Efficiency of spinal anesthesia versus general anesthesia for lumbar spinal surgery: a retrospective analysis of 544 patients.

BACKGROUND: Previous studies have shown varying results in selected outcomes when directly comparing spinal anesthesia to general in lumbar surgery. Some studies have shown reduced surgical time, postoperative pain, time in the postanesthesia care unit (PACU), incidence of urinary retention, postoperative nausea, and more favorable cost-effectiveness with spinal anesthesia. Despite these results, the current literature has also shown contradictory results in between-group comparisons. MATERIALS AND METHODS: A retrospective analysis was performed by querying the electronic medical record database for surgeries performed by a single surgeon between 2007 and 2011 using procedural codes 63030 for diskectomy and 63047 for laminectomy: 544 lumbar laminectomy and diskectomy surgeries were identified, with 183 undergoing general anesthesia and 361 undergoing spinal anesthesia (SA). Linear and multivariate regression analyses were performed to identify differences in blood loss, operative time, time from entering the operating room (OR) until incision, time from bandage placement to exiting the OR, total anesthesia time, PACU time, and total hospital stay. Secondary outcomes of interest included incidence of postoperative spinal hematoma and death, incidence of paraparesis, plegia, post-dural puncture headache, and paresthesia, among the SA patients. RESULTS: SA was associated with significantly lower operative time, blood loss, total anesthesia time, time from entering the OR until incision, time from bandage placement until exiting the OR, and total duration of hospital stay, but a longer stay in the PACU. The SA group experienced one spinal hematoma, which was evacuated without any long-term neurological deficits, and neither group experienced a death. The SA group had no episodes of paraparesis or plegia, post-dural puncture headaches, or episodes of persistent postoperative paresthesia or weakness. CONCLUSION: SA is effective for use in patients undergoing elective lumbar laminectomy and/or diskectomy spinal surgery, and was shown to be the more expedient anesthetic choice in the perioperative setting.

Giant cystic sacral schwannoma mimicking tarlov cyst: a case report.

PURPOSE: To present a rare case of a giant schwannoma of the sacrum mimicking a Tarlov cyst. METHODS: A 58-year-old woman had a 1-year history of low back pain. MRI revealed a large cystic mass in the sacral canal with bony erosion. Radiological diagnosis of Tarlov cyst was made. RESULTS: The patient underwent surgical treatment for the lesion, which revealed a solid mass. Histopathological examination of the tumor confirmed the diagnosis of schwannoma. The postoperative course was uneventful and the patient has had significant improvement in her pain 1 month postoperatively. CONCLUSION: Giant cystic schwannoma of the sacrum is a very rare diagnosis overlooked by practitioners for more common cystic etiologies, but its treatment is significantly different. Care should be taken to include this diagnosis in a differential for a cystic sacral mass.

Cerebrospinal fluid leaks and their management after anterior cervical discectomy and fusion: a report of 13 cases and a review of the literature.

STUDY DESIGN: Retrospective medical record review and literature review. OBJECTIVE: To identify cases where a cerebrospinal fluid (CSF) leak occurred during an anterior cervical discectomy and fusion (ACDF) and to create a management algorithm based on the findings. SUMMARY OF BACKGROUND DATA: ACDF is a commonly performed spinal operation. It is effective with very low complication rates. One rare complication of ACDF is a CSF leak. There is limited information on the management of CSF leaks after ACDF and management is on a surgeon-by-surgeon basis. METHODS: We reviewed 3 surgeons' case logs and identified cases where a CSF leak was encountered during ACDF and reviewed the patients' medical records, operative reports and imaging to determine how these leaks were managed. We also performed a PubMed search for articles about the presentation and management of CSF leaks after ACDF. RESULTS: Thirteen CSF leaks were identified in 1223 ACDFs, corresponding to a CSF leak rate of 1%. Of these, 9 were successfully treated with intraoperative repair. Postoperative lumbar drainage was used in the remaining 4 patients and was successful in 1 patient. Three patients underwent neck re-exploration and attempted delayed repair. Three patients, including one who was found to have hydrocephalus, ultimately required continuous CSF diversion via shunting. We identified 7 case reports of CSF leak in ADCF in the literature and 1 article that reviewed the prevalence and management of this complication. CONCLUSION: CSF leak after ACDF is an uncommon complication that can usually be repaired. We provide a stepwise management strategy for CSF leaks in ACDF.

Sustained neuronal hyperexcitability is evident in the thalamus after a transient cervical radicular injury.

STUDY DESIGN: This study used extracellular electrophysiology to examine neuronal hyperexcitability in the ventroposterolateral nucleus (VPL) of the thalamus in a rat model of painful radiculopathy. OBJECTIVE: The goal of this study was to quantify evoked neuronal excitability in the VPL at day 14 after a cervical nerve root compression to determine thalamic processing of persistent radicular pain. SUMMARY OF BACKGROUND DATA: Nerve root compression often leads to radicular pain. Chronic pain is thought to induce structural and biochemical changes in the brain affecting supraspinal signaling. In particular, the VPL of the thalamus has been implicated in chronic pain states. METHODS: Rats underwent a painful transient C7 nerve root compression or sham procedure. Ipsilateral forepaw mechanical allodynia was assessed on days 1, 3, 5, 7, 10, and 14 and evoked thalamic neuronal recordings were collected at day 14 from the contralateral VPL, whereas the injured forepaw was stimulated using a range of non-noxious and noxious mechanical stimuli. Neurons were classified on the basis of their response to stimulation. RESULTS: Behavioral sensitivity was elevated after nerve root compression starting at day 3 and persisted until day 14 (P < 0.049). Thalamic recordings at day 14 demonstrated increased neuronal hyperexcitability after injury for all mechanical stimuli (P < 0.024). In particular, wide dynamic range neurons demonstrated significantly more firing after injury compared with sham in response to von Frey stimulation (P < 0.0001). Firing in low threshold mechanoreceptive neurons was not different between groups. CONCLUSION: These data demonstrate that persistent radicular pain is associated with sustained neuronal hyperexcitability in the contralateral VPL of the thalamus. These findings suggest that thalamic processing is altered during radiculopathy and these changes in neuronal firing are associated with behavioral sensitivity. LEVEL OF EVIDENCE: N/A.

Regional anesthesia versus general anesthesia for surgery on the lumbar spine: a review of the modern literature.

Lumbar spine surgery can be performed using different anesthetic techniques such as general endotracheal anesthesia (GA) or spinal-based regional anesthesia (RA). Several studies have been performed comparing these two anesthetic techniques and have revealed disparate results. As such, we set out to review the relevant literature. We performed a literature search for clinical articles comparing cohorts of patients who underwent RA versus GA for lumbar spine surgeries. We compared results of these studies between groups with respect to the following outcome variables: heart rate (HR), mean arterial pressure (MAP), blood loss, duration of surgery, time spent in the PACU, post-operative analgesic use or pain scores, urinary retention rates, and nausea or anti-emetic requirements. Eleven studies were identified that compared cohorts of patients who underwent GA or RA. Of these, 4 were randomized control trials, 3 were case control trials, 2 were prospective cohorts, and 2 retrospective analyses. Seven-out-of-seven studies reported reduced HRs and MAPs in the RA compared to GA group, and 7/9 studies reported a lower incidence of post-operative analgesic requirement and/or decreased pain scores for the RA group. Our review of the literature suggests that both RA and GA are safe and effective techniques for lumbar spine surgery and that RA may prove a better alternative than GA for healthy patients undergoing simple lumbar decompression procedures or for patients who are at high risk for general anesthetic complications.

Salmon and human thrombin differentially regulate radicular pain, glial-induced inflammation and spinal neuronal excitability through protease-activated receptor-1.

