Summary Of Evidence

N/A

Analysis of Evidence

N/A 

Notice: It is not appropriate to bill Medicare for services that are not covered (as described by this entire LCD) as if they are covered. When billing for non-covered services, use the appropriate modifier.

Compliance with the provisions in this policy may be monitored and addressed through post payment data analysis and subsequent medical review audits.

History/Background and/or General Information

Neurophysiology Evoked Potentials (NEPs) for the purpose of this LCD include:

1. Somatosensory Evoked Potentials/Responses (SEPs/SERs),
2. Brainstem Auditory Evoked Potentials/Responses (BAEPs/BAERs), and
3. Visual Evoked Potentials/Responses (VEPs/VERs)

Evoked potential studies are recorded electrical responses to stimulation of a sensory system. When a sensory impulse reaches the brain, a specific Electroencephalographic (EEG) response is produced (evoked) in the cortical area appropriate to the modality and site of the stimulus. By computer averaging techniques, the evoked responses of repetitive stimuli can be separated from the spontaneous EEG activity. Evoked potentials are clinically useful in evaluating the functional integrity of the somatosensory or special sensory pathways. Different latencies and wave patterns help to localize lesions ranging from the end organ through the nervous system to the cerebral cortex. Often defects in these pathways are not otherwise evident. Evoked potentials are also used to monitor neural pathways when patients are anesthetized during surgery and to document brain death. The following are tests that evaluate potentials evoked by stimulation of the peripheral or cranial nerves:

SEPs/SERs evaluate the pathways from nerves in the extremities through the spinal cord, to the brainstem or cerebral cortex upon stimulation of peripheral axon.

SEPs have an advantage in that it evaluates the entire somatosensory pathway and it is possible to distinguish between lesions located in the peripheral nerve, in the dorsal column pathway, or both.

VEPs/VERs evaluate the visual nervous system pathways from the eyes to the occipital cortex of the brain. VEP or VER involves stimulation of the retina and optic nerve with a shifting checkerboard pattern or flash method. This external visual stimulus causes measurable electrical activity in neurons within the visual pathways. This is called the Visual Evoked Response (VER) and is recorded by electroencephalography electrodes located over the occiput. Using special computer techniques, the evoked responses measured over multiple trials are amplified and averaged. A characteristic waveform is produced. With pattern-shift VER, the waveform normally appears as a straight line with a single positive peak (100 msec after stimulus presentation). Abnormalities in this characteristic waveform may be seen in a variety of pathologic processes involving the optic nerve and its radiations. Pattern-shift VER is a highly sensitive means of documenting lesions in the visual system. It is especially useful when the disease process is subclinical, e.g., ophthalmologic exam is normal and patient lacks visual symptoms.

BAEPs/BAERs evaluate the auditory nerve pathways from the ears through the brain stem. A clicking sound is presented to one ear at a time. The electrical activity of this signal is recorded by electrodes on the scalp. The averaged response is displayed as a waveform that contains peaks and troughs, which correspond to various points along the hearing pathway. The time between these peaks is measured and compared to normal data. A delay in a component of the response might indicate an abnormality at specific anatomic sites in the acoustic nerve or brainstem.

Covered Indications

Somatosensory Evoked Potentials and Responses (SEPs/SERs) are appropriate for the following indications:

1. Spinal cord trauma
2. Degenerative, non-traumatic spinal cord lesions (e.g., cervical spondylosis with myelopathy)
3. Multiple sclerosis
4. Spinocerebellar degeneration
5. Myoclonus
6. Coma
7. Intraoperative monitoring
8. Subacute combined degeneration
9. Other diseases of myelin (e.g., adrenoleukodystrophy, adrenomyeloneuropathy, metachromatic leukodystrophy, and Pelizaeus-Merzbacher disease)
10. Syringomyelia
11. Hereditary spastic paraplegia

 Brainstem Auditory Evoked Potentials and Responses (BAEPs/BAERs) are appropriate:

1. For one or more of the following conditions:
   
   • Asymmetric hearing loss
   • Unilateral tinnitus
   • Sudden hearing loss
   • Cerebellopontine angle tumor
   • Demyelinating disorder
   • Functional hearing loss
   • Ototoxic drug therapy monitoring including chemotherapy or antibiotics
   • Auditory neuropathy
   • Acoustic neuroma
2. Preoperative baseline for:
   
   • Posterior fossa surgery
   • Cochlear implant
3. Postoperative testing for:
   
   • Cochlear implant

Note: Please refer to LCD L35007, Vestibular and Audiologic Function Studies for additional information regarding BAEPs/BAERs.

Visual Evoked Potentials or Responses (VEPs/VERs) are appropriate for the following indications:

1. Confirm diagnosis of multiple sclerosis when clinical criteria are inconclusive.
2. Detect optic neuritis at an early, subclinical stage.
3. Evaluate diseases of the optic nerve, such as:
   
   • Ischemic optic neuropathy
   • Pseudotumor cerebri
   • Toxic amblyopias
   • Nutritional amblyopias
   • Neoplasms compressing the anterior visual pathways
   • Optic nerve injury or atrophy
   • Hysterical blindness (to rule out)
4. Monitor the visual system during optic nerve (or related) surgery (monitoring of short-latency evoked potential studies).

 Limitations

The following are considered not reasonable and necessary and therefore will be denied:

1. 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.
2. There is no need for SEPs in the diagnosis of most neuropathies because the conventional nerve conduction study can identify them and no added information is obtained from SEPs.

Place of Services (POS)

For additional information on services performed in an Independent Diagnostic Testing Facility (IDTF), please refer to Local Coverage Determination (LCD) L35448 Independent Diagnostic Testing Facility (IDTF).

Provider Qualifications

Testing shall be performed by physicians who have evidence of training, and expertise to perform and interpret these tests. Physicians must have knowledge, training, and expertise to perform and interpret these tests, and to assess and train personnel working with them. This Training and expertise must have been acquired within the framework of an accredited school, residency or fellowship program.

Notice: Services performed for any given diagnosis must meet all of the indications and limitations stated in this policy, the general requirements for medical necessity as stated in CMS payment policy manuals, any and all existing CMS national coverage determinations, and all Medicare payments rules. Refer to Billing and Coding: Neurophysiology Evoked Potentials (NEPs), A56773, for applicable CPT/HCPCS codes and diagnosis codes.

The redetermination process may be utilized for consideration of services performed outside of the reasonable and necessary requirements in this LCD.