Subhas K. Konar, Shyamal C. Bir, Tanmoy K. Maiti, Papireddy Bollam and Anil Nanda
Isadore Max Tarlov, an early neurosurgeon, made several important contributions to the field of spine surgery. He described sacral perineural cysts, now known as Tarlov cysts. Dr. Tarlov also introduced the knee-chest patient position to facilitate exposure and hemostasis in lumbar surgery. In addition, he developed the use of fibrin glue in nerve repair. His book on mechanisms of spinal compression was published in 1957. He published a book of essays titled Principles of Parsimony in Medical Practice that remains highly relevant in today's medical world.
Subhas K. Konar, Shyamal C. Bir, Tanmoy K. Maiti and Anil Nanda
The incidence of primary spinal cord glioblastoma multiforme (GBM) in the pediatric age group is very rare. Only a few case series and case reports have been published in the literature; therefore, overall survival (OS) outcome and the as-yet poorly defined management options are not discussed in detail. The authors performed a cumulative survival analysis of all reported cases of pediatric spinal cord GBM to identify the predictive factors related to final survival outcome.
A comprehensive search for relevant articles was performed on PubMed's electronic database MEDLINE for the period from 1950 to 2015 using the search words “malignant spinal cord tumor” and “spinal glioblastoma multiforme.” This study was limited to patients younger than 18 years of age. Survival rates for children with various tumor locations and treatments were collected from the published articles and analyzed.
After an extensive literature search, 29 articles met the study inclusion criteria. From the detailed information in these articles, the authors found 53 children eligible for the survival analysis. The majority (45%) of the children were more than 12 years old. Thirty-four percent of the cases were between 7 and 12 years of age, and 21% were younger than 7 years. In the Kaplan-Meier survival analysis, children younger than 7 years of age had better survival (13 months) than the children older than 7 years (7–12 years: 10 months, > 12 years: 9 months; p = 0.01, log-rank test). Fifty-five percent of the children were female and 45% were male. A cervical tumor location (32%) was the most common, followed by thoracic (28.3%). Cervicothoracic (18.9%) and conus (18.8%) tumor locations shared the same percentage of cases. Cervical tumors had a worse outcome than tumors in other locations (p = 0.003, log-rank test). The most common presenting symptom was limb weakness (53%), followed by sensory disturbances (25%). Median OS was 10 months. The addition of adjuvant therapy (radiotherapy [RT] and/or chemotherapy [CT]) after surgery significantly improved OS (p = 0.01, log-rank test). Children who underwent gross-total resection and RT had better outcomes than those who underwent subtotal resection and RT (p = 0.04, log-rank test). Cerebrospinal fluid spread, hydrocephalus, brain metastasis, and spinal metastasis were not correlated with OS in primary spinal GBM.
Adjuvant therapy after surgery had a beneficial effect on overall outcome of spinal GBM in the pediatric age group. Gross-total resection followed by RT produced a better outcome than subtotal resection with RT. Further large-scale prospective study is required to establish the genetic and molecular factors related to OS in primary GBM of the spinal cord in pediatric patients.
Anil Nanda, Shyamal C. Bir, Tanmoy K. Maiti, Subhas K. Konar, Symeon Missios and Bharat Guthikonda
The clinical significance of the Simpson system for grading the extent of meningioma resection and its role as a predictor of the recurrence of World Health Organization (WHO) Grade I meningiomas have been questioned in the past, echoing changes in meningioma surgery over the years. The authors reviewed their experience in resecting WHO Grade I meningiomas and assessed the association between extent of resection, as evaluated using the Simpson classification, and recurrence-free survival (RFS) of patients after meningioma surgery.
Clinical and radiological information for patients with WHO Grade I meningiomas who had undergone resective surgery over the past 20 years was retrospectively reviewed. Simpson and Shinshu grading scales were used to evaluate the extent of resection. Statistical analysis was conducted using Kaplan-Meier curves and Cox proportional-hazards regression.
Four hundred fifty-eight patients were eligible for analysis. Overall tumor recurrence rates for Simpson resection Grades I, II, III, and IV were 5%, 22%, 31%, and 35%, respectively. After Cox regression analysis, Simpson Grade I (extensive resection) was revealed as a significant predictor of RFS (p = 0.003). Patients undergoing Simpson Grade I and II resections showed significant improvement in RFS compared with patients undergoing Grade III and IV resections (p = 0.005). Extent of resection had a significant effect on recurrence rates for both skull base (p = 0.047) and convexity (p = 0.012) meningiomas. Female sex and a Karnofsky Performance Scale score > 70 were also identified as independent predictors of RFS after resection of WHO Grade I meningioma.
