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Amey Savardekar, Manjul Tripathi, Deepak Bansal, Kim Vaiphei and Sunil K. Gupta

Langerhans cell histiocytosis (LCH) of the CNS is a rare entity, known to involve primarily the hypothalamicpituitary region, with the clinical hallmark of diabetes insipidus. There have been a few reports of CNS LCH involving the brainstem as intraparenchymal enhancing lesions, but this has never been the presenting complaint of LCH. The authors report on a 7-year-old boy who presented with right cerebellopontine syndrome, in whom a well-defined, solid, enhancing lesion in the brainstem was diagnosed. Clinicoradiological differential diagnosis included glioma and tuberculosis. Biopsy revealed atypical histiocytes positive for CD68, CD1a, and S100 protein; these are the diagnostic features of LCH on histopathological examination. The rapid growth of the lesion was controlled with a chemotherapeutic regimen of cladribine.

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Amey R. Savardekar, Devi P. Patra, Jai D. Thakur, Vinayak Narayan, Nasser Mohammed, Papireddy Bollam and Anil Nanda

OBJECTIVE

Total tumor excision with the preservation of neurological function and quality of life is the goal of modern-day vestibular schwannoma (VS) surgery. Postoperative facial nerve (FN) paralysis is a devastating complication of VS surgery. Determining the course of the FN in relation to a VS preoperatively is invaluable to the neurosurgeon and is likely to enhance surgical safety with respect to FN function. Diffusion tensor imaging–fiber tracking (DTI-FT) technology is slowly gaining traction as a viable tool for preoperative FN visualization in patients with VS.

METHODS

A systematic review of the literature in the PubMed, Cochrane Library, and Web of Science databases was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and those studies that preoperatively localized the FN in relation to a VS using the DTI-FT technique and verified those preoperative FN tracking results by using microscopic observation and electrophysiological monitoring during microsurgery were included. A pooled analysis of studies was performed to calculate the surgical concordance rate (accuracy) of DTI-FT technology for FN localization.

RESULTS

Fourteen studies included 234 VS patients (male/female ratio 1:1.4, age range 17–75 years) who had undergone preoperative DTI-FT for FN identification. The mean tumor size among the studies ranged from 29 to 41.3 mm. Preoperative DTI-FT could not visualize the FN tract in 8 patients (3.4%) and its findings could not be verified in 3 patients (1.2%), were verified but discordant in 18 patients (7.6%), and were verified and concordant in 205 patients (87.1%).

CONCLUSIONS

Preoperative DTI-FT for FN identification is a useful adjunct in the surgical planning for large VSs (> 2.5 cm). A pooled analysis showed that DTI-FT successfully identifies the complete FN course in 96.6% of VSs (226 of 234 cases) and that FN identification by DTI-FT is accurate in 90.6% of cases (205 of 226 cases). Larger studies with DTI-FT–integrated neuronavigation are required to look at the direct benefit offered by this specific technique in preserving postoperative FN function.

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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.

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Nasser Mohammed, Amey R. Savardekar, Devi Prasad Patra, Vinayak Narayan and Anil Nanda

OBJECTIVE

Neurosurgical infections due to multidrug-resistant organisms have become a nightmare that neurosurgeons are facing in the 21st century. This is the dawn of the so-called postantibiotic era. There is an urgent need to review and evaluate ways to reduce the high mortality rates due to these infections. The present study evaluates the efficacy of combined intravenous plus intrathecal or intraventricular (IV + IT) therapy versus only intravenous (IV) therapy in treating postneurosurgical Acinetobacter baumannii infections.

METHODS

The authors performed a meta-analysis of all peer-reviewed studies from the PubMed, Cochrane Library database, ScienceDirect, and EMBASE in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Five studies were finally included in the present analysis: 126 patients were studied who had postneurosurgical A. baumannii infection. The Cochrane collaboration tool was used to evaluate risk of bias, and a test of heterogeneity was performed. The I2 statistic was calculated. The patients were divided into 2 groups: the IV group received only intravenous therapy and the IV + IT group received both intravenous and intrathecal or intraventricular antimicrobial therapy. The outcome was mortality attributed specifically to A. baumannii infection in postneurosurgical cases. The pooled data were analyzed using the Cochran-Mantel-Haenszel method in a fixed-effects model.

