RECORDING ELECTRODES - FOR SENSORY STUDIES

The arrangement of active (G1) electrode, reference electrode (G2), and ground electrodes follows the same principle as in motor conduction, except that, in place of muscle, G1 and G2 electrodes are placed over the sensory nerves.

Sensory nerves are evaluated by stimulating a nerve while recording from the same nerve at a different site.

Antidromic sensory NCSs are performed by stimulating nerve proximally and recording distally along the sensory nerves, whereas orthodromic studies are obtained by stimulating it distally and recording it proximally along the nerve (i.e. recording sensory potentials as they travel towards CNS). See figure.

Ring electrodes are convenient to record the sensory potentials from digital nerves over the proximal and distal interphalangeal joints.


Reference:

1. Sethi RK, Thompson LL. The Electromyographer’s Handbook, Boston/Toronto: Little, Brown and Company, 2nd edition
2. Aminoff, MJ. Electrodiagnosis in Clinical Neurology: Nerve conduction studies, New York: Churchill Livingston, 4th edition