In this patient cohort, a significant association was noted between extent of resection and rates of tumor recurrence. In the authors' experience the Simpson grading system maintains its relevance and prognostic value and can serve an important role for patient education. Even though complete tumor resection is the goal, surgery should be tailored to each patient according to the risks and surgical morbidity.
Tanmoy K. Maiti, Shyamal C. Bir, Devi Prasad Patra, Piyush Kalakoti, Bharat Guthikonda and Anil Nanda
Spinal meningiomas are benign tumors with a wide spectrum of clinical and radiological features at presentation. The authors analyzed multiple clinicoradiological factors to predict recurrence and functional outcome in a cohort with a mean follow-up of more than 4 years. The authors also discuss the results of clinical studies regarding spinal meningiomas in the last 15 years.
The authors retrospectively reviewed the clinical and radiological details of patients who underwent surgery for spinal tumors between 2001 and 2015 that were histopathologically confirmed as meningiomas. Demographic parameters, such as age, sex, race, and association with neurofibromatosis Type 2, were considered. Radiological parameters, such as tumor size, signal changes of spinal cord, spinal level, number of levels, location of tumor attachment, shape of tumor, and presence of dural tail/calcification, were noted. These factors were analyzed to predict recurrence and functional outcome. Furthermore, a pooled analysis was performed from 13 reports of spinal meningiomas in the last 15 years.
A total of 38 patients were included in this study. Male sex and tumors with radiological evidence of a dural tail were associated with an increased risk of recurrence at a mean follow-up of 51.2 months. Ventral or ventrolateral location, large tumors, T2 cord signal changes, and poor preoperative functional status were associated with poor functional outcome at 1-year follow-up.
Spine surgeons must be aware of the natural history and risk factors of spinal meningiomas to establish a prognosis for their patients.
Connor A. Wathen, Leonardo A. Frizon, Tanmoy K. Maiti, Kenneth B. Baker and Andre G. Machado
Ischemic stroke is a leading cause of disability worldwide, with profound economic costs. Poststroke motor impairment is the most commonly encountered deficit resulting in significant disability and is the primary driver of stroke-associated healthcare expenditures. Although many patients derive some degree of benefit from physical rehabilitation, a significant proportion continue to suffer from persistent motor impairment. Noninvasive brain stimulation, vagal nerve stimulation, epidural cortical stimulation, and deep brain stimulation (DBS) have all been studied as potential modalities to improve upon the benefits derived from physical therapy alone. These neuromodulatory therapies aim primarily to augment neuroplasticity and drive functional reorganization of the surviving perilesional cortex.
The authors have proposed a novel and emerging therapeutic approach based on cerebellar DBS targeted at the dentate nucleus. Their rationale is based on the extensive reciprocal connectivity between the dentate nucleus and wide swaths of cerebral cortex via the dentatothalamocortical and corticopontocerebellar tracts, as well as the known limitations to motor rehabilitation imposed by crossed cerebellar diaschisis. Preclinical studies in rodent models of ischemic stroke have shown that cerebellar DBS promotes functional recovery in a frequency-dependent manner, with the most substantial benefits of the therapy noted at 30-Hz stimulation. The improvements in motor function are paralleled by increased expression of markers of synaptic plasticity, synaptogenesis, and neurogenesis in the perilesional cortex. Given the findings of preclinical studies, a first-in-human trial, Electrical Stimulation of the Dentate Nucleus Area (EDEN) for Improvement of Upper Extremity Hemiparesis Due to Ischemic Stroke: A Safety and Feasibility Study, commenced in 2016. Although the existing preclinical evidence is promising, the results of this Phase I trial and subsequent clinical trials will be necessary to determine the future applicability of this therapy.
Shyamal C. Bir, Devi Prasad Patra, Tanmoy K. Maiti, Hai Sun, Bharat Guthikonda, Christina Notarianni and Anil Nanda
Adult-onset hydrocephalus is not commonly discussed in the literature, especially regarding its demographic distribution. In contrast to pediatric hydrocephalus, which is related to a primary CSF pathway defect, its development in adults is often secondary to other pathologies. In this study, the authors investigated the epidemiology of adult-onset hydrocephalus as it pertains to different etiologies and in reference to age, sex, and race distributions.
