Intraoperative Nerve Monitoring to Prevent Peripheral Nerve Injury During Low-Flow Vascular Malformation Embolization

Purpose: To assess the efficacy of intraoperative neurophysiologic monitoring (IONM) as a method to minimize iatrogenic peripheral nerve injury during embolization of low-flow vascular malformations (LFVMs).

Materials and Methods: With institutional review board exemption and Health Insurance Portability and Accountability Act compliance, we derived a study cohort of 49 patients with LFVMs, including venous malformation (VM), lymphatic malformation (LM), and mixed vascular malformations (MVM) treated with percutaneous embolization using sclerosants such as ethanol, Sotradecol, bleomycin, and doxycycline (LM) performed from 2004 to 2019 and who received IONM for lesions that are adjacent to one or more peripheral nerve(s).

Results: In the study cohort of 49 patients (mean age, 30.1 years; range, 5–71 years; 61% female), the mean follow-up period was 5.56 years (range <1–14.8 years). VM constituted 74% of the lesions, 17% were LM, and 4% were MVM. Including retreatments, 84 sessions were performed with a total of 319 sites treated. Intraoperatively, abnormal neurophysiologic findings were noted in 35% (29 of 84) of the treatment sessions, and 9.5% (8 of 84) of all sessions were terminated prematurely because of significant electrophysiologic changes. Ethanol was the sclerosant used in all sessions that were terminated early. The overall complication rate was 3.6% (3 of 84). The minor non-neurologic complication rate was 2.4% (n = 2/84, superficial skin burn). One patient, 1.2% (1 of 84) of sessions, developed transient facial muscle weakness that resolved without additional treatment. No patient developed major complications or long-term neurologic impairment.

Conclusions: IONM may improve the safety of vascular malformation embolization procedures by providing a real-time assessment of any ongoing damage and by facilitating intraprocedural planning to prevent irreversible nerve injury.