Nerve Conduction Studies (95900-95904) (February 2008) February 2008 page 2
Coding Communication:Nerve Conduction Studies (95900-95904)
The following AMA responses to six commonly asked questions help to clarify concerns about coding for nerve conduction studies.
Why are nerve conduction studies performed?
Nerve conduction studies (NCSs) are performed to aid in the diagnoses of diseases and injuries of the peripheral nervous system. Nerve conduction studies assess the speed (conduction velocity and/or latency), size (amplitude), and shape of the response to an applied stimulus. Pathological findings include conduction slowing, conduction block, absent nerve response, and/or low amplitude response. NCS results can also assess the degree of demyelination and axon loss in the segments of the nerve studied. This portion of the electrodiagnostic medicine (EDX) evaluation is typically a non-invasive procedure performed either by a physician or by a qualified health care professional alone or technologist under direct supervision of the physician.
How are NCSs performed?
Motor NCSs (95900 and 95903) are performed by applying electrical stimulation at various points along the course of a motor nerve while recording the electrical response from an appropriate muscle. Response parameters include amplitude, latency, configuration, and motor conduction velocity.
Sensory NCSs (95904) are performed by applying electrical stimulation near a nerve and recording the response from a distant site along the nerve. Response parameters include amplitude, latency, configuration, and sensory conduction velocity.
Mixed NCSs (code 95904, which may still be used to code for mixed nerve studies, even though the reference to the term mixed was dropped from the descriptor) are performed by applying electrical stimulation near a nerve containing both motor and sensory fibers (ie, a mixed nerve) and recording from a different location along that nerve that also contains both motor and sensory nerve fibers. Response parameters include amplitude, latency, configuration, and both sensory and motor conduction velocities.
How are nerve conduction studies reported when performed on multiple places along a nerve and branches?
CPT code 95904, Nerve conduction, amplitude and latency/ velocity study, each nerve; sensory, identifies a specific nerve's ability to conduct electrical signals within the nervous system. The testing can be performed for different parts of a specific nerve (ie, different segments of a given nerve) to identify local pathological responses, if they exist. CPT code 95904 is reported only once when multiple sites on the same nerve are stimulated or recorded. However, if nerve conduction studies are performed on two different branches of a given motor or sensory nerve, then the appropriate code from the 95900-95904 series may be reported for each branch studied.
How is Appendix J used to define nerves and their branches?
Appendix J in the CPT codebook lists the individual branches of sensory, motor, and mixed nerves. A section of the appendix is provided below to illustrate the following examples.
Excerpted from Appendix J
Sensory and Mixed Nerves Assigned to Code 95904
1.Upper extremity sensory and mixed nerves
1.Lateral antebrachial cutaneous sensory nerve
2.Medial antebrachial cutaneous sensory nerve
3.Medial brachial cutaneous sensory nerve
1.Median sensory nerve to the first digit
2.Median sensory nerve to the second digit
3.Median sensory nerve to the third digit
4.Median sensory nerve to the fourth digit
5.Median palmar cutaneous sensory nerve
6.Median palmar mixed nerve
5.Posterior antebrachial cutaneous sensory nerve
6.Radial sensory nerve
1.Radial sensory nerve to the base of the thumb
2.Radial sensory nerve to digit 1
1.Ulnar dorsal cutaneous sensory nerve
2.Ulnar sensory nerve to the fourth digit
3.Ulnar sensory nerve to the fifth digit
4.Ulnar palmar mixed nerve
The guidelines in Appendix J of CPT 2008 indicate that "each nerve constitutes one unit of service." From a CPT coding perspective, as long as the testing is performed on different nerves or nerve branches on the list (Appendix J), multiple units should be reported. For example, it is appropriate to report one unit of service for each of the individual branches of the median nerve when performing sensory or mixed nerve testing. Referring back to the excerpt from Appendix J on page 2, items I.D.1- I.D.6 each constitute one unit of service. Therefore, from a CPT coding perspective, the median sensory nerve to the second digit (I.D.2) and the median palmar mixed nerve (I.D.6) are reported with CPT code 95904 used twice, once for each branch tested.
Another specific example of two distinct branches of a sensory nerve is testing performed on the ulnar sensory nerve (stimulate on anterior aspect of wrist, record from the fifth digit [I.G.3]). Another branch is the dorsal cutaneous branch of the ulnar sensory nerve (I.G.1.), which is tested by stimulating above the wrist on the posterior aspect of the wrist and recording from the dorsum of the hand.
Can you explain the parenthetical note that indicates that one should "report 95900, 95903, and/or 95904 only once when multiple sites on the same nerve are stimulated or recorded?"
This descriptor language is intended to clarify that testing of a single nerve in any of the three nerve conduction CPT codes includes all different stimulation sites along the individual motor, sensory, or mixed nerves that are tested. To qualify as a single nerve conduction study, please refer to Appendix J of the CPT codebook (each line on the list of nerves refers to a different nerve which, when tested, should be reported as an individual unit of the appropriate code). This means that if "inching" (or studying the same nerve by moving the stimulating electrode closer to the recording electrode) is used to pinpoint a problem in a nerve, it is still reported as one unit of the CPT code for the test.
When nerve conduction studies are performed on two distinct branches of a given motor or sensory nerve, then it is appropriate to report more than one code from the 95900- 95904 series of codes. It should be noted that most nerves have a contralateral counterpart, and bilateral testing is often necessary for comparison; if comparison is needed, the nerve testing on each side may be reported separately. In addition, the motor (95900 or 95903) testing is distinct from sensory (95904) studies on an individual nerve. A mixed nerve inherently involves motor and sensory testing at the same time and is reported with 95904 only.
Is there a limit of studies typically performed for a specific diagnosis?
The table that closes out Appendix J in the codebook indicates the number of studies commonly performed per diagnosis. For example, for bilateral carpal tunnel syndrome, six sensory nerve conduction studies may be reasonable in order to arrive at a final diagnosis in 90% of the patients with that single diagnosis. In almost all studies, this will appropriately include evaluation of one or more nerves that have normal test results.