Posterior Fossa Approach Research Articles

SURG-06. FRAMELESS STEREOTACTIC INTRACRANIAL CATHETER PLACEMENT FOR DELIVERY OF INTRATUMORAL CELLULAR THERAPIES

Abstract BACKGROUND As the leading disease-related cause of death in children, pediatric brain tumors, and in particular diffuse midline glioma, require novel treatment approaches. Cellular-based therapies offer promise, but challenges still exist in defining their optimal delivery route. Emerging data from our group suggest there may be a role for intratumoral injection in treatment algorithms. We here describe a surgical workflow for intratumoral injection of cellular therapies that utilizes existing and widely used neurosurgical technologies that can be incorporated into future clinical trials. METHODS Infusion target and catheter trajectory was planned using standard pre-operative MRI. Components from an FDA-approved frameless stereotactic intracranial biopsy system were chosen such that they would accept and guide an FDA-approved rigid intracranial catheter system intended for MR-guided procedures. Following catheter insertion, an intraoperative CT was used to determine accuracy of catheter placement by merging the image with the pre-operative MRI. RESULTS The proposed system was tested in a simulated fashion using a phantom cranial model registered to an accompanying brain MRI. The stereotactic biopsy mount was affixed to the skull at the planned entry site for a posterior fossa approach to the pons. Catheter insertion depth was determined using the stereotactic system and the catheter was inserted to this depth through the biopsy mount. Intraoperative CT confirmed the catheter tip location which correlated with the planned infusion target with sub-millimetric accuracy. CONCLUSION Our proposed intratumoral delivery method using frameless stereotaxy shows promise for use in future clinical trials that require intratumoral delivery of cellular therapies. Utilizing FDA-approved devices allows for quick integration into protocols and their wide-spread use makes the approach generalizable. This approach also eliminates the need for MR-guided procedures which can increase cost and require significant hospital resources to perform. Future work will be aimed at streamlining the intraoperative workflow.

Review of surgical spproaches for posterior fossa tumors in pediatric population and illustrative cases

Introduction/Background: Posterior fossa tumors are common in the pediatric population, and various surgical approaches have been described to reach them based on their specific location. This paper aims to review the most common posterior fossa approaches in pediatric patients and present illustrative cases to provide insights into their successful application in specific clinical scenarios. Case report: Three cases are presented, each demonstrating a different approach and surgical outcome. Case 1 involved a telovelar approach for the resection of a medulloblastoma, resulting in complete removal without neurological deficits. Case 2 required a combination of telovelar and supracerebellar infratentorial approaches to achieve gross total resection of a pilocytic astrocytoma. In Case 3, an occipital transtentorial approach was utilized to access and completely resect an atypical teratoid rhabdoid tumor. Connclusion: The paper discusses the telovelar and transvermian approaches, the supracerebellar infratentorial approach, the transtentorial suboccipital approach, and intraventricular endoscopy as individual or combined approaches for posterior fossa tumors. The presented cases highlight the importance of tailoring the surgical approach to each patient and provide valuable insights for neurosurgeons managing similar clinical scenarios.

The Brainstem Cavernoma Case Series: A Formula for Surgery and Surgical Technique.

