CPT code 61850: Cortical electrode implant, burr-hole approach, no stereotaxy2026 Medicare rate & RVUs in California

CMS doesn’t publish an office rate for 61850 in California.

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

What 61850 covers

Code 61850 describes cranial access through one or more small twist-drill or burr holes to place an electrode array on the cerebral cortex. A neurosurgeon may perform this for cortical neurostimulation in a patient with focal epilepsy. The code includes securing the array when fixation is performed; it does not describe a craniotomy-based cortical approach or implantation of a subcortical array.

Choose this code when the operative report supports cortical electrode placement through burr-hole or twist-drill access without stereotactic guidance. Document the target, approach, electrode placement, and any fixation performed. CMS classifies the service as major surgery: the day-before preoperative visit and 90 days of related postoperative care are included. For multiple procedures in one session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% reduction. Modifier 50 is inappropriate for this service. An assistant at surgery may be paid; co-surgeons and team surgery are not permitted.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where 61850 pays more and less in California

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

29 of 29 payment localities

How the 61850 rate is calculated

Each of 61850’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

Payment rules and modifiers for 61850

61850 has a 90-day global period: related visits in that window are included in the surgery payment.

What modifiers do to the payment

When to use modifier 51

61850 compared with similar codes

How to choose

61860Cortical electrodesCraniotomy or craniectomy

Both codes concern cortical electrode implantation without stereotactic guidance. Choose 61850 for twist-drill or burr-hole access and 61860 when the operative approach is craniotomy or craniectomy.

61863Brain electrode placementSubcortical, without microelectrode recording

Code 61850 is for a cortical target; 61863 is for a subcortical array placed without stereotactic guidance.

61867Neuroelectrode placementSubcortical, with microelectrode recording

Code 61867 describes subcortical array placement with stereotactic guidance, unlike 61850's cortical target and nonstereotactic approach.

Codes related to 61850

Related codes aren’t interchangeable: bill the code that matches the service performed.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Open CMS sourceHow we calculate rates