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Journal: Journal of neurosurgery

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OBJECTIVEInternal carotid artery (ICA) injuries during endoscopic endonasal surgery (EES) are catastrophic complications. Alongside the advancements in medical instrumentation and material, there is a need to modify previous treatment modalities and principles.METHODSA retrospective review of 3658 patients who underwent EES performed at the authors' institution between January 2012 and December 2017 was conducted. Ultimately, 20 patients (0.55%) with ICA injury following EES were enrolled for analysis. Data collection included demographic data, preoperative diagnosis, injury setting, repair method, and immediate and follow-up angiographic and clinical outcomes.RESULTSAmong the 20 patients, 11 received immediate endovascular therapy and 9 were treated only with packing. Of the 11 patients who received endovascular treatment, 6 were treated by covered stent and 5 by parent artery occlusion (PAO). The preservation rate of injured ICA increased from 20.0% (1 of 5) to 83.3% (5 of 6) after the Willis covered stent graft became available in January 2016. Of the 20 patients in the study, 19 recovered well and 1 patient-who had a pseudoaneurysm and was treated by PAO with a detachable balloon-suffered epistaxis after the hemostat in her nasal cavity was removed in ward, and she died later that day. The authors speculated that the detachable balloon had shifted to the distal part of ICA, although the patient could not undergo a repeat angiogram because she quickly suffered shock and could not be transferred to the catheter room. After the introduction of a hybrid operating room (OR), one patient whose first angiogram showed no ICA injury was found to have a pseudoaneurysm. He received endovascular treatment when he was brought for a repeat angiogram 5 days later in the hybrid OR after removing the hemostat in his nasal cavity. Of the 4 surviving patients treated with PAO, no external carotid artery-ICA bypass was required. The authors propose a modified endovascular treatment protocol for ICA injuries suffered during EES that exploits the advantage of the covered stent graft and the hybrid OR.CONCLUSIONSThe endovascular treatment protocol used in this study for ICA injuries during EES was helpful in the management of this rare complication. Willis stent placement improved the preservation rate of injured ICA during EES. It would be highly advantageous to manage this complication in a hybrid OR or by a mobile C-arm to get a clear intraoperative angiogram.

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OBJECTIVE Tourette syndrome (TS) is a complex neuropsychiatric disorder characterized by multiple motor and phonic tics. While pharmacological and behavioral therapy can be effective in most patients, a subset of patients remains refractory to treatment. Increasing clinical evidence from multiple centers suggests that deep brain stimulation (DBS) of the medial thalamus can be effective in many cases of refractory TS. METHODS The authors retrospectively reviewed outcomes in 13 patients with refractory TS who underwent medial thalamic DBS performed by their team over a 7-year period. Patients were evaluated by a multidisciplinary team, and preoperative objective assessments were performed using the Yale Global Tic Severity Scale (YGTSS) and Yale-Brown Obsessive Compulsive Scale. YGTSS scores were calculated at visits immediately postoperatively and at the most recent follow-up in patients with a minimum of 6 months of postoperative follow-up. Coordinates of the active DBS contacts were calculated and projected onto each patient’s pre- and postoperative images. RESULTS Patients showed an average decrease of 37% (p = 0.0063) in the total tic severity at their first postoperative visit. At their latest visit, their scores achieved significance, decreasing from preoperative scores by an average of 50% (p = 0.0014). The average position of the active contact was noted to be at the junction of the posterior ventralis oralis internus/centromedian-parafascicular nuclei. Device-related complications occurred in 2 patients, necessitating additional surgeries. All patients continued to use the system at last follow-up. CONCLUSIONS The authors' data are consistent with the small but growing body of literature supporting DBS of the ventralis oralis internus/centromedian-parafascicular thalamus as an effective and relatively safe treatment for severe, refractory TS.

Concepts: Deep brain stimulation, Thalamus, Tourette syndrome, Treatment of Tourette syndrome, Tic, Tic disorder

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OBJECT This study directly compares the number and severity of subconcussive head impacts sustained during helmet-only practices, shell practices, full-pad practices, and competitive games in a National Collegiate Athletic Association (NCAA) Division I-A football team. The goal of the study was to determine whether subconcussive head impact in collegiate athletes varies with practice type, which is currently unregulated by the NCAA. METHODS Over an entire season, a cohort of 20 collegiate football players wore impact-sensing mastoid patches that measured the linear and rotational acceleration of all head impacts during a total of 890 athletic exposures. Data were analyzed to compare the number of head impacts, head impact burden, and average impact severity during helmet-only, shell, and full-pad practices, and games. RESULTS Helmet-only, shell, and full-pad practices and games all significantly differed from each other (p ≤ 0.05) in the mean number of impacts for each event, with the number of impacts being greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. The cumulative distributions for both linear and rotational acceleration differed between all event types (p < 0.01), with the acceleration distribution being similarly greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. For both linear and rotational acceleration, helmet-only practices had a lower average impact severity when compared with other event types (p < 0.001). However, the average impact severity did not differ between any comparisons of shell and full-pad practices, and games. CONCLUSIONS Helmet-only, shell, and full-pad practices, and games result in distinct head impact profiles per event, with each succeeding event type receiving more impacts than the one before. Both the number of head impacts and cumulative impact burden during practice are categorically less than in games. In practice events, the number and cumulative burden of head impacts per event increases with the amount of equipment worn. The average severity of individual impacts is relatively consistent across event types, with the exception of helmet-only practices. The number of hits experienced during each event type is the main driver of event type differences in impact burden per athletic exposure, rather than the average severity of impacts that occur during the event. These findings suggest that regulation of practice equipment could be a fair and effective way to substantially reduce subconcussive head impact in thousands of collegiate football players.

Concepts: Mode, Arithmetic mean, Mean, Geometric mean, College football, American football, Type system, Interquartile mean

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Object Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that often arise from major peripheral nerves. Approximately half of MPNSTs arise in patients with neurofibromatosis Type 1 (NF1) who, in comparison with patients without NF1, present at younger ages and with larger tumors that are commonly associated with extensive plexiform neurofibromas. These tumors therefore pose a particularly difficult treatment challenge because of the morbidity often associated with attempted gross-total resection (GTR). Here, the authors aim to examine what role the extent of resection and other covariates play in the long-term survival of patients with NF1 in the setting of MPNST. Methods The authors retrospectively reviewed the records of 23 adult patients with NF1 who underwent surgery for MPNSTs at their institution between 1991 and 2008. The primary end points of the study were mortality, local recurrence, and metastasis. Kaplan-Meier survival curves were evaluated for all patients. Differences for each of the primary end points were evaluated based on cause-specific covariates, which included tiered tumor size, tumor location, grade, resection margin status, postoperative weakness, and use of chemotherapy and radiation therapy. Multivariate analysis was performed using Cox proportional hazards models. Results Gross-total resection (p = 0.01) and surgical margin status (p = 0.034) had a statistically important role in prolonging overall survival in patients with NF1 by univariate analysis. When tumor size, location, grade, postoperative weakness, and radiation therapy were also taken into account using multivariate analysis, GTR continued to be a significant prognostic factor (p = 0.035). Conclusions These findings suggest that GTR offers significant long-term benefit on survival in patients with NF1. Benefit on survival occurred independently of all other covariates, suggesting that complete resection should be the principal goal of treatment in this patient population.

Concepts: Cancer, Oncology, Survival analysis, Action potential, Multivariate statistics, Malignant peripheral nerve sheath tumor, Nerve sheath tumor, Peripheral nervous system

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Object Patients with ruptured anterior communicating artery (ACoA) aneurysms have historically been observed to have poor neuropsychological outcomes, and ACoA aneurysms have accounted for a higher proportion of ruptured than unruptured aneurysms. Authors of this study aimed to investigate the morphological and clinical characteristics predisposing to ACoA aneurysm rupture. Methods Data from 140 consecutive patients with ACoA aneurysms managed at the authors' facility between July 2003 and November 2011 were retrospectively reviewed. Patients with (78) and without (62) aneurysm rupture were divided into groups, and morphological and clinical characteristics were compared. Morphological characteristics were evaluated based on 3D CT angiography and included aneurysm location, dominance of the A(1) portion of the anterior cerebral artery, direction of the aneurysm dome around the ACoA, aneurysm bleb(s), size of the aneurysm and its neck, aneurysm-parent artery angle, and existence of other intracranial unruptured aneurysms. Results Patients with ruptured ACoA aneurysms were significantly younger (a higher proportion were younger than 60 years of age) than those with unruptured lesions, and a significantly smaller proportion had hypercholesterolemia. A significantly larger proportion of patients with ruptured aneurysms showed an anterior direction of the aneurysm dome around the ACoA, had a bleb(s), and/or had an aneurysm size ≥ 5 mm. Multivariate logistic regression analysis showed that an anterior direction of the aneurysm dome around the ACoA (OR 6.0, p = 0.0012), the presence of a bleb(s) (OR 22, p < 0.0001), and an aneurysm size ≥ 5 mm (OR 3.16, p = 0.035) were significantly associated with ACoA aneurysm rupture. Conclusions Findings in the present study demonstrated that the anterior projection of an ACoA aneurysm may be related to rupturing. The authors would perhaps recommend treatment to patients with unruptured ACoA aneurysms that have an anterior dome projection, a bleb(s), and a size ≥ 5 mm.

