Neuromonitoring During First Rib Resections For Thoracic Outlet Syndrome
Priyam Vyas, MD, Jeremy McCallister, AuD, CNIM, DABNM, Ralph Ierardi, MD, Sonya Tuerff, MD.
Christiana Care, Wilmington, DE, USA.
OBJECTIVES: Surgical treatment for thoracic outlet syndrome (TOS) frequently involves scalenectomy and resection of the first cervical rib through a supraclavicular approach. The most significant post-operative neurologic complications associated with these procedures include injuries to the brachial plexus, long thoracic nerve and phrenic nerve. The literature has described post-operative rates of injuries; plexus injuries range from 0.6%-37.5%, phrenic nerve injuries vary from 0.6%-2.2% and long thoracic nerve injuries range from 0% - 0.4%. We retrospectively review intraoperative neuromonitoring changes during the surgical treatment of Thoracic Outlet Syndrome (TOS) in an effort to reveal the nature, pattern and timing of neurologic injuries that may occur during these procedures. We also describe the efficacy, sensitivity and specificity of neuromonitoring with respect to detection of post-operative neurologic injuries.
METHODS: 122 procedures monitored for 115 patients. 7 patients received bilateral procedures. Ages ranged from 15 to 65 years with a mean of 35. Surgical treatment was performed through the supraclavicular approach and involved anterior scalenectomy, first rib resection and neurolysis. Spontaneous EMG, stimulated EMG and motor evoked potentials (MEP) recorded from upper extremity muscles innervated by the brachial plexus. Spontaneous and stimulated EMG as well as motor evoked potentials recorded from the serratus anterior muscle, diaphragm innervated, and ulnar nerve evoked potentials. RESULTS: Alerts occurred in 82 (67%) of the procedures. 169 isolated or concurrent “alert events” were noted. 98% of the alerts involved the brachial plexus followed by the phrenic nerve (2%). No long thoracic nerve or ulnar nerve SSEP alerts were noted. The overall rate of new deficits was 2.4%. CONCLUSIONS: Overall specificity was 94% and sensitivity was 33% but, notably, sensitivity was 100% since monitoring of long thoracic and phrenic nerves has been added to the neuromonitoring protocol. Stimulated EMG is a good prognostic indicator of post-operative phrenic nerve function and the post op injury rate associated with this study group (2.4%) compares favorably with other studies which have documented injury rates as high as 37%. Clinicians should be vigilant of the portion of the procedure with highest nerve injury rate and should consider neuromonitoring as a tool for injury prevention.
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