potential abnorm alities is high (95%); (2) compound muscle action potential abnormalit ies are less frequent (37%) and less pronounced; (3) the needle electr ode examination is always abnormal (100%), revealing acute and chronic motor axon toss, with the latter predominating; (4) the clinical onse t is heterogeneous for both the site of onset (bulbar, upper extremity , lower extremity, combination) and the symptomatology (sensory, motor , sensorimotor); (5) focal onsets were reported in the majority (79%); and (6) there is a strong correlation between the clinical onset (bot h site and symptomatology) and the maximal EDX abnormalities. Thus, th e EDX features or Kennedy's disease are consistent with a slowly progr essive and very chronic degeneration of the anterior horn cells and do rsal root ganglia. Although the clinical onsets are heterogenous, the EDX features are homogenous and unique, consisting of a diffuse, very slowly progressive anterior horn cell disorder coupled with a sensory neuropathy/neuronopathy that mimics an acquired process. (C) 1997 John Wiley & Sons, Inc.