[The clinical diagnostic value of studies using magnetic stimulation]

To assess the clinical value of magnetic stimulation in various neurological disorders.

A retrospective, descriptive study.

Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Enschede.

Evaluation of motor pathways by magnetic stimulation of the human brain and peripheral nervous system is a new, noninvasive technique. A magnetic field pulse, produced by a wire coil, induces a small stimulating current applied to the motor cortex, cervical or lumbar spine or peripheral nerves. Muscle responses can be recorded by EMG recording systems in upper and lower extremities. Central conduction times can be obtained by computing latency differences between cortical and cervical or lumbar stimulation respectively. Magnetic motor evoked potentials were recorded in 60 patients with various neurological disorders, including multiple sclerosis, motor neuron disease, spinal and peripheral disorders.

Abnormal motor evoked potentials were recorded in 5 of 8 patients with multiple sclerosis, 5 of 5 with motor neuron disorder, 5 of 6 with hereditary spastic paraplegia, 12 of 16 with various spinal disorders, 6 of 11 with lower motor neuron disorders, 0 of 4 with hysterical paralyses and 7 of the 10 remaining patients. However, these abnormalities were non-specific and could be suspected in most cases after physical examination.

Magnetic stimulation is a painless and safe technique of which the clinical usefulness is still limited. It is likely that it will gain an important place in diagnosing neurological disorders, especially with involvement of motor pathways.