Intraoperative neurophysiological testing may be used to identify/prevent
complications during surgery on the nervous system, its blood supply, or
adjacent tissue.  
  
Monitoring can identify new neurologic impairment, identify, or separate
nervous system structures (e.g., around or in a tumor), and can demonstrate
which tracts or nerves are still functional. Intraoperative neurophysiological
testing may provide relative reassurance to the surgeon that no identifiable
complication has been detected up to a certain point, allowing the surgeon to
proceed further and provide a more thorough or careful surgical intervention
than would have been provided in the absence of monitoring.  
  
Some high-risk patients may be candidates for a surgical procedure only if
monitoring is available. To establish medical necessity the following
guidelines must be followed:

Intraoperative testing may be indicated with the following types of surgery:

  1. Surgery of the aortic arch, its branch vessels, or thoracic aorta, including internal carotid artery surgery, when there is risk of cerebral ischemia
  2. Resection of epileptogenic brain tissue or tumor
  3. Resection of brain tissue close to the primary motor cortex and requiring brain mapping
  4. Protection of cranial nerves:  

    1. tumors that are optic, trigeminal, facial, auditory nerves
    2. cavernous sinus tumors
    3. oval or round window graft
    4. endolymphatic shunt for Meniere's disease
    5. vestibular section for vertigo
    6. microvascular decompression of cranial nerves
  5. Correction of scoliosis or deformity of spinal cord involving traction on the cord
  6. Protection of spinal cord where work is performed in close proximity to cord as in the removal of old hardware or where there have been numerous interventions
  7. Spinal instrumentation requiring pedicle screws or distraction
  8. Decompressive procedures on the spinal cord or cauda equina carried out for myelopathy or claudication where function of spinal cord or spinal nerves is at risk
  9. Resection of:  

    1. Spinal cord tumors
    2. Neuromas of peripheral nerves or brachial plexus, when there is risk to major sensory or motor nerves
  10. Surgery for:
    1. intracranial AV malformations
    2. arteriovenous malformation of spinal cord
    3. surgery for intractable movement disorders
    4. cerebral vascular aneurysms
  11. Arteriography, during which there is a test occlusion of the carotid artery
  12. Circulatory arrest with hypothermia
  13. Distal aortic procedures, where there is risk of ischemia to spinal cord
  14. Leg lengthening procedures, where there is traction on sciatic nerve or other nerve trunks
  15. Basil ganglia movement disorders
  16. Surgery as a result of traumatic injury to spinal cord/brain
  17. Deep brain stimulation

**Limitations**  
For reimbursement, this test must be requested by the operating surgeon and
the monitoring must be performed by a physician, other than:

The operating surgeon The technical/surgical assistant; or The
anesthesiologist rendering the anesthesia

The benefits of intraoperative neurophysiologic testing are attainable under
optimal recording and interpreting conditions.  
  
Due to the nature of these services and the potential for significant
morbidity in some procedures requiring intraoperative monitoring, Medicare
expects to see these services used in the hospital setting only. As the level
of anesthesia may significantly impact the ability to interpret intraoperative
studies, continuous communication between the anesthesiologist and the
monitoring physician is expected when medically indicated.  
  
It is also expected that a specifically trained technician, preferably
registered with one of the credentialing organizations, will be in continuous
attendance in the operating room, recording and monitoring a single surgical
case, with either the physical or electronic capacity for real-time
communication with the supervising neurologist or other physician trained in
neurophysiology.  
  
Intraoperative monitoring is not medically necessary in situations where
historical data and current practices reveal no potential for damage to neural
integrity during surgery. Monitoring under these circumstances will exceed the
patient's medical need.  
  
Due to the potential risk for morbidity with many of the above noted surgeries
and the need for explicit and focused attention to both the monitoring and the
procedure, Medicare does not expect to see operating surgeons submitting
claims for this code. Monitoring may be performed from a remote site, as long
as a trained technician (see detail above) will be in continuous attendance in
the operating room, with either the physical or electronic capacity for real-
time communication with the supervising physician (MD/DO). Technical criteria
(mandatory) include that at least 8 recording channels be available (16 if EEG
is monitored) for all intraoperative neurophysiological monitoring. The
remotely supervising physician must have the ability to watch the tracings as
they are obtained in real-time in the operating room, as well as the baseline
electrophysiological test and the monitoring tracings from earlier in the
case.  
  
Technical criteria (mandatory) for remote monitoring also include (a) routine
real-time auditory or written communication between the supervising physician
and the operating room and (b) the capability for telephone communications as
needed between the supervising physician and the monitoring technologist,
operating surgeon, and the anesthesiologist.  
  
The equipment must also provide for all of the monitoring modalities that may
be applied - auditory-evoked response,
electroencephalography/electrocorticography, electromyography and nerve
conduction, and somatosensory-evoked response.  
  
Undivided attention to a unique patient may be required during some surgeries,
such as during response to acute events or identification of the cerebral
cortex to be resected or spared from resection. The monitoring physician must
have a plan in place to transfer care to another physician of any other case
during those times. When paying undivided attention to a unique patient, the
physician must code and bill only for that one case during those times. For
other medically necessary intraoperative neurophysiologic monitoring, a
physician may monitor up to three cases simultaneously.  
  
Medicare does not provide for reimbursement of "incident to" care in the
hospital setting. More than one patient may be monitored at once; however,
claims for physician services must be submitted only for the time devoted to
monitoring when attention is directed exclusively to one patient.