Somatosensory evoked potential monitoring detection of carotid compression during ACDF surgery in a patient with a vascularly isolated hemisphere.
The authors report herein a case of anterior cervical discectomy and fusion (ACDF) surgery in which findings on somatosensory evoked potential (SSEP) monitoring led to the correction of carotid artery compression in a patient with a vascularly isolated hemisphere (no significant collateral blood vessels to the carotid artery territory). The amplitude of the cortical SSEP component to left ulnar nerve stimulation progressively decreased in multiple runs, but there were no changes in the cervicomedullary SSEP component to the same stimulus. When the lateral (right-sided) retractor was removed, the cortical SSEP component returned to baseline. The retraction was then intermittently relaxed during the rest of the operation, and the patient suffered no neurological morbidity. Magnetic resonance angiography demonstrated a vascularly isolated right hemisphere. During anterior cervical spine surgery, carotid artery compression by the retractor can cause hemispheric ischemia and infarction in patients with inadequate collateral circulation. The primary purpose of SSEP monitoring during ACDF surgery is to detect compromise of the dorsal column somatosensory pathways within the cervical spinal cord, but intraoperative SSEP monitoring can also detect hemispheric ischemia. Concurrent recording of cervicomedullary SSEPs can help differentiate cortical SSEP changes due to hemispheric ischemia from those due to compromise of the dorsal column pathways. If there are adverse changes in the cortical SSEPs but no changes in the cervicomedullary SSEPs, the possibility of hemispheric ischemia due to carotid artery compression by the retractor should be considered.
Departments of 1 Neurology.|Neuroscience, and.
Alan D
AD
Legatt
Ruth & Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Avra S
AS
Laarakker
Neurosurgery, Montefiore Medical Center and the Albert Einstein College of Medicine, Bronx, New York; and.
Jonathan P
JP
Nakhla
Neurosurgery, Montefiore Medical Center and the Albert Einstein College of Medicine, Bronx, New York; and.
Rani
R
Nasser
Neurosurgery, Montefiore Medical Center and the Albert Einstein College of Medicine, Bronx, New York; and.
David J
DJ
Altschul
D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology; D002545:Brain Ischemia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D017536:Carotid Artery, Common / Q000503:physiopathology*; D002574:Cervical Vertebrae / Q000601:surgery*; D017586:Diskectomy / Q000009:adverse effects / Q000379:methods*; D005073:Evoked Potentials, Somatosensory; D007839:Functional Laterality; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*
ACDF = anterior cervical discectomy and fusion; ACoA = anterior communicating artery; BP = blood pressure; CCA = common carotid artery; EMG = electromyographic; ICA = internal carotid artery; IOM = intraoperative monitoring; MEP = motor evoked potential; MRA = MR angiogram; PCA = posterior cerebral artery; PCoA = posterior communicating artery; SSEP = somatosensory evoked potential; TES = transcranial electrical stimulation; anterior cervical discectomy and fusion; carotid artery compression; circle of Willis; intraoperative neurophysiological monitoring; isolated hemisphere; somatosensory evoked potentials; technique