Fibrillation and sharp-waves: do we need them to diagnose ALS?
BACKGROUND
Fibrillation/sharp-waves (fibs-sw) are considered an essential neurophysiological marker in Amyotrophic Lateral Sclerosis (ALS). We investigated how frequently an initial electrophysiological (EMG) evaluation, performed in ALS patients, revealed no fibs-sw.


METHODS
The initial EMG studies from 68 ALS patients were analysed. The presence of fibs-sw in at least two muscles of each limb and two cranial-innervated muscles was assessed.


RESULTS
We observed no fibs-sw in cranial-innervated muscles, and 7/15 bulbar-onset patients had no fibs-sw in limb muscles. Two of 28 upper-limb-onset patients, who had a short history before EMG, showed no fibs-sw. All lower-limb-onset patients had fibs-sw. Generally patients with no fibs-sw had diffuse abundant fasciculations.


CONCLUSIONS
The absence of fibs-sw should not necessarily preclude the neurophysiological diagnosis of ALS in bulbar-onset patients. Early affected upper-limb-onset patients might show no fibs-sw, but profuse fasciculations associated with mild to moderate denervation-reinnervation in weak muscles are found.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology; D004576:Electromyography; D005207:Fasciculation / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology