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Section: Diagnostic Medical
Number: M-13
Topic: Neurophysiological Studies
Effective Date: January 1, 2012
Issued Date: January 2, 2012
Date Last Reviewed: 10/2010

General Policy Guidelines

Indications and Limitations of Coverage

Neurophysiological studies may be reimbursed individually whether performed independently or in conjunction with each other.

However, if a provider reports any neurophysiological studies (92586, 95812, 95813, 95816, 95819, 95822, 95827, 95925, 95926, 95927, 95928, 95929, 95930, 95938, 95939, 95950, 95951, 95954, 95956) in addition to comprehensive evoked response audiometry (92585), the charges should be combined and processed under code 92585 (e.g., 92585 + 92589 = 92585). Modifier 59 may be reported with a non-E/M service, to identify it as distinct or independent from other non-E/M services performed on the same day. When modifier 59 is reported, the patient’s records must support its use in accordance with CPT guidelines.

Magnetoencephalography and Magnetic Source Imaging
Magnetoencephalography (MEG)(95965, 95966, 95967) and Magnetic Source Imaging (MSI)(S8035) are eligible for use in the presurgical evaluation of certain patients with medically refractory epilepsy.* This includes:

  • non-lesional superficial cortical epilepsy
  • lesional epilepsy within or adjacent to the eloquent cortex, 
  • epilepsy associated with large structural lesions, 
  • ongoing or recurrent seizure activity following previous resections for epilepsy, and
  • cases where the seizure focus has not been detected or well localized by traditional methods.

*Medically refractory epilepsy refers to the failure of adequate trials of different classes of FDA approved antiepilepsy medications to control seizure activity, when taken in appropriate doses and carefully monitored for effectiveness and patient compliance.

MEG/MSI is also considered eligible for use in presurgical functional brain mapping (PSFBM)(96020) for the preoperative evaluation of intracranial lesions located near the eloquent cortex or essential functional areas of the brain.

Other uses of MEG/MSI are considered experimental/investigational, and are not covered. A participating, preferred, or network provider can bill the member for the non-covered service.

Intraoperative Neurophysiology Monitoring (INM)
Intraoperative neurophysiology monitoring should be reported under procedure code 95920, regardless of the specific monitoring performed (e.g., brainstem auditory evoked response, somatosensory evoked potentials, etc.). If any of the testing codes for neurophysiological monitoring which are addressed below in the "Description" area of this policy are reported in conjunction with 95920, the services should be combined and processed under 95920 (e.g., 95925 + 95920 = 95920). Modifier 59 may be reported with a non-E/M service, to identify it as distinct or independent from other non-E/M services performed on the same day. When modifier 59 is reported, the patient’s records must support its use in accordance with CPT guidelines.

Intraoperative neurophysiology monitoring is an eligible service when it is performed by either a licensed physician (MD or DO) or an INM certified technician for any of the following indications:

Intracranial Surgery

  • Cerebral vascular aneurysms
  • Surgical management or embolization of intracranial arteriovenous (AV) malformations
  • Arteriography, during which there is a test occlusion of the carotid artery
  • Clipping of intracranial anterior or posterior circulation aneurysm
  • Resection of brain tissue close to the primary motor or other eloquent cortex and requiring brain mapping
  • Resection of tumors that affect optic, trigeminal, facial, auditory nerves
  • Resection of cavernous sinus tumors
  • Resection of epileptogenic brain tissue or tumor
  • Excision of posterior fossa tumor involving any motor cranial nerve, cranial nerve nuclei or neural (motor/sensory) pathway
  • Surgery for intracranial tumor where there is risk of injury to brain vascular supplies
  • Posterior fossa decompression for chiari malformation
  • Surgery for basal ganglia movement disorders
  • Surgery for intractable movement disorders
  • Microvascular cranial nerve decompression
  • Surgery for glomus jugulare tumor
  • Implantation of electrodes for deep brain stimulation

Orthopedic Surgery

  • Leg lengthening procedures, where there is traction on the sciatic nerve or other nerve trunks
  • Revision of total hip replacement
  • Hip resurfacing
  • Repair of pelvic and acetabular fracture
  • Placement of sacroiliac screw fixation
  • Total arthroscopic shoulder repair
  • Open shoulder repair
  • Thermal shoulder capsulorraphy
  • Removal of first rib for management of thoracic outlet syndrome

Otolaryngolic Procedures

  • Parotidectomy when there is risk of injury to the facial nerve and its branches
  • Thyroidectomy when there is risk of injury to the recurrent and superior laryngeal nerves
  • Partial or radical neck dissection
  • Revision mastoidectomy
  • Tympanomastoidectomy
  • Translabyrinthine excision of acoustic neuromas
  • Vestibular nerve section
  • Facial nerve decompression
  • Repair of middle fossa cerebrospinal fluid leak
  • Endolymphatic shunt for Meniere’s Disease
  • Oval or round window graft

