Upper-limb somatosensory evoked potential monitoring in lumbosacral spine surgery: a prognostic marker for position-related ulnar nerve injury

Complications associated with prone positioning in elective spinal surgery

“…Ulnar nerve injury can occur due to direct pressure over the cubital tunnel at the elbow, excessive flexion of the elbow (> 90 degrees), malposition of a blood pressure cuff, or with accidental change in position of the arm during surgery, such as the arm falling off of the armboard. Chung et al [30] noted in a recent study that the ulnar nerve is more vulnerable to ischemia from brachial artery compression than are the median and radial nerves, with immediate loss of SSEPs seen in that case. They also noted that obesity was a risk factor for the development of ulnar nerve palsy following prone positioning.…”

“…Ophthalmological complications ION [14] Obesity, male sex, Wilson frame use, longer anesthetic duration, greater estimated blood loss, increased ratio of crystalloid to colloid Posterior ION [13] Blood loss greater than 4 L, persistent relative hypotension Anterior ION [16] Atherosclerosis, diabetes Central retinal artery occlusion [5,13] External compression of the eye Cortical blindness [13] Profound hypotension, prolonged hypoxia, cardiac arrest, thromboembolism Neurologic complications Acute cervical myelopathy [20] Cervical spondylosis, neck extension, paralytic anesthesia Brachial plexopathy [21] Extension, external rotation, and abduction of the arm, ipsilateral rotation and lateral flexion of neck, shoulder braces Ulnar nerve palsy [30] Obesity, inadequate elbow padding Myocutaneous complications Compartment syndrome [34][35][36] Padding directly over the compartment, obesity Pressure ulcers [37,38] Procedure duration, advanced age, obesity, steroid administration Femoral head avascular necrosis [42] Pressure over the groin, hypotension ION: Ischemic optic neuropathy.…”

“…The brachial plexus innervates all upper limb musculature (except for the trapezius and levator scapulae) and supplies sensation to the upper limb with the exception of the axillary, superior shoulder, and dorsal scapular innervated regions. The plexus is fixed at the cervical vertebrae and the axillary fascia [21] , increasing the [14] Reverse trendelenburg positioning, colloid administration by anesthesia, limit prolonged intraoperative hypotension Posterior ION [13] Limit prolonged intraoperative hypotension Anterior ION [16] None Central retinal artery occlusion [5,13] Avoid compression of the globe Cortical blindness [13] Limit prolonged intraoperative hypotension Neurologic complications Acute cervical myelopathy [20] Thorough history and preoperative imaging, careful neck positioning during patient transfers and surgical procedure Brachial plexopathy [21] Careful anatomic positioning of the arm, limiting extension and external rotation of shoulder Ulnar nerve palsy [30] Avoid compression and pressure at the elbow, maintain arm position during procedure (avoid arm falling off of arm board) Myocutaneous complications Compartment syndrome [34][35][36] Avoid pressure on anterior thigh and leg, avoid extremely long surgical procedures. Extra care with obese patients Pressure ulcers [37,38] Pad bony prominences.…”

“…They also noted that obesity was a risk factor for the development of ulnar nerve palsy following prone positioning. Intraoperative neuromonitoring can help detect and prevent the development of symptoms [30] . A preoperative physical exam is also valuable for identifying preexisting cubital tunnel syndrome, which increases the likelihood of postoperative palsy.…”

EMG and Evoked Potentials in the Operating Room During Spinal Surgery

“…SSEPs are mediated by primarily through the dorsal column (Nuwer, 1999) or dorsal spinocerebellar tracts (York, 1985). SSEPs are used to assess the functional status of somatosensory pathways during surgical procedures which affect peripheral nerve or plexus (Prielipp et al, 1999;Chung et al, 2009), spinal cord (deformity correction, traumatic spinal fracture, tumor removal, Duffau, 2008), and brain (carotid endarterectomy, aneurysm repair, Friedman et al, 1991;Lam et al, 1991). For upper extremity SSEP recordings, cortical (C3, C4 of the international 10-20 system, reference to Fz) and subcortical SSEPs (cervical spinous process, reference to Fz) are monitored upon alternate stimulation of the median or ulnar nerve at the wrist (stimulation intensity of ~20 mA, stimulation frequency of 3.1 Hz, stimulation duration of 0.5 msec) through surface electrodes (Fig.…”