Microsurgical anatomy and approaches to thalamic gliomas. Part 2: Maximal safe resection of thalamic gliomas improves outcomes. A single-center experience.

OBJECTIVE: As presented in Part 1 of this series, thalamic gliomas (TGs) are deep-seated, difficult-to-access tumors surrounded by vital neurovascular structures. Given their high operative morbidity, TGs have historically been considered inoperable lesions. Although maximal safe resection (MSR) has become the treatment standard for lobar and even deep-seated mediobasal temporal and insular gliomas, the eloquent location of TGs has precluded this management strategy, with biopsy and adjuvant treatment being the mainstay. The authors hypothesized that MSR can be achieved with low morbidity and mortality for TGs, thus resulting in improved outcomes. METHODS: A retrospective single-center study was performed on all TG patients from 2006 to 2020. Clinical, imaging, and pathology reports were obtained. Univariate and multivariate analyses were performed to determine prognostic variables. Case examples illustrate various approaches and the rationale for staging resections of more complex TGs. RESULTS: A total of 42 patients (26 males, 16 females), among them 12 pediatric (29%) cases, were included. Their mean age was 36.0 ± 21.4 (median 30, range 3-73) years. The median maximal tumor diameter was 45 (range 19-70) mm. Eighteen patients (43%) had a prior stereotactic needle tumor biopsy, with the ultimate diagnosis changed for 7 patients (39%) following microsurgical resection. The most common surgical approaches were transtemporal (29%), anterior interhemispheric transcallosal (29%), and superior parietal lobule (25%). Overall, the combined subtotal and gross-total resection rate was 95% (n = 40). Low-grade gliomas (LGGs; grades I and II) comprised one-third of the group, whereas half of the patients had glioblastoma multiforme. There were no operative mortalities. Although temporary postoperative motor deficits were observed in 12 patients (28.6%), all improved during the early postoperative period except 1 (2.4%), who had mild residual hemiparesis. Two patients required CSF diversion for hydrocephalus. The 2-year overall survival rate was 90% for LGG patients and 15% for high-grade glioma (HGG) patients. Multivariate analysis revealed that histological grade, age, and extent of resection were independent prognostic factors associated with survival. CONCLUSIONS: Management of TGs is challenging, with resection avoided by many, if not most, neurosurgeons, especially for HGGs. The results reported here demonstrate improved outcomes with resection, particularly in younger LGG patients. The authors therefore advocate for MSR for a select cohort of TG patients using carefully planned surgical approaches, contemporary intraoperative adjuncts, and meticulous microsurgical techniques.

Microsurgical anatomy and approaches to thalamic gliomas. Part 1: A cartography guide for navigating to the thalamus. Integrating 3D model rendering with anatomical dissections.

OBJECTIVE: The selection of appropriate microsurgical approaches to treat thalamic pathologies is currently largely subjective. The objective of this study was to provide a structured cartography map for surgical navigation to treat gliomas involving different surfaces of the thalamus. METHODS: Fifteen formalin-fixed, silicone-injected cadavers (30 sides) were dissected, and 10 adult brain specimens (20 sides) were used to illustrate thalamic microsurgical anatomy using the Klingler fiber dissection technique. Exposures and trajectories for the six most common microsurgical approaches were depicted using MR data from healthy subjects converted into surface-rendered 3D virtual brain models. Additionally, thalamic surfaces exposed with all six approaches were color mapped on the virtual 3D model and compared side-by-side in 360° views with previously reported microsurgical approaches. These 3D models were then used in conjunction with topographic data to guide cadaveric dissection steps. RESULTS: There are two general surgical routes to thalamic lesions: the subarachnoid transcisternal and transcortical routes. The transcisternal route consists of the following three approaches: 1) anterior interhemispheric transcallosal approach, which exposes the anterior and superior thalamus; 2) posterior interhemispheric transcallosal approach, which exposes the posterosuperior thalamus; and 3) supracerebellar infratentorial approach, which exposes the posteromedial cisternal thalamus and can be extended laterally to approach the posterolateral thalamus by cutting the tentorium. The three transcortical approaches are the 1) superior parietal lobule approach, which exposes the posterosuperior thalamus and is particularly advantageous in the setting of hydrocephalus; 2) transtemporal gyrus approach, which exposes the inferolateral thalamus; and 3) transsylvian transinsular approach, which exposes the lateral thalamus (slightly more superiorly and posteriorly) and is advantageous for pathologies extending laterally into the peduncle, lenticular nucleus, or insula. CONCLUSIONS: Microsurgical approaches to thalamic gliomas continue to be challenging. Nonetheless, safe and effective cisternal, ventricular, and cortical corridors can be developed with thoughtful planning, anatomical understanding, and knowledge of the advantages, risks, and limitations of each approach. In some cases, it is wise to combine these approaches with staged procedures, as the authors demonstrate in Part 2. In Part 1 of this two-part series, they discuss thalamic microsurgical anatomy and illustrate the trajectory and exposures of all six approaches to guide decision-making. Part 2 discusses their thalamic glioma microsurgical case series, which utilizes these microsurgical approaches.