RESULTS

The total number of patients in the IV-only group was 73, and the number of patients in the IV + IT group was 53. The mean duration of intravenous therapy was 27 days. The mean duration of intrathecal colistin was 21 days. The intravenous dose of colistin ranged from 3.75 to 8.8 MIU per day. The dose of intrathecal colistin ranged between 125,000 and 250,000 IU per day. The overall calculated odds ratio for mortality for the IV + IT group after pooling the data was 0.16 (95% CI 0.06–0.40, p < 0.0001). The patients who received IV + IT therapy had an 84% lower risk of dying due to the infection compared with those who received only IV therapy.

CONCLUSIONS

There is an 84% lower risk of mortality in patients who have been treated with combined intrathecal or intraventricular plus intravenous antimicrobial therapy versus those who have been treated with intravenous therapy alone. The intrathecal or intraventricular route should be strongly considered when dealing with postneurosurgical multidrug-resistant A. baumannii infections.

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Devi Prasad Patra, Amey Rajan Savardekar, Rimal Hanif Dossani, Vinayak Narayan, Nasser Mohammed and Anil Nanda

OBJECTIVE

Gamma Knife radiosurgery (GKRS) has emerged as a promising treatment modality for patients with classical trigeminal neuralgia (TN); however, considering that almost half of the patients experience post-GKRS failure or lesion recurrence, a repeat treatment is typically necessary. The existing literature does not offer clear evidence to establish which treatment modality, repeat GKRS or microvascular decompression (MVD), is superior. The present study aimed to compare the overall outcome of patients who have undergone either repeat GKRS or MVD after failure of their primary GKRS; the authors do so by conducting a systematic review and meta-analysis of the literature and analysis of data from their own institution.

METHODS

The authors conducted a systematic review and meta-analysis of the PubMed, Cochrane Library, Web of Science, and CINAHL databases to identify studies describing patients who underwent either repeat GKRS or MVD after initial failed GKRS for TN. The primary outcomes were complete pain relief (CPR) and adequate pain relief (APR) at 1 year. The secondary outcomes were rate of postoperative facial numbness and the retreatment rate. The pooled data were analyzed with R software. Bias and heterogeneity were assessed using funnel plots and I2 tests, respectively. A retrospective analysis of a series of patients treated by the authors who underwent repeat GKRS or MVD after post-GKRS failure or relapse is presented.

RESULTS

A total of 22 studies met the selection criteria and were included for final data retrieval and meta-analysis. The search did not identify any study that had directly compared outcomes between patients who had undergone repeat GKRS versus those who had undergone MVD. Therefore, the authors’ final analysis included two groups: studies describing outcome after repeat GKRS (n = 17) and studies describing outcome after MVD (n = 5). The authors’ institutional study was the only study with direct comparison of the two cohorts. The pooled estimates of primary outcomes were APR in 83% of patients who underwent repeat GKRS and 88% of those who underwent MVD (p = 0.49), and CPR in 46% of patients who underwent repeat GKRS and 72% of those who underwent MVD (p = 0.02). The pooled estimates of secondary outcomes were facial numbness in 32% of patients who underwent repeat GKRS and 22% of those who underwent MVD (p = 0.11); the retreatment rate was 19% in patients who underwent repeat GKRS and 13% in those who underwent MVD (p = 0.74). The authors’ institutional study included 42 patients (repeat GKRS in 15 and MVD in 27), and the outcomes 1 year after retreatment were APR in 80% of those who underwent repeat GKRS and 81% in those who underwent MVD (p = 1.0); CPR was achieved in 47% of those who underwent repeat GKRS and 44% in those who underwent MVD (p = 1.0). There was no difference in the rate of postoperative facial numbness or retreatment.

CONCLUSIONS

The current meta-analysis failed to identify any superiority of one treatment over the other with comparable outcomes in terms of APR, postoperative facial numbness, and retreatment rates. However, MVD was shown to provide a better chance of CPR compared with repeat GKRS.

