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May 1962

Reversible Effects of Ultrasound on Spinal Reflexes

Author Affiliations

From the Medical Acoustics Laboratory of the Department of Surgery (Neurosurgery), Massachusetts General Hospital, and the Department of Physiology, Harvard Medical School.
Research Fellow of the National Foundation for Infantile Paralysis and of the Neurosurgical Service, Department of Surgery, Massachusetts General Hospital (Dr. Shealy).

Arch Neurol. 1962;6(5):374-386. doi:10.1001/archneur.1962.00450230036005

Introduction  This investigation is one of 3 studies1,2 undertaken so explore the potentialities of high-intensity ultrasound in experimental neurology. Recently there has been increasing interest in this field. Techniques have been developed for producing lesions of constant size and shape at selected sites in the central nervous system.3-6 Less attention has been paid to the effects of ultrasound on functioning neural circuits. Concurrent studies on the peripheral nerves of frogs1 and cats2 show that focused ultrasound will block axonal conduction reversibly or irreversibly, depending upon dosage. The smallest axons, the delta fibers and the C fibers, are most sensitive to irradiation.In these experiments a segment of the cat's spinal cord was irradiated with ultrasound; the effects of the irradiation on the transmission of reflexes through that segment were followed oscillographically, and histological studies were carried out on the irradiated tissue.Spinal reflexes, elicited and recorded