Advertisement for orthosearch.org.uk
You currently have no access to view or download this content. Please log in with your institutional or personal account if you should have access to through either of these
The Bone & Joint Journal Logo

Receive monthly Table of Contents alerts from The Bone & Joint Journal

Comprehensive article alerts can be set up and managed through your account settings

View my account settings

Spine

Neurophysiological tests of respiratory function by compound muscle action potentials from the diaphragm

DETECTION OF LESIONS IN THE HIGHER CERVICAL CORD



Download PDF

Abstract

We recorded compound muscle action potentials (CMAPs) from the diaphragm in 15 normal volunteers, nine patients with lesions of the lower cervical cord (C5 to C8), one completely quadriplegic patient (C6) and seven patients with lesions at a higher cervical level (C1 to C4). Transcranial magnetic stimulation and electrical stimulation of the phrenic nerve were carried out.

When the centre of the coil was placed on the interauricular line at a point 3 cm lateral to the vertex on the scalp, the CMAPs from the diaphragm had the largest amplitude and the shortest latency. There was no difference in the mean latency of the CMAPs recorded by transcranial magnetic stimulation in the normal volunteers and in the patients with lesions of the lower cervical cord. In the quadriplegic patient, the latency of the CMAPs was not delayed, but was prolonged in the patients with lesions at a higher level. Those evoked by electrical stimulation of the phrenic nerve were not prolonged in the patients with higher lesions.

Our findings suggest that the prolongation of the latency by transcranial magnetic stimulation reflects dysfunction of the higher cervical cord. The combination of transcranial magnetic stimulation and electrical stimulation of the phrenic nerve can detect the precise level of the lesion in the motor tract to the diaphragm.


Correspondence should be sent to Dr Y. Kawaguchi.

For access options please click here