Neostigmine-induced fasciculations--a useful diagnostic test?

Previous studies have concluded that provocation of fasciculations by neostigmine indicates a lesion of lower motor neurones. We performed 20 control experiments in 18 healthy volunteers. Ten subjects received an intramuscular injection of 1.0 mg neostigmine per 60 kg body weight. All showed fasciculations, most profusely after 30-60 minutes, on average in 6-7 muscle groups. Ten other tests with half the dosage provoked fasciculations in eight cases (2-3 muscle groups on average). Neostigmine-induced fasciculations should therefore not be interpreted as a sign of disease.