Reference voluntary jitter values using disposable monopolar needle electrodes in the extensor digitorum communis muscle.

OBJECTIVE: To measure normal variability in neuromuscular transmission in the extensor digitorum communis (EDC) muscle voluntarily activated using a disposable monopolar needle electrode (MNPE). METHODS: We examined the EDC muscle using MNPE in 50 healthy volunteers (12 male and 38 female, mean age: 41.5+/-12.9 years, age range: 18-74 years). The high-pass filter setting was 3 kHz. RESULTS: Jitter values are expressed as the mean consecutive difference (MCD) of 20 potential pairs. Mean MCD (n=50) was 21.3+/-3 micros (upper 95% confidence limit (CL): 27.3 micros). Mean MCD in all potential pairs (n=1000) was 21.3+/-6.6 micros (upper 95% CL: 34 micros). Mean MCD for the 18th highest value was 28+/-4.7 micros (upper 95% CL: 37.5 micros). CONCLUSION: The suggested practical upper limit for mean MCD was set to 28 micros; for outliers it was 38 micros. SIGNIFICANCE: The present study defines the normative value for jitter recorded with disposable MNPE, which is a low-cost alternative for the evaluation of neuromuscular transmission, although certain precautions must be taken.

The effect of oxcarbazepine on bone metabolism.

OBJECTIVE: Long term use of several antiepileptic drugs is known to cause alteration in bone metabolism. Therefore, we investigated the effect of new antiepileptic drug, oxcarbazepine, on bone metabolism. METHODS: Twenty eight patients who were on oxcarbazepin therapy (18 female, 10 males; mean age: 27.82 +/- 10.98 years (range: 15-45)) with no additional antiepileptic drug use history in one year period prior to the study and 28 control subjects were involved in the study. Measurement of calcium, phosphate, alkaline phosphatase and Vitamin D3 levels and bone density measurements with DEXA method were performed in patient and age-matched control groups. The baseline parameters were compared with the control group and with those measured at the end of one year. RESULTS: The biochemical (calcium, phosphate, alkaline phosphatase and Vitamin D3) parameters and densitometry values after one year of therapy were not different than the baseline values indicating that those were not affected by the therapy (P > 0.05). CONCLUSIONS: In previous studies, anticonvulsant drugs that induce enzymes increase bone degradation by causing vitamin D deficiency. According to the results of this study, oxcarbazepin with little effect on enzyme induction was shown not to affect bone mineral metabolism.

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.

Evaluation of neuromuscular transmission by using monopolar needle electrode.

OBJECTIVE: To evaluate the value of single-fibre electromyography (SFEMG) with monopolar electrode (MNPE) in revealing neuromuscular transmission dysfunction. MATERIAL AND METHODS: We examined the extensor digitorum communis muscle by using single-fibre electrode (SFE) and MNPE sequentially, in randomly assigned 20 healthy volunteers and in 17 patients with known myasthenia gravis (MG). The high-pass filter setting was 3 kHz for MNPE. Ten individual jitter values were calculated for each electrode in every muscle. Repetitive nerve stimulation (RNS) test on trapezius muscle was performed on 15 patients. RESULTS: In controls, the mean jitter values were 27 +/- 9 (10-59) micro s with SFE, and 21 +/- 7.2 (9-56) micro s with MNPE (P = 0.001). In the MG group, the mean jitter values were 52.4 +/- 38 (12-221) micro s with SFE, and 51.8 +/- 34.7 (12-179) micro s with MNPE. Both electrodes identified junction dysfunction in 14 patients. RNS revealed decrement in four patients but 11. CONCLUSION: SFEMG with SFE is still the gold standard; however, SFEMG with MNPE is superior to RNS like SFEMG with SFE.

Myasthenia gravis: how to treat?

Myasthenia Gravis is an acquired autoimmune disorder caused by a neuromuscular transmission defect which is clinically characterized by fluctuating weakness of voluntary muscles and fatigability. It can be diagnosed by clinical features, clinical, pharmacological and electrophysiological tests and serological evaluation. Treatment modalities include symptomatic treatment in the form of cholinesterase inhibitors and plasmapheresis and immunotherapy in the form of immunosuppressant medications, immunomodulating therapy and thymectomy. No single regimen is appropriate for all patients and up to now no mode of therapy has been proven to be clearly superior. The response to any form of treatment is difficult to assess because the severity of symptoms fluctuate. We retrospectively analyzed the clinical records of 33 myasthenia gravis patients which were managed at our clinic between 1995-2003. All patients were treated with anticholinesterase medications sometime during their treatment. Most patients recieved immunosupressant and/or immunomodulator therapy. Patients were referred for thymectomy when indicated. We evaluated the outcome with different treatment modalities, focusing on the role of thymectomy. We also investigated the possible correlations between clinicopathological features and clinical outcome. We conclude that as for the medical treatment of myasthenia gravis azathioprine plus steroid improves the outcome; and for the surgical treatment, early thymectomy should be performed in all generalize myasthenia patients.