Michael S. Virk

Vagus nerve stimulation vs. corpus callosotomy in the treatment of Lennox–Gastaut syndrome: A meta-analysis

PURPOSE Lennox-Gastaut syndrome (LGS) is an epileptogenic disorder that arises in childhood and is typically characterized by multiple seizure types, slow spike-and-wave complexes on EEG and cognitive impairment. If medical treatment fails, patients can proceed to one of two palliative surgeries, vagus nerve stimulation (VNS) or corpus callosotomy (CC). Their relative seizure control rates in LGS have not been well studied. The purpose of this paper is to compare seizure reduction rates between VNS and CC in LGS using meta-analyses of published data. METHODS A systematic search of Pubmed, Ovidsp, and Cochrane was performed to find articles that met the following criteria: (1) prospective or retrospective study, (2) at least one patient diagnosed with Lennox-Gastaut syndrome, and (3) well-defined measure of seizure frequency reduction. Seizure reduction rates were divided into seizure subtypes, as well as total seizures, and categorized as 100%, >75%, and >50%. Patient groups were compared using chi-square tests for categorical variables and t-test for continuous measures. Pooled proportions with 95% confidence interval (95% CI) of seizure outcomes were estimated for total seizures and seizure subtypes using random effects methods. RESULTS 17 VNS and 9 CC studies met the criteria for inclusion. CC had a significantly better outcome than VNS for >50% atonic seizure reduction (80.0% [67.0-90.0%] vs. 54.1% [32.1-75.4%], p<0.05) and for >75% atonic seizure reduction (70.0% [48.05-87.0%] vs. 26.3% [5.8-54.7%], p<0.05). All other seizure types, as well as total number of seizures, showed no statistically significant difference between VNS and CC. CONCLUSIONS CC may be more beneficial for LGS patients whose predominant disabling seizure type is atonic. For all other seizure types, VNS offers comparable rates to CC.

Opposing roles for serotonin in cholinergic neurons of the ventral and dorsal striatum

Significance The ventral striatum (vSt) and dorsal striatum (dSt) take part in different neuronal circuits that mediate emotional and motoric behaviors, respectively. vSt and dSt are populated by similar types of neurons, and little is known about the molecular differences between neurons of these regions. We report here that, in mice, serotonin [5-Hydroxytryptamine (5-HT)] oppositely regulates the excitability of cholinergic interneurons of the vSt and dSt. Postsynaptic 5-HT1A receptors and presynaptic 5-HT1B receptors synergistically mediate inhibition of ACh release from cholinergic neurons of the vSt. Deletion of 5-HT1B from cholinergic neurons resulted in an impairment in hedonic, but not motoric behavior. The present results contribute to our understanding of the specific functional roles of these brain areas. Little is known about the molecular similarities and differences between neurons in the ventral (vSt) and dorsal striatum (dSt) and their physiological implications. In the vSt, serotonin [5-Hydroxytryptamine (5-HT)] modulates mood control and pleasure response, whereas in the dSt, 5-HT regulates motor behavior. Here we show that, in mice, 5-HT depolarizes cholinergic interneurons (ChIs) of the dSt whereas hyperpolarizing ChIs from the vSt by acting on different 5-HT receptor isoforms. In the vSt, 5-HT1A (a postsynaptic receptor) and 5-HT1B (a presynaptic receptor) are highly expressed, and synergistically inhibit the excitability of ChIs. The inhibitory modulation by 5-HT1B, but not that by 5-HT1A, is mediated by p11, a protein associated with major depressive disorder. Specific deletion of 5-HT1B from cholinergic neurons results in impaired inhibition of ACh release in the vSt and in anhedonic-like behavior.

Minimally invasive versus open fusion for Grade I degenerative lumbar spondylolisthesis: analysis of the Quality Outcomes Database

