**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.