Neurology & Pain Management Coding Alert

Question: What is a -mixed- nerve? How should I report nerve conduction studies for a mixed nerve?


Arkansas Subscriber

Answer: When you see the term -mixed nerve,- you should note that most of the peripheral nerves in your body are mixed nerves in that they contain both motor and sensory nerve fibers. You have few purely sensory or motor nerves.

This may seem to cloud the possibility of tracking down which nerves are -mixed- for the purposes of coding, but with the addition of Appendix J in CPT 2006, making this determination became much easier.

The Electrodiagnostic Medicine Listing of Sensory, Motor, and Mixed Nerves not only spells out which nerves constitute separately identifiable sites for nerve conduction but also divides them into motor or sensory/mixed categories.

For nerves identified as sensory or mixed, the appendix points you to 95904 (Nerve conduction, amplitude and latency/velocity study, each nerve; sensory).

Know the difference: For the purposes of coding, 95904 describes both sensory and mixed nerve studies, but that doesn't mean these two studies are the same thing. In both cases, the neurologist stimulates a nerve at one site and records over the same nerve at another site. If both the stimulation and recording sites have sensory and motor fibers, it is a mixed nerve study. If either the stimulation or the recording site have purely sensory fibers, it a sensory NCS.