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Jennifer A. Kosty, Juan Mejia-Munne, Rimal Dossani, Amey Savardekar and Bharat Guthikonda

Jacques Jean Lhermitte (1877–1959) was among the most accomplished neurologists of the 20th century. In addition to working as a clinician and instructor, he authored more than 800 papers and 16 books on neurology, neuropathology, psychiatry, and mystical phenomena. In addition to the well-known “Lhermitte’s sign,” an electrical shock–like sensation caused by spinal cord irritation in demyelinating disease, Lhermitte was a pioneer in the study of the relationship between the physical substance of the brain and the experience of the mind. A fascinating example of this is the syndrome of peduncular hallucinosis, characterized by vivid visual hallucinations occurring in fully lucid patients. This syndrome, which was initially described as the result of a midbrain insult, also may occur with injury to the thalamus or pons. It has been reported as a presenting symptom of various tumors and as a complication of neurosurgical procedures. Here, the authors review the life of Lhermitte and provide a historical review of the syndrome of peduncular hallucinosis.

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Nasser Mohammed, Devi Prasad Patra, Vinayak Narayan, Amey R. Savardekar, Rimal Hanif Dossani, Papireddy Bollam, Shyamal Bir and Anil Nanda

OBJECTIVE

Spondylosis with or without spondylolisthesis that does not respond to conservative management has an excellent outcome with direct pars interarticularis repair. Direct repair preserves the segmental spinal motion. A number of operative techniques for direct repair are practiced; however, the procedure of choice is not clearly defined. The present study aims to clarify the advantages and disadvantages of the different operative techniques and their outcomes.

METHODS

A meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The following databases were searched: PubMed, Cochrane Library, Web of Science, and CINAHL (Cumulative Index to Nursing and Allied Health Literature). Studies of patients with spondylolysis with or without low-grade spondylolisthesis who underwent direct repair were included. The patients were divided into 4 groups based on the operative technique used: the Buck repair group, Scott repair group, Morscher repair group, and pedicle screw–based repair group. The pooled data were analyzed using the DerSimonian and Laird random-effects model. Tests for bias and heterogeneity were performed. The I2 statistic was calculated, and the results were analyzed. Statistical analysis was performed using StatsDirect version 2.

RESULTS

Forty-six studies consisting of 900 patients were included in the study. The majority of the patients were in their 2nd decade of life. The Buck group included 19 studies with 305 patients; the Scott group had 8 studies with 162 patients. The Morscher method included 5 studies with 193 patients, and the pedicle group included 14 studies with 240 patients. The overall pooled fusion, complication, and outcome rates were calculated. The pooled rates for fusion for the Buck, Scott, Morscher, and pedicle screw groups were 83.53%, 81.57%, 77.72%, and 90.21%, respectively. The pooled complication rates for the Buck, Scott, Morscher, and pedicle screw groups were 13.41%, 22.35%, 27.42%, and 12.8%, respectively, and the pooled positive outcome rates for the Buck, Scott, Morscher, and pedicle screw groups were 84.33%, 82.49%, 80.30%, and 80.1%, respectively. The pedicle group had the best fusion rate and lowest complication rate.

CONCLUSIONS

The pedicle screw–based direct pars repair for spondylolysis and low-grade spondylolisthesis is the best choice of procedure, with the highest fusion and lowest complication rates, followed by the Buck repair. The Morscher and Scott repairs were associated with a high rate of complication and lower rates of fusion.

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Vinayak Narayan, Amey R. Savardekar, Devi Prasad Patra, Nasser Mohammed, Jai D. Thakur, Muhammad Riaz and Anil Nanda

OBJECTIVE

Walter E. Dandy described for the first time the anatomical course of the superior petrosal vein (SPV) and its significance during surgery for trigeminal neuralgia. The patient’s safety after sacrifice of this vein is a challenging question, with conflicting views in current literature. The aim of this systematic review was to analyze the current surgical considerations regarding Dandy’s vein, as well as provide a concise review of the complications after its obliteration.

