Electromyography tests in patients with implanted cardiac devices are safe regardless of magnet placement.

Methods: We compared the problems or complications associated with electrodiagnostic testing in 77 patients with implanted cardiac devices. Thirty tests were performed after magnet placement, and 47 were performed without magnet application.

Results: All electrodiagnostic tests were performed safely in all patients without any serious effect on the implanted cardiac devices with or without magnet placement.

Clinical utility of sensory nerve conduction of medial femoral cutaneous nerve.

Introduction: In this investigation we report on the clinical utility of sensory nerve conduction studies of the medial femoral cutaneous (MFC) nerve.

Methods: Sensory nerve conduction of the MFC nerve was assessed in 22 patients for whom this test was considered clinically necessary.

Results: MFC nerve conduction was abnormal in 4 cases of MFC neuropathy.

Abnormal dip phenomenon: a characteristic electrophysiological marker in interdigital neuropathy of the foot.

Objective: The nerve conduction findings in interdigital neuropathy of the foot (IDN; Morton's neuroma) have rarely been reported. We analyzed the nerve conduction data in 23 patients with suspected IDN studied between 1982 and 2002.

Method: Diagnosis of IDN was made on the basis of clinical features.

Electrophysiological differences in seropositive and seronegative Lambert-Eaton myasthenic syndrome.

In order to determine whether there is any difference between voltage-gated calcium-channel antibody (VGCC-Ab)-positive and -negative groups in Lambert-Eaton myasthenic syndrome (LEMS), we compared the clinical and electrophysiological features between 13 patients with VGCC-Ab and 6 VGCC-Ab-negative patients. No obvious difference was observed in the various clinical features or findings on single-fiber electromyography between seropositive and seronegative cases. In seropositive cases, the compound muscle action potential (CMAP) amplitude was lower but the increment on post-exercise facilitation (PEF) and high-rate stimulation (HRS) was significantly higher than in the seronegative group, indicating that the repetitive nerve stimulation (RNS) test in the seropositive group is more typical of LEMS and more severe.

Repetitive nerve stimulation of facial muscles in MuSK antibody-positive myasthenia gravis.

To better define electrophysiological abnormalities in myasthenia gravis (MG) patients with muscle-specific tyrosine kinase (MuSK) antibodies (Ab), we compared electrophysiological features of 14 MuSK Ab-positive, 73 acetylcholine receptor antibody (AChR Ab)-positive, and 22 MuSK and AChR Ab-negative (seronegative) patients with generalized disease. Repetitive nerve stimulation (RNS) abnormalities were observed in 86% of MuSK Ab-positive and 82% of AChR Ab-positive patients but in only 55% of seronegative patients. RNS decrements in the orbicularis oculi were more common and severe in the MuSK Ab-positive patients than the other two groups.

Electrophysiological diagnostic criteria of Lambert-Eaton myasthenic syndrome.

Various parameters of the repetitive nerve stimulation (RNS) test of the abductor digiti quinti muscle were analyzed statistically in 34 patients with Lambert-Eaton myasthenic syndrome (LEMS). The sensitivity and specificity of the increments after exercise and after 50-HZ stimulation for the diagnosis of LEMS were compared with reference values in 40 normal subjects and data from 538 tests in patients with myasthenia gravis (MG). When we used a 100% increment (the "gold standard") as the normal limit for the postexercise facilitation (PEF) or the high-rate stimulation (HRS) test, the diagnosis of LEMS was confirmed in 29 (85%) cases.

Myokymia, neuromyotonia, dermatomyositis, and voltage-gated K+ channel antibodies.

A young woman presented with facial myokymia in association with dermatomyositis. There was no evidence of peripheral neuropathy. Needle electromyography showed prominent myokymic discharges and brief neuromyotonic discharges in addition to many small-amplitude, short-duration motor unit potentials.

Respiratory failure in lambert-eaton myasthenic syndrome precipitated by calcium-channel blockers: report of a case and literature review.

There have been a few reports in the literature documenting the effects of calcium-channel blockers in Lambert-Eaton myasthenic syndrome (LEMS). We report a case of a patient with LEMS who developed respiratory failure after administration of diltiazem and verapamil. A patient with LEMS, associated with small-cell carcinoma in remission, developed multifocal atrial tachycardia, necessitating the use of diltiazem and verapamil, which led to respiratory failure and intubation 5 days after admission.