Peripheral Nerve Surgery

  • Excision of neuromas of peripheral nerves of brachial plexus, when there is risk to major sensory or motor nerves
  • Brachial plexus reconstruction

Robotic Assisted Procedures

  • Preservation of recurrent laryngeal nerves during robotic-assisted thyroidectomy
  • Prevention of brachial plexus or other peripheral nerve injury during robotic-assisted laparoscopic hysterectomy

Spinal Procedures

  • Surgery for arteriovenous malformation of spinal cord
  • Correction of scoliosis or kyphosis, or deformity of spinal cord involving traction on the cord
  • Surgery for degenerative spinal disorders
  • Decompressive procedures on the spinal cord or cauda equina carried out for myelopathy or claudication where the function of the spinal cord or spinal nerves and associated vascular supplies and/or spinal nerve roots are at risk for iatrogenic injury
  • Spinal instrumentation requiring pedicle screw anchoring or insertion, interbody fusion cages or distraction devices where there is risk of injury to the spinal cord or nerve roots
  • Protection of the spinal cord where work is performed in close proximity to the spinal cord as in the placement or removal of hardware or where there have been previous surgical interventions
  • Placement of spinal cord stimulator in the cervical or thoracic spine
  • Surgery for spinal stabilization due to traumatic injury or disease
  • Surgery for spinal cord tumors, (e.g., cauda equina excision)
  • Surgery for spinal dysraphism
  • Surgical treatment for syringomyelia
  • Excision of primary or metastatic spinal bone tumor

Vascular/Cardiovascular/Endovascular Procedures

  • Surgery of the aortic arch, its branch vessels, or thoracic aorta, when there is a risk of cerebral ischemia
  • Distal aortic procedures, in which there is a risk of ischemia to the spinal cord
  • Carotid artery surgery, including carotid endarterectomy
  • Resection of carotid body tumor
  • Procedures requiring circulatory arrest with hypothermia, (not including surgeries performed under circulatory bypass [e.g., coronary artery bypass or ventricular aneurysms])
  • Arteriography, during which there is a test occlusion of the artery
  • Therapeutic embolization for aneurysm, arteriovenous malformation or fistula
  • Transluminal angioplasty

Intraoperative neurophysiology monitoring will be considered eligible when performed by either a licensed physician (MD or DO) or an INM certified technician. 

The actual interpretation of the INM data will be considered eligible only when it has been performed by a licensed physician (MD or DO). The physician must be performing the interpretation in real time. 

The physician may be in the O.R. suite or at a remote site with the INM data relayed via digital transmission or closed circuit television. When digital transmission  or closed circuit television is used, there must be the ability for continuous or immediate contact with the operating surgeon to ensure that information about the patient’s status can be immediately communicated. The interpreting physician must be someone other than the operating physician (surgeon), the technical surgical assistant, or the anesthesiologist rendering the anesthesia for the procedure. The written interpretation of the INM data must be documented within the patient’s medical record.


Neurophysiological studies is a generic term for objective tests performed via sophisticated electronic equipment to detect various neurological dysfunctions. They include the following studies:

  • Electroencephalography (EEG) - 95812-95813, 95816-95822, 95827, 95950, 95951, 95954, 95956
  • Evoked response audiometry (ERA) - 92585, 92586
  • Visual evoked potential (VEP) - 95930
  • Central auditory testing
  • Somatosensory evoked potential (SEP) testing -95925, 95926, 95927, 95938
  • Central motor evoked potential study (transcranial motor stimulation) - 95928, 95929, 95939 

(The above codes represent testing performed in a nonoperative setting.)

NOTE: Evoked response audiometry (92585, 92586) can also be reported as:

  • Brain stem auditory evoked response (BAER)
  • Electrophysiological response audiometry
  • Electrical response audiometry
  • Evoked potential audiometry
  • Low or high level biophysical EEG

Magnetoencephalography (MEG) measures neurological activity of the brain using magnetic fields. It is used for fundamental study of the brain, and for clinical studies and assessment of patients with specific neurological disorders. MEG is a noninvasive functional imaging technique in which the weak magnetic forces associated with the electrical activity of the brain are recorded externally on the scalp. Using mathematical modeling, the recorded data are then analyzed to provide an estimated location of the electrical activity. This information can be superimposed on an anatomic image of the brain, typically an MRI, to produce a functional/anatomic image of the brain, referred to as magnetic source imaging (MSI)

MEG and MSI have been found to be useful in the anatomical localization of areas of seizure focus and epileptogenic lesions of the brain, and in predicting outcomes in surgical resections for intractable temporal lobe epilepsy and brain lesions.

The primary advantage of MSI is that while the conductivity and thus measurement of electrical activity as recorded by the EEG is altered by surrounding brain structures, the magnetic fields are not. Therefore, MSI permits a high resolution functional/anatomic image. This allows precise localization of epileptiform activity and anatomical identification of brain lesions. Use of MEG/MSI in presurgical functional brain mapping (PSFBM) helps to determine whether surgical resection of a brain lesion is feasible, and improves the safety and accuracy of tumor resection while reducing the risk of postoperative functional deficits.

Intraoperative Neurophysiology Monitoring
Intraoperative neurophysiology monitoring is used to identify complications to the nervous system during certain surgical procedures. Evoked responses are constantly monitored for changes which could imply damage to the nervous system. The intent of this monitoring is to alert the surgeon so that he may possibly alter the surgical procedure to avoid permanent neurological damage.

Procedure Codes


Traditional (UCR/Fee Schedule) Guidelines

Refer to General Policy Guidelines

FEP Guidelines

This medical policy may not apply to FEP.  Medical policy is not an authorization, certification, explanation of benefits or a contract.  Benefits are determined by the Federal Employee Program.

Comprehensive / Wraparound / PPO / Major Medical Guidelines

Refer to General Policy Guidelines

Any reference in this bulletin to non-billable services by a network provider may not be applicable to Major Medical.

Managed Care (HMO/POS) Guidelines

Refer to General Policy Guidelines



03/1994, Intraoperative neurophysiology testing, coding for
03/1995, Intraoperative neurophysiology monitoring, codes and reimbursement for
06/2005, Blue Shield covers real time on-site and remote-location intraoperative neurophysiological monitoring
08/2007, Magnetoencephalography (MEG) and Magnetic Source Imaging (MSI) now eligible
12/2008, MEG/MSI eligible for presurgical functional brain mapping (PSFBM)
02/2011, Intraoperative neurophysiology monitoring (INM) eligibility outlined


Epilepsy Surgery, Resection Volume and MSI Localization in Lesional Frontal Lobe Epilepsy, Elsevier Ireland, Ltd., 08/2003

Magnetoencephalography (MEG) Predicts Focal Epileptogenicity in Cavarnomas, The Journal of Neurology, Neurosurgery and Psychiatry, 2004

Does Magnetoencephalography Add to Scalp Video-EEG as a Diagnostic Tool in Epilepsy Surgery? Neurology, Volume 62, 03/2004

Magnetoencephalography Source Localization and Surgical Outcome in Temporal Lobe Epilepsy, Elsevier Ireland, Ltd, 06/2004

Application of Magnetoencephalography in Epilepsy Patients with Widespread Spike or Slow-wave Activity, Epilepsia, Volume 46, Number 8, 2005

Detection of Epileptiform Activity by Human Interpreters: Blinded Comparison Between Electroencephalography and Magnetoencephalography, Epilepsia, Volume 46, Number 1, 2005

Dynamic Statistical Parametric Mapping for Analyzing the Magnetoencephalographic Epileptiform Activity in Patients with Epilepsy, Journal of Child Neurology, Volume 20, 04/2005

Toward the Substitution of Invasive Electroencephalography in Epilepsy Surgery, The Journal of Clinical Neurophysiology, Volume 22, Number 4, 08/2005

Magnetic Source Imaging Localizes Epileptogenic Zone in Children with Tuberous Sclerosis Complex, Neurology, Volume 66, 04/2006

Reliability of Language Mapping with Magnetic Source Imaging in Epilepsy Surgery Candidates, Elsevier Ireland, Ltd, 04/2006

Magnetoencephalography/Magnetic Source Imaging, MPRM, Policy 6.01.21, 12/12/2006

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Albertstone CD, Skirboll SL, Benzel EC, Sanders JA, Hart BL, Baldwin NG, Tessman CL, Davis JT, Lee RR. Magnetic source imaging and brain surgery: presurgical and intraoperative planning in 26 patients. Journal of Neurosurgery. 2000;92:79-90. 

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Papanicolaou AC, Simos PG, Castillo EM, Billingsley RL, Buchanan S, Wheless J, Maggio V, Maggio WW.  Magnetoencephalography: a noninvasive alternative to the wada procedure. Journal of Neurosurgery. 2004;100:867-76. 

Ganslandt O, Buchfelder M, Hastreiter P, Grummich P, Fahlbusch R, Nimsky C. Magnetic source imaging supports clinical decision making in glioma patients. Clinical Neurology and Neurosurgery. 2004;107:20-26.

