Neuromuscular transmission in migraine: a single-fiber EMG study in clinical subgroups.
OBJECTIVE
To search for impairment of neuromuscular transmission by single-fiber electromyography (SFEMG) in patients with common forms of migraine.


BACKGROUND
P/Q Ca(2+) channels are genetically abnormal in most cases of familial hemiplegic migraine (International Headache Society [IHS] code 1.2.3) and may be involved in other types of migraine. Besides in the brain, these channels are found in motor nerve endings, where they control stimulation-induced acetylcholine release. If they are functionally abnormal, the neuromuscular transmission might be impaired.


METHODS
Sixty-two migraineurs (18 without aura, IHS code 1.1; 19 with typical aura, IHS code 1.2.1; 10 with prolonged aura, IHS code 1.2.2; 15 with and without aura) and 16 healthy control subjects underwent stimulation SFEMG. Results were expressed as the mean value of consecutive differences (MCD) and percentage of single-fiber abnormalities (abnormal jitter or impulse blocking).


RESULTS
Average MCD was comparable in control subjects and migraineurs (17.1 +/- 2.6 versus 17.5 +/- 4.7 microsec). By contrast, single-fiber abnormalities were found in 17 patients but in none of the control subjects (p = 0.036). Most of these patients had unilateral sensorimotor symptoms and/or aphasia and/or loss of balance during the aura. SFEMG abnormalities were significantly correlated with the occurrence of these clinical features and with a diagnosis of migraine with prolonged aura.


CONCLUSIONS
Stimulation SFEMG shows mild abnormalities of neuromuscular transmission in a subgroup of migraineurs with aura, characterized by clinical features frequently found in human P/Q Ca(2+) channelopathies. These abnormalities might thus be due to genetically modified P/Q Ca(2+) channels.
Ambrosini
A
A
Mediterranean Neurological Institute, IRCCS Neuromed, Pozzilli, Italy.
Maertens de Noordhout
A
A
Schoenen
J
J
D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015220:Calcium Channels / Q000235:genetics; D016009:Chi-Square Distribution; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D020325:Migraine with Aura / Q000503:physiopathology*; D020326:Migraine without Aura / Q000503:physiopathology*; D009412:Nerve Fibers / Q000502:physiology; D009469:Neuromuscular Junction / Q000503:physiopathology*; D020864:Calcium Channels, N-Type
D015220:Calcium Channels; C105656:CACNA1A protein, human; D020864:Calcium Channels, N-Type