Background and Objectives: Cavernous malformations (CM) are vascular malformations with low blood flow. The removal of brainstem CMs (BS) is associated with high surgical morbidity, and there is no general consensus on when to treat deep-seated BS CMs. The aim of this study is to compare the surgical outcomes of a series of deep-seated BS CMs with the surgical outcomes of a series of superficially located BS CMs operated on at the Department of Neurosurgery, College of Tuebingen, Germany. Materials and Methods: A retrospective evaluation was performed using patient charts, surgical video recordings, and outpatient examinations. Factors were identified in which surgical intervention was performed in cases of BS CMs. Preoperative radiological examinations included MRI and diffusion tensor imaging (DTI). For deep-seated BS CMs, a voxel-based 3D neuronavigation system and electrophysiological mapping of the brainstem surface were used. Results: A total of 34 consecutive patients with primary superficial (n = 20/58.8%) and deep-seated (n = 14/41.2%) brainstem cavernomas (BS CM) were enrolled in this comparative study. Complete removal was achieved in 31 patients (91.2%). Deep-seated BS CMs: The mean diameter was 14.7 mm (range: 8.3 to 27.7 mm). All but one of these lesions were completely removed. The median follow-up time was 5.8 years. Two patients (5.9%) developed new neurologic deficits after surgery. Superficial BS CMs: The median diameter was 14.9 mm (range: 7.2 to 27.3 mm). All but two of the superficial BS CMs could be completely removed. New permanent neurologic deficits were observed in two patients (5.9%) after surgery. The median follow-up time in this group was 3.6 years. Conclusions: The treatment of BS CMs remains complex. However, the results of this study demonstrate that with less invasive posterior fossa approaches, brainstem mapping, and neuronavigation combined with the use of a blunt "spinal cord" dissection technique, deep-seated BS CMs can be completely removed in selected cases, with good functional outcomes comparable to those of superficial BS CM.

Posterior Fossa Approaches Using the Leksell Vantage Frame with a Virtual Planning Approach in a Series of 10 Patients-Feasibility, Accuracy, and Pitfalls.

The open-face design of the Leksell Vantage frame provides many advantages. However, its more rigid, contoured design offers less flexibility than other frames. This is especially true for posterior fossa approaches. This study explores whether these limitations can be overcome by tailored frame placement using a virtual planning approach. The posterior fossa was accessed in ten patients using the Leksell Vantage frame. Frame placement was planned with the Brainlab Elements software, including a phantom-based (virtual) pre-operative planning approach. A biopsy was performed in all patients; in four, additional laser ablation surgery was performed. The accuracy of virtual frame placement was compared to actual frame placement. The posterior approach was feasible in all patients. In one case, the trajectory had to be adjusted; in another, the trajectory was switched from a right- to a left-sided approach. Both cases showed large deviations from the initially planned frame placement. A histopathological diagnosis was achieved in all patients. The new Leksell Vantage frame can be used to safely target the posterior fossa with a high diagnostic success rate and accuracy. Frame placement needs to be well-planned and executed. This can be facilitated using specific software solutions as demonstrated.

Occipital interhemispheric transtentorial approach in pediatric patients for lesions of the superomedial cerebellum: operative findings and results.

The occipital interhemispheric transtentorial (OITT) approach is frequently used for accessing the pineal region. There are scarce reports of using the OITT to access superior cerebellar lesions. This approach affords the patient several advantages over traditional posterior fossa approaches. This study is to describe and evaluate clinical outcomes in a single surgeon case series of the OITT approach for pediatric patients with lesions of the superior cerebellum. All pediatric patients who underwent an OITT craniotomy for a superior cerebellar lesion by a single surgeon over a 5-year period were included in this retrospective analysis. Patient demographics and clinical data were collected. Thirteen pediatric patients were identified. Cases included twelve tumors and one arteriovenous malformation. Gross total resection was achieved in 92% of cases. No patients developed posterior fossa syndrome. Two patients had transient homonymous hemianopsia that resolved by 1month post-operatively. There were no permanent neurological deficits. For superomedial cerebellar lesions presenting to the tentorial surface of the superior cerebellum in patients with normal to steep tentorial angles, the OITT approach is effective and safe. This approach has a low risk of posterior fossa syndrome and permanent visual deficits when applied appropriately. Patient selection is critical for maximizing the advantages of the OITT for superior cerebellar lesions.

