Distinguishing clinical and electrodiagnostic features of X-linked bulbospinal neuronopathy.
X-linked bulbospinal neuronopathy (XLBSN) or Kennedys disease is a rare inherited neuromuscular disease characterized by adult-onset muscle weakness, usually in a limb-girdle distribution. It is frequently misdiagnosed despite a distinctive clinical presentation, usually due to the absence of a clear family history, and perhaps also due to failure of recognition. Accurate diagnosis is crucial for genetic counseling purposes and because alternative diagnoses usually carry a poorer prognosis. We evaluated 4 patients with XLBSN and one symptomatic female heterozygote patient. Based on our clinical observations in these patients and a systematic review of previously reported cases, the following clinical and electrophysiologic features when present in the setting of adult-onset muscle weakness, are strongly suggestive of the disorder: 1) facial weakness, 2) facial twitching or fasciculations, 3) tongue weakness and atrophy, 4) postural hand tremor, 5) hypo- or areflexia, and 6) absent or low-amplitude sensory nerve action potentials despite clinically normal sensation. We also hypothesize regarding the possibility of partial expression of the abnormal XLBSN gene in a symptomatic heterozygote female patient.
Meriggioli
M N
MN
Department of Neurological Sciences, Rush University, Chicago, Illinois 60612, USA. mmeriggi@neuro.rush.edu
Rowin
J
J
Sanders
D B
DB
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D004568:Electrodiagnosis; D004594:Electrophysiology; D005152:Facial Muscles / Q000503:physiopathology; D005260:Female; D008040:Genetic Linkage / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000235:genetics / Q000503:physiopathology; D009134:Muscular Atrophy, Spinal / Q000175:diagnosis* / Q000235:genetics* / Q000503:physiopathology; D010375:Pedigree; D014059:Tongue / Q000503:physiopathology; D014960:X Chromosome / Q000235:genetics*