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CPT 61598: Transpetrosal Approach to Posterior Cranial Fossa or Skull Base

CPT code 61598 denotes a complex open neurosurgical skull base procedure using a transpetrosal approach to reach the posterior cranial fossa, jugular foramen, or midline skull base. This code captures extensive approaches that may include ligation of the superior petrosal and/or sigmoid sinuses to optimize access. Nationally, codes for posterior fossa and skull base surgery are important for hospital resource planning, surgical quality monitoring, and payer coverage determinations because they reflect high-acuity, resource-intensive care.

Key payers in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical intent and usual site of service for 61598, plus a framework for understanding where this service fits within neurosurgical and hospital billing lines. The publication summarizes typical clinical context and highlights the aspects of billing and coding that affect national payment considerations. Data not provided in the input (for example, associated taxonomies, ICD-10 pairings, payer-specific coverage edits, and utilization benchmarks) are noted as unavailable where applicable. The focus is clinical description and functional billing context for payers, health system coding teams, and policy analysts.

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Billing Code Overview

CPT code 61598 describes a neurosurgical procedure in which the surgeon accesses the posterior cranial fossa, jugular foramen, or midline skull base using a transpetrosal approach. The procedure may include ligation of the superior petrosal sinus and/or sigmoid sinus when required to improve access to a lesion or defect. The selection of the specific transpetrosal variant is determined by the location and size of the lesion.

Service type: Open neurosurgical skull base approach

Typical site of service: Inpatient hospital operating room

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CPT 61598: Transpetrosal Approach to Posterior Cranial Fossa or Skull Base

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Billing Code Overview

Service type: Open neurosurgical skull base approach

Typical site of service: Inpatient hospital operating room

Clinical & Coding Specifications

Clinical Context

A 54-year-old patient presents with progressive cranial neuropathies, cerebellar signs, and imaging demonstrating a contrast-enhancing lesion of the posterior cranial fossa abutting the petrous temporal bone and jugular foramen. The neurosurgical team schedules a transpetrosal skull base approach to resect the lesion and/or repair a dural defect. Preoperative workflow includes MRI with and without contrast, CT temporal bone for petrous anatomy, cranial nerve testing, anesthesia pre-op assessment, and informed consent discussing potential hearing loss, facial nerve dysfunction, and venous sinus ligation. Intraoperatively the surgeon performs a tailored transpetrosal approach to the posterior cranial fossa and jugular foramen, which may include ligation of the superior petrosal sinus and/or sigmoid sinus for exposure, microsurgical tumor resection or repair, and closure with watertight dural reconstruction. Postoperative care includes neurosurgical ICU monitoring, serial neurologic exams, postoperative imaging, management of cerebrospinal fluid leak risk, and coordination of otolaryngology or neurotology for concurrent middle ear or mastoid work if performed.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when the operative report documents significantly greater work, time, and complexity beyond typical for `61598`.
`23`	Unusual anesthesia	Use when general anesthesia is contraindicated and an unusual anesthesia circumstance is documented.
`26`	Professional component	Use when billing is split and only the surgeon’s professional service is reported separate from facility technical component.
`50`	Bilateral procedure	Use if identical transpetrosal approaches are performed on both sides in the same operative session.
`51`	Multiple procedures	Use when `61598` is billed along with additional distinct surgical procedures during the same operative session.
`52`	Reduced services	Use when the service is partially reduced or not completed as documented.
`53`	Discontinued procedure	Use when the planned transpetrosal approach is terminated due to extenuating circumstances prior to completion.
`62`	Two surgeons	Use when two surgeons from different specialties perform distinct portions of the operation concurrently.
`66`	Surgical team approach	Use when a surgical team (e.g., complex skull base case) performs the procedure and team billing is appropriate.
`78`	Return to OR for related procedure following initial procedure	Use when the patient returns to the operating room for a related procedure during the postoperative period.
`79`	Unrelated procedure or service by the same physician during the postoperative period	Use when an unrelated procedure is performed by the same physician during the global period.
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services as the primary surgeon	Use when an allowed advanced practice clinician performs the service as primary operator per payer rules.
`LT`	Left side	Use to indicate the procedure was performed on the left anatomical side.
`RT`	Right side	Use to indicate the procedure was performed on the right anatomical side.