Concepts: Regression analysis, Atherosclerosis, Anterior cerebral artery, Aneurysm, Cerebral aneurysm, Arteries of the head and neck, Circle of Willis, Anterior communicating artery

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Object The focus of the present study was the evaluation of outcomes after unstaged and staged-volume Gamma Knife surgery (GKS) in children harboring intracranial arteriovenous malformations (AVMs). Methods Twenty-two children (median age 9.5 years) underwent GKS for AVMs and were followed up for at least 2 years thereafter. The disease manifested with intracranial hemorrhage in 77% of cases. In 68% of patients the lesion affected eloquent brain structures. The volume of the nidus ranged from 0.1 to 6.7 cm(3). Gamma Knife surgery was guided mainly by data from dynamic contrast-enhanced CT scans, with preferential targeting of the junction between the nidus and draining vein. The total prescribed isodose volume was kept below 4.0 cm(3), and the median margin dose was 22 Gy (range 20-25 Gy). If the volume of the nidus was larger than 4.0 cm(3), a second radiosurgical session was planned for 3-4 years after the first one. Nine patients in the present series underwent unstaged radiosurgery, whereas staged-volume treatment was scheduled in 13 patients. Results Complete obliteration of the AVM was noted in 17 (77%) of 22 patients within a median period of 47 months after the last radiosurgical session. Complete obliteration of the lesion occurred in 89% of patients after unstaged treatment and in 62.5% after staged GKS. Four (67%) of 6 high-grade AVMs were completely obliterated. Complications included 3 bleeding episodes, the appearance of a region of hyperintensity on T(2)-weighted MR images in 2 patients who had no symptoms, and reappearance of the nidus in the vicinity of the completely obliterated AVM in 1 patient. Conclusions Radiosurgery is a highly effective management option for intracranial AVMs in children. For larger lesions, staged GKS may be applied successfully. Initial targeting of the nidus adjacent to the draining vein and application of a sufficient radiation dose to a relatively small volume (≤ 4 cm(3)) provides a good balance between a high probability of obliteration and a low risk of treatment-related complications.

Concepts: Brain tumor, Anatomical pathology, Radiobiology, Gamma knife, Neurosurgery, Congenital disorders, Arteriovenous malformation, Cerebral arteriovenous malformation

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Object Overdrainage of CSF remains an unsolved problem in shunt therapy. The aim of the present study was to evaluate treatment options on overdrainage-related events enabled by the new generation of adjustable gravity-assisted valves. Methods The authors retrospectively studied the clinical course of 250 consecutive adult patients with various etiologies of hydrocephalus after shunt insertion for different signs and symptoms of overdrainage. Primary and secondary overdrainage were differentiated. The authors correlated the incidence of overdrainage with etiology of hydrocephalus, opening valve pressure, and patient parameters such as weight and size. Depending on the severity of overdrainage, they elevated the opening pressure, and follow-up was performed until overdrainage was resolved. Results The authors found 39 cases (15.6%) involving overdrainage-related problems-23 primary and 16 secondary overdrainage. The median follow-up period in these 39 patients was 2.1 years. There was no correlation between the incidence of overdrainage and any of the following factors: sex, age, size, or weight of the patients. There was also no statistical significance among the different etiologies of hydrocephalus, with the exception of congenital hydrocephalus. All of the “complications” could be resolved by readjusting the opening pressure of the valve in one or multiple steps, avoiding further operations. Conclusions Modern adjustable and gravity-assisted valves enable surgeons to set the opening pressure relatively low to avoid underdrainage without significantly raising the incidence of overdrainage and to treat overdrainage-related clinical and radiological complications without surgical intervention.

Concepts: Medicine, Surgery, Cerebrospinal fluid, Hydrocephalus, Valve, Etiology, Shunt

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Object This study aims to show the relationship between clinical outcome in patients who underwent surgical decompression for Chiari malformation (CM) and postoperative imaging studies, with particular emphasis on the subarachnoid cisterns of the posterior fossa. Methods One hundred seventy-seven patients with CM, including 97 with syringomyelia, underwent posterior fossa decompressive surgery. Both the dura and arachnoid were opened in 150 of these patients, and 135 underwent reduction of the cerebellar tonsils. The patients' clinical signs and symptoms were evaluated at 2 time points after surgery. Their imaging studies were analyzed specifically for the size of the retrotonsillar and subtonsillar cisterns and the syringomyelic cavities. The authors evaluated the relationship between these imaging findings and clinical parameters. Results Clinical improvement correlated strongly with enlargement of the subarachnoid cisterns, and enlargement of the cisterns also correlated with reduction in size of the syrinx cavities. Symptoms related to syringomyelia responded to reduction in size of the syrinx cavities. Conclusions Surgical decompression of the posterior fossa should aim to create relatively large subarachnoid cisterns and reduce the size of the syrinx cavity. Reduction of the cerebellar tonsils by surgical means, together with duraplasty, achieves this goal and thereby improves the clinical outcome for patients with CM. An incidental observation of the study is that obesity increases the likelihood of headache in patients with CM.

