Reusable ground strap and plate

The ground in nerve conduction sits between the stimulation point and the recording point, and it decides the size of the stimulus artefact. An inadequate ground gives an initial deflection that masks the onset of the response, and the latency becomes impossible to measure cleanly.

The velcro strap is the most practical solution: it tightens around the wrist, forearm or leg, it carries its own lead, and it consumes nothing. Three lengths, 25, 40 and 70 cm, cover from a child wrist to an adult thigh.

The 30 mm plate is the other approach, held by a strap or tape. It offers a frank metal surface, useful when the strap cannot be placed.

In both cases contact is made with conductive gel. A ground applied dry to unprepared skin does not work, and that is the commonest mistake on this channel.