Incidence, Characteristics, and Outcomes of Pseudomeningocele and Cerebrospinal Fluid Fistula after Posterior Fossa Surgery

Posterior fossa approaches are common neurosurgical procedures. Rates of postoperative infection, pseudomeningocele, and cerebrospinal fluid (CSF) fistula are high; however, evidence regarding predisposing risk factors and treatment outcomes remain sparse. A retrospective cohort study was carried out of all posterior fossa surgeries conducted at a single institution between January 2015 and October 2019. Univariate statistical methods and stepwise logistic regression were used to assess which factors contributed most to risk of development of postoperative complications. A total of 269 patients were included; 18.6% experienced any postoperative complication, 13% developed either pseudomeningocele or CSF fistula, and 9.7% developed an infection. In multivariate analysis, development of a pseudomeningocele was significantly associated with previous cranial surgery (hazard ratio [HR], 3.15; 95% confidence interval [CI], 1.12-9.28; P= 0.0391). Development of a CSF fistula was significantly associated with index surgery for resection of neoplasm (HR, 7.65; 95% CI, 1.86-22.31; P= 0.0174). Development of an infection was significantly associated with concurrent CSF fistula (HR, 7.16; 95% CI, 1.91-23.19; P= 0.0041) and concurrent pseudomeningocele (HR, 3.41; 95% CI, 1.37-5.95; P=0.0082) and nonsignificantly associated with diabetes requiring treatment (HR, 2.42; 95% CI, 0.69-8.50; P= 0.168). Other hypothesized risk factors for these complications, such as nonmidline approaches to the posterior fossa, watertight duraplasty, use of dural fibrin sealant, and cranioplasty were not associated with these complications on multivariate analysis. Although many patients with pseudomeningocele were successfully managed with observation, only 38% of patients in whom CSF diversion was attempted avoided surgery. History of diabetes, cranioplasty, revision surgery, and surgery for tumor resection are identified as risk factors for the development of infection, pseudomeningocele, and CSF fistula, respectively.

Three-Dimensional Modeling for Augmented and Virtual Reality-Based Posterior Fossa Approach Selection Training: Technical Overview of Novel Open-Source Materials.

Selection of skull base approaches is a critical skill for complex cranial surgery, which demands nuanced understanding of neuroanatomy and pathology. To develop novel pedagogical resources for approach selection education and assessment. A prospectively maintained skull base registry was screened for posterior fossa tumors amenable to 3-dimensional (3D) modeling of multiple operative approaches. Inclusion criteria were high-resolution preoperative and postoperative computed tomography and MRI studies (≤1 mm) and consensus that at least 3 posterior fossa craniotomies would provide feasible access. Cases were segmented using Mimics and modeled using 3-Matic. Clinical Vignettes, Approach Selection Questionnaire, and Clinical Application Questionnaire were compiled for implementation as a teaching/testing tool. Seven cases were selected, each representing a major posterior fossa approach group. 3D models were rendered using clinical imaging for the primary operative approach, as well as a combination of laboratory neuroanatomic data and extrapolation from comparable craniotomies to generate 2 alternative approaches in each patient. Modeling data for 3D figures were uploaded to an open-sourced database in a platform-neutral fashion (.x3d) for virtual/augmented reality and 3D printing applications. A semitransparent model of each approach without pathology and with key deep structures visualized was also modeled and included for comprehensive understanding. We report a novel series of open-source 3D models for skull base approach selection training, with supplemental resources. To the best of our knowledge, this is the first such series designed for pedagogical purposes in skull base surgery or centered on open-source principles.

Commentary: Three-Dimensional Modeling for Augmented and Virtual Reality-Based Posterior Fossa Approach Selection Training: Technical Overview of Novel Open-Source Materials.

Commentary: Three-Dimensional Modeling for Augmented and Virtual Reality-Based Posterior Fossa Approach Selection Training: Technical Overview of Novel Open-Source Materials.

Reappraisal of the types of hypoglossal canal: endocranial approach.