OBJECTIVE Lumbar spondylolisthesis is a degenerative condition that can be surgically treated with either open or minimally invasive decompression and instrumented fusion. Minimally invasive surgery (MIS) approaches may shorten recovery, reduce blood loss, and minimize soft-tissue damage with resultant reduced postoperative pain and disability. METHODS The authors queried the national, multicenter Quality Outcomes Database (QOD) registry for patients undergoing posterior lumbar fusion between July 2014 and December 2015 for Grade I degenerative spondylolisthesis. The authors recorded baseline and 12-month patient-reported outcomes (PROs), including Oswestry Disability Index (ODI), EQ-5D, numeric rating scale (NRS)-back pain (NRS-BP), NRS-leg pain (NRS-LP), and satisfaction (North American Spine Society satisfaction questionnaire). Multivariable regression models were fitted for hospital length of stay (LOS), 12-month PROs, and 90-day return to work, after adjusting for an array of preoperative and surgical variables. RESULTS A total of 345 patients (open surgery, n = 254; MIS, n = 91) from 11 participating sites were identified in the QOD. The follow-up rate at 12 months was 84% (83.5% [open surgery]; 85% [MIS]). Overall, baseline patient demographics, comorbidities, and clinical characteristics were similarly distributed between the cohorts. Two hundred fifty seven patients underwent 1-level fusion (open surgery, n = 181; MIS, n = 76), and 88 patients underwent 2-level fusion (open surgery, n = 73; MIS, n = 15). Patients in both groups reported significant improvement in all primary outcomes (all p < 0.001). MIS was associated with a significantly lower mean intraoperative estimated blood loss and slightly longer operative times in both 1- and 2-level fusion subgroups. Although the LOS was shorter for MIS 1-level cases, this was not significantly different. No difference was detected with regard to the 12-month PROs between the 1-level MIS versus the 1-level open surgical groups. However, change in functional outcome scores for patients undergoing 2-level fusion was notably larger in the MIS cohort for ODI (-27 vs -16, p = 0.1), EQ-5D (0.27 vs 0.15, p = 0.08), and NRS-BP (-3.5 vs -2.7, p = 0.41); statistical significance was shown only for changes in NRS-LP scores (-4.9 vs -2.8, p = 0.02). On risk-adjusted analysis for 1-level fusion, open versus minimally invasive approach was not significant for 12-month PROs, LOS, and 90-day return to work. CONCLUSIONS Significant improvement was found in terms of all functional outcomes in patients undergoing open or MIS fusion for lumbar spondylolisthesis. No difference was detected between the 2 techniques for 1-level fusion in terms of patient-reported outcomes, LOS, and 90-day return to work. However, patients undergoing 2-level MIS fusion reported significantly better improvement in NRS-LP at 12 months than patients undergoing 2-level open surgery. Longer follow-up is needed to provide further insight into the comparative effectiveness of the 2 procedures.

Stereotactic navigation for the prepsoas oblique lateral lumbar interbody fusion: technical note and case series

The prepsoas retroperitoneal approach is a minimally invasive technique used for anterior lumbar interbody fusion. The approach may have a more favorable risk profile than the transpsoas approach, decreasing the risks that come with dissecting through the psoas muscle. However, the oblique angle of the spine in the prepsoas approach can be disorienting and challenging. This technical report provides an overview of the use of navigation in prepsoas oblique lateral lumbar interbody fusion in a series of 49 patients.

170 The Accuracy of Multimodality Intraoperative Neuromonitoring to Predict Postoperative Neurological Deficits Following Cervical Laminoplasty.

INTRODUCTION The utility multimodality intraoperative neuromonitoring (IONM) to predict postoperative neural deficits following cervical laminoplasty remains unclear. The purpose of this study is to determine whether multimodality IONM can predict postoperative C5 palsy. METHODS We retrospectively reviewed 131 consecutive patients with cervical myelopathy who underwent open door laminoplasty utilizing motor evoked potential (MEP) monitoring combined with somatosensory-evoked potentials (SSEP) and free-running electromyography (EMG). We reviewed abnormal findings in the IONM record including EMG, MEP, and SSEP changes documented as transient or persist at the end of surgery. RESULTS Postoperative C5 palsy occurred in 3 patients (2.2%). Two were acute in onset and one occurred 4 days postoperatively. Significant MEP alerts occurred in 12 patients. Four patients had MEP intraoperative alerts in their deltoid or biceps, of which 2 alerts were transient and 2 alerts were persistent at the end of surgery. Significant intraoperative SSEP change was not observed in this study. For the prediction of postoperative acute-onset C5 palsy, MEP alerts in the deltoid or biceps had 100% sensitivity and 98.4% specificity. Transient or persistent MEP alerts in the deltoid or biceps have the same positive predictive value with sensitivity of 50.0% and specificity of 99.2%. CONCLUSION The incidence of any neurological deficit including C5 palsy during laminoplasty while utilizing multimodality IONM was relatively low. MEP alerts in the deltoids or biceps had 100% sensitivity and 98.4% specificity to predict a postoperative acute C5 palsy.Abstract The utility multimodality intraoperative neuromonitoring (IONM) to predict postoperative neural deficits following cervical laminoplasty remains unclear. The purpose of this study is to determine whether multimodality IONM can predict postoperative C5 palsy. We retrospectively reviewed 131 consecutive patients with cervical myelopathy who underwent open door laminoplasty utilizing motor evoked potential (MEP) monitoring combined with somatosensory-evoked potentials (SSEP) and free-running electromyography (EMG). We reviewed abnormal findings in the IONM record including EMG, MEP, and SSEP changes documented as transient or persist at the end of surgery. Postoperative C5 palsy occurred in 3 patients (2.2%). Two were acute in onset and one occurred 4 days postoperatively. Significant MEP alerts occurred in 12 patients. Four patients had MEP intraoperative alerts in their deltoid or biceps, of which 2 alerts were transient and 2 alerts were persistent at the end of surgery. Significant intraoperative SSEP change was not observed in this study. For the prediction of postoperative acute-onset C5 palsy, MEP alerts in the deltoid or biceps had 100% sensitivity and 98.4% specificity. Transient or persistent MEP alerts in the deltoid or biceps have the same positive predictive value with sensitivity of 50.0% and specificity of 99.2%. The incidence of any neurological deficit including C5 palsy during laminoplasty while utilizing multimodality IONM was relatively low. MEP alerts in the deltoids or biceps had 100% sensitivity and 98.4% specificity to predict a postoperative acute C5 palsy.

Transoral Odontoidectomy and C1-2 Posterior Fusion Complication

Atlantoaxial instability results from the loss of the structural integrity of the C1–C2 articulation. Loss of alignment of the C1–C2 joint puts the neurovascular structures—the spinal cord at the cervicomedullary junction and the vertebral arteries—at risk for injury. Treatment is focused on restoring proper alignment, decompressing the neural elements, and stabilizing the joint with instrumentation so that bony fusion can occur. The case presented here is of a 67-year-old osteoporotic male with a traumatic dens fracture and C1–C2 subluxation, resulting in spinal cord compression, and vertebral artery dissection. Halo traction was initially pursued to realign the C1–C2 joint, but the patient had a skull fracture from the halo fixation pins. The patient’s halo was repositioned, and he underwent a posterior occipital-cervical instrumentation. He then underwent a transoral odontoidectomy which was complicated by durotomy. Strategies for surgical management and the spectrum of surgical complications are presented.

Lateral Prepsoas (Oblique) Approach Nuances

The prepsoas oblique approach to the lumbar spine provides many similar benefits of the transpsoas lateral approach. Because the psoas is not traversed, however, many of the postoperative complications associated with psoas violation are reduced. Working at an oblique angle to the spine can be challenging and the approach may be unfamiliar for the surgeon. Thais article provides a technical description and nuances of the approach.

Editorial. Nuances of restoration of lumbar lordosis using an MIS anterior column release versus posterior 3-column osteotomy

L eveque et al.1 present a comparison of pedicle subtraction osteotomy (PSO) to lateral interbody fusion and anterior column realignment (LLIF-ACR) for restoring lumbar lordosis in patients with spinal deformity. This is a retrospective chart review from a single institution, spanning 2010–2015, that generated 14 patients in the PSO group and 13 in the LLIF-ACR group. Patients who had a PSO were excluded if they had a preexisting fusion of more than 4 levels or if there was an additional lateral approach incorporating hyperlordotic grafts (angulation > 15°). There are several intraand perioperative issues to note. The primary finding is that equivalent correction of lumbar lordosis was achieved in the LLIF-ACR cohort with approximately 50% of the blood loss of the PSO cohort (1466 ml vs 2910 ml for the PSO group, p < 0.01). Patients who received antifibrinolytic agents were excluded from this study. The total operative time and length of stay were equivalent in the 2 groups. Where procedures for patients in either group were staged, estimated blood loss and operative time were combined to include the net total. The authors use pelvic incidence–lumbar lordosis (PILL) ratios as the primary spinopelvic parameter to compare the groups preand postoperatively. They reported the same degree of correction in the PSO and LLIF-ACR groups. They also noted that lordosis correction is equivalent to 54% of the hyperlordotic cage angle. Thus, when 30° cages are used, approximately 15° of correction was achieved on average. This paper has a few shortcomings. There are no standardized patient-reported outcomes. There is no fusion evaluation. A third-party observer should ideally be used to assess bony fusion by evaluating radiographs or a CT scan. There was no preoperative assessment of bone quality in the patients; we typically assess osteoporosis with a preoperative bone density study in patients who are having multilevel deformity correction surgery. Finally, the PSO group was followed for 25.5 months, whereas the LLIFACR group was followed for 13.2 months. This may create a bias when evaluating outcomes such as “reoperation for pseudarthrosis” since it is not yet known if the LLIF-ACR patients will need late revision surgery at 1–2 years after surgery, as their duration of follow-up is short. Restoring lumbar lordosis is one of the primary goals of treating patients with adult spinal deformity characterized by sagittal imbalance. Anterolateral approaches including lateral interbody techniques with anterior longitudinal ligament (ALL) release and hyperlordotic graft placement have emerged as a new option. These “minimally invasive techniques” are being suggested as potential alternatives to PSO in selected patients. The complications associated with PSO are now well documented, but we do not yet know the full complication profile for LLIF-ACR2 There is the potential for iliac vessel injury with the LLIF-ACR, and this is not typically a complication associated with PSO. However, comparison studies are sparse in the literature. Algorithms outlining a rational approach to addressing spinal deformity through a variety of minimally invasive and open techniques are now becoming more sophisticated.3 Not all patients are candidates for the minimally invasive correction of spinal deformity, and patient selection is the key. The authors are to be commended for contributing important data that facilitate our understanding of these 2 strategies.