Surgical · Other

Electrocorticography performed directly on exposed cortical tissue during an open cranial surgical procedure to map brain function or localize seizure foci.

Verified May 8, 2026 · 5 sources ↓

Medicare: $1,973.33
Total RVUs: 59.08
Global, days
Region: Other

Drawn from CMSAsetAanAAPC

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 5 cited references ↓

Operative note must confirm electrodes were placed directly on exposed cortical surface during open cranial surgery — not scalp EEG
Clinical indication documented: seizure localization, functional cortical mapping, or confirmation of resection margins
Interpreting physician's signed report with description of electrode placement sites, cortical areas sampled, and electrographic findings
If modifier 26 is appended, separate professional interpretation report required — not just a co-signature on the surgeon's note
If billed same-day as a neurosurgical procedure, documentation must establish 95829 as a distinct, independently indicated service to support modifier 59 or XS

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

26 Professional component 59 Distinct service XS Separate structure

What this code covers

Source · Editorial summary grounded in 5 cited references ↓

CPT 95829 covers an electrocorticogram (ECoG) performed at surgery — direct recording from electrodes placed on the exposed cerebral cortex during an open cranial procedure. The primary use cases are epilepsy surgery (identifying the seizure-onset zone and confirming resection margins) and functional cortical mapping (delineating eloquent cortex for motor, sensory, or language function prior to resection). Because the electrodes are applied directly to cortical tissue rather than through the scalp, the signal resolution is far superior to surface EEG and cannot be substituted by it.

The code carries a XXX global period, meaning no standard pre- or post-operative period applies — bill each date of service on its own merits. 95829 is designated a 'separate procedure,' which means it is bundled when performed as an incidental component of a larger service but is separately reportable when it constitutes a distinct, independently indicated study. Modifier 59 or XS may be required to unbundle it from a primary neurosurgical procedure when payer edits fire. Do not stack 95940 (continuous intraoperative neurophysiology monitoring, per 15 minutes) with 95829 — the two codes describe overlapping services and cannot be billed together on the same encounter.

Billing appears predominantly under Neurology and Orthopedic Surgery in the CMS Physician Data File, reflecting both the interpreting neurophysiologist and the surgical team. Place of service is almost always 21 (inpatient hospital) or 22 (on-campus outpatient hospital). Modifier 26 is appropriate when the neurologist provides only the professional interpretation component and a separate entity owns the technical equipment.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	6.05
Practice expense RVU	52.61
Malpractice RVU	0.42
Total RVU	59.08
Medicare national rate	$1,973.33
Global period	days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$1,973.33

Common denial reasons

The recurring reasons claims for CPT 95829 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Bundling edit fires when 95829 is billed same-day as the primary neurosurgical procedure without modifier 59 or XS
95940 billed on the same claim — payers treat continuous IOM and ECoG as overlapping services and deny one
Missing or unsigned interpretation report; claim processed as lacking medical necessity documentation
Modifier 26 applied without a separate, identifiable professional interpretation document on file
Place of service mismatch — code is inpatient-facility–appropriate and may deny if billed under an office POS

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01Can 95829 and 95940 be billed together on the same case?

No. 95940 covers continuous intraoperative neurophysiology monitoring billed per 15-minute increment; 95829 covers the electrocorticogram itself. Billing both on the same encounter creates a bundling conflict — payers will deny one. The AAPC coding community has flagged this edit explicitly.

02When does modifier 59 apply to 95829?

Use modifier 59 (or XS for a distinct service at a separate anatomical location) when 95829 is billed same-day as the primary neurosurgical procedure and an NCCI edit fires. The modifier signals that ECoG was a distinct, separately indicated service — but documentation must back that up.

03What does 'separate procedure' mean for 95829?

It means the code is bundled into larger services when performed as an incidental component of that surgery. It is separately reportable only when ECoG constitutes a distinct, independently indicated study. If it's integral to the neurosurgical procedure, you cannot bill it separately without a modifier and supporting documentation.

04Is modifier 26 appropriate for the interpreting neurologist?

Yes, when the neurologist or neurophysiologist provides only the professional interpretation and a separate entity owns the recording equipment, append modifier 26. A standalone, signed interpretation report is required — a co-signature on the surgical note is not sufficient.

05What ICD-10 diagnoses support medical necessity for 95829?

Drug-resistant focal epilepsy (G40.1x9, G40.2x9) and intracranial neoplasms adjacent to eloquent cortex are the most consistently covered indications. Confirm LCD or NCD coverage with the specific payer — Medicare coverage criteria vary by contractor.

06Does 95829 have a global period?

The global period is XXX, meaning the standard 10- or 90-day global package does not apply. Bill each date of service independently. Pre- and post-operative visits are not bundled into this code.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures the cortical electrode placement method, anatomical sites recorded, laterality, clinical indication (seizure focus vs. functional mapping), and the interpreting physician's identity from dictation. That prevents the most common audit flag: operative notes that reference 'intraoperative EEG' without specifying direct cortical contact, which payers use to reclassify the service as a routine scalp EEG and deny 95829.

See how Mira captures CPT 95829 documentation