Distinctive electrophysiological features of denervated muscle in uremic patients.

Abnormal spontaneous activity is a hallmark of acute or subacute denervation of skeletal muscle, particularly in patients with uremic neuropathy. We report 5 patients in whom such activity was unexpectedly minimal or absent.

Novel measurement for automated interference pattern analysis of the diaphragm.

The automated interference pattern analysis for limb muscles was modified to take into account the unique features of the needle EMG of the diaphragm. The modification was successful in recording more accurately the number of small and large segments and the activity levels with inspiratory effort. "Clouds" were generated in ten healthy subjects.

Repetitive phrenic nerve stimulation study in normal subjects.

In patients with myasthenia gravis (MG), it may be difficult to determine by clinical methods if respiratory insufficiency is due to a defect in neuromuscular transmission. We therefore studied the technique of repetitive electrical stimulation of the phrenic nerve in 6 healthy subjects. It was easily performed and quite reproducible.

Subacute uremic and diabetic polyneuropathy.

We present 4 patients who had a subacute, predominantly motor polyneuropathy associated with diabetes mellitus and end-stage renal disease. Electrophysiological studies and muscle biopsy indicated a primary axonal degeneration of nerve with secondary segmental demyelination, and mild to moderate, acute and chronic denervation of muscle. A relative absence of denervation potentials on needle electromyography was an unusual feature.

Central and peripheral respiratory electrophysiological studies in myotonic dystrophy.

Acute and chronic respiratory failure is a common and potentially life-threatening feature in patients with myotonic dystrophy (MD). The causes may be varied, and can involve both the central and peripheral nervous system. To evaluate the incidence of respiratory muscle involvement and the function of the central motor inspiratory pathway to phrenic motor neurons we performed magnetic stimulation of the cortex and cervical spinal cord, phrenic nerve conduction studies and needle EMG of diaphragm and intercostal muscles in 25 patients with MD.