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Nicholas Theodore, Paul M. Arnold and Ankit I. Mehta

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Ankit Patel, Sameer Ruparel, Tarun Dusad, Gaurav Mehta and Vishal Kundnani

OBJECTIVE

Spinal osteotomy in pediatric patients is challenging due to various factors. For correction of severe rigid kyphoscoliosis in children, numerous techniques with anterior or posterior or combined approaches, as well as multilevel osteotomies, have been described. These techniques are associated with prolonged operative times and large amounts of blood loss. The purpose of this study was to evaluate the clinical and radiologically confirmed efficacy of a modification of the apical spinal osteotomy (ASO) technique—posterior-only single-level asymmetric closing osteotomy—in pediatric patients with severe rigid kyphoscoliosis.

METHODS

The authors performed a retrospective study of a case series involving pediatric patients with severe spinal deformity operated on by a single surgeon at a single institution over a period of approximately 5 years. The inclusion criteria were age < 14 years, rigid thoracic/thoracolumbar/lumbar kyphosis (> 70°) with or without neurological deficit and with or without scoliosis, and a minimum of 2 years of follow-up. Patients with cervical or lumbosacral kyphoscoliosis were excluded from the study. Demographic and clinical parameters, including age, sex, etiology of kyphoscoliosis, neurological examination status (Frankel grade), and visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were noted. Operative parameters (level of osteotomy, number of levels fused, duration of surgery, blood loss, and complications) were also recorded. Radiological assessment was done for preoperative and postoperative kyphosis and scoliosis as well as the final Cobb angle. Similarly, sagittal vertical axis (SVA) correction was calculated. Fusion was assessed in all patients at the final follow-up evaluation.

RESULTS

A total of 26 pediatric patients (18 male and 8 female) with a mean age of 9 years met the inclusion criteria and had data available for analysis, and all of these patients had severe scoliosis as well as kyphosis. Comparison of preoperative and postoperative values showed a significant improvement (p < 0.05) in radiological, clinical, and functional parameters (Cobb angle for scoliosis and kyphosis, SVA, VAS, and ODI). With respect to kyphosis, the mean preoperative Cobb angle was 96.54°, the mean postoperative angle was 30.77°, and the mean angle at final follow-up was 34.81° (average loss of correction of 4.23°), for a final average correction of 64.15%. With respect to scoliosis, the mean preoperative angle was 52.54°, the mean postoperative angle was 15.77°, and the mean angle at final follow-up was 19.42° (average loss of correction of 3.66°), for a final average correction of 60.95%. The preoperative SVA averaged 7.6 cm; the mean SVA improved to 3.94 cm at the end of 2 years. Bony fusion was achieved in all patients. The mean number of levels fused was 5.69. The mean operative time was 243.46 minutes, with an average intraoperative blood loss of 336.92 ml. Nonneurological complications occurred in 15.39% of patients (2 dural tears, 1 superficial infection, 1 implant failure). At the 2-year follow-up, 25 of the 26 patients had maintained or improved their neurological status. One patient developed paraplegia immediately after the operation and recovered only partially.

CONCLUSIONS

Analysis of data from this series of 26 cases indicates that this posterior-approach single-level technique is effective for the correction of severe rigid kyphoscoliosis in pediatric patients, providing good clinical and radiological results in most cases.

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Abhinav K. Reddy, James S. Ryoo, Steven Denyer, Laura S. McGuire and Ankit I. Mehta

OBJECTIVE

The aim of this study was to illustrate the demographic characteristics of meningioma patients and observe the effect of adjuvant radiation therapy on survival by using the Surveillance, Epidemiology, and End Results (SEER) database. More specifically, the authors aimed to answer the question of whether adjuvant radiotherapy following resection of atypical meningioma confers a cause-specific survival benefit. Additionally, they attempted to add to previous characterizations of the epidemiology of primary meningiomas and assess the effectiveness of the standard of care for benign and anaplastic meningiomas. They also sought to characterize the efficacy of various treatment options in atypical and anaplastic meningiomas separately since nearly all other analyses have grouped these two together despite varying treatment regimens for these behavior categories.