Chronic neck pain is a major problem with common causes including disc herniation and spondylosis that compress the spinal nerve roots. Cervical nerve root compression in the rat produces sustained behavioral hypersensitivity, due in part to the early upregulation of pro-inflammatory cytokines, the sustained hyperexcitability of neurons in the spinal cord and degeneration in the injured nerve root. Through its activation of the protease-activated receptor-1 (PAR1), mammalian thrombin can enhance pain and inflammation; yet at lower concentrations it is also capable of transiently attenuating pain which suggests that PAR1 activation rate may affect pain maintenance. Interestingly, salmon-derived fibrin, which contains salmon thrombin, attenuates nerve root-induced pain and inflammation, but the mechanisms of action leading to its analgesia are unknown. This study evaluates the effects of salmon thrombin on nerve root-mediated pain, axonal degeneration in the root, spinal neuronal hyperexcitability and inflammation compared to its human counterpart in the context of their enzymatic capabilities towards coagulation substrates and PAR1. Salmon thrombin significantly reduces behavioral sensitivity, preserves neuronal myelination, reduces macrophage infiltration in the injured nerve root and significantly decreases spinal neuronal hyperexcitability after painful root compression in the rat; whereas human thrombin has no effect. Unlike salmon thrombin, human thrombin upregulates the transcription of IL-1ß and TNF-α and the secretion of IL-6 by cortical cultures. Salmon and human thrombins cleave human fibrinogen-derived peptides and form clots with fibrinogen with similar enzymatic activities, but salmon thrombin retains a higher enzymatic activity towards coagulation substrates in the presence of antithrombin III and hirudin compared to human thrombin. Conversely, salmon thrombin activates a PAR1-derived peptide more weakly than human thrombin. These results are the first to demonstrate that salmon thrombin has unique analgesic, neuroprotective and anti-inflammatory capabilities compared to human thrombin and that PAR1 may contribute to these actions.

Civilian gunshot wounds to the atlantoaxial spine: a report of 10 cases treated using a multidisciplinary approach.

OBJECT: Gunshot wounds to the atlantoaxial spine are uncommon injuries and rarely require treatment, as a bullet traversing this segment often results in a fatal injury. Additionally, these injuries are typically biomechanically stable. The authors report a series of 10 patients with gunshot wounds involving the lateral mass and/or bodies of the atlantoaxial complex. Their care is discussed and conclusions are drawn from these cases to identify the optimal treatment for these injuries. METHODS: A retrospective review was conducted of patients presenting to the emergency rooms of 3 institutions with gunshot wounds involving the atlantoaxial spine. Mechanism of injury and neurological status were obtained, as was the extent of the osteoligamentous, vascular, and neurological injuries. Nonoperative and operative treatment, complications, and clinical and radiographic outcome were recorded. The data were then analyzed to determine the neurological and biomechanical prognosis of these injuries, the utility of the various diagnostic modalities in the acute management of the injuries, and the nature and effectiveness of the nonoperative and operative treatment modalities. RESULTS: Ten patients with gunshot wounds involving the lateral mass and/or bodies of the atlantoaxial complex were identified. All but 2 patients sustained a vertebral artery injury. Each patient was evaluated using cervical radiographs, CT scans, and vascular imaging, 8 in the form of digital subtraction angiography and 2 with high-resolution CT angiography. Uncomplicated patients were treated conservatively using cervical collar immobilization, local wound care, and antibiotics. One patient was treated using a halo for instability and 1 underwent posterior fusion following a posterolateral decompression for delayed myelopathy. One patient underwent transoral resection of a bullet fragment. One patient underwent embolization for a symptomatic arteriovenous fistula and a second patient underwent a neck exploration and a jugular vein ligation. None of the patients received anticoagulation therapy. The mean follow-up duration was 13 months. All but 2 patients regained their previous functional status and all ultimately attained a mechanically stable spine. CONCLUSIONS: These 10 patients represent a rare form of cervical spine penetrating injury. Unilateral gunshot wounds to the atlantoaxial complex are usually stable and the need for acute surgical intervention is rare. Unilateral vertebral artery injury is well tolerated and any information provided by angiography does not alter the acute management of the patient. Vascular complications from gunshot wounds can be managed effectively by endovascular techniques.

