title: Defining normal duration for afterdischarges with repetitive nerve stimulation: a pilot study.
abstract: The presence of afterdischarges on repetitive nerve stimulation may be useful to diagnose cramp fasciculation syndrome, however, the presence and normal duration of afterdischarges has not been well-defined in the normal population and individuals with other neuromuscular diseases. The aim of this pilot study was to describe the distribution of afterdischarge durations in normal controls and patients with peripheral neuropathy. The estimated seventy-fifth percentiles of the afterdischarge durations following tibial nerve repetitive nerve stimulation at 2, 5, 10, and 20 Hz were 315, 688, 745, and 928 milliseconds for 18 normal patients, and 143, 31, 323, and 542 milliseconds for 18 peripheral neuropathy patients respectively. Afterdischarge durations were similar in peripheral neuropathy patients and controls. These findings suggest that afterdischarge durations of more than 500 milliseconds are common in normal controls without subjective cramps and patients with peripheral neuropathy, with some durations beyond 1,000 milliseconds. Therefore, the presence of afterdischarges on repetitive nerve stimulation should be interpreted with caution when evaluating patients for hyperexcitable nerve syndromes.
authors.affiliation: Department of Neurology, Mayo Clinic Jacksonville, Jacksonville, Florida 32224, USA. cindy_bodkin@yahoo.com
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Bodkin
authors.forename: Kathleen D
authors.initials: KD
authors.lastname: Kennelly
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Boylan
authors.forename: Julia E
authors.initials: JE
authors.lastname: Crook
authors.forename: Michael G
authors.initials: MG
authors.lastname: Heckman
authors.forename: Devon I
authors.initials: DI
authors.lastname: Rubin
mesh_terms: D000328:Adult; D005207:Fasciculation / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D009120:Muscle Cramp / Q000209:etiology / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis / Q000503:physiopathology*; D010865:Pilot Projects; D013979:Tibial Nerve / Q000503:physiopathology*; D004561:Transcutaneous Electric Nerve Stimulation