Is intraoperative neurophysiological monitoring valuable predicting postoperative neurological recovery?

OBJECTIVES: We investigated the ability of intraoperative neurophysiological monitoring to predict postoperative neurological recovery in intradural-extramedullary spinal cord tumors. METHODS: From 2010 to 2014, we operated on 173 intradural-extramedullary spinal cord tumor patients with intraoperative neurophysiological monitoring. We retrospectively compared preoperative and postoperative clinical status using a modified McCormick grading scale and correlated with intraoperative neurophysiological monitoring. We followed patients for at least 1 year and correlated neurological outcomes with intraoperative changes in intraoperative neurophysiological monitoring. We then compared the degree of intraoperative neurophysiological monitoring change with the duration of the neurological deficit. RESULTS: Monitorability was 92% and 57% with transcranial motor-evoked potential and somatosensory-evoked potential modalities, respectively. Waveform attenuation on transcranial motor-evoked potentials was detected in 8.17% of cases. For somatosensory-evoked potentials, waveform attenuation was detected in 7% of the patients. A multimodality approach incorporating any transcranial motor-evoked potential changes had a sensitivity of 0.91 and a specificity of 0.98. The McCormick grade scale increased until 1 month in patients with alarm criteria on transcranial motor-evoked potentials (P<0.05). CONCLUSIONS: Patients suffered neurological deterioration in case of abolishment or >50% irreversible attenuation of the waveform in transcranial motor-evoked potentials. All patients gradually recovered after 1 postoperative month with alarm criteria from 50% to 80% irreversible amplitude drop on transcranial motor-evoked potentials.

Combined motor- and somatosensory-evoked potential monitoring for spine and spinal cord surgery: correlation of clinical and neurophysiological data in 85 consecutive procedures.

STUDY DESIGN: Prospective study. OBJECTIVES: The primary objective of neurophysiological monitoring during surgery is to prevent permanent neurological sequelae. To avoid neurological injury, we applied somatosensory-evoked potentials (SEPs) and/or motor-evoked potentials (MEPs). We evaluated whether the combination of SEP and MEP for spinal surgery may be beneficial. SETTING: Asian Medical Center, University of Ulsan College of Medicine, Seoul, Korea. METHODS: Combined SEP/MEP monitoring was attempted in 100 consecutive procedures for spinal operations. Trains of transcranial electrical stimulation over the motor cortex were used to elicit MEPs from the muscles of the upper/lower limbs. The tibial and median nerves were stimulated to record SEP. RESULTS: Combined SEP/MEP recording was successfully achieved in 85 of 100 operations. In 61 of 85 operations (71%), SEP and MEP were stable, and all patients remained neurologically intact after surgery. Significant MEP changes were recorded in 20 operations, either combined with (n=4) or without (n=16) SEP changes. In 7 of these 20 operations, MEP recovered to some extent after surgical intervention, and these patients showed no neurological changes. In the remaining 13 operations, MEP did not recover and the patients had a transient (n=4) or a permanent (n=3) motor deficit. Significant SEP changes with stable MEP were observed in four operations, all of which were not related to postoperative motor deficit. CONCLUSION: Combined SEP/MEP monitoring provided higher sensitivity and higher positive/negative predictive value than single-modality monitoring techniques. Detection of MEP changes and adjustment of surgical strategy may prevent irreversible pyramidal tract damage.

Reversible aggravation of neurological deficits after steroid medication in patients with venous congestive myelopathy caused by spinal arteriovenous malformation.

SUMMARY: Steroids are empirically used to medicate patients with myelopathy of unknown etiology. We report the reversible aggravation of neurological status after steroid administration in a patient with venous congestive myelopathy (VCM). We retrospectively evaluated 36 patients with angiographically confirmed spinal arteriovenous malformation (SAVM) from a prospectively collected neurointerventional database. We evaluated steroid medication and neurological aggravation using Aminoff grading and analyzed using Fisher's exact test whether steroid medication is related to neurological aggravation and spinal cord edema as demonstrated on MR T2-WI. Among 26 patients who had been treated with steroids, ten had aggravated neurological deficits. The aggravation in these ten patients was related to the steroid medication (P = 0.039 in all patients) and only marginally to VCM with spinal cord edema as seen on T2-WI (P = 0.074). Aggravation caused by using a high intravenous dose (250-1000 mg) of methylprednisolone or dexamethasone at 8-20 mg/day slowly decreased after stopping the steroid medication. Steroids were reversibly detrimental in patients with VCM caused by SAVM. A history of neurological aggravation after the use of steroids may suggest the diagnosis of SAVM associated with VCM.

Spinal epidural extraskeletal Ewing sarcoma: MR findings in two cases.

