CPT® Code 93896

1. Indications

The vasoreactivity study performed with a transcranial Doppler study is indicated for the following conditions:

• Cerebrovascular Disease - Patients with known cerebrovascular diseases affecting the carotid and/or vertebrobasilar arteries require evaluation of their cerebrovascular reactivity.
• Pre-Surgical Assessment - The study may be performed prior to surgical procedures that could impact blood flow to the brain, to assess the cerebrovascular reserve and ensure adequate blood supply during and after the surgery.

2. Procedure

The procedure for conducting a vasoreactivity study with a transcranial Doppler study involves several key steps:

• Preparation - The patient is positioned comfortably, and gel is applied to the skin over the areas where the Doppler probe will be placed. This gel enhances the transmission of ultrasound waves, ensuring accurate readings.
• Probe Placement - A hand-held Doppler probe is positioned on the skin, specifically targeting the middle cerebral arteries (MCAs) bilaterally. This positioning is crucial for obtaining reliable measurements of blood flow velocity.
• Baseline Monitoring - Continuous monitoring of the MCAs is initiated during a resting phase to establish baseline blood flow velocity measurements. This phase is essential for comparison with post-physiological challenge results.
• Physiological Challenge - The study includes a physiological challenge, which may involve breath holding, hyperventilation, or inhalation of a gas mixture with elevated carbon dioxide levels. These challenges are designed to provoke changes in blood flow velocity.
• Pharmacological Intervention - Alternatively, the study may involve the administration of acetazolamide or another drug that alters cerebral blood flow, further assessing the cerebrovascular reserve.
• Post-Challenge Monitoring - Following the physiological challenge, continuous monitoring of blood flow velocity in the MCAs is performed to capture the changes that occur as a result of the induced stress on the cerebrovascular system.
• Data Analysis - A computer program analyzes the collected data, calculating the change in blood flow from baseline to post-physiological challenge. This analysis provides insights into the patient's cerebrovascular reserve.
• Report Generation - The physician reviews the Doppler images and the computer-generated calculations, compiling a written report that details the findings, including the assessment of collateral blood flow channels that may sustain cerebral perfusion during vascular incidents.

3. Post-Procedure

After the vasoreactivity study is completed, the patient may be monitored briefly to ensure there are no immediate adverse effects from the physiological challenges or pharmacological interventions. The physician will review the results and provide a detailed report, which may include recommendations for further evaluation or treatment based on the findings. Patients are typically advised to resume normal activities unless otherwise directed. Follow-up appointments may be scheduled to discuss the results and any necessary interventions based on the study's outcomes.