Abstract:
Short-latency somatosensory evoked potentials (SEPs) represent electrophysiologic responses of the somatosensory pathways to stimulation. Somatosensory testing involves the application of a series of brief electrical stimuli over peripheral nerves (e.g., the median, peroneal, and tibial nerves) and recording the resulting evoked potentials over proximal portions of the nerves and central pathways which were stimulated, the plexus, spine and/or scalp. Action potentials recorded from these sites are averaged by a computer to improve signal clarity and then displayed in standard formats on the computer’s screen as well as in printed form.
A physician trained in interpreting clinical evoked potential studies analyzes the waveforms. The waveforms obtained should be described by nerve being stimulated, the recording sites, peak latencies, interpeak intervals (when appropriate), and amplitudes of the significant components. The nerves most commonly stimulated are the median nerve at the wrist for testing in the upper extremity, and the posterior tibial nerve at the ankle or common peroneal nerve (CPN) at the knee for the lower extremity.
SEPs evaluate the entire somatosensory pathway from the site of stimulation up to the cerebral cortex. It is possible to distinguish between lesions located in the peripheral nerve, in the dorsal column spinal cord pathway, or higher centers in the brain up through the cortex. In general there is no need for SEP in the diagnosis of most peripheral neuropathies because the conventional nerve conduction studies or needle EMG can identify these types of lesions and no added information is obtained from SEP. This local coverage determination discusses medically necessary indications and limitations for SEPs.
Indications:
Medicare will consider the use of short-latency somatosensory evoked potentials to be medically reasonable and necessary to assist in the diagnosis of certain neuropathologic states (as described below) in order to provide information for treatment decisions and also for intraoperative electrophysiological monitoring during spinal surgeries in which there is risk of additional nerve or spinal cord injury. However, it is not anticipated that such monitoring will be medically necessary for the typical cervical or lumbar root decompression procedures.
SEPs are used to evaluate the more proximal segments of nerves and the integrity of the central somatosensory pathways when abnormality of conduction through the brain and/or brainstem, spinal cord, and/or peripheral nerves is suspected. This utilization would include conditions such as multiple sclerosis, cervical spondylosis with myelopathy, coma, spinal cord trauma, myoclonus, Friedreich’s ataxia, syringomyelia, spinal cord tumors, spinal stenosis and other conditions where there is spinal cord compression.
Limitations:
SEP studies are appropriate only when a detailed clinical history and neurologic examination and appropriate diagnostic tests such as imaging studies, electromyogram, and nerve conduction studies make a lesion (or lesions) of the central somatosensory pathways a likely and reasonable differential diagnostic possibility.
The Medicare Physician Fee Schedule Database (MPFSDB) physician supervision indicator for CPT codes 95925, 92526, 95927 and 95938 have Level 21 for the technical component. Level 21 defined as: Procedure may be performed by a technician with certification under general supervision of a physician; otherwise must be performed under direct supervision of a physician. Procedure may also be performed by a PT with ABPTS certification without physician supervision.
Program Memorandum Transmittal B-01-28/Change Request 850 sets forth revised levels of physician supervision required for diagnostic tests payable under the Medicare Physician Fee Schedule. Effective July 1, 2001, certain codes in the range of CPT 95860-95937 were assigned new supervision levels (21, 22, 6a, 66, 77 or 77a). This implementation date would make it possible for physical therapists to acquire the certification required to perform these services without supervision. A physical therapist who is presently certified by the American Board of Physical Therapy Specialties can perform procedures assigned level of 21, 22, 66, 6a, 77, or 77a without supervision. These numeric levels assigned to the CPT codes are listed in the Medicare Physician Fee Schedule Database (MFSDB). Physical therapists who do not possess the ABPTS (American Board of Physical Therapy Specialties) certification by July 1, 2001, may continue to furnish those tests that require the certification if they have been furnishing such diagnostic tests prior to May 1, 2001.
Therefore, if authorized by state law Physical Therapists are allowed the technical portion of the test.
Nurse practitioners, clinical nurse specialists, and physician assistants are not defined as physicians under §1861(r) of the Act. Therefore, they may not function as supervisory physicians under the diagnostic tests benefit (§1861(s)(3) of the Act). However, when these practitioners personally perform diagnostic tests as provided under §1861(s)(2)(K) of the Act, §1861(s)(3) does not apply and they may perform diagnostic tests pursuant to State scope of practice laws and under the applicable State requirements for physician supervision or collaboration. (CMS Publication 100-02, Medicare Benefit Policy Manual, Chapter 15: Section 80: Requirements for Diagnostic X-Ray, Diagnostic Laboratory, and Other Diagnostic Tests).
CMS Publication 100-08, Program Integrity Manual, Chapter 13, Section 5.1 outlines that <> "reasonable and necessary" services are "ordered and/or furnished by qualified personnel." Provision of interpretation and/or supervision of these tests will be considered medically reasonable and necessary only if performed by appropriately trained providers. Training and expertise must have been acquired within the framework of an accredited residency and/or fellowship program in the applicable specialty/subspecialty. If this skill has been acquired as continuing medical education, the courses must be comprehensive, offered, sponsored or endorsed by an academic institution in the United States and/or by the applicable specialty/subspecialty society in the United States, and designated by the American Medical Association (AMA) or the American Osteopathic Association (AOA) as Category 1 Credit. Documentation of training must be available upon request.
It is expected that the training and experience would include:
- existing knowledge of the anatomic structures and neurophysiologic events underlying the generation of evoked potentials;
- the influences of stimulus parameters and other experimental variables on the responses that are recorded;
- relevant normative data and statistics; and
- the clinical significance and pathologic correlates of dysfunctional neural pathways demonstrated by evoked potential alterations.
It is anticipated only allopathic or osteopathic physicians will have the necessary training to meet these requirements.
