Posterior Fossa Surgery Research Articles

National multicentered retrospective review of clinical and intraoperative factors associated with the development of cerebellar mutism after pediatric posterior fossa tumor resection.

Cerebellar mutism (CM) is characterized by a significant loss of speech in children following posterior fossa (PF) surgery. The biological origin of CM remains unclear and is the subject of ongoing debate. Significant recovery from CM is less likely than previously described despite rigorous multidisciplinary neuro-rehabilitational efforts. A national multi-centered retrospective review of all children undergoing PF resection in four midsized Canadian academic pediatric institutions was undertaken. Patient, tumor and surgical factors associated with the post-operative development of CM were reviewed. Retrospective identification of PF surgery patients including those developing and those that did not (internal control). The study identified 258 patients across the 4 centers between 2010 and 2020 (mean age 6.73years; 42.2% female). Overall, CM was experienced in 19.5% of patients (N = 50). Amongst children who developed CM histopathology included medulloblastoma (35.7%), pilocytic astrocytoma (32.6%) and ependymoma (17.1%). Intraoperative impression of adherence to the floor of the 4th ventricle was positive in 36.8%. Intraoperative abrupt changes in blood pressure and/or heart rate were identified in 19.4% and 17.8% of cases. The clinical resolution of CM was rated to be complete, significant resolution, slight improvement, no improvement and deterioration in 56.0%, 8.0%, 20.0%, 14.0% and 2.0%, respectively. In the cohort of children who experienced post-operative CM as compared to their no-CM counterpart, proportionally more tumors were felt to be adherent to the floor of the 4th ventricle (56.0% vs 49.5%), intraoperative extent of resection was a GTR (74% vs 68.8%) and changes in heart rate were noted (≥ 20% from baseline) (26.0% vs 15.9%). However, a multiple regression analysis identified only abrupt changes in HR (OR 5.97, CI (1.53, 23.1), p = 0.01) to be significantly associated with the development of post-operative CM. As a devastating surgical complication after posterior fossa tumor surgery with variable clinical course, identifying and understanding the operative cues and revising intraoperative plans that optimizes the child's neurooncological and clinical outcome are essential.

The “state of the art” of intraoperative neurophysiological monitoring: An Italian neurosurgical survey

IntroductionIntraoperative Neurophysiological Monitoring (IOM) is widely used in neurosurgery but specific guidelines are lacking. Therefore, we can assume differences in IOM application between Neurosurgical centers. Research questionThe section of Functional Neurosurgery of the Italian Society of Neurosurgery realized a survey aiming to obtain general data on the current practice of IOM in Italy. Materials and methodsA 22-item questionnaire was designed focusing on: volume procedures, indications, awake surgery, experience, organization and equipe. The questionnaire has been sent to Italian Neurosurgery centers. ResultsA total of 54 centers completed the survey. The annual volume of surgeries range from 300 to 2000, and IOM is used in 10–20% of the procedures. In 46% of the cases is a neurologist or a neurophysiologist who performs IOM. For supra-tentorial pathology, almost all perform MEPs (94%) SSEPs (89%), direct cortical stimulation (85%). All centers perform IOM in spinal surgery and 95% in posterior fossa surgery. Among the 50% that perform peripheral nerve surgery, all use IOM. Awake surgery is performed by 70% of centers. The neurosurgeon is the only responsible for IOM in 35% of centers. In 83% of cases IOM implementation is adequate to the request. Discussion and conclusionsThe Italian Neurosurgical centers perform IOM with high level of specialization, but differences exist in organization, techniques, and expertise. Our survey provides a snapshot of the state of the art in Italy and it could be a starting point to implement a consensus on the practice of IOM.

Reoperation-requiring postoperative intracranial haemorrhage after posterior fossa craniotomy: Retrospective case-series

IntroductionStudies report rates of treatment-requiring postoperative intracranial haemorrhage after craniotomy around 1–2%, but do not distinguish between supratentorial and posterior fossa operations. Reports about intracranial haemorrhages’ temporal occurrence show conflicting results. Recommendations for duration of postoperative monitoring vary. Research questionTo determine the rate, temporal pattern and clinical presentation of reoperation-requiring postoperative intracranial posterior fossa haemorrhage. Material and methods: This retrospective case-series identified cases operated with posterior fossa craniotomy or craniectomy between January 1, 2007 and December 31, 2021 by an electronic search in the patient administrative database, and collected data about patient- and treatment characteristics, postoperative monitoring, and the occurrence of haemorrhagic and other serious postoperative complications. ResultsWe included 62 (n = 34, 55% women) cases with mean age 48 (interquartile range 50) years operated for tumours (n = 34, 55%), Chiari malformations (n = 18, 29%), ischemic stroke (n = 6, 10%) and other lesions (n = 3, 5%). One (2%) 66-year-old woman who was a daily smoker operated with decompressive craniectomy and infarct resection, developed a reoperation-requiring postoperative intracranial haemorrhage after 25.5 h. In four (6%) cases, other serious complications requiring reoperation or transfer from the post anaesthesia care unit or regular bed wards to the intensive care unit occurred after 0.5, 6, 9 and 54 h, respectively. Discussion and conclusionTreatment-requiring postoperative intracranial haemorrhage and other serious complications after posterior fossa craniotomies occur over a wide timespan and are difficult to capture with a standardized postoperative monitoring time. This indicates that the duration of monitoring should be individualized based on assessment of risk factors.

Risk Factors for Central Nervous System Infections After Craniotomy.

The central nervous system (CNS) is less prone to infection owing to protection from the brain-blood barrier. However, craniotomy destroys this protection and increases the risk of infection in the brain of patients who have undergone craniotomy. CNS infection after craniotomy significantly increases the patient's mortality rate and disability. Controlling the occurrence of intracranial infection is very important for post-craniotomy patients. CNS infection after craniotomy is caused by several factors such as preoperative, intraoperative, and post-operative factors. Craniotomy may lead to postsurgical intracranial infection, which is mainly associated with surgery duration, infratentorial (posterior fossa) surgery, cerebrospinal fluid leakage, drainage tube placement, unregulated use of antibiotics, glucocorticoid use, age, diabetes, and other systemic infections. Understanding the risk factors of CNS infection after craniotomy can benefit reducing the incidence of intracranial infectious diseases. This will also provide the necessary guidance and evidence in clinical practice for planning to control intracranial infection in patients with craniotomy.

Slow-Chronic Progressive Hydrocephalus as Complication of Microvascular Decompression for Trigeminal Neuralgia: A Case Report

Microvascular decompression (MVD) is one of the well-established treatment options for trigeminal neuralgia that may include posterior fossa surgery. However, Several complications were noted as being part of posterior fossa surgery and hydrocephalus is very rare to occur, especially the slow-chronic onset type. The pathophysiology is still unclear, but surgeons and patients must be warned about this possible surgical adverse event. Here we report a case of slow-chronic hydrocephalus in a 66-years old male who has a history of MVD procedure due to left trigeminal neuralgia. A shunt procedure was performed, in which after the surgery the patient’s complaints were resolved, and discharged without any morbidity.

Postoperative Cerebrospinal Fluid-Related Complications After Posterior Fossa and Posterolateral Skull Base Surgeries: Development of a Predictive Model and Clinical Risk Score

ObjectivePostoperative pseudomeningocele (PMC) and cerebrospinal fluid (CSF) leak are common complications following posterior fossa and posterolateral skull base surgeries. We sought to (1) determine the rate of CSF-related complications and (2) develop a perioperative model and risk score to identify the highest-risk patients for these events. MethodsThis was a retrospective cohort of 450 patients undergoing posterior fossa and posterolateral skull base procedures from 2016-2020. Logistic regressions were performed for predictor selection on three pre-specified models: (1) a priori variables, (2) predictors selected by large effect sizes, and (3) predictors with p-value ≤ 0.100 on univariable analysis. A final model was created via elimination of nonsignificant predictors, and the integer-based Post-Operative CSF-related Complications (POCC) clinical risk score was derived. Internal validation was done using 10-fold cross-validation (cv) and bootstrapping with uniform shrinkage. Results115 (25.6%) patients developed PMC/CSF leak. Age > 55 (OR 0.560 [95% CI 0.328-0.954]), BMI > 30 (OR 1.88 [95% CI 1.14-3.10]), and postoperative CSF diversion (OR 2.85 [95% CI 1.64-5.00]) were associated with CSF leak/PMC. Model 2 was the most predictive (cvAUROC 0.690). The final risk score was devised using age, BMI class, dural repair technique, use of bone substitute, and duration of postoperative CSF diversion. The POCC Score performed well (cvAUROC 0.761) and was highly specific (96.1%). ConclusionsWe have created the first generalizable and predictive risk score to identify at risk patients for CSF-related complications. The POCC Score may improve surveillance, inform doctor-patient discussions regarding risks of surgery, and assist in perioperative management.

Evaluation of the Sigmoid Sinus Morphology by Cone Beam Computed Tomography; Touchstone of the Posterior Cranial Fossa

OBJECTIVEIn this study, we aimed to analyze the relationship of sigmoid sinus (SS) with external auditory canal, facial nerve and mastoid cells from an anatomical point of view, to define the position of sigmoid sinus during transmastoid, translabyrinthine, retrosigmoid (lateral suboccipital) approaches, in tympanomastoidectomy and posterior cranial fossa surgery. METHODSIn this study, the morphological structures associated with the sigmoid sinus were evaluated in cone beam computed tomography images taken between 2015-2022 years. The images of 68 males and 106 females, aged 18-65 years, obtained from the archive of xxx University Faculty of Dentistry, Department of Oral and Maxillofacial Radiology were analysed. RESULTSThe most common sigmoid sinus pattern was type II with a rate of 60.8% (n=209); the second was type III with 20.6% (n=71); and the least common was type I with 18.6% (n=64). While the distance between the horizontal line passing through the external auditory canal and facial nerve and the anterior contour of the sigmoid sinus was highest in type I (right 7.26±1.62, left 7.44±.97), it was lowest in type III (right 4, 40±1.50, left 4.84±1.16) (p<0.05). CONCLUSIONThis study hihglights the importance of the sigmoid sinus position in surgeries, with special reference to otological, neurotological and posterior cranial fossa surgeries. In order to avoid intraoperative complications, each patient should be evaluated preoperatively by appropriate radiological methods.

Risk of postoperative scalp necrosis in the occipital artery region after posterior cranial fossa surgery.

Ischemia-induced postoperative scalp necrosis in the superficial temporal artery (STA) region is known to occur after STA-middle cerebral artery anastomoses. However, no reports have evaluated the risk of postoperative scalp necrosis in the occipital artery (OA) region. This study examined the surgical procedures that pose a risk for postoperative scalp necrosis in the OA region following posterior cranial fossa surgery. Patients who underwent initial posterior fossa craniotomy at our institution from 2015 to 2022 were included. Clinical information was collected using medical records. Regarding surgical procedures, we evaluated the incision design and whether a supramuscular scalp flap was prepared. The supramuscular scalp flap was defined as a scalp flap dissected from the sternocleidomastoid and/or splenius capitis muscles. A total of 392 patients were included. Postoperative scalp necrosis occurred in 19 patients (4.8%). There were 296 patients with supramuscular scalp flaps, and supramuscular scalp flaps prepared in all 19 patients with postoperative necrosis. Comparing incision designs among patients with supramuscular scalp flap, a hockey stick-shaped scalp incision caused postoperative necrosis in 14 of 73 patients (19.1%), and the odds of postoperative scalp necrosis were higher with the hockey stick shape than with the retro-auricular C shape (adjusted odds ratio: 12.2, 95% confidence interval: 3.86-38.3, p = 0.00002). In all the cases, ischemia was considered to be the cause of postoperative necrosis. The incidence of postoperative necrosis is particularly high when a hockey stick-shaped scalp incision is combined with a supramuscular scalp flap.

Arachnoid Welding—A Simple and Economical Method of Arachnoid Closure to Prevent Cerebrospinal Fluid Leak

Collection of cerebrospinal fluid (CSF) in the subdural compartment is a major cause of postoperative morbidity, especially for posterior fossa surgeries. Arachnoid closure techniques, including suturing of the arachnoid and use of synthetic sealants, have been described in the literature. However, they are not always feasible or effective and have not been universally adopted. We describe the technique of arachnoid welding for a case of brainstem cavernoma. This is a simple, cost-effective, and easily reproducible technique using readily available bipolar cautery kept at a low-current setting. At the end of surgery, the arachnoid leaflets are closely approximated, and bipolar cautery is used to seal the edges together. An illustrative video shows the technical nuances of this procedure. This technique can also be applied for arachnoid closure at other cranial and spinal sites. Arachnoid closure can act as an effective natural barrier to keep CSF in its physiological subarachnoid compartment. It provides an additional barrier to prevent CSF leak. It also prevents morbidity associated with adhesions and arachnoiditis. Proper closure of arachnoid makes durotomy during repeat surgery much easier and avoids injury to the underlying pia. A brief review of related literature shows the benefits of closing the arachnoid before dural closure and the different techniques that have been described so far. The arachnoid welding technique has a wide application, is easy to learn, and can be used especially for posterior fossa surgeries in which rates of CSF leak are the highest.

Postoperative pediatric cerebellar mutism syndrome: A literature review

Introduction: Postoperative pediatric cerebellar mutism syndrome (POPCMS) is a significant complication observed after posterior fossa surgery for tumors, particularly in pediatric neurosurgery. This paper presents a literature review on the physiopathology, diagnosis, treatment, and long-term outcomes of POPCMS.&#x0D; Methods: A systematic review following PRISMA guidelines, searching for articles published in PubMed, Web of Science, and Lilacs in the last ten years. Inclusion criteria involved studies on human subjects under 18 years of age, focusing on the pathophysiology, diagnosis, treatment, and outcome of POPCMS.&#x0D; Results: The review identified 34 studies on POPCMS for final inclusion. Preoperative risk factors commonly associated with cerebellar mutism included midline tumor location, diagnosis of medulloblastoma, younger age at diagnosis, preoperative language impairment, brainstem infiltration, and tumor histology. The SHH subgroup was found to reduce the risk of CMS. Diagnostic criteria for POPCMS included language impairment, emotional lability, hypotonia, oropharyngeal dysfunction, dysphagia, cerebellar motor syndrome, cerebellar cognitive affective syndrome, and brainstem dysfunction. Treatment approaches varied, with medications showing potential benefits. Rehabilitation options for speech and language deficits were limited. Cognitive remediation programs showed promise in improving academic achievement and attention. A significant proportion of patients experienced clinical improvement. &#x0D; Conclusion: POPCMS remains a challenging complication following posterior fossa surgery. Further research is needed to develop standardized diagnostic criteria, effective treatments, and rehabilitation strategies to improve long-term outcomes for patients with POPCMS.

Cerebellar Mutism after posterior fossa tumor surgery: is it predictable, preventable, treatable?

Introduction: Posterior fossa tumors pose challenges in pediatric neurosurgery and can lead to complications such as cerebellar mutism, affecting speech and motor abilities. This study aims to describe the evolution of cerebellar mutism and identify relevant factors in its pathophysiology and prognosis. Methods: A review was conducted on three cases of children who underwent surgery for posterior fossa tumors by the same surgical team and developed postoperative cerebellar mutism. The study analyzed preoperative clinical presentation, mutism manifestation, and recovery. Additionally, a literature review was performed on the emergence, evolution, and prognosis. Results: Case 1 involved a 3-year-old girl with medulloblastoma who experienced mutism, behavioral changes, and self-mutilation after surgery. Symptoms resolved after one month but recurred with a subsequent operation, resolving again after a month. Case 2 featured a 15-year-old girl who developed severe posterior fossa syndrome, including mutism, dysarthria, aphasia, and motor impairments. With support care, she gradually improved over a year. Case 3 involved a 4-year-old boy with cerebral palsy and a posterior fossa tumor. He experienced akinetic mutism, resolved over time with rehabilitation therapies. Discussion: Cerebellar mutism following posterior fossa surgery has implications for patient recovery. It primarily involves impairment of cerebellar outflow pathways rather than direct brainstem or cortical lesions. Identifying at-risk patients remains challenging, though younger age and specific tumor characteristics may increase the likelihood of mutism. Rehabilitation, including physical and speech therapies, plays a crucial role in promoting recovery. Effective communication and support for patients and their families are essential during the recovery process.

Posterior Fossa Tumors Special Edition. Celebrating 4 years!

Posterior fossa tumors account for approximately half of the central nervous system tumors in children. Major technological advances, mainly in the fields of molecular biology and neuroimaging, have modified their classification, leading to a more detailed description of these entities. Certain modifications in the general nomenclature introduced by the 2021 WHO classification of tumors of the CNS have an impact on how we approach the posterior fossa tumors described in this study. The focus of this annual special issue is posterior fossa tumors in children. There were several emerging technologies and approaches in the diagnosis and treatment of posterior fossa tumors in children. It's important to note that medical technology and research are continually evolving, so there may have been further advancements in this field since then. Here are some promising technologies and strategies that were being explored: Advanced Imaging Techniques: Functional MRI (fMRI): This technology helps in mapping the brain's functional areas, allowing surgeons to plan their approach more accurately and minimize damage to critical brain regions. Diffusion Tensor Imaging (DTI): DTI provides information on the brain's white matter tracts, aiding surgeons in preserving essential neural pathways during surgery. Spectroscopy: It helps in identifying tumor types and differentiating between tumor tissue and healthy brain tissue. Surgical Navigation Systems: The use of advanced navigation systems during surgery allows for precise tumor localization and safer tumor removal, minimizing damage to surrounding healthy tissue. Brain Ultrasound and iMRI: Some hospitals are equipped with iMRI suites that allow real-time imaging during surgery. Most common brain ultrasound helps a lot during the posterior fossa surgery and can use simultaneously with neuronavigation system. Minimally Invasive Techniques: Minimally invasive procedures, such as endoscopic surgery, are being explored for certain types of posterior fossa tumors. These techniques can reduce recovery times and complications. Intraoperative monitoring (IOM), also known as intraoperative neurophysiological monitoring (IONM), is a critical technique used during certain surgeries to monitor the nervous system's function in real-time. It helps surgeons and medical teams assess the integrity of neural structures, particularly the brain and spinal cord, during surgical procedures. Genomic and Molecular Analysis: Advances in genomic and molecular analysis of tumors can provide insights into the specific genetic mutations driving the tumor's growth. This information can help guide treatment decisions, including targeted therapies. Radiation Therapy Advancements: Techniques like proton therapy and stereotactic radiosurgery are being used to precisely target tumors while minimizing damage to surrounding healthy tissue, which is especially important in pediatric cases. Immunotherapy: Immunotherapy approaches, such as checkpoint inhibitors, are being investigated for their potential in treating certain types of posterior fossa tumors in children. These therapies aim to harness the body's immune system to fight the tumor. Personalized Medicine: Tailoring treatment plans to the individual characteristics of each patient's tumor is becoming increasingly important. This includes considering factors such as tumor genetics, location, and the child's overall health. Telemedicine and Remote Consultations: Telemedicine technologies enable pediatric neuro-oncologists to collaborate with experts worldwide, improving the quality of care, especially in regions with limited access to specialized healthcare. This special issue covers the different aspects of posterior fossa tumors surgery. We wish to thank all the authors for their tremendous contributions, and we hope that you will have the same interest and pleasure to read this special issue as we have had to edit it.

Modified 30-Degree Head-Up Tilt Park Bench Position in Semielective Posterior Fossa Surgery in a Patient with Pheochromocytoma

AbstractVon Hippel–Lindau (VHL) disease is a rare genetic disorder associated with the central nervous system and visceral organs. Pheochromocytomas occur in 10% of VHL patients, while cerebellar tumors are common tumors in VHL syndrome, with an incidence of 60%. The most common position for posterior fossa operations is the park bench or lateral decubitus position. These positions have primarily replaced the sitting position. However, the advantages of the supine position cannot be overlooked. The coexistence of pheochromocytoma and the cerebellar tumor may require modification in surgical position and anesthesia management in line with possible pathophysiological changes. We present the anesthesia management in posterior fossa surgery in patients with postponed pheochromocytoma surgery. The present case highlights the importance of a multidisciplinary team approach and anesthetic management.

Effect of Ketamine and Dexmedetomidine as Adjuvant to Total Intravenous Anesthesia on Intraoperative Cranial Nerve Monitoring in the Patients Undergoing Posterior Fossa Craniotomies-A Randomized Quadruple Blind Placebo-Controlled Study.

Objectives Total intravenous anesthesia (TIVA) is used during surgery with intraoperative neurophysiological monitoring. Addition of adjuvant may minimize suppression of potentials by reducing doses of propofol. We studied the effect of addition of ketamine or dexmedetomidine to propofol-fentanyl-based TIVA on corticobulbar motor evoked potential (CoMEP) in patients undergoing posterior fossa surgeries. Materials and Methods Forty-two patients were assigned to three groups ( n = 14 each), Group S-saline, Group D-dexmedetomidine (0.25 μg/kg/h), and Group K-ketamine (0.25 mg/kg/h). Patients received propofol and fentanyl infusions along with study drugs. CoMEPs were recorded from muscles innervated by cranial nerves bilaterally at predefined intervals (T baseline , T 2 , T 3 , T 4 , and T 5 ). Effect on amplitude and latency of CoMEPs was assessed. Results A significant fall in CoMEP amplitude was observed across all analyzed muscles at time T 4 and T 5 in saline and dexmedetomidine group as compared with ketamine group, p -value less than 0.05. A significant increase in latency was observed at T4 and T5 among groups ( p -value, D vs. K = 0.239, D vs. S = 0.123, and K vs. S = 0.001). Conclusion Both ketamine and dexmedetomidine provide and allow effective recording of CoMEPs. Ketamine emerges as a better agent especially when prolonged surgical duration is expected as even propofol-fentanyl-based TIVA adversely affects CoMEPs when used for long duration.