This study aims to classify the endocranial variations inside the Hypoglossal Canal (HC) and evaluate the elements of the HC region in terms of sizes, diameters, and distances to the nearby surgical landmarks. The present study was done on 18 adult human fixed cadaver heads bilaterally. The internal opening of HC was examined for the presence of dural or osseos septations in the canal and was classified into five types (Type 1-5). The dimensions of hypoglossal nerve (CN XII) and the distance of intracranial openings of HC from the jugular foramen and jugular tubercle were measured. The prevalence of endocranial HC types were determined on both sides as follows: type 1 (23.53% left, 6.25% right), type 2 (37.5% right, 5.88% left), type 3 (52.94% left, 25% right), type 4 (18.75% right, 17.65% left), type 5 (12.5% right). Understanding the endocranial HC types is crucial for neurosurgeons in the differential diagnosis of various intracranial pathologies for the posterior cranial fossa approach. Knowing the anatomical relationships between the adjacent structures and symmetrical organization of the HC according to the types is crucial in determining surgical strategies and preserving adjacent structures.

Minipterional Approach for Middle Fossa Skull Base Lesions: Technical Note.

Surgical access to the middle fossa can be technically challenging. As neurosurgery evolves to minimally invasive approaches, the objective of this study is to demonstrate the extension of the Minipterional approach to access the middle fossa. We present a new surgical approach to the middle fossa for the treatment of secondary trigeminal neuralgia. Three cases are reported to illustrate the following techniques: a patient with petrotentorial meningioma and trigeminal neuralgia, a patient with an arachnoid cyst compressing the fifth nerve, and a patient with a middle cerebral artery aneurysm and a long history of TN (trigeminal neuralgia) refractory to medical and surgical treatments. All three experienced full symptom controls with no permanent neurological deficits. Therefore, the Minipterional technique might represent a feasible, effective, and safe option to treat refractory secondary TN. It also allows approaching these lesions when the posterior fossa approach is compromised by anatomical distortion and enables the simultaneous treatment of secondary trigeminal neuralgia and other lesions, such as aneurysms and meningiomas.

Anatomy of the greater occipital nerve: implications in posterior fossa approaches.

Because of its superficial location in the dorsal regions of the scalp, the greater occipital nerve (GON) can be injured during neurosurgical procedures, resulting in post-operative pain and postural disturbances. The aim of this work is to specify the course of the GON and how its injuries can be avoided while performing posterior fossa approaches. This study was carried out at the department of anatomy at Bordeaux University. 4 specimens were dissected to study the GON course. Posterior fossa approaches (midline suboccipital, paramedian suboccipital, retrosigmoid and petrosal) were performed on 4 other specimens to assess potential risks of GON injuries. The GON runs around the obliquus capitis inferior (100%), crosses the semispinalis capitis (100%) and the trapezius (75%) or its aponeurosis (25%). Direct GON injuries can be seen in paramedian suboccipital approaches. Stretching of the GON can occur in midline suboccipital and paramedian suboccipital approaches. We found no evidence of direct or indirect GON injury in retrosigmoid or petrosal approaches. Our study provides interesting data regarding the risk GON injury in posterior fossa approaches. Direct GON injuries in paramedian suboccipital approaches can be avoided with careful dissection. Placing retractors in contact with the periosteum and performing a minimal retraction may help to avoid excessive GON stretching in midline suboccipital and paramedian suboccipital approaches. Furthermore, the incision for retrosigmoid approaches should be as lateral as possible and not too caudal. Finally, avoiding extreme patient positioning reduces the risk of GON stretching in all approaches.

Microsurgical Neurovascular Anatomy of the Brain: The Posterior Circulation (Part II)

