CPT® Code 95928

A central motor evoked potential (MEP) study is a diagnostic procedure that assesses the functionality of the motor pathways in the brain and their connection to the muscles in the upper limbs. This study involves the application of electrical stimulation to the motor area of the cerebral cortex, which is the region of the brain responsible for voluntary movement. The stimulation is followed by the recording of electrical activity from peripheral muscles, such as the biceps, triceps, abductor pollicis brevis, and abductor digiti minimi, located in the upper extremities. The primary goal of this procedure is to evaluate how well the motor pathways are functioning, which can provide valuable insights into various neurological conditions. Before conducting the MEP recording, baseline nerve conduction studies are performed to establish a reference point for comparison. During the procedure, electrodes are strategically placed on the skin over the targeted muscles, and their impedances are checked to ensure accurate readings. The optimal scalp location for stimulation is identified for each muscle tested, and the threshold for eliciting a motor response is determined. The stimulation of the motor cortex generates MEPs, which are then recorded and analyzed. Key measurements include the amplitude or strength of the response and the speed of the response, indicated by the onset latency, which are compared to the baseline nerve conduction study results. Additionally, the study involves testing the compound muscle action potential (CMAP) by stimulating the ulnar nerve for the abductor digiti minimi muscle. The strength of the MEP response is expressed as a percentage of the CMAP strength, and the central motor conduction time (CMCT) is calculated. The procedure also assesses the dissociation between excitatory and inhibitory effects of transcranial stimulation, which is crucial for understanding the motor pathway's integrity. The entire process is repeated for multiple muscles in both the ipsilateral and contralateral upper extremities, ensuring a comprehensive evaluation of motor function. Finally, the physician reviews the collected data and generates a detailed report of the findings, which aids in diagnosing and managing neurological disorders.