Summary & Overview
CPT 95958: Wada Activation Test with EEG Monitoring
CPT code 95958 represents the Wada activation test, a preoperative neurodiagnostic procedure that uses temporary cerebral anesthesia and electroencephalographic monitoring to evaluate hemispheric language and memory dominance prior to ablative epilepsy surgery or select tumor resections. This test informs surgical planning by identifying functional localization that affects risks of postoperative cognitive deficits. Nationally, the code matters because it supports clinically necessary assessments for complex neurosurgical cases that impact patient selection and surgical approach.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context, expected site-of-service settings, and the types of benchmarks and policy issues typically associated with high-complexity neurodiagnostic services. The publication highlights reimbursement benchmarks and coverage considerations, coding guidance for clinical documentation, and policy developments that affect preoperative neurodiagnostic testing utilization. It also outlines what clinical teams and billing staff should expect when this service is reported in relation to neurosurgical care pathways.
Data not available in the input for associated taxonomies, specific ICD-10 pairings, and related billing codes is noted where relevant elsewhere in the publication.
Billing Code Overview
CPT code 95958 describes the Wada activation test performed prior to ablative surgery for epilepsy and sometimes before tumor resection. The procedure includes electroencephalographic (EEG) monitoring while a cerebral hemisphere is temporarily anesthetized to assess language and memory lateralization.
Service type: Neurological diagnostic procedure with intraoperative EEG monitoring
Typical site of service: Hospital inpatient or outpatient surgical setting, or ambulatory surgical center, where preoperative neurodiagnostic testing and EEG monitoring can be performed.
Clinical & Coding Specifications
Clinical Context
A 34-year-old right-handed patient with medically refractory temporal lobe epilepsy is scheduled for preoperative language and memory lateralization testing prior to planned left anterior temporal lobectomy. The patient is admitted to the neurointerventional suite or an inpatient neurology unit. Under awake sedation and local anesthesia, a neurointerventionalist or neurosurgeon places a femoral arterial catheter for selective carotid artery injection. The neuropsychology team administers standardized language and memory tasks while the interventional team injects amobarbital into the ipsilateral and contralateral carotid distributions in separate trials. Continuous electroencephalographic monitoring is performed during and after each injection to document hemispheric activation, seizure activity, and after-discharges. Findings inform surgical planning to spare dominant-hemisphere language cortex and to estimate postoperative memory risk. Typical sites of service include an inpatient neurosurgery or neurology unit, an interventional radiology suite, or an ambulatory surgical center when available and appropriate. Common clinical workflow steps: pre-procedure anesthesia and consent, baseline EEG and neurocognitive testing, arterial catheter placement, sequential Wada injections with EEG monitoring, post-procedure neurologic and EEG observation, and multidisciplinary case review for surgical decision-making.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the physician’s professional interpretive services for EEG monitoring during the Wada test when the technical component is billed separately. |