Introduction:Vascular complications of posterior fossa surgery are often deadly although widely preventable through in-depth knowledge of the microsurgical neurovascular anatomy of the infratentorial region and careful surgical planning. The target of this study is to provide a synoptic overview of the normal anatomy and anatomic variants of the infratentorial neurovascular system, critical to safely operate tumors and neurovascular pathologies of the posterior fossa.Methods:Two fresh-frozen and five formalin-fixed cadaveric heads were used. Cervical arteries and internal jugular veins were injected with red and blue latex, respectively. The heads were dissected under a surgical microscope, with magnifications ranging between 3x to 40x, focusing on the infratentorial region. The infratentorial arteries, their collaterals and perforating branches, the brainstem and cerebellar veins, the tentorial venous sinuses, and the relative vascular territories were summarized according to a synoptic approach.Results:The vertebral artery, basilar artery (BA), and posterior cerebral artery (PCA) are the main sources of the arterial supply of the brainstem and cerebellum through the posterior inferior cerebellar artery (PICA), the anterior inferior cerebellar artery (AICA), the superior cerebellar artery (SCA), and the perforating arteries. The perforating arteries of the vertebrobasilar system derive from the PICA, BA, AICA, SCA, and PCA, and provide for a key contribution to the vascularization of the midbrain, pons, medulla oblongata, fourth ventricle, cerebellar and cerebral peduncles, thalamus, hypothalamus, subthalamus, posterior part of the internal capsule, and optic tract. The distal segments and branches of the PCA also add a significant arterial supply to the temporal, occipital, and parietal lobes. The venous outflow of the posterior fossa is a prerogative of the internal jugular veins via the tentorial venous sinuses.Conclusion:A perfect mastery of the arterial, venous, and cisternal anatomy of the infratentorial region is vital for the planning and execution of the whole range of posterior fossa approaches.

Impact of the Extent of Microsurgical Resection in Sphenopetro-clival Meningiomas Trough a Multistaged Approach: A Volumetric Analysis.

Objective Sphenopetroclival meningiomas (SPCMs) represent a challenge for surgical treatment. The authors used an objective volumetric analysis to assess the effect of the grade of resection and different surgical strategies that may affect the outcome of this tumors. Methods Over a period of 4 years, patients with SPCMs were treated using a middle versus posterior fossa approach, or a two-stage surgery combining both approaches, based on the tumor location in relation to the petrous ridge and tumor volume. Retrospectively, all cases were analyzed with regard to tumor volume, extent of resection (EOR), functional outcome, and complications. Results Twenty-seven patients with SPCMs met the inclusion criteria, and the mean follow-up was 24.8 months. Eleven patients underwent a two-stage surgery, while 16 patients had their SPCMs resected via a single craniotomy. Mean EOR was 87.6% and gross total resection was achieved in 48% of patients. Patients with greater EOR had better functional outcomes ( r = 0.81, p < 0.01). Greater EOR was not accompanied by a significant increase in surgical complications. There was a trend toward lower postoperative volumes and better EOR with our two-stage approach (2.2 vs. 3.2 cm 3 , p = 0.09; and 94.1 vs. 91.2%, p = 0.49, respectively), without an increase in the rate of complications (18.7 vs. 18.2%, p = 0.5). Conclusion Staging of the surgical resection of larger tumors may lead to greater EOR, and this strategy should be considered for larger tumors.

Logistic Regression Analysis of Risk Factors for Intracranial Infection After Multiple Traumatic Craniotomy and Preventive Measures.

The aim of this study was to study the risk factors of intracranial infection after traumatic craniotomy in multiple trauma to provide references for clinical prevention and control of intracranial infection. A total of 34 multiple trauma patients treated with craniotomy and complicated with intracranial infection from February 2012 to December 2016 in the department of neurosurgery of our hospital were selected as infection group, and 60 multiple trauma patients who had not been infected after craniotomy during the same period were selected as control group. Related risk factors were screened by univariate analysis at first and analyzed by Logistic regression. Of the 34 patients in the infection group, 13 cases were cured, 21 cases improved, whereas in the control group, 15 cases were cured and 45 cases improved. There was no significant difference in prognosis between the 2 groups (P > 0.05). Univariate analysis showed that surgical approach, surgical duration, postoperative cerebrospinal fluid leakage, and external drainage were important factors for intracranial infection after craniotomy (P < 0.05). Further Logistic regression analysis showed that postoperative external drainage, cerebrospinal fluid leakage, surgical time, and posterior fossa approaches were independent risk factors for intracranial infection after craniotomy. High attention should be paid to the risk factors of intracranial infection after craniotomy such as postoperative cerebrospinal fluid leakage, external drainage, surgical duration and approach, and taking effective preventive measures to reduce the incidence of intracranial infection after craniotomy in patients with multiple traumatic injuries.