SUMMARY: We report the CT myelography and MR findings of two cases of extraskeletal Ewing sarcoma involving the spinal epidural and paravertebral spaces in a middle-aged man (case 1) and a young woman (case 2). In both cases CT myelography showed epidural and paravertebral masses on one side, with widening of the ipsilateral neural foramina at the C5-C6 level in case 1 and at the C7-T1 level in case 2. On MR images, the masses were isointense to muscle on T1-weighted images, hyperintense on T2-weighted images, and showed moderate enhancement on contrast-enhanced T1-weighted images. In one case, all pulse sequences showed linear signal voids, representing the vertebral artery encasement within the mass. The intradural component connected with the main mass was detected in the other case.

Spinal epidural cavernous hemangioma: MR findings.

PURPOSE: Cavernous hemangiomas with a spinal epidural location are very uncommon vascular tumors in contrast to those in the vertebral body. The purpose of this study was to describe the radiologic findings, focusing on the MR studies, of spinal epidural cavernous hemangiomas. METHOD: Five pathologically proven cases of spinal epidural cavernous hemangioma were retrospectively reviewed. MR (n = 5) and CT (n = 1) were evaluated. RESULTS: The level was thoracic (n = 4) or lumbosacral (n = 1). The mass was located in the epidural space and showed paravertebral extension in all cases. It showed a lobulated contour in all cases and encircled the spinal cord partially with a larger posterior (n = 3) or anterior (n = 1) component in four cases. In all cases, the mass showed high signal intensity on T2-weighted images and homogeneous, strong enhancement. Adjacent bony erosion (n = 5) and intervertebral neural foraminal widening (n = 4) were common. CONCLUSION: Spinal epidural cavernous hemangioma shows characteristic MR findings of a lobulated contoured epidural mass partially encircling the spinal cord with a larger posterior component in the spinal canal, high signal intensity on T2-weighted images, and homogeneous, strong enhancement.

Preoperative transarterial embolization of spinal tumor: embolization techniques and results.

BACKGROUND AND PURPOSE: The techniques of preoperative embolization of hypervascular spinal tumors, which has been known to be helpful for completing tumor resection, have not been described in detail. The purpose of this study was to analyze the technique and to evaluate the safety and value of preoperative transarterial embolization of hypervascular spinal tumors. METHODS: Eighteen patients with hypervascular spinal tumors underwent transarterial embolization before surgery. The lesions were located between the upper cervical and lower lumbar spine: C1-T1 (n = 6), T5-L3 (n = 11), and L5 (n = 1); they arose intradurally in six patients and extradurally in 12. Thirty-one arteries were embolized with polyvinyl alcohol (PVA) particles (150-500 microm), and, in 18 of these, pieces of gelatin sponge were added for proximal pedicular embolization. The criteria for judging the effectiveness of embolization were completeness of tumor removal and estimated blood loss during surgery. RESULTS: Tumor embolization was total in eight patients, nearly total in seven, subtotal in one, and partial in two. There were no symptomatic complications associated with embolization. Tumors were totally removed in 17 patients and nearly totally removed in one. The average estimated blood loss during surgery was 1100 mL (range, 200-6000 mL) for all 18 patients, and 1540 mL in patients with extradural tumors. CONCLUSION: Preoperative embolization of hypervascular spinal tumors is safe and effective. It can make complete resection of a tumor possible and can make an unresectable tumor resectable. Superselection or flow control is necessary to achieve effective devascularization and to avoid complications.

Complications during anterior surgery of the lumbar spine: an anatomically based study and review.

Procedures involving anterior surgical decompression and fusion are being performed with increasing frequency for the treatment of a variety of pathological processes of the spine including trauma, deformity, infection, degenerative disease, failed-back syndrome, discogenic pain, metastases, and primary spinal neoplasms. Because these operations involve anatomy that is often unfamiliar to many neurological and orthopedic surgeons, a significant proportion of the associated complications are not related to the actual decompressive or fusion procedure but instead to the actual exposure itself. To understand the nature of these injuries, a detailed anatomical study and dissection was undertaken in six cadaveric specimens. Critical structures at risk in the abdomen and retroperitoneum were identified, and their anatomical relationships were categorized and photographed. These structures included the psoas muscle, kidneys, ureters, diaphragm and crura, esophageal hiatus, thoracic duct, greater splanchnic nerves, phrenic nerves, sympathetic chains, medial arcuate ligament, superior and inferior hypogastric plexus, segmental and radicular vertebral vessels, aorta, vena cava, median sacral artery, common iliac vessels, iliolumbar veins, lumbosacral plexus, and presacral hypogastric plexus. Based on these dissections and an extensive review of the literature, the authors provide a detailed anatomically based discussion of the complications associated with anterior lumbar surgery.

MRI in presumed cervical anterior spinal artery territory infarcts.

We report the MRI findings in two patients with presumed cervical spinal cord infarcts in the anterior spinal artery territory. MRI revealed abnormal signal intensities and/or band-like enhancement in the anterior two-thirds of the cervical spinal cord, corresponding to the vascular territory of the anterior spinal artery. Clinically there was an anterior spinal cord syndrome.