Concepts: Medicine, Symptom, Medical diagnosis, Medical sign, Meninges, Arnold-Chiari malformation, Syringomyelia, Dura mater

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Object Transcranial MR-guided focused ultrasound surgery (MRgFUS) is evolving as a treatment modality in neurosurgery. Until now, the trigeminal nerve was believed to be beyond the treatment envelope of existing high-frequency transcranial MRgFUS systems. In this study, the authors explore the feasibility of targeting the trigeminal nerve in a cadaveric model with temperature assessments using computer simulations and an in vitro skull phantom model fitted with thermocouples. Methods Six trigeminal nerves from 4 unpreserved cadavers were targeted in the first experiment. Preprocedural CT scanning of the head was performed to allow for a skull correction algorithm. Three-Tesla, volumetric, FIESTA MRI sequences were performed to delineate the trigeminal nerve and any vascular structures of the cisternal segment. The cadaver was positioned in a focused ultrasound transducer (650-kHz system, ExAblate Neuro, InSightec) so that the focus of the transducer was centered at the proximal trigeminal nerve, allowing for targeting of the root entry zone (REZ) and the cisternal segment. Real-time, 2D thermometry was performed during the 10- to 30-second sonication procedures. Post hoc MR thermometry was performed on a computer workstation at the conclusion of the procedure to analyze temperature effects at neuroanatomical areas of interest. Finally, the region of the trigeminal nerve was targeted in a gel phantom encased within a human cranium, and temperature changes in regions of interest in the skull base were measured using thermocouples. Results The trigeminal nerves were clearly identified in all cadavers for accurate targeting. Sequential sonications of 25-1500 W for 10-30 seconds were successfully performed along the length of the trigeminal nerve starting at the REZ. Real-time MR thermometry confirmed the temperature increase as a narrow focus of heating by a mean of 10°C. Postprocedural thermometry calculations and thermocouple experiments in a phantom skull were performed and confirmed minimal heating of adjacent structures including the skull base, cranial nerves, and cerebral vessels. For targeting, inclusion of no-pass regions through the petrous bone decreased collateral heating in the internal acoustic canal from 16.7°C without blocking to 5.7°C with blocking. Temperature at the REZ target decreased by 3.7°C with blocking. Similarly, for midcisternal targeting, collateral heating at the internal acoustic canal was improved from a 16.3°C increase to a 4.9°C increase. Blocking decreased the target temperature increase by 4.4°C for the same power settings. Conclusions This study demonstrates focal heating of up to 18°C in a cadaveric trigeminal nerve at the REZ and along the cisternal segment with transcranial MRgFUS. Significant heating of the skull base and surrounding neural structures did not occur with implementation of no-pass regions. However, in vivo studies are necessary to confirm the safety and efficacy of this potentially new, noninvasive treatment.

Concepts: Neuroanatomy, Skull, Cranial nerves, Trigeminal nerve, Trigeminal neuralgia

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Object In this paper the authors describe an association between increased body mass index (BMI) and Chiari malformation Type I (CM-I) in adults, as well as its relationship to the development of syringomyelia. Methods In the period between January 2004 and December 2011, the senior author reviewed the data for all CM-I patients with or without syringomyelia and neurological deficit. Analyzed factors included clinical status (headaches and neurological signs), radiological characteristics of syringomyelia (diameter and vertical extent of syrinx), BMI, and relationship of age to BMI, syrinx diameter, and vertical extent of syrinx. Results Sixty consecutive adults had CM-I, 26 of whom also had syringomyelia. The mean BMI among all patients was 30.35 ± 7.65, which is Class I obesity (WHO), and was similar among patients with or without syringomyelia. Extension of the vertical syrinx was greater in overweight patients (p = 0.027) than in those with a normal body weight. Evidence of de novo syrinx formation was found in 2 patients who gained an average BMI of 10.8 points. After repeated decompression and no change in holocord syrinx width or vertical extent, a reduction in the syrinx was seen after BMI decreased 11.7 points in one individual. No correlation was found between patient age and BMI, age and vertical extension of the syrinx, and age and diameter of the syrinx. Conclusions An association between increased BMI and CM-I in adults was recognized. Gaining weight may influence the de novo creation of a syrinx in adults who previously had minimally symptomatic or asymptomatic CM-I, and reducing weight can improve a syrinx after unsuccessful surgical decompression. Therefore, a reduction in body weight should be recommended for all overweight and obese patients with CM-I.

Concepts: Nutrition, Obesity, Mass, Body mass index, Body shape, Body weight, Arnold-Chiari malformation, Syringomyelia