Electrophysiological Findings at Early Stage of Guillain-Barré Syndrome / 中国康复理论与实践

@#ObjectiveTo explore the characteristics of electrodiagnostic abnormalities at early stage of Guillain-Barré syndrome, and to determine which is the common most frequent and sensitive nerve conduction pattern. MethodsWe retrospectively reviewed the neurophysiological studies of all patients with Guillain-Barré Syndrome discharged from S. Anna Hospital in Ferrara, Italy from 2001 to 2007. Results26 patients (81%) had abnormal F wave. 11 patients (34%) had low amplitude or absent SAPs. 13 patients (41%) reduced compound muscle action potential, slowed conduction velocity, prolonged distal latency and conduction block were more fewer (respectively 12.5%, 25% and 6%). Only in 1 patient we had normal findings. ConclusionF wave is more sensitive than nerve conduction study at early stage of Guillain-Barré Syndrome. Abnormalities of F wave (frequency reduced, prolonged latency) are the most frequent and earlier test for Guillain-Barré Syndrome.

Botulinum toxin type A reduces capsaicin-evoked pain and neurogenic vasodilatation in human skin.

The effect of Botulinum Toxin type A (BoNT/A) on pain and neurogenic vasodilatation induced by application to the human skin of thermal stimuli and capsaicin was evaluated in a double blind study. A capsaicin cream (0.5 ml of a 0.075%) was applied to the skin of both forearms of eighteen subjects randomly pretreated with either BoNT/A (Botox) or 0.9% saline (NS). Capsaicin was applied to a skin area either inside (protocol A) or adjacent to the BoNT/A treated area (protocol B). Pre-treatment with BoNT/A did not affect thermal-specific and thermal-pain thresholds (by quantitative sensory testing). However, capsaicin-induced pain sensation (by a visual analogue scale), flare area (by acetate sheet) and changes in cutaneous blood flow (CBF, by laser Doppler flowmetry) were reduced when capsaicin was administered inside (protocol A) the BoNT/A treated area. In Protocol B, capsaicin-induced pain was unchanged, and capsaicin-induced flare/increase in CBF were reduced only in the area treated with BoNT/A, but not in the BoNT/A untreated area. Results indicate that (i) BoNT/A reduces capsaicin-induced pain and neurogenic vasodilatation without affecting the transmission of thermal and thermal-pain modalities; (ii) reduction in capsaicin-induced pain occurs only if capsaicin is administered into the BoNT/A pretreated area; (iii) reduction in neurogenic vasodilatation by BoNT/A does not contribute to its analgesic action. BoNT/A could be tested for the treatment of conditions characterised by neurogenic inflammation and inflammatory pain.

The excitability of the trigeminal motor system in sleep bruxism: a transcranial magnetic stimulation and brainstem reflex study.

AIMS: Since sleep bruxism (SB) is characterized by grinding and clenching of the teeth during sleep and could be an exaggerated manifestation of normal spontaneous rhythmic masticatory muscle activity, the aim of this study was to obtain a neurophysiological assessment of the excitability of the central jaw motor pathways in patients with signs and symptoms suggestive of SB. METHODS: A total of 30 subjects diagnosed with SB on the basis of self-report of tooth grinding were studied using the "recovery cycle" of the masseter inhibitory reflex (MIR) elicited by electric and magnetic stimulation of the mental nerves and by recording the motor potentials evoked in masseter muscles by transcranial magnetic stimulation. Tests were done during daytime, when the subjects were awake. The data obtained were compared with data from a population of normal subjects. RESULTS: In the putative SB patients and in normal subjects, the MIRs evoked by single electric and magnetic stimuli were similar. With paired stimuli, the degree of suppression of the late silent period was significantly lower (P < .01) in the patients compared to normal subjects, particularly for magnetic stimuli, at various interstimulus intervals. No significant differences were found between the 2 groups of subjects in the masseter motor potentials evoked by transcranial magnetic stimulation. CONCLUSION: Although the data were only obtained during wakefulness in patients self-reporting signs and symptoms suggestive of SB, the findings suggest that an abnormal excitability of the central jaw motor pathways may be present in SB subjects. This increased excitability could derive from an impaired modulation of brainstem inhibitory circuits and not from altered cortical mechanisms. These results support the view that bruxism is mainly centrally mediated and that it involves subcortical structures. The study also indicates that use of the MIR elicited by the double-shock technique could be valuable in the evaluation of bruxism.

Preoperative and postoperative electroneurographic facial nerve monitoring in patients with parotid tumors.

OBJECTIVE: To assess the value of clinical (House-Brackmann grading) and neurophysiological (conventional electroneurography) monitoring of the facial nerve before and after (at day 10 and day 80) microsurgical parotidectomy in a group of patients with parotid tumors. STUDY DESIGN AND SETTING: From January 7, 1999, to February 27, 2001, 33 patients were evaluated for parotid neoplasms confirmed by cytologic examination: 27 were benign and 6 were malignant epithelial tumors. All patients underwent preoperative electroneurography of the affected side and the normal contralateral side. RESULTS: Preoperatively, 27 of 33 patients with benign lesions had normal facial nerve function on clinical and neurophysiological evaluation, while 3 of 6 patients with malignant lesions showed compound muscle action potential abnormalities of amplitude and latency, in the absence of facial nerve deficits. At the first postoperative evaluation, 2 of 6 patients with epithelial cancer and 4 of 27 patients with benign tumors had an absence of voluntary activity and compound muscle action potentials after nerve stimulation at the stylomastoid foramen; 1 patient with a malignant lesion and 5 patients with benign tumors had a transient facial palsy with amplitude reduction or latency prolongation of compound muscle action potential. This abnormality persisted in 2 of 27 patients at the second evaluation performed at day 80 after surgery. In 2 of 6 patients with malignant lesions, the day-80 electroneurogram showed a complete absence of nerve conduction. CONCLUSION: Electroneurography is a sensitive tool for monitoring clinically silent facial nerve function deficits in the context of preoperative tumor-induced damage and postsurgical early and late follow-up of nerve function.

Botulinum neurotoxin serotypes A and C do not affect motor units survival in humans: an electrophysiological study by motor units counting.

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.