General Session: Tumor, Trauma, Infection - Hall F

Presented by: J.W. Silverstein

Author(s):

J.W. Silverstein(1), M.J. Goldstein(2), N.P. Shah(3), D. Porter(4), R. Madhok(5), J.F. Harrington, Jr.(6), S.K. Basra(7)

(1) Neuro Protective Solutions, Clinical Neurophysiology, Hauppauge, NY, United States
(2) Orthopedic Associates of Manhasset, Great Neck, NY, United States
(3) Connecticut Neck and Back Specialists, Danbury, NY, United States
(4) Neuro Protective Solutions, Hauppauge, NY, United States
(5) Neuroaxis Neurosurgical Associates, New York, NY, United States
(6) Neuro Brain & Spine Surgery, Stony Brook, NY, United States
(7) Long Island Spine Specialists, Commack, NY, United States

Abstract

Background Context: C5 neuropraxia is a known, poorly understood complication of cervical spine surgery and has a reported incidence as high as 30% in some studies. Weakness of the deltoid and biceps muscles present immediately postoperatively or in a delayed fashion. The exact etiology remain elusive and controversy regarding the efficacy and utility of neuromonitoring for intraoperative detection of these injuries exist.

Purpose: To describe a novel approach to monitoring for C5 nerve root palsies by evaluating motor evoked potential recordings (MEP) and spontaneous electromyographic recordings (s-EMG) from the three heads of the deltoid muscles along with standard MEP/EMG target muscle recordings contemporaneously.

Study Design: A retrospective analysis of a prospective case series was performed.

Methods: A group of board-certified neurophysiologists, fellowship trained orthopedic spine and neurological surgeons performed and monitored 498 anterior or posterior cervical spine surgeries over the course of one year. The three heads of the deltoid muscles, biceps, triceps, hand, and feet muscles were evaluated intraoperatively with MEP and EMG. The surgeon was informed to any spontaneous EMG activity from the deltoid and/or biceps muscle groups and alerts were also given if there were any significant degradation of the deltoid and/or biceps MEP recordings.

Results: 6 patients (1.2%) presented with post-operative C5 palsies. 4/6 presented with delayed onset C5 neuropraxia ranging from 3 hours post-operatively to 3 days post-operatively. None of the delayed onset palsies were detected intraoperatively with EMG or MEP monitoring. These 4 cases were performed posteriorly. The remaining 2 procedures exhibited intraoperative MEP deterioration with no relevant s-EMG activity noted. Patient 1 presented with a complete attenuation of the bilateral proximal MEP recordings (three heads of the deltoids & biceps) after the C5 level was decompressed during a posterior cervical fusion (All acquired distal MEP recordings remained intact). This patient awoke with immediate onset bilateral C5 palsies. Patient 2 underwent a C3-C7 ACDF and presented with a significant attenuation of the left anterior deltoid and left biceps MEP recordings just after placement of the interbody cage at C5-C6. The left middle and left posterior deltoids along with the right deltoids and biceps MEP recordings never deviated from their acquired baseline status. This patient awoke with an immediate partial C5 palsy (2/5 left deltoids, 3+/5 left biceps).

Conclusion: C5 palsy is a complication that is seen following anterior or posterior approaches to the spine. The complication may be acute or delayed. Acute injury may be detected with MEP/EMG monitoring. If the injury occurs in a delayed fashion, it will likely not be detected using MEP/EMG monitoring. Recording MEPs from all 3 heads of the deltoid muscles along with biceps muscles increases our sensitivity and specificity in detecting iatrogenic C5 sequelae. In this cohort, the investigators found s-EMG activity alone from the deltoids and/or biceps muscle groups was not an indicator for postoperative C5 nerve root function. More study is needed to establish better statistical methods, better modality efficacy, and a better understanding of intraoperative countermeasures that may be employed when an alert is encountered.