The roles of mechanical compression and chemical irritation in regulating spinal neuronal signaling in painful cervical nerve root injury.

Both traumatic and slow-onset disc herniation can directly compress and/or chemically irritate cervical nerve roots, and both types of root injury elicit pain in animal models of radiculopathy. This study investigated the relative contributions of mechanical compression and chemical irritation of the nerve root to spinal regulation of neuronal activity using several outcomes. Modifications of two proteins known to regulate neurotransmission in the spinal cord, the neuropeptide calcitonin gene-related peptide (CGRP) and glutamate transporter 1 (GLT-1), were assessed in a rat model after painful cervical nerve root injuries using a mechanical compression, chemical irritation or their combination of injury. Only injuries with compression induced sustained behavioral hypersensitivity (p≤0.05) for two weeks and significant decreases (p<0.037) in CGRP and GLT-1 immunoreactivity to nearly half that of sham levels in the superficial dorsal horn. Because modification of spinal CGRP and GLT-1 is associated with enhanced excitatory signaling in the spinal cord, a second study evaluated the electrophysiological properties of neurons in the superficial and deeper dorsal horn at day 7 after a painful root compression. The evoked firing rate was significantly increased (p=0.045) after compression and only in the deeper lamina. The painful compression also induced a significant (p=0.002) shift in the percentage of neurons in the superficial lamina classified as low- threshold mechanoreceptive (sham 38%; compression 10%) to those classified as wide dynamic range neurons (sham 43%; compression 74%). Together, these studies highlight mechanical compression as a key modulator of spinal neuronal signaling in the context of radicular injury and pain.

Determination of grade and subtype of meningiomas by using histogram analysis of diffusion-tensor imaging metrics.

PURPOSE: To determine whether histogram analysis of diffusion-tensor (DT) magnetic resonance (MR) imaging metrics, including tensor shape measurements, can help determine the grades and subtypes of meningiomas. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study. Nine atypical, three anaplastic, and 39 typical meningiomas were retrospectively studied. The 39 typical meningiomas included one secretory meningioma and 11 fibroblastic, 11 transitional, 14 meningothelial, and two angiomatous meningiomas. DT imaging metrics, including fractional anisotropy, mean diffusivity, linear anisotropy coefficient, planar anisotropy coefficient (CP), spherical anisotropy coefficient (CS), and eigenvalue skewness (SK), as well as normalized signal intensity from contrast-enhanced T1- and T2-weighted images, were measured from the enhancing region of the tumor. Mean, variance, skewness, and kurtosis were extracted from the histograms. A two-level decision tree was designed, and a multivariate logistic regression analysis was used at each level to determine the best model for classification. RESULTS: Histogram skewness of SK and kurtosis of SK were significantly higher in atypical and anaplastic meningiomas than in typical meningiomas (P<.01). Among typical meningiomas, significant differences in histogram measures of CP and CS between fibroblastic meningiomas and other subtypes were observed (P<.01). The best model for differentiating atypical and anaplastic meningiomas from typical meningiomas consisted of mean and skewness of SK and kurtosis of T1 signal intensity, with an area under the receiver operating characteristic curve (AUC) of 0.946. The best model for differentiating fibroblastic meningiomas from other subtypes consisted of skewness of T2 signal intensity and kurtosis of CP (AUC, 0.970). CONCLUSION: Histogram analysis of DT imaging metrics can help determine the grades and subtypes of meningiomas, which can better assist in surgical planning.

Paradoxical lateralization of brain potentials during imagined foot movements.

Though each foot is controlled primarily by the contralateral hemisphere, the event-related brain potentials preceding an overt foot movement are largest over the ipsilateral side of the head. Because such "paradoxical lateralization" results from the spatial organization of the motor homunculus, it can provide a sign of motor-cortex activation. We report paradoxical lateralization in the potentials accompanying imagined foot movements, thereby demonstrating a contribution of cortical areas directly involved in movement execution.