Eli's Rehab Report

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


Texas 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, which means you'll have to do some digging into which of these two terms suits the nerve best before deciding on your nerve conduction studies (NCS) code.

You've got three coding options for reporting NCS for either motor or sensory nerves:

• Motor NCS (95900, Nerve conduction, amplitude and latency/velocity study, each nerve; motor, without F-wave study and 95903, ... motor, with F-wave study) describes stimulation of motor nerve fibers at various points along a motor nerve. The physiatrist records responses from a muscle innervated by those fibers. Codes 95900 and 95903 differ in that the latter includes the recording of F-waves. F-waves are often used to measure nerve conduction velocity and are particularly useful for evaluating conduction problems in the proximal region of nerves (such as portions of nerves near the spinal cord).

Note: CPT does not contain a code to describe F-wave recording only.

• Sensory NCS (95904, ... sensory) involves stimulation of sensory fibers, with recording on a different site along the same nerve. And sensory NCS can also involve stimulation of a nerve containing motor and sensory fibers while recording over an exclusively sensory branch of the same nerve.

In 2002, CPT eliminated the term "or mixed" from the 95904 descriptor to avoid the misconception that 95904 bundled motor and sensory studies. In other words, instead of reimbursing for one motor study (95900/95903) and one sensory study (95904), the insurer mistakenly paid for a single "mixed" study (95904). A true mixed NCS, however, is separate and distinct from either sensory or motor studies.

You Be the Coder and Reader Questions were reviewed by Marvel Hammer, RN, CPC, CCS-P, CHCO, owner of MJH Consulting in Denver.