Grover KM, Bowyer SM, Rock ML, Rosenblum KM, Moran JE, Smith BJ, Barkley GL. Retrospective review of MEG visual evoked hemifield responses prior to resection of temporo-parieto-occipital lesions. Journal of Neuro-Oncology. 2005.

Makela J, Forss N, Jaaskelainen J, Kirveskari E, Korvenoja A, Paetau R. Magnetoencephalography in neurosurgery. Neurosurgery. 2006;59:493-511. 

Grummich P, Nimsky C, Pauli E, Buchfelder M, Ganslandt O. Combining fMRI and MEG increases the reliability of pre-surgical language localization: a clinical study of the difference between and congruence of both modalities. Neuroimage. 2006;32:1793-1803.

Korvenoja A, Kirveskari, Aronen HJ, Avikainen S, Brander A Huttunen J, Ilmoniemi RJ, Jaaskelainen JE, Kovala T, Makela JP, Salli E, Seppa M. Sensorimotor cortex localization: comparison of magnetoencephalography, functional MR imaging, and intraoperative cortical mapping. Radiology. 2006;241:213-22.

Kamada K, Sawamura Y, Takeuchi F, Kuriki S, Kawai K, Morita A, Todo T. Expressive and receptive language areas determined by a non-invasive reliable method using functional magnetic resonance imaging and magnetoencephalography. 2007;60:296-306.

Larsen S, Kikinis R, Talos IF, Weinstein D, Wells W, Golby A. Quantitative comparison of functional MRI and direct electrocortical stimulation for functional mapping. International Journal of Medical Robotics and Computer-Assisted Surgery. 2007;3:262-70.

Stippich C, Rapps N, Dreyhaupt J, Durst A, Kress B, Nennig E, Tronnier VM, Sartor K. Localizing and lateralizing language in patients with brain tumors: feasibility of routine preoperative functional MR imaging in 81 consecutive patients. Radiology. 2007;243:828-36.

Tharin S, Golby A.  Functional brain mapping and its applications to neurosurgery. Neurosurgery. 2007;60:185-201.

Chakraborty A, McEvoy AW.  Presurgical functional mapping with functional MRI. Current Opinion Neurology. 2008;24:446-51.

Bizzi A, Blasi V, Falini A, Ferroli P, Cadioli M, Danesi U, Aquino D, Marras C, Caldiroli D, Broggi G. Presurgical functional MR imaging of language and motor functions: validation with intraoperative electrocortical mapping. Radiology. 2008;248:579-89.

Knowlton RC. Can Magnetoencephalography aid epilepsy surgery? Epilepsy Curr. 2008;8(1):1-5.

Lau M, Yam D, Burneo JG. A systematic review on MEG and its use in the presurgical evaluation of localization-related epilepsy. Epilepsy Res. 2008;79(2-3):97-104.

Munoz-Yunta JA, Ortiz T, Palau-Baduell M, Martin-Munoz L, et al. Magnetoencephalographic pattern of epileptiform activity in children with early-onset autism spectrum disorders. Clin Neurophysiol. 2008;119(3):626-34.

Sutherling WW, Mamelak AN, Thyerlei D, et al. Influence of magnetic source imaging for planning intracranial EEG in epilepsy. Neurology. 2008;71(13):990-6.

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Chang EF, Nagarajan SS, Mantle M, et al. Magnetic source imaging for the surgical evaluation of electroencephalography-confirmed secondary bilateral synchrony in intractable epilepsy. J Neurosurg. 2009;111(6):1248-56.

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American Academy of Otolaryngology - Head and Neck Surgery. Facial nerve monitoring policy. Available at Accessed September 23, 2010.

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Table Attachment

Text Attachment

Procedure Code Attachments

Diagnosis Codes

ICD-9 Diagnosis Codes

Covered Diagnosis Codes

For procedure codes 95965, 95966, 95967, S8035 (MEG/MSI), including but not limited to:


ICD-10 Diagnosis Codes

Covered Diagnosis Codes

For procedure codes 95965, 95966, 95967, S8035 (MEG/MSI), including but not limited to:




Medical policies do not constitute medical advice, nor are they intended to govern the practice of medicine. They are intended to reflect Highmark's reimbursement and coverage guidelines. Coverage for services may vary for individual members, based on the terms of the benefit contract.

Highmark retains the right to review and update its medical policy guidelines at its sole discretion. These guidelines are the proprietary information of Highmark. Any sale, copying or dissemination of the medical policies is prohibited; however, limited copying of medical policies is permitted for individual use.

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