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In humans, botulinum neurotoxin (BoNT) serotype A (BoNT/A) is a useful therapeutic tool, but different BoNT serotypes may be useful when a specific immune resistance related to BoNT/A is proved. BoNT serotype F (BoNT/F) was injected into human muscles but its effects are shorter compared to BoNT/A, whereas BoNT serotype B (BoNT/B) is effective in humans only if injected at very high doses. BoNT serotype C (BoNT/C) has a general profile of action similar to BoNT/A. Nevertheless, a comparison between these different BoNTs in human has not yet been reported. To establish the general profile of these different BoNTs in humans and the spread in near and untreated muscles we conducted an electrophysiological evaluation in 12 healthy volunteers by injecting BoNT/A (BOTOX 15MU), BoNT/B (NeuroBloc 1500MU), BoNT/F (15MU), BoNT/C (15MU) and a saline solution (placebo) in the abductor digiti minimi muscle (ADM) in a double-blind manner. The compound muscle action potential (CMAP) amplitude variation, before and at 2, 4, 6 and 8 weeks after the injections, was evaluated in the ADM, the fourth dorsal interosseus, the first dorsal interosseus and the abductor pollicis brevis APB. We detected an earlier recovery for BoNT/F when compared to the other BoNTs. No significant differences in the local or distant BoNT spread was observed among the different serotypes. We conclude that in humans, BoNT/B and BoNT/C have a general profile similar to BoNT/A and as such these serotypes could be alternative therapies to BoNT/A. BoNT/F might be useful when only a short duration of neuromuscular blockade is required., (Copyright 2004 Movement Disorder Society)

Objectives: Botulinum neurotoxin serotype A (BoNT/A) is a valid therapy for dystonia but repeated BoNT/A injections may induce a clinical immuno-resistance that could be overcome by using other BoNT serotypes. In vitro experiments and our preliminary investigations in vivo, indicate that botulinum neurotoxin serotype C (BoNT/C) could be an effective alternative to BoNT/A. Moreover, in cultured neurons 'in vitro' BoNT/C has been reported to be more toxic than BoNT/A., Methods: To verify this possibility, we compare the effect of BoNT/C and BoNT/A on the motor units count in humans by using the electrophysiological motor unit number estimation (MUNE) technique ('multiple point nerve stimulation'). Preliminarily, BoNT/C and BoNT/A dosage was calibrated in a mouse hemidiaphragm neuromuscular junction preparation. Subsequently, 8 volunteers were treated with 3IU of BoNT/C in the extensor digitorum brevis muscle of one foot and 3IU of BoNT/A in the contralateral one. Other 4 subjects were similarly injected at higher doses (10IU of BoNT/C or BoNT/A) to detect a possible dose-toxic effect., Results: In both groups, no statistically significant variations in MUNE counting or single motor unit potential size were detected after 4 months from injections, when it was evident a recovery from the BoNTs blockade., Conclusions: We conclude that BoNT/C, similarly to BoNT/A, is safe and effective in humans and it could be proposed for a clinical use.

Muscular hypotrophy due to arm or leg immobilization (MH) in absence of neuromuscular pathologies was tested by EMG spectral analysis, in order to identify a possible neurophysiological method able to analyze this kind of particular clinical picture. Two different groups of patients were tested. In group 1 the patients were suffering from vastus medialis muscle MH due to meniscus surgery, in group 2 the patients were suffering from biceps brachii muscle MH after humerus fracture. A significant difference between normal and pathological muscles was found and the methods may be useful in the neurophysiological evaluation of MH.