T12-L3 Nerve Transfer-Induced Locomotor Recovery in Rats with Thoracolumbar Contusion: Essential Roles of Sensory Input Rerouting and Central Neuroplasticity.

Locomotor recovery after spinal cord injury (SCI) remains an unmet challenge. Nerve transfer (NT), the connection of a functional/expendable peripheral nerve to a paralyzed nerve root, has long been clinically applied, aiming to restore motor control. However, outcomes have been inconsistent, suggesting that NT-induced neurological reinstatement may require activation of mechanisms beyond motor axon reinnervation (our hypothesis). We previously reported that to enhance rat locomotion following T13-L1 hemisection, T12-L3 NT must be performed within timeframes optimal for sensory nerve regrowth. Here, T12-L3 NT was performed for adult female rats with subacute (7-9 days) or chronic (8 weeks) mild (SCImi: 10 g × 12.5 mm) or moderate (SCImo: 10 g × 25 mm) T13-L1 thoracolumbar contusion. For chronic injuries, T11-12 implantation of adult hMSCs (1-week before NT), post-NT intramuscular delivery of FGF2, and environmentally enriched/enlarged (EEE) housing were provided. NT, not control procedures, qualitatively improved locomotion in both SCImi groups and animals with subacute SCImo. However, delayed NT did not produce neurological scale upgrading conversion for SCImo rats. Ablation of the T12 ventral/motor or dorsal/sensory root determined that the T12-L3 sensory input played a key role in hindlimb reanimation. Pharmacological, electrophysiological, and trans-synaptic tracing assays revealed that NT strengthened integrity of the propriospinal network, serotonergic neuromodulation, and the neuromuscular junction. Besides key outcomes of thoracolumbar contusion modeling, the data provides the first evidence that mixed NT-induced locomotor efficacy may rely pivotally on sensory rerouting and pro-repair neuroplasticity to reactivate neurocircuits/central pattern generators. The finding describes a novel neurobiology mechanism underlying NT, which can be targeted for development of innovative neurotization therapies.

Outcome measures in neurosurgery: Is a unified approach better? A literature review.

Background: Accurate assessment and evaluation of health interventions are crucial to evidence-based care. The use of outcome measures in neurosurgery grew with the introduction of the Glasgow Coma Scale. Since then, various outcome measures have appeared, some of which are disease-specific and others more generally. This article aims to address the most widely used outcome measures in three major neurosurgery subspecialties, "vascular, traumatic, and oncologic," focusing on the potential, advantages, and drawbacks of a unified approach to these outcome measures. Methods: A literature review search was conducted by using PubMed MEDLINE and Google scholar Databases. Data for the three most common outcome measures, The Modified Rankin Scale (mRS), The Glasgow Outcome Scale (GOS), and The Karnofsky Performance Scale (KPS), were extracted and analyzed. Results: The original objective of establishing a standardized, common language for the accurate categorization, quantification, and evaluation of patients' outcomes has been eroded. The KPS, in particular, may provide a common ground for initiating a unified approach to outcome measures. With clinical testing and modification, it may offer a simple, internationally standardized approach to outcome measures in neurosurgery and elsewhere. Based on our analysis, Karnofsky's Performance Scale may provide a basis of reaching a unified global outcome measure. Conclusion: Outcome measures in neurosurgery, including mRS, GOS, and KPS, are widely utilized assessment tools for patients' outcomes in various neurosurgical specialties. A unified global measure may offer solutions with ease of use and application; however, there are limitations.

Dynamic interaction between cerebrospinal fluid and sinovenous pressure in idiopathic intracranial hypertension: a case report.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a common neurosurgical condition, and the exact pathophysiology remains elusive. Cerebral sinovenous stenosis (CSS) and the resultant decreased venous outflow have been labelled as a potential contributors to the pathophysiology of IIH. We describe the effect of cerebrospinal fluid (CSF) drainage on sinovenous pressure in a patient with IIH and a radiographic evidence of CSS. CASE DESCRIPTION: A patient in their 40s with a diagnoses of IIH and imaging finding of focal stenosis of the distal left transverse sinus. To