Nikhil R. Nayak

Microsurgical treatment of sacral perineural (Tarlov) cysts: case series and review of the literature

OBJECTIVE Tarlov cysts (TCs) occur most commonly on extradural components of the sacral and coccygeal nerve roots. These lesions are often found incidentally, with an estimated prevalence of 4%-9%. Given the low estimated rates of symptomatic TC and the fact that symptoms can overlap with other common causes of low-back pain, optimal management of this entity is a matter of ongoing debate. Here, the authors investigate the effects of surgical intervention on symptomatic TCs and aim to solidify the surgical criteria for this disease process. METHODS The authors performed a retrospective review of data from consecutive patients who were surgically treated for symptomatic TCs from September 2011 to March 2013. Clinical evaluations and results from surveying pain and overall health were used. Univariate statistical analyses were performed. RESULTS Twenty-three adults (4 males, 19 females) who had been symptomatic for a mean of 47.4 months were treated with laminectomy, microsurgical exposure and/or imbrication, and paraspinous muscle flap closure. Eighteen patients (78.3%) had undergone prior interventions without sustained improvement. Thirteen patients (56.5%) underwent lumbar drainage for an average of 8.7 days following surgery. The mean follow-up was 14.4 months. Univariate analyses demonstrated that an advanced age (p = 0.045), the number of noted perineural cysts on preoperative imaging (p = 0.02), and the duration of preoperative symptoms (p = 0.03) were associated with a poor postoperative outcome. Although 47.8% of the patients were able to return to normal activities, 93.8% of those surveyed reported that they would undergo the operation again if given the choice. CONCLUSIONS This is one of the largest published studies on patients with TCs treated microsurgically. The data suggest that patients with symptomatic TCs may benefit from open microsurgical treatment. Although outcomes seem related to patient age, duration of symptoms, and extent of disease demonstrated on imaging, further study is warranted and underway.

Endoscopic approaches to brainstem cavernous malformations: Case series and review of the literature

Background: Symptomatic cavernous malformations involving the brainstem are frequently difficult to access via traditional methods. Conventional skull-base approaches require significant brain retraction or bone removal to provide an adequate operative corridor. While there has been a trend toward limited employment of the most invasive surgical approaches, recent advances in endoscopic technology may complement existing methods to access these difficult to reach areas. Case Descriptions: Four consecutive patients were treated for symptomatic, hemorrhagic brainstem cavernous malformations via fully endoscopic approaches (endonasal, transclival; retrosigmoid; lateral supracerebellar, infratentorial; endonasal, transclival). Together, these lesions encompassed all three segments of the brainstem. Three of the patients had complete resection of the cavernous malformation, while one patient had stable residual at long-term follow up. Associated developmental venous anomalies were preserved in the two patients where one was identified preoperatively. Three of the four patients maintained stable or improved neurological examinations following surgery, while one patient experienced ipsilateral palsies of cranial nerves VII and VIII. The first transclival approach resulted in a symptomatic cerebrospinal fluid leak requiring re-operation, but the second did not. Although there are challenges associated with endoscopic approaches, relative to our prior microsurgical experience with similar cases, visualization and illumination of the surgical corridors were superior without significant limitations on operative mobility. Conclusion: The endoscope is a promising adjunct to the neurosurgeons ability to approach difficult to access brainstem cavernous malformations. It allows the surgeon to achieve well-illuminated, panoramic views, and by combining approaches, can provide minimally invasive access to most regions of the brainstem.

Minimally Invasive Surgery for Traumatic Fractures in Ankylosing Spinal Diseases

Study Design Retrospective case series. Objective Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are two related diseases that significantly increase the risk of unstable spinal fractures from seemingly trivial trauma. Given the older age and higher surgical risk profile of most of these patients, minimally invasive (MIS) approaches to the treatment of such fractures may reduce operative risk and physiologic stress. Methods Eleven consecutive patients with hyperextension thoracolumbar injuries and a diagnosis of AS or DISH admitted to a single level I trauma center between June 2009 and June 2014 were retrospectively reviewed. All patients were treated with MIS stabilization. In addition, the patients were administered the Oswestry Disability Index and EuroQol-5D surveys to evaluate patient-reported outcomes regarding disability and health-related quality of life, respectively. Results Of the 11 patients, 10 were alive at the time of review. The mean follow-up time was 28 months. The average age was 77 years old with a mean body mass index of 34. All patients had severe systemic disease, American Society of Anesthesiologists grade III, with multiple medical comorbidities. Seven segments on average were included in the operative construct. There were no instrumentation failures or nonunions requiring revision surgery. The average postoperative Oswestry disability index was 21.5% (range: 0 to 34%), corresponding to low to moderate disability, and the average EuroQol-5D utility score was 0.77 (range: 0.60 to 1), a similar average postoperative utility value to those published in the literature on elective surgery for degenerative lumbar conditions. Conclusions MIS stabilization, when used on patients with good preoperative neurologic status, can successfully manage spinal fractures in patients with AS and DISH and preserve a favorable postoperative quality of life with limited disability.

Microvascular Decompression Versus Stereotactic Radiosurgery for Trigeminal Neuralgia: A Decision Analysis

Introduction: Both microvascular decompression (MVD) and stereotactic radiosurgery (SRS) have been demonstrated to be effective in treating medically refractory trigeminal neuralgia. However, there is controversy over which one offers more durable pain relief and the patient selection for each treatment. We used a decision analysis model to calculate the health-related quality of life (QOL) for each treatment. Methods: We searched PubMed and the Cochrane Database of Systematic Reviews for relevant articles on MVD or SRS for trigeminal neuralgia published between 2000 and 2015. Using data from these studies, we modeled pain relief and complication outcomes and assigned QOL values. A sensitivity analysis using a Monte Carlo simulation determined which procedure led to the greatest QOL. Results: MVD produced a significantly higher QOL than SRS at a seven-year follow-up. Additionally, MVD patients had a significantly higher rate of complete pain relief and a significantly lower rate of complications and recurrence. Conclusions: With a decision-analytic model, we calculated that MVD provides more favorable outcomes than SRS for the treatment of trigeminal neuralgia.

Advanced Multi-Axis Spine Testing: Clinical Relevance and Research Recommendations.

Back pain and spinal degeneration affect a large proportion of the general population. The economic burden of spinal degeneration is significant, and the treatment of spinal degeneration represents a large proportion of healthcare costs. However, spinal surgery does not always provide improved clinical outcomes compared to non-surgical alternatives, and modern interventions, such as total disc replacement, may not offer clinically relevant improvements over more established procedures. Although psychological and socioeconomic factors play an important role in the development and response to back pain, the variation in clinical success is also related to the complexity of the spine, and the multi-faceted manner by which spinal degeneration often occurs. The successful surgical treatment of degenerative spinal conditions requires collaboration between surgeons, engineers, and scientists in order to provide a multi-disciplinary approach to managing the complete condition. In this review, we provide relevant background from both the clinical and the basic research perspectives, which is synthesized into several examples and recommendations for consideration in increasing translational research between communities with the goal of providing improved knowledge and care. Current clinical imaging, and multi-axis testing machines, offer great promise for future research by combining invivo kinematics and loading with in-vitro testing in six degrees of freedom to offer more accurate predictions of the performance of new spinal instrumentation. Upon synthesis of the literature, it is recommended that in-vitro tests strive to recreate as many aspects of the in-vivo environment as possible, and that a physiological preload is a critical factor in assessing spinal biomechanics in the laboratory. A greater link between surgical procedures, and the outcomes in all three anatomical planes should be considered in both the in-vivo and in-vitro settings, to provide data relevant to quality of motion, and stability.

Tracking patient-reported outcomes in spinal disorders.

Background: Patient-reported outcome measures (PROMs) quantify health status from the patients point of view. While the number of published outcomes studies grows each year, so too has the number of instruments being reported, leading to confusion on which instruments are appropriate to use for various spinal conditions. Methods: A broad search was conducted to identify commonly used PROMs in patients undergoing spinal surgery. We searched PubMed for combinations of terms related to anatomic location and a measure of patient-reported outcome in the title or text. We supplemented the search using the “related articles” feature of PubMed and by manually searching the bibliographies of selected articles. Results: Major categories of PROMs in spine surgery include health-related quality-of-life, pain, and disease-specific disability, for which several different instrument options were identified and detailed. The minimal clinically important difference varies between instruments and differentiates statistical significance from clinical significance. In addition, the accurate estimation of costs has become a challenging but intrinsically linked variable to outcomes as increased attention is paid to the relative value of surgical interventions. Conclusion: While a number of PROMs are available for tracking outcomes in spine surgery, only a handful appear to be widely used. At least one instrument from each category should be measured pre- and post-operatively to quantify treatment effect. In addition, while the primary goal is to select the most appropriate instruments for the patients condition, one should keep in mind sustainability of efforts with regard to patient and administrative burden.

Surgical Approaches for the Treatment of Multilevel Cervical Ossification of the Posterior Longitudinal Ligament: Results of a Decision Analysis

BACKGROUND Ossification of the posterior longitudinal ligament (OPLL) often leads to cervical myelopathy. Although multiple procedures have been shown to be effective in the treatment of OPLL, outcomes are less predictable than in degenerative cervical myelopathy, and surgery is associated with high rates of complications and reoperation, which affect quality of life. In this study, we performed a decision analysis using postoperative complication data and health-related quality of life (HRQoL) utility scores to assess the average expected health utility and 5-year quality-adjusted life years (QALYs) associated with the most common surgical approaches for multilevel cervical OPLL. METHODS We searched Medline, EMBASE, and the Cochrane Library for relevant articles published between 1990 and October 2017. Meta-analytically pooled complication data and HRQoL utility scores associated with each complication were evaluated in a long-term model. RESULTS The overall incidence of perioperative complications ranged from 6.2% for laminectomy alone to 11.0% for anterior decompression and fusion. Revision surgery for hardware/fusion failure or progression was highest for laminectomy alone (3.0%) and lowest for laminectomy and fusion (1.6%). Laminoplasty resulted in the highest 5-year QALYs gained, compared with laminectomy and anterior approaches (P < 0.001). There was no significant difference in QALY gained between laminectomy-fusion and laminoplasty. CONCLUSION The results suggest that owing to the higher rates of complications associated with anterior cervical approaches, laminoplasty may result in improved long-term outcomes from an HRQoL standpoint. These findings may guide surgeons in cases where either procedure is a reasonable option.

328 A Propensity-Based Analysis of the Use of Prothrombin Complex Concentrate Prior to Emergent Neurosurgical Procedures.

INTRODUCTION Reversal of anticoagulation is required to mitigate the risk of intracranial bleeding before urgent neurosurgical procedures. New pharmacological agents, such as multifactor prothrombin complex concentrate (PCC; Kcentra), promise rapid efficacy but may raise the probability of thrombotic complications above vitamin K infusion or administration of fresh frozen plasma (FFP). In this study, we examined the rate of thrombotic complications in neurosurgical patients who received either PCC or FFP and Vitamin K before undergoing urgent surgery. METHODS Sixty-three consecutive patients who received anticoagulation reversal for urgent neurosurgical procedures were identified between 2008 and 2014 at a level I trauma center. They were divided into 2 cohorts based on reversal method, either PCC (n = 28) or FFP/Vitamin K (n = 35). The rate of thrombotic complications within 72 hours of reversal was compared using a 2-sample t test. To minimize selection bias, a multivariate propensity score-matching analysis was then used to identify a control group of FFP patients most similar to patients in the PCC group based on age, sex, trauma, altered mental status, and preexisting heart failure. RESULTS Thrombotic complications were uncommon but not rare in this neurosurgical population, occurring in 8.3% of treated patients (3/63). There was no difference in thrombotic complication rate between groups, 7.14% (2/28; PCC group) vs 2.86% (1/28; FFP group; P = ns). Propensity matching analysis verified this finding after controlling for any selection bias. CONCLUSION Thrombotic complications in neurosurgical patients requiring rapid reversal at a level I trauma center are uncommon but not rare. New pharmacological agents have similar rates of thrombotic complications as FFP. In this limited sample, use of PCC did not pose a significant increase in risk compared with FFP in the management of intracranial bleeding.

Comparing Utility Scores in Common Spinal Radiculopathies: Results of a Prospective Valuation Study.

Study Design Prospective observational study. Objective To determine whether preference-based health utility scores for common spinal radiculopathies vary by specific spinal level. Methods We employed a standard gamble study using the general public to calculate individual preference-based quality of life for four common radiculopathies: C6, C7, L5, and S1. We compared utility scores obtained for each level of radiculopathy with analysis of variance and t test. Multivariable regression was used to test the effects of the covariates age, sex, and years of education. We also reviewed the literature for publications reporting EuroQol-5 Dimensions (EQ-5D) scores for patients with radiculopathy. Results Two hundred participants were included in the study. Average utility for the four spinal levels fell within a narrow range (0.748 to 0.796). There were no statistically significant differences between lumbar and cervical radiculopathies, nor were there significant differences among the different spinal levels (F = 0.0850, p = 0.086). Age and sex had no significant effect on utility scores. There was a significant correlation between years of education and utility values for S1 radiculopathy (p = 0.037). On review of the literature, no study separated utility values by specific spinal level. EQ-5D utilities for both cervical and lumbar radiculopathy were considerably lower than the results of our study. Conclusions Utility values associated with the most common levels of cervical and lumbar radiculopathy do not significantly differ from each other, validating the current practice of grouping utility by spinal segment rather than by specific root levels. The discrepancy in average utility values between our study and the EQ-5D highlights the need to be mindful of the underlying instruments used when assessing outcomes studies from different sources.

Aneurysmal vasculopathy in human-acquired immunodeficiency virus-infected adults: Imaging case series and review of the literature

Background Intracranial vasculopathy in adult patients with human-acquired immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) is a rare but increasingly recognized disease entity. Objective We aimed to contribute to and summarize the adult literature describing patients with HIV/AIDS who have intracranial vasculopathy. Methods A retrospective review of adult patients with HIV/AIDS undergoing diagnostic cerebral angiography at our institution from 2007–2013 was performed. A literature review of relevant existing studies was performed. Results Five adult patients with HIV-related aneurysmal and occlusive vasculopathy were diagnosed and/or treated at our institution. A comprehensive review of the literature yielded data from 17 series describing 28 adult patients with HIV/AIDS and intracranial vasculopathy. Our review suggests that low CD4 count, motor weakness, and meningismus may be associated with the sequelae of intracranial vasculopathy/vasculitis in patients with HIV/AIDS. Conclusion Patients with HIV/AIDS who have aneurysmal and stenotic vascular disease may benefit from earlier surveillance with the onset of neurological symptoms. The roles of medical, open surgical, and endovascular therapy in this unique entity will be further defined as the pathological basis of the disease is better understood.