Summary & Overview

CPT 95940: Intraoperative Neurophysiological Monitoring During Brain Surgery

CPT code 95940 is an add-on code for continuous intraoperative neurophysiological monitoring (IOM) performed by a provider other than the surgeon or anesthesia staff during a separately reportable brain surgery. Reported in 15-minute units, the code captures monitoring activities such as EEG, EMG, evoked potentials, or nerve conduction studies intended to assess and preserve nervous system function while the operative procedure is underway. Nationally, utilization of intraoperative monitoring is clinically significant for risk mitigation in complex neurosurgical cases and factors into perioperative resource planning and billing workflows.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of how the code is used in clinical practice, unitization and reporting considerations, typical sites of service, and common payer coverage patterns. The publication also summarizes benchmarks for utilization and reimbursement where available, highlights policy updates affecting add-on intraoperative monitoring codes, and provides clinical context for when continuous neurophysiological monitoring is applied during brain surgery.

Data not available in the input for associated taxonomies, specific ICD-10 diagnoses, related codes, and detailed payer-specific payment rates.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare95940CPTintraoperative monitoringneurophysiologyEEGEMGevoked potentialsbrain surgeryoperative monitoring

Billing Code Overview

CPT code 95940 describes continuous intraoperative neurophysiological monitoring performed by a provider other than the surgeon or anesthesia team during a separately reportable brain surgery. The service consists of neurophysiology tests such as electroencephalography (EEG), electromyography (EMG), evoked potentials, or nerve conduction studies performed to monitor nervous system function throughout the surgical period.

Service type: Continuous intraoperative neurophysiological monitoring (IOM) as an add-on service, reported in 15-minute units
Typical site of service: Intraoperative setting during brain surgery (operating room or other procedure room where the covered surgical service is performed)

Clinical & Coding Specifications

Clinical Context

A 52-year-old patient is undergoing resection of a left temporal lobe tumor under general anesthesia. A neurophysiology technologist or neurologist (not the operating surgeon or anesthesia team) is requested to provide continuous intraoperative neurophysiologic monitoring (IONM) for the duration of the brain surgery to assess cerebral and cranial nerve function. The monitoring team places and interprets awake or intraoperative electroencephalography (EEG) leads and may perform periodic or continuous evoked potential testing and nerve conduction assessments as clinically indicated. The IONM provider documents baseline signals before critical portions of the procedure, communicates real-time changes to the surgical team, and records events and interventions. Billing for the monitoring is reported in 15-minute increments using the add-on code 95940 appended to the primary surgical code for the separately reportable brain surgery. Typical site of service is an inpatient or outpatient hospital operating room during neurosurgical procedures. The typical patient scenario includes preoperative setup in the OR, continuous monitoring during tumor resection or vascular procedures, and post-procedure documentation and handoff to the surgical team.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component

Taxonomy Code	Specialty	Notes
2084P0200X	Neurology	Neurologists with intraoperative monitoring expertise who interpret `EEG`/evoked potentials and oversee technical staff.
2084N0400X	Clinical Neurophysiology	Specialists focused on diagnostic and intraoperative neurophysiology monitoring services.
246Z00000X	Electroneurodiagnostic Technologist	Technologists who perform electrode placement and real-time data acquisition under physician supervision.
2086S0120X	Neurosurgery	Neurosurgeons coordinate with monitoring teams; surgeons do not bill `95940` but are integral to workflow.
207Q00000X	Anesthesiology	Anesthesiologists interact with monitoring data for anesthetic adjustments but do not bill this monitoring add-on code.

ICD-10 Code	Description	Clinical Relevance
`G93.6`	Cerebral edema	Monitoring may detect changes in cortical function during procedures with risk of brain swelling.
`C71.9`	Malignant neoplasm of brain, unspecified	Common indication for craniotomy with intraoperative monitoring during tumor resection.
`I60.9`	Subarachnoid hemorrhage, unspecified	Vascular neurosurgery for aneurysm repair where monitoring helps detect ischemia.
`G45.9`	Transient cerebral ischemic attack, unspecified	Procedures to address cerebrovascular disease may use monitoring to assess neurologic integrity.
`G35`	Multiple sclerosis	Demyelinating disease patients undergoing neurosurgical procedures may require neurophysiologic monitoring to assess functional pathways.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`95940`	Continuous intraoperative neurophysiology monitoring, each 15 minutes (add-on code)	Primary add-on code for continuous monitoring during separately reportable brain surgery; billed in 15-minute increments by the monitoring provider.
`95812`	Electroencephalogram (EEG) monitoring for prolonged recording up to 24 hours; single day recording	May be performed pre- or postoperatively for baseline or prolonged EEG assessment; not used intraoperatively but clinically related.
`95920`	Continuous intraoperative neurophysiological monitoring, with interpretation and reporting, per hour (non-specific example)	Represents other continuous monitoring paradigms; some payors recognize hourly reporting for monitoring services in addition to add-on codes (verify payor rules).
`95925`	Cortical stimulation mapping (intraoperative)	Performed adjunctively during brain tumor resection for eloquent cortex mapping; often occurs in same operative session as `95940`.
`95886`	Needle electromyography; limited study	EMG may be used in surgeries at risk for peripheral nerve injury; EMG testing can be part of intraoperative monitoring battery billed by the monitoring provider.

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