U-shaped durotomy for midline posterior fossa tumor removal: technical note and evaluation of results.

The classical dura opening for midline posterior fossa tumors in and around the 4th ventricle and the craniocervical junction is a Y-shaped incision. Several potential problems are associated with this technique. We used a technical variant, the U-shaped durotomy, previously described by Rhoton, offering several advantages. We report on the surgical results of the technique in a consecutive series of posterior fossa cases in children and adolescents. In all midline posterior fossa approaches, a U-shaped dural incision is standard in our institution. All cases were retrospectively analyzed regarding hydrocephalus, placement of EVD or lumbar drain, need for ETV or shunting during follow-up, and frequency of duraplasty, of pseudomeningocele, of primary watertight dural closure, of CSF leakage, and of venous sinus hemorrhage at opening. Fifty pediatric patients were included. In all easy occipital sinus, control was achieved and no additional dural retraction for tumor exposure required. In 49/50 patients, a primary watertight dura closure without duraplasty was achieved, also in re-do cases with previous U-shaped opening. One patient received a small periostium graft after having had a duraplasty following Y-shaped opening beforehand. No CSF fistula ever occurred and no pseudomeningocele was detected in any follow-up MRI. The U-shaped durotomy for dorsal midline approach to the 4th ventricle and craniocervical junction provides wide exposure to all tumors and allows for primary and watertight dura closure. Compared to published results and complications of classic Y-shaped dural opening, this method of durotomy and closure seems most advantageous.

Spontaneous Pneumoventricle Following Bariatric Surgery

Pneumoventricle is a common postoperative event following posterior fossa approach, or any transventricular approach, with a benign evolution, rarely life-threatening. However, spontaneous pneumoventricle is a rare condition, almostalways secondary to cerebrospinal fluid (CSF) leakage, with possible worse evolution. We report a 57 years-old woman, previously healthy, submitted 7 months previously to a bariatric surgery, with 110 pounds (50 Kg) weight loss since that, who developed 1 month later headache, hemiparesis and urinary incontinence, secondary to a spontaneous pneumoventricle.

Improved CT Imaging for Mastoid Emissary Vein Visualization Prior to Posterior Fossa Approaches.

Background The clinical relevance of emissary veins (EVs) is often neglected. However, for posterior fossa approaches, especially in semisitting positions, these transosseous connections become potentially life threatening. Therefore, knowledge of the presence and configuration of EVs is essential in preoperative planning. We report on the use of preoperative computed tomography (CT) imaging techniques to visualize EVs reliably. Methods A total of 100 consecutive patients were evaluated by helical CT in bone window mode reconstructed using the standard technique (4.5-mm slices) and the high-resolution technique (1 mm) for the posterior fossa. The presence and size of the EVs, their entry point in the sigmoid sinus, their predilection site, and their visibility using either CT technique were evaluated. Statistical analyses included a comparison of the data from both sides of the head. Results We noted impressive anatomical variations (high standard deviations) in the number, size, and intraosseous length of the EVs among the study population and between the sides (right and left) of an individual patient; however, no statistical significance was observed for any of these parameters. The detection rate of EVs in thin-slice CT scans versus standard CT scans is significantly different (p = 0.0001 on both sides). Conclusions Thin-slice CT is essential in the preoperative planning of posterior fossa approaches to identify the presence and the course of EVs, reducing preventable approach-related morbidity during surgery.

Chiari type I malformation with high foramen magnum anomaly.