Taxonomy Code	Specialty	Notes
2084P0800X	Neurosurgery	Primary specialty performing skull base and posterior fossa approaches.
207L00000X	Otolaryngology - Head & Neck Surgery (Neurotology)	Frequently involved when mastoid or petrous work and hearing preservation are considerations.
208800000X	Neurological Surgery - Skull Base	Subspecialty focus on complex skull base resections and skull base reconstruction.
207K00000X	Otolaryngology	General otolaryngology involvement for middle ear/mastoid components.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D32.0`	Benign neoplasm of cerebral meninges	Meningiomas of the posterior fossa or petroclival region accessible via transpetrosal approach.
`C71.7`	Malignant neoplasm of brain, cerebellum	Primary posterior fossa brain tumors requiring skull base approaches for resection.
`C79.3`	Secondary malignant neoplasm of brain and cerebral meninges	Metastatic lesions to posterior fossa that may require aggressive skull base exposure.
`G51.0`	Bell's palsy (facial nerve palsy)	Facial nerve dysfunction may be a presenting symptom or a postoperative complication considered in planning approach.
`H90.3`	Sensorineural hearing loss, bilateral	Hearing status assessment influences approach selection and intraoperative neurophysiology; risk of hearing loss is a consideration.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`61598`	Transpetrosal approach to posterior cranial fossa, jugular foramen, or midline skull base; may include ligation of superior petrosal and/or sigmoid sinus	Primary procedure described; approach code used for access to lesions in these regions.
`69990`	Microsurgical techniques, requiring use of operating microscope (List separately in addition to code for primary procedure)	Often reported in conjunction with `61598` when microsurgical magnification is used for tumor resection or microsurgical reconstruction.
`61620`	Craniectomy for cranial base lesion, supratentorial or infratentorial	May be used for additional cranial base bone removal or exposure techniques in the same operative setting when distinct from the transpetrosal approach.
`61618`	Craniectomy for cranial base lesion; posterior fossa	Often accompanies complex posterior fossa exposures or extensions of the transpetrosal approach.
`61595`	Repair of dural defect, cranial base (when performed as separate reconstructive procedure)	Used when extensive dural repair or grafting is performed as a distinct reconstructive step related to the approach.

CPT 61595: Transtemporal Approach to Posterior Cranial Fossa/Skull Base

CPT-61596-TRANSCOCHLEAR-APPROACH-SKULL-BASE-LESION

CPT 61596: Transcochlear Approach to Skull Base Lesions

CPT-61597-FAR-LATERAL-TRANSCONDYLAR-SKULL-BASE-APPROACH

CPT 61597: Far Lateral Transcondylar Skull-Base Approach

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when the operative report documents significantly greater work, time, and complexity beyond typical for `61598`.
`23`	Unusual anesthesia	Use when general anesthesia is contraindicated and an unusual anesthesia circumstance is documented.
`26`	Professional component	Use when billing is split and only the surgeon’s professional service is reported separate from facility technical component.
`50`	Bilateral procedure	Use if identical transpetrosal approaches are performed on both sides in the same operative session.
`51`	Multiple procedures	Use when `61598` is billed along with additional distinct surgical procedures during the same operative session.
`52`	Reduced services	Use when the service is partially reduced or not completed as documented.
`53`	Discontinued procedure	Use when the planned transpetrosal approach is terminated due to extenuating circumstances prior to completion.
`62`	Two surgeons	Use when two surgeons from different specialties perform distinct portions of the operation concurrently.
`66`	Surgical team approach	Use when a surgical team (e.g., complex skull base case) performs the procedure and team billing is appropriate.
`78`	Return to OR for related procedure following initial procedure	Use when the patient returns to the operating room for a related procedure during the postoperative period.
`79`	Unrelated procedure or service by the same physician during the postoperative period	Use when an unrelated procedure is performed by the same physician during the global period.
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services as the primary surgeon	Use when an allowed advanced practice clinician performs the service as primary operator per payer rules.
`LT`	Left side	Use to indicate the procedure was performed on the left anatomical side.
`RT`	Right side	Use to indicate the procedure was performed on the right anatomical side.