Perioperative Management and Anesthesia in Patients with Hemifacial Spasm Undergoing Microvascular Decompression: A Case Report

Introduction: Microvascular decompression (MVD) is an operation performed to treat a symptom of hemifacial spasm. Hemifacial spasm is described as a disorder of neuromuscular movement characterized by repeated to persistent involuntary contractions affecting the muscles innervated by the facial nerve.&#x0D; Case presentation: A 33-year-old woman came to consciousness with complaints of twitching on the right side of her face since 1 year ago. Initially, the complaint was felt for the first time 3 years ago, only on the upper right eyelid, but it has been getting worse over the past year. Magnetic resonance imaging (MRI) was obtained vascular loop on the right anterior inferior cerebellar artery (AICA) in level cerebellar pontine angle (CPA). MVD is a unilateral neurosurgical procedure in the axial section of the posterior fossa. Positions that can be used are supine and modified lateral decubitus or park bench. The management of anesthesia-related to posterior fossa surgery includes, first, the effect of the drug on the ability of the lungs to hold air from entering the venous circulation. Intravenous administration of anesthetics, for example, fentanyl, can maintain a higher threshold for retaining air bubbles in the pulmonary circulation compared with inhalational anesthetics.&#x0D; Conclusion: Optimal hemodynamic monitoring, good analgesia, and adequate muscle relaxation are the principles of anesthesia monitoring that aim to facilitate the operator in finding access to the disturbed nerve complex.

Intraoperative ultrasound-guided ventricular cannulation in patients with normal-sized ventricles

IntroductionMany pathologies require normal-sized ventricle cannulation, which may be technically challenging even with neuronavigation guidance. This study presents a series of ventricular cannulation of normal-sized ventricles using intraoperative ultrasound (iUS) guidance and the outcomes of patients treated by this technique, for the first time. MethodsThe study included patients who underwent ultrasound-guided ventricular cannulation of normal-sized ventricles (either ventriculoperitoneal (VP) shunting or Ommaya reservoir) between January 2020 and June 2022. All patients underwent iUS-guided ventricular cannulation from the right Kocher's point. The inclusion criteria for normal-sized ventricles were as follows: (1) Evans index <30%, and (2) widest third ventricle diameter <6mm. Medical records and pre-, intra- and post-operative imaging were retrospectively analyzed. ResultsNine of the 18 included patients underwent VP shunt placement; 6 had idiopathic intracranial hypertension (IIH), 2 had resistant cerebrospinal fluid fistula following posterior fossa surgery, and 1 had iatrogenic intracranial pressure elevation following foramen magnum decompression. Nine patients underwent Ommaya reservoir implantation, 6 of whom had breast carcinoma and leptomeningeal metastases and 3 hematologic disease and leptomeningeal infiltration. All catheter tip positions were achieved in a single attempt, and none were placed suboptimally. Mean follow-up was 10 months. One IIH patient (5.5%) had early shunt infection which necessitated shunt removal. ConclusioniUS is a simple and safe method for accurate cannulation of normal-sized ventricles. It provides an effective real-time guidance option for challenging punctures.

Rare Event of Intraoral Kinking of Endotracheal Tube Upon Prone Positioning in a Patient Undergoing Posterior Fossa Surgery

Prone position is commonly employed for many surgical procedures including neurosurgeries, spine surgeries, urological procedures, and in refractory ARDS patients. An endotracheal tube is a conduit to provide a secured airway to the patient. But in case of any equipment failure, it can cause catastrophic events. Intra-oral kinking is a rarer event. It can pose a major troubleshooting standstill owing to the inaccessible view of the kinked portion and the rarity of its occurrence to cross the clinician’s mind in the emergency scenario. We thus report this as the first such case of intraoral kinking against the soft palate in the prone position.

The Occipitalis Muscle as an Adjunct Superficial Landmark for the Transverse Sinus and Transverse-Sigmoid Junction: An Anatomical Study With Application to Posterior Cranial Fossa Surgery.

Although neuronavigation systems are widely used for identifying deep intracranial structures, additional superficial anatomical landmarks can be useful when this technology is not available or is not working properly. Herein, we investigate the potential of the occipitalis muscle (OM), rarely mentioned in neurosurgical literature, as a superficial landmark for the transverse sinus (TS) and transverse-sigmoid sinus junction (TSJ). Eighteen adult cadaveric heads underwent dissection. The borders of the OM were identified and measured. The muscle was then removed and the bone underlying the muscle was drilled. The relationships between the OM and the underlying dural venous sinuses were then investigated by using a surgical microscope. The OM is a quadrangular-shaped muscle, that invariably crosses the lambdoid suture, showing relationships with the TS inferiorly and the TSJ laterally. The medial border was located a mean of 2.7 cm from the midline and its lower edge was a mean of 1.6 cm above the TS. The inferior border was found between the lambdoid suture and the superior nuchal line in all the specimens. The medial half of the inferior margin was placed on average 1.1 cm superiorly to the TS while the lateral margin ran just above or over the TS. The lateral border was located a mean of 1.1 cm medially to the asterion and approximated the mastoid notch, being within 1-2 cm from it. The TSJ was between 2.1 and 3.4 cm lateral to OM lateral border. A combination of superficial anatomical landmarks can be useful for surgical planning. We found that the OM represents a valuable aide for neurosurgeons and is a reliable landmark for the deeper-lying TS and TSJ.

Ondine's curse: clinical presentation with diaphragmatic pacing and spontaneous respiratory recovery. Illustrative case.

The complexity of posterior fossa surgery can often lead to rare complications due to the anatomy involved. Vestibular schwannoma resection is a common pathology in the posterior fossa, often requiring surgical intervention. Given the proximity of this space to the brainstem, cranial nerve VII/VIII complex, and posterior inferior cerebellar artery (PICA), neurovascular complications are not infrequent. A rare vascular complication from this surgical approach is a lateral medullary infarction from injury to the lateral medullary segment of the proximal PICA, leading to central hypoventilation syndrome (CHS). This report presents a unique case of a 51-year-old man who underwent a retrosigmoid craniectomy for resection of a vestibular schwannoma. Following surgery, the patient was unable to be weaned off the ventilator and was noted to become apneic while he slept, a clinical picture consistent with Ondine's curse. This report discusses the anatomical considerations of this surgical corridor leading to this complication and the management of a patient with acquired Ondine's curse and reviews the scarce literature on this uncommon cause of acquired CHS.

Rates of cerebrospinal fluid leak and pseudomeningocele formation after posterior fossa craniotomy versus craniectomy: A systematic review and meta-analysis.

Postoperative cerebrospinal fluid (CSF) leak is a major concern after posterior fossa surgery with significant clinical implications. It has been postulated that replacing the bone flap, performing a craniotomy, would reinforce the surgical closure and decrease rates of CSF leak. This systematic review and meta-analysis compared the rate of CSF leak after posterior fossa craniotomies versus craniectomies. Three databases were searched for English studies comparing the primary outcome, rate of CSF leak, after adult posterior fossa craniotomies versus craniectomies. Secondary outcomes included the rate of postoperative pseudomeningocele formation, CSF leak and pseudomeningocele formation, CSF diversion, revision surgery, and infection. Pooled estimates and relative risks for dichotomous outcomes were calculated using Review Manager 5.4, with corresponding 95% confidence intervals (CIs). A total of 1250 patients (635 craniotomies and 615 craniectomies), from nine studies, were included in the final analysis. Even though rates of CSF leak favored craniotomies, the difference did not reach statistical significance in our pooled analysis (Risk Ratio: 0.71, 95% Confidence Interval: 0.45-1.14, p-value = 0.15, Heterogeneity I-squared = 0%). On the other hand, comparing the rates of pseudomeningocele formation and CSF leak, as a combined outcome, or pseudomeningocele formation only showed a significant difference favoring craniotomies. The quality of evidence in this meta-analysis was graded as having a high risk of bias based on the risk of bias in non-randomized studies - of exposure criteria. Based on evidence with high risk of bias, rates of postoperative CSF leak and pseudomeningocele formation favored posterior fossa craniotomies over craniectomies. Further research with more robust methodology is required to validate these findings.