A 14-year-old male with a neck pain and hypoesthesia in the upper extremities was diagnosed with Chiari type I malformation (CMI) and syringomyelia. The posterior part of the occipital bone was removed via cranio-cervical decompression. The accuracy of measuring the posterior cranial fossa (PCF) and foramen magnum (FM) dimensions were evaluated and compared with the literature. The linear PCF and FM dimensions as well as volumes were measured using computed tomography (CT) images with different techniques. The volume data were compared with similar data from literature. Use of the posterior fossa approach remains controversial when treating patients with minor little brain stem dislocation, small PCF, and or incomplete C1, but the approach can easily be applied if FM and PCF sizes are known. Linear measurements that were assessed for concordance with CT measurements had the best agreement. Quantification of PCF volume and high FM should be taken into consideration for differential diagnosis of tonsillar herniation and prediction of surgical outcome in CMI.

Paradigm Shift in Management Strategies of Craniocerebral Missile Injuries Improving Survival Rates and Functional Outcome Score

Introduction With development of firearms, civilian violence, ethnic clashes, militancy, terrorist attack, and military operations there is a worldwide increase in incidence of craniocerebral missile injuries. The mortality of patients with craniocerebral missile injuries is high, and if the victim survives, functional outcome is poor. In spite of high mortality, no proper attention was given in last five decades in improving surgical techniques and resuscitation patterns of patients with craniocerebral missile injuries. Problems Considered The problems are many, but the two problems highlighted are decreased survival because of the inadequate pre-op resuscitation and poor functional outcome due to aggressive surgery. Therefore, the study was performed to evaluate the outcome of early and less aggressive surgical strategy and aggressive preoperative resuscitation in patients with penetrating injuries and also to look for factors prognosticating outcome. Methods A series of 96 patients with craniocerebral missile injuries to head were managed at a single center over a period of 3 years is presented. Aggressive resuscitation was done in all hemodynamically unstable patients and patients with coagulopathy either with blood products, hyperosmolar therapy or ionotropic support on protocols of damage control resuscitation. Blood product therapy consisted of packed red blood corpuscles, fresh frozen plasma (FFP) and platelets. Hypertonic saline was used for hyperosmolar resuscitation, and for ionotropic support dopamine, adrenalin, and vasopressin were used. Minimum debridement of the missile tract was done and maximum cortical tissue was preserved. Results Neurosurgical procedures contemplated on 78 patients. Criteria for craniotomy were—Glasgow Coma Scale (GCS) of 8 with intracranial bone fragments/significant clot, and raised intracranial pressure. Surgical approach were frontotemporal exposure (41%, n = 32/78), frontoparietal exposure (22%, n = 18/78), retrosigmoid exposure (2%, n = 2/78), combined middle and posterior fossa approach (2%, n = 2/78), and decompressive craniectomy (43%, n = 24/78). Procedures done were debridement of devitalized tissue (100%, n = 78/78), extraction of bone fragment (43%, n = 17/39), extraction of metallic pellet (62%, n = 42/67), lax duraplasty (100%, n = 78/789), debridement of missile tract (100%, n = 78/78). Overall, 36 patients were operated within 8 hours and 22 patients were operated within 14 hours. Median age group were 26 years, 81% were male, surgical mortality of 18%, and overall mortality was 33%. Conclusion This study indicates the factors prognosticating outcomes and supports that less aggressive surgery and aggressive preoperative resuscitation has decreased surgical mortality rates and improved functional outcomes.

Direct visualization of the murine dorsal cochlear nucleus for optogenetic stimulation of the auditory pathway.

Investigation into the use of virus-mediated gene transfer to arrest or reverse hearing loss has largely been relegated to the peripheral auditory system. Few studies have examined gene transfer to the central auditory system. The dorsal cochlear nucleus (DCN) of the brainstem, which contains second order neurons of the auditory pathway, is a potential site for gene transfer. In this protocol, a technique for direct and maximal exposure of the murine DCN via a posterior fossa approach is demonstrated. This approach allows for either acute or survival surgery. Following direct visualization of the DCN, a host of experiments are possible, including injection of opsins into the cochlear nucleus and subsequent stimulation by an optical fiber coupled to a blue light laser.Other neurophysiology experiments, such as electrical stimulation and neural injector tracings are also feasible.The level of visualization and the duration of stimulation achievable make this approach applicable to a wide range of experiments.