Taxonomy Code	Specialty	Notes
2084P0800X	Neurosurgery	Primary specialty performing skull base and posterior fossa approaches.
207L00000X	Otolaryngology - Head & Neck Surgery (Neurotology)	Frequently involved when mastoid or petrous work and hearing preservation are considerations.
208800000X	Neurological Surgery - Skull Base	Subspecialty focus on complex skull base resections and skull base reconstruction.
207K00000X	Otolaryngology	General otolaryngology involvement for middle ear/mastoid components.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D32.0`	Benign neoplasm of cerebral meninges	Meningiomas of the posterior fossa or petroclival region accessible via transpetrosal approach.
`C71.7`	Malignant neoplasm of brain, cerebellum	Primary posterior fossa brain tumors requiring skull base approaches for resection.
`C79.3`	Secondary malignant neoplasm of brain and cerebral meninges	Metastatic lesions to posterior fossa that may require aggressive skull base exposure.
`G51.0`	Bell's palsy (facial nerve palsy)	Facial nerve dysfunction may be a presenting symptom or a postoperative complication considered in planning approach.
`H90.3`	Sensorineural hearing loss, bilateral	Hearing status assessment influences approach selection and intraoperative neurophysiology; risk of hearing loss is a consideration.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`61598`	Transpetrosal approach to posterior cranial fossa, jugular foramen, or midline skull base; may include ligation of superior petrosal and/or sigmoid sinus	Primary procedure described; approach code used for access to lesions in these regions.
`69990`	Microsurgical techniques, requiring use of operating microscope (List separately in addition to code for primary procedure)	Often reported in conjunction with `61598` when microsurgical magnification is used for tumor resection or microsurgical reconstruction.
`61620`	Craniectomy for cranial base lesion, supratentorial or infratentorial	May be used for additional cranial base bone removal or exposure techniques in the same operative setting when distinct from the transpetrosal approach.
`61618`	Craniectomy for cranial base lesion; posterior fossa	Often accompanies complex posterior fossa exposures or extensions of the transpetrosal approach.
`61595`	Repair of dural defect, cranial base (when performed as separate reconstructive procedure)	Used when extensive dural repair or grafting is performed as a distinct reconstructive step related to the approach.

CPT 61595: Transtemporal Approach to Posterior Cranial Fossa/Skull Base

CPT-61596-TRANSCOCHLEAR-APPROACH-SKULL-BASE-LESION

CPT 61596: Transcochlear Approach to Skull Base Lesions

CPT-61597-FAR-LATERAL-TRANSCONDYLAR-SKULL-BASE-APPROACH

CPT 61597: Far Lateral Transcondylar Skull-Base Approach

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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CPT 61598: Transpetrosal Approach to Posterior Cranial Fossa or Skull Base

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Billing Code Overview

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CPT 61598: Transpetrosal Approach to Posterior Cranial Fossa or Skull Base

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

CPT 61598: Transpetrosal Approach to Posterior Cranial Fossa or Skull Base

Sign up for cpt 61598 policy alerts

Billing Code Overview

CPT 61598: Transpetrosal Approach to Posterior Cranial Fossa or Skull Base

Sign up for cpt 61598 policy alerts

Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

What clinical procedure does CPT 61598 describe and where is it typically performed?

Which modifiers are commonly applicable when billing CPT 61598?

What other CPT codes are commonly billed with or related to 61598?

Which specialties and taxonomy codes are most relevant to procedures coded with 61598?

What ICD‑10 diagnoses are listed as related to use of CPT 61598?

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

What clinical procedure does CPT 61598 describe and where is it typically performed?

Which modifiers are commonly applicable when billing CPT 61598?

What other CPT codes are commonly billed with or related to 61598?

Which specialties and taxonomy codes are most relevant to procedures coded with 61598?

What ICD‑10 diagnoses are listed as related to use of CPT 61598?

References