The authors retrospectively reviewed the clinical notes of 2001 patients with adult-onset hydrocephalus who presented to Louisiana State University Health Sciences Center within a 25-year span. Significant differences between the groups were analyzed by a chi-square test; p < 0.05 was considered significant.
The overall mean (± SEM) incidence of adult hydrocephalus in this population was 77 ± 30 per year, with a significant increase in incidence in the past decade (55 ± 3 [1990–2003] vs 102 ± 6 [2004–2015]; p < 0.0001). Hydrocephalus in a majority of the patients had a vascular etiology (45.5%) or was a result of a tumor (30.2%). The incidence of hydrocephalus in different age groups varied according to various pathologies. The incidence was significantly higher in males with normal-pressure hydrocephalus (p = 0.03) or head injury (p = 0.01) and higher in females with pseudotumor cerebri (p < 0.0001). In addition, the overall incidence of hydrocephalus was significantly higher in Caucasian patients (p = 0.0002) than in those of any other race.
Knowledge of the demographic variations in adult-onset hydrocephalus is helpful in achieving better risk stratification and better managing the disease in patients. For general applicability, these results should be validated in a large-scale meta-analysis based on a national population database.
Anil Nanda, Devi Prasad Patra, Amey Savardekar, Tanmoy K. Maiti and Piyush Kalakoti
Meningiomas arising from the posterior clinoid process pose a great surgical challenge because of their location and propensity to cause critical neurovascular compression. The authors’ patient was a 66-year-old female who had a large posterior clinoid meningioma with significant brainstem compression that was operated on through the retrosigmoid approach. This 3D surgical video emphasizes the various technical concepts that are important to preserving compressed neural and vascular structures during the surgery. It would also be interesting to note the extent of visualization around the posterior clinoid region gained through a retrosigmoid corridor.
The video can be found here: https://youtu.be/CBmT_0ov0YA.
Devi Prasad Patra, Shyamal C. Bir, Tanmoy K. Maiti, Piyush Kalakoti, Hugo Cuellar, Bharat Guthikonda, Hai Sun, Christina Notarianni and Anil Nanda
Despite significant advances in the medical field and shunt technology, shunt malfunction remains a nightmare of pediatric neurosurgeons. In this setting, the ability to preoperatively predict the probability of shunt malfunction is quite compelling. The authors have compared the preoperative radiological findings in obstructive hydrocephalus and the subsequent clinical course of the patient to determine any association with overall shunt outcome.
This retrospective study included all pediatric patients (age < 18 years) who had undergone ventriculoperitoneal shunt insertion for obstructive hydrocephalus. Linear measurements were taken from pre- and postoperative CT or MRI studies to calculate different indices and ratios including Evans' index, frontal horn index (FHI), occipital horn index (OHI), frontooccipital horn ratio (FOHR), and frontooccipital horn index ratio (FOIR). Other morphological features such as bi- or triventriculomegaly, right-left ventricular symmetry, and periventricular lucency (PVL) were also noted. The primary clinical outcomes that were reviewed included the need for shunt revision, time interval to first shunt revision, frequency of shunt revisions, and revision-free survival.
A total of 121 patients were eligible for the analysis. Nearly half of the patients (47.9%) required shunt revision. The presence of PVL was associated with lower revision rates than those in others (39.4% vs 58.2%, p = 0.03). None of the preoperative radiological indices or ratios showed any correlation with shunt revision. Nearly half of the patients with shunt revision required early revision (< 90 days of primary surgery). The reduction in the FOHR was high in patients who required early shunt revision (20.16% in patients with early shunt revision vs 6.4% in patients with late shunt revision, p = 0.009). Nearly half of the patients (48.3%) requiring shunt revision ultimately needed more than one revision procedure. Greater occipital horn dilation on preoperative images was associated with a lower frequency of shunt revision, as dictated by a high OHI and a low FOIR in patients with a single shunt revision as compared with those in patients who required multiple shunt revisions (p = 0.029 and 0.009, respectively). The mean follow-up was 49.9 months. Age was a significant factor affecting shunt revision–free survival. Patients younger than 6 months of age had significantly less revision-free survival than the patients older than 6 months (median survival of 10.1 vs 94.1 months, p = 0.004).
Preoperative radiological linear indices and ratios do not predict the likelihood of subsequent shunt malfunction. However, patients who required early shunt revision tended to have greater reductions in ventricular volumes on postoperative images. Therefore a greater reduction in ventricular volume is not actually desirable, and a ventricular volume high enough to reduce intracranial pressure is instead to be aimed at for long-term shunt compliance.