METHODS

A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A thorough literature search was conducted on PubMed, Web of Science, and the Cochrane database; articles were selected systematically based on the PRISMA protocol and reviewed completely, and then relevant data were summarized and discussed.

RESULTS

A total of 35 publications pertaining to the SPV were included and reviewed. Although certain studies report almost negligible complications of SPV sectioning, there are reports demonstrating the deleterious effects of SPV obliteration when achieving adequate exposure in surgical pathologies like trigeminal neuralgia, vestibular schwannoma, and petroclival meningioma. The incidence of complications after SPV sacrifice (32/50 cases in the authors’ series) is 2/32 (6.2%), and that reported in various case series varies from 0.01% to 31%. It includes hemorrhagic and nonhemorrhagic venous infarction of the cerebellum, sigmoid thrombosis, cerebellar hemorrhage, midbrain and pontine infarct, intracerebral hematoma, cerebellar and brainstem edema, acute hydrocephalus, peduncular hallucinosis, hearing loss, facial nerve palsy, coma, and even death. In many studies, the difference in incidence of complications between the SPV-sacrificed group and the SPV-preserved group was significant.

CONCLUSIONS

The preservation of Dandy’s vein is a neurosurgical dilemma. Literature review and experiences from large series suggest that obliterating the vein of Dandy while approaching the superior cerebellopontine angle corridor may be associated with negligible complications. However, the counterview cannot be neglected in light of some series showing an up to 30% complication rate from SPV sacrifice. This review provides the insight that although the incidence of complications due to SPV obliteration is low, they can happen, and the sequelae might be worse than the natural history of the existing pathology. Therefore, SPV preservation should be attempted to optimize patient outcome.

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Nestor G. Rodriguez-Martinez, Amey Savardekar, Eric W. Nottmeier, Stephen Pirris, Phillip M. Reyes, Anna G. U. S. Newcomb, George A. C. Mendes, Samuel Kalb, Nicholas Theodore and Neil R. Crawford

OBJECTIVE

Transvertebral screws provide stability in thoracic spinal fixation surgeries, with their use mainly limited to patients who require a pedicle screw salvage technique. However, the biomechanical impact of transvertebral screws alone, when they are inserted across 2 vertebral bodies, has not been studied. In this study, the authors assessed the stability offered by a transvertebral screw construct for posterior instrumentation and compared its biomechanical performance to that of standard bilateral pedicle screw and rod (PSR) fixation.

METHODS

Fourteen fresh human cadaveric thoracic spine segments from T-6 to T-11 were divided into 2 groups with similar ages and bone quality. Group 1 received transvertebral screws across 2 levels without rods and subsequently with interconnecting bilateral rods at 3 levels (T8–10). Group 2 received bilateral PSR fixation and were sequentially tested with interconnecting rods at T7–8 and T9–10, at T8–9, and at T8–10. Flexibility tests were performed on intact and instrumented specimens in both groups. Presurgical and postsurgical O-arm 3D images were obtained to verify screw placement.

RESULTS

The mean range of motion (ROM) per motion segment with transvertebral screws spanning 2 levels compared with the intact condition was 66% of the mean intact ROM during flexion-extension (p = 0.013), 69% during lateral bending (p = 0.015), and 47% during axial rotation (p < 0.001). The mean ROM per motion segment with PSR spanning 2 levels compared with the intact condition was 38% of the mean intact ROM during flexion-extension (p < 0.001), 57% during lateral bending (p = 0.007), and 27% during axial rotation (p < 0.001). Adding bilateral rods to the 3 levels with transvertebral screws decreased the mean ROM per motion segment to 28% of intact ROM during flexion-extension (p < 0.001), 37% during lateral bending (p < 0.001), and 30% during axial rotation (p < 0.001). The mean ROM per motion segment for PSR spanning 3 levels was 21% of intact ROM during flexion-extension (p < 0.001), 33% during lateral bending (p < 0.001), and 22% during axial rotation (p < 0.001).

CONCLUSIONS

Biomechanically, fixation with a novel technique in the thoracic spine involving transvertebral screws showed restoration of stability to well within the stability provided by PSR fixation.