Felix Chang, MD

All Publications

• Percutaneous Cervical Cordotomy for Refractory Cancer Pain With General Anesthesia and Neuromonitoring: A Case Report. Pain practice : the official journal of World Institute of Pain Ahmed, S., Huang, Y., Polat, M., Chang, F., Lopez, J. R., McGeoch, P. D., Buch, V. P., Heidari, S. N., Wu, A., Neugarten, C., Carroll, I., Brose, W. G., Lanzman, B., Ramayya, A. G. 2026; 26 (7): e70193

  Abstract

  Cancer-related pain remains one of the most debilitating symptoms in patients with advanced malignancy, with a significant proportion experiencing pain refractory to standard medical therapy. Percutaneous cordotomy is an established intervention targeting the spinothalamic pathway and can provide meaningful relief in appropriately selected patients; however, its use has declined and is typically performed in awake patients.A 54-year-old woman with metastatic gallbladder carcinoma presented with severe, unilateral, nociceptive abdominal pain refractory to medical and interventional treatments. Given her limited life expectancy and persistent symptoms, she underwent percutaneous cervical cordotomy. At the patient's request, the procedure was performed under general anesthesia. We achieved excellent localization for safe ablation using intraoperative CT and neuromonitoring guidance. Postoperatively, she reported complete resolution of her primary pain (8-10/10 to 0/10) on postoperative Day 1. She developed expected contralateral "mirror pain," which was less severe and manageable. Pain relief was sustained during early follow-up, although later recurrence was attributed to disease progression rather than procedural failure.This case demonstrates that percutaneous cordotomy can be performed safely and effectively under general anesthesia with the aid of intraoperative CT and neuromonitoring. This approach may expand the applicability of cordotomy in carefully selected patients with refractory cancer pain, particularly when patient comfort is a priority.

  View details for DOI 10.1111/papr.70193

  View details for PubMedID 42613854

  View details for PubMedCentralID PMC13486940

• Safety and Feasibility of Transcranial Motor-Evoked Potentials During Intraoperative Neurophysiologic Monitoring in Patients With Deep Brain Stimulators. Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society Meyers, N., Keroles, M., Cho, S. C., Gummi, R., Le, S., Lee, L., Nguyen, V., Tippur, A., Lopez, J. R., Chang, F. 2026

  Abstract

  PURPOSE: Transcranial motor-evoked potentials (TcMEPs) are routinely used for intraoperative neurophysiologic monitoring to assess corticospinal tract integrity. However, data regarding the use of TcMEPs in patients with implanted deep brain stimulator (DBS) devices remain limited. This study aims to evaluate the safety and feasibility of TcMEP monitoring in patients with implanted DBS systems undergoing a variety of surgical procedures.METHODS: A retrospective review was conducted using clinical and neurophysiologic data from patients with DBS devices who underwent surgery with TcMEP monitoring at a single institution between 2014 and 2024. Patient demographics, surgical and device information, TcMEP stimulation parameters, and intraoperative neurophysiologic monitoring documentation, as well as intraoperative and postoperative clinical notes were reviewed.RESULTS: Sixteen patients were identified who underwent 19 surgical procedures with TcMEP monitoring. Reliable TcMEP signals were successfully obtained in all patients across a variety of surgical procedures, DBS targets, and stimulation parameters (80-520 V, 147-1,388 mA). No TcMEP-related intraoperative or postoperative complications were identified, and DBS device functionality remained preserved. However, active DBS stimulation during surgery generated electrical artifacts that interfered with other intraoperative neurophysiologic monitoring modalities, including somatosensory evoked potentials and EEG (electroencephalogram).CONCLUSIONS: Transcranial motor-evoked potentials monitoring is safe and feasible in patients with implanted DBS devices undergoing a variety of surgical procedures. Standard TcMEP stimulation parameters can be implemented without significant modification. To minimize interference with multimodal intraoperative neurophysiologic monitoring, DBS devices should be turned off during monitoring. Further studies are needed to establish standardized guidelines for TcMEP monitoring in patients with DBS and other intracranial neurostimulation devices.

  View details for DOI 10.1097/WNP.0000000000001249

  View details for PubMedID 41925348

• Multimodal Intraoperative Neurophysiologic Monitoring Including Transcranial Motor Evoked Potentials for the Detection of Cerebral Ischemia During Carotid Endarterectomy. Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society Gummi, R., Hirschauer, T., Chang, F., Tippur, A., Keroles, M., Meyers, N., Nguyen, V., Lee, L., Cho, S. C., López, J. R., Le, S. 2026

  Abstract

  Carotid endarterectomy (CEA) is a common surgical intervention, but the perioperative stroke risk may be as high as 12%, with an average reported rate approximately 3%. Intraoperative neurophysiologic monitoring (IONM) can provide real-time feedback to guide the surgical team on whether or not to place a temporary shunt to reduce the length of time that cerebral blood flow is interrupted. In this study, the authors assessed the utility of adding transcranial motor evoked potentials (tcMEPs) to other IONM modalities in early detection of cerebral ischemia during CEAs.The authors conducted a retrospective review of CEA cases from 2010 to 2020 at this center and included all CEA cases with electroencephalogram (EEG), somatosensory evoked potentials (SSEPs) and tcMEPs. The authors analyzed the IONM reports for case details. The primary study end points were types of IONM changes and their relative onsets to carotid occlusion.The authors identified 254 patients who underwent 274 CEAs using multimodal IONM. In 35 (12.7%) cases, there were critical IONM changes with 33 (12.0%) demonstrating changes during clamping of the carotid artery. Of these 35 cases, changes in both SSEPs and tcMEPs were observed in 20 (57.1%), only SSEP changes in 8 (22.9%), and only tcMEP changes in 2 (5.7%). In 5 cases, tcMEP loss was noted to precede other IONM changes. In total, 82% of significant changes were observed within the first 10 minutes of carotid clamping.This large cohort study shows that multimodal IONM with tcMEPs can contribute to the early detection of cerebral ischemia during CEA.

  View details for DOI 10.1097/WNP.0000000000001241

  View details for PubMedID 41637738

• Averaged Blink Reflex Potential: A Novel Method of Monitoring for Intraoperative Facial Nerve Injury Gummi, R., Keroles, M., Meyers, N., Cho, S., Le, S., Lee, L., Nguyen, V., Tippur, A., Lopez, J., Chang, F. LIPPINCOTT WILLIAMS & WILKINS. 2025

  View details for DOI 10.1212/WNL.0000000000212244

  View details for Web of Science ID 001715455903110

• Intraoperative Neurophysiologic Monitoring of Cerebrovascular Disorders Intraoperative Monitoring Lopez, J. R., Chang, F. W. Springer, Cham. 2022; 1: 611–659

  View details for DOI 10.1007/978-3-030-95730-8_28

• Intraoperative Neurophysiologic Monitoring for Thoracic and Thoracoabdominal Aortic Procedures Intraoperative Monitoring Chang, F. W., Lopez, J. R. Springer, Cham. 2022; 1: 661–708

  View details for DOI 10.1007/978-3-030-95730-8_29