METHODS

SEER data from 1973 to 2015 were queried using appropriate ICD-O-3 codes for benign, atypical, and anaplastic meningiomas. Patient demographics, tumor characteristics, and treatment choices were analyzed. The effects of treatment were examined using a multivariate Cox proportional hazards model and Kaplan-Meier survival analysis.

RESULTS

A total of 57,998 patients were included in the analysis of demographic, meningioma, and treatment characteristics. Among this population, cases of unspecified WHO tumor grade were excluded in the multivariate analysis, leaving a total of 12,931 patients to examine outcomes among treatment paradigms. In benign meningiomas, gross-total resection (HR 0.289, p = 0.013) imparted a significant cause-specific survival benefit over no treatment. In anaplastic meningioma cases, adjuvant radiotherapy imparted a significant survival benefit following both subtotal (HR 0.089, p = 0.018) and gross-total (HR 0.162, p = 0.002) resection as compared to gross-total resection alone. In atypical tumors, gross-total resection plus radiotherapy did not significantly change the hazard risk (HR 1.353, p = 0.628) compared to gross-total resection alone. Similarly, it was found that adjuvant radiation did not significantly benefit survival after a subtotal resection (HR 1.440, p = 0.644).

CONCLUSIONS

The results of this study demonstrate that the role of adjuvant radiotherapy, especially after the resection of atypical meningioma, remains somewhat unclear. Thus, given these results, prospective randomized clinical studies are warranted to provide clear information on the effects of adjuvant radiation in meningioma treatment.

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Matthew K. Tobin, Joseph R. Geraghty, Herbert H. Engelhard, Andreas A. Linninger and Ankit I. Mehta

Intramedullary spinal cord tumors have low incidence rates but are associated with difficult treatment options. The majority of patients with these tumors can be initially treated with an attempted resection. Unfortunately, those patients who cannot undergo gross-total resection or have subtotal resection are left with few treatment options, such as radiotherapy and chemotherapy. These adjuvant treatments, however, are associated with the potential for significant adverse side effects and still leave patients with a poor prognosis. To successfully manage these patients and improve both their quality of life and prognosis, novel treatment options must be developed to supplement subtotal resection. New research is underway investigating alternative therapeutic approaches for these patients, including directed, localized drug delivery and nanomedicine techniques. These and other future investigations will hopefully lead to promising new therapies for these devastating diseases.

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Bhargav Desai, Ying Hsu, Benjamin Schneller, Jonathan G. Hobbs, Ankit I. Mehta and Andreas Linninger

Aquaporin-4 (AQP4) channels play an important role in brain water homeostasis. Water transport across plasma membranes has a critical role in brain water exchange of the normal and the diseased brain. AQP4 channels are implicated in the pathophysiology of hydrocephalus, a disease of water imbalance that leads to CSF accumulation in the ventricular system. Many molecular aspects of fluid exchange during hydrocephalus have yet to be firmly elucidated, but review of the literature suggests that modulation of AQP4 channel activity is a potentially attractive future pharmaceutical therapy. Drug therapy targeting AQP channels may enable control over water exchange to remove excess CSF through a molecular intervention instead of by mechanical shunting. This article is a review of a vast body of literature on the current understanding of AQP4 channels in relation to hydrocephalus, details regarding molecular aspects of AQP4 channels, possible drug development strategies, and limitations. Advances in medical imaging and computational modeling of CSF dynamics in the setting of hydrocephalus are summarized. Algorithmic developments in computational modeling continue to deepen the understanding of the hydrocephalus disease process and display promising potential benefit as a tool for physicians to evaluate patients with hydrocephalus.

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Mari Kusumi, Takanori Fukushima, Ankit I. Mehta, Hamidreza Aliabadi, Yoichi Nonaka, Allan H. Friedman and Kiyotaka Fujii

Object

The combined petrosal approach is a suitable technique for the resection of medium-to-large petroclival meningiomas (PCMs). Multiple technical modifications have been reported to increase the surgical corridor, including the method of dural and tentorial opening. The authors describe their method of dural opening and tentorial resection, and detail the microanatomy related to their technique to clarify pitfalls and effects.

Methods

The relationship of temporal bridging veins and cranial nerves (CNs) around the tentorial resection area was examined during the combined petrosal approach in 20 cadaveric specimens. The authors also reviewed their 23 consecutive clinical cases treated using this technique between 2002 and 2010, focusing on the effects and risks of the procedure.

