Investigation of neuromuscular transmission in some rare types of migraine.

The aim of this study was to delineate any dysfunction of neuromuscular transmission (NMT) by single-fibre electromyography (SFEMG) in some rare types of migraine. Recent studies have shown subclinical dysfunction of NMT in migraine with aura and cluster headache by using SFEMG, whereas another recent study has shown NMT to be normal in familial hemiplegic migraine (FHM) with CACNA1A mutations. Thirty patients with rare primary headache syndromes [18 with sporadic hemiplegic migraine (SHM), six with FHM and six with basilar-type migraine (BM)] and 15 healthy control subjects without any headache complaints underwent nerve conduction studies, EMG and SFEMG during voluntary contraction of the extensor digitorum communis muscle. Ten to 20 different potential pairs were recorded and individual jitter values calculated. The results obtained from patient groups were compared with those from the normal subjects. Of 600 individual jitter values of the patients, 27 (4.5%) were abnormally high, whereas only 3/205 (1.5%) jitter values from normal subjects were abnormal. Abnormal NMT was found in 4/30 (13.3%) patients (three SHM and one BM), but in none of the control subjects. Only in SHM patients was the number of individual abnormal jitter values slightly but significantly different from normal controls. The present study demonstrates that subclinical NMT abnormality is slightly present in only SHM and BM patients, but not in FHM patients.

Subclinical neuromuscular transmission abnormality detected by single-fibre EMG is more pronounced in cluster headache than in migraine with aura.

The aim was to investigate neuromuscular transmission (NMT) by single-fibre EMG (SFEMG) in a large series of patients having migraine with aura (MA) or cluster headache (CH). Recent studies using SFEMG have shown subclinical dysfunction of NMT in MA and CH. Forty-three patients having MA, 51 with CH and 38 healthy control subjects underwent nerve conduction studies, EMG and SFEMG during voluntary contraction of the extensor digitorum communis muscle. Twenty different potential pairs were recorded and individual, mean and total abnormal individual jitter values were calculated. The results obtained from MA patients were compared with those from CH patients. In MA patients, 32 of 860 jitters were abnormally high, whereas 73 of 1020 of the jitters showed this abnormality in CH patients. None of the control subjects, five MA patients (11.6%) and 11 CH patients (21.6%) were designated as having subclinical NMT abnormality. Thus, patients having junction dysfunction were significantly more common in the CH group. The subclinical NMT abnormality shown by SFEMG is more common in CH than in MA. These two primary headache syndromes may have some shared functional abnormality of NMT constituents which is more evident in CH.

Spinal accessory nerve function after neck dissections.

The aim of this study was to evaluate spinal accessory nerve function after functional neck dissection (FND) and radical neck dissection (RND) by monitoring the nerve with electromyographic (EMG) examinations. A prospective, double-blind, clinical study was undertaken in 21 patients (42 neck side dissections) operated on for head and neck malignant diseases, separated into two groups: 10 neck sides in the RND group and 32 neck sides in the FND group. Electromyographic examinations were performed pre-operatively and post-operatively in the third week and third and ninth months. Additionally, a questionnaire, modified from the neck dissection impairment index, was applied to all the patients in order to assess shoulder function in the ninth post-operative month. All patients had maximum EMG scores pre-operatively. Following the operation, motor amplitudes decreased in both groups. At the third post-operative month, amplitudes decreased to their lowest values. As expected, the decreases in amplitude and EMG score were more prominent in the RND group. Following reinnervation, the amplitudes of the trapezius motor response increased in the FND group but never reached pre-operative values (during the time of follow up). The FND group scores for pain, neck and shoulder stiffness, and disability in heavy object lifting, light object lifting and reaching overhead were significantly lower than those of the RND group. In FND, one aims to preserve anatomically the spinal accessory nerve, and it is presumed to be intact after the procedure. However, using EMG nerve function monitoring, our study revealed that profound spinal nerve injury was detected immediately after FND surgery, which tended to improve over subsequent months but had not regained its original function by the end of the ninth post-operative month.