Results

In the authors' method, the tentorial resection extends from 5 to 10 mm anterior to the junction of the sigmoid sinus and the superior petrosal sinus (“sinodural point”) to the trigeminal fibrous ring and the dural sleeve of CN IV. Temporal bridging veins enter the transverse sinus no more than 5 mm anterior to the sinodural point. The CN IV should be freed from its tentorial dural sleeve while avoiding disruption of the posterior cavernous sinus. The clinical data demonstrate a total resection rate of 78.3%, intraoperative estimated blood loss < 400 ml at a rate of 80.9%, and a venous congestion rate of 0%.

Conclusions

Understanding the anatomical relationship between the tentorium and temporal bridging veins and CNs IV–VI allows neurosurgeons the ability to develop a combined petrosal approach to PCMs that will effectively supply a wide operative corridor after resecting the tentorium, while significantly devascularizing tumors.

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Austin K. Mattox, Ankit I. Mehta, Peter M. Grossi, Thomas J. Cummings and D. Cory Adamson

Dermatofibrosarcoma protuberans (DFSP) is an uncommon, locally aggressive, malignant cutaneous tumor that sparingly presents on the scalp. Dermatofibrosarcomas often result from the formation of a fusion oncogene on translocated or supernumerary ring chromosomes 17 and 22, causing the overexpression of PDGFRβ driven by the COL1A1 promoter. Because of uncertainty surrounding appropriate treatment of aggressive scalp DFSP, the authors performed an extensive review of the available data from a MEDLINE (Ovid) search to describe the clinical presentation and treatment options for this rare tumor. Their search identified 39 different cases, including the illustrative case presented in this study.

Adjuvant therapy for this malignant lesion is not universally established in the literature. In the present case, the authors successfully treated a locally invasive scalp DFSP with presurgical therapy that specifically inhibited the PDGFβ receptor. Imatinib significantly shrank the DFSP tumor mass, reduced hypervascularity, reduced metabolic activity on PET scanning, and permitted a safe gross-total resection. Although wide excision and Mohs micrographic surgery remain the standard surgical treatments for DFSP, the authors illustrate that presurgical chemotherapeutic treatment by imatinib provides a critical adjunct to traditional therapy.

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Isaac O. Karikari, Ankit I. Mehta, Can Solakoglu, Carlos A. Bagley, Michael C. Ain and Oren N. Gottfried

Object

Spinopelvic parameters in children with achondroplasia have not been described. Because they observed a unique sagittal spinopelvic phenotype in some achondroplastic children with very horizontal sacrums, the authors sought to quantify the spinopelvic parameters in a pediatric patient population.

Methods

A retrospective review was performed to identify all children (age range 1 month–10 years) with a diagnosis of achondroplasia between 2004 and 2009. Clinical and radiographic data were analyzed for age, sex, lumbar lordosis (LL), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). Differences among these variables were analyzed using a 2-tailed, unpaired Student t-test.

Results

Forty children, 23 males and 17 females, with achondroplasia were identified during the study period. The mean age was 2.6 years. Two groups of patients were identified based on PT (that is, negative or positive tilt and horizontal or not horizontal sacrum). A negative PT was identified in all children with an extremely horizontal sacrum. Seventeen children had a negative PT (mean −16.6°), and the mean parameters in this group were 65.4° for LL, 31.7° for TLK, 18.5° for TK, 43.3° for SS, and 26.4° for PI. Twenty-three children had a positive PT (mean 17.9°), and the mean parameters in this group were 53.4° for LL, 41.5° for TLK, 9.6° for TK, 30.8° for SS, and 43.8° for PI. A statistically significant difference was observed for LL (p = 0.01), TLK (p = 0.05), SS (p = 0.006), PT (p = 0.006), and PI (0.0002).

Conclusions

Spinopelvic parameters in achondroplasia are potentially dichotomous. The future implications of this observation are not known and will need to be explored in future long-term studies that follow pediatric patients with achondroplasia through adulthood.

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Aladine A. Elsamadicy, Owoicho Adogwa, Emily Lydon, Amanda Sergesketter, Rayan Kaakati, Ankit I. Mehta, Raul A. Vasquez, Joseph Cheng, Carlos A. Bagley and Isaac O. Karikari

OBJECTIVE

Depression is the most prevalent affective disorder in the US, and patients with spinal deformity are at increased risk. Postoperative delirium has been associated with inferior surgical outcomes, including morbidity and mortality. The relationship between depression and postoperative delirium in patients undergoing spine surgery is relatively unknown. The aim of this study was to determine if depression is an independent risk factor for the development of postoperative delirium in patients undergoing decompression and fusion for deformity.

METHODS

The medical records of 923 adult patients (age ≥ 18 years) undergoing elective spine surgery at a single major academic institution from 2005 through 2015 were reviewed. Of these patients, 255 (27.6%) patients had been diagnosed with depression by a board-certified psychiatrist and constituted the Depression group; the remaining 668 patients constituted the No-Depression group. Patient demographics, comorbidities, and intra- and postoperative complication rates were collected for each patient and compared between groups. The primary outcome investigated in this study was rate of postoperative delirium, according to DSM-V criteria, during initial hospital stay after surgery. The association between depression and postoperative delirium rate was assessed via multivariate logistic regression analysis.

RESULTS

Patient demographics and comorbidities other than depression were similar in the 2 groups. In the Depression group, 85.1% of the patients were taking an antidepressant prior to surgery. There were no significant between-group differences in intraoperative variables and rates of complications other than delirium. Postoperative complication rates were also similar between the cohorts, including rates of urinary tract infection, fever, deep and superficial surgical site infection, pulmonary embolism, deep vein thrombosis, urinary retention, and proportion of patients transferred to the intensive care unit. In total, 66 patients (7.15%) had an episode of postoperative delirium, with depressed patients experiencing approximately a 2-fold higher rate of delirium (10.59% vs 5.84%). In a multivariate logistic regression analysis, depression was an independent predictor of postoperative delirium after spine surgery in spinal deformity patients (p = 0.01).

CONCLUSIONS

The results of this study suggest that depression is an independent risk factor for postoperative delirium after elective spine surgery. Further studies are necessary to understand the effects of affective disorders on postoperative delirium, in hopes to better identify patients at risk.

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Owoicho Adogwa, Aladine A. Elsamadicy, Amanda Sergesketter, Victoria D. Vuong, Ankit I. Mehta, Raul A. Vasquez, Joseph Cheng, Carlos A. Bagley and Isaac O. Karikari

OBJECTIVE

Wound infections following spinal surgery for deformity place a high toll on patients, providers, and the health care system. The prophylactic application of intraoperative vancomycin powder has been shown to lower the infection risk after thoracolumbar decompression and fusion for deformity correction. The purpose of this study was to assess the microbiological patterns of postoperative surgical site infections (SSIs) after prophylactic use of vancomycin powder in adult patients undergoing spinal deformity surgery.

METHODS

All cases involving adult patients who underwent spinal deformity reconstruction at Duke University Medical Center between 2011 and 2013 with a minimum of 3 months of clinical follow-up were retrospectively reviewed. In all cases included in the study, crystalline vancomycin powder was applied to the surgical bed for infection prophylaxis. Baseline characteristics, operative details, rates of wound infection, and microbiological data for each case were gathered by direct medical record review.

RESULTS

A total of 1200 consecutive spine operations were performed for deformity between 2011 and 2013. Review of the associated records demonstrated 34 cases of SSI, yielding an SSI rate of 2.83%. The patients’ mean age (± SD) was 62.08 ± 14.76 years. The patients’ mean body mass index was 30.86 ± 7.15 kg/m2, and 29.41% had a history of diabetes. The average dose of vancomycin powder was 1.41 ± 2.77 g (range 1–7 g). Subfascial drains were placed in 88% of patients. All SSIs occurred within 30 days of surgery, with deep wound infections accounting for 50%. In 74% of the SSIs cultures were positive, with about half the organisms being gram negative, such as Citrobacter freundii, Proteus mirabilis, Morganella morgani, and Pseudomonas aeruginosa. There were no adverse clinical outcomes related to the local application of vancomycin.

CONCLUSIONS

Our study suggests that in the setting of prophylactic vancomycin powder use, the preponderance of SSIs are caused by gram-negative organisms or are polymicrobial. Further randomized control trials of prophylactic adjunctive measures are warranted to help guide the choice of empirical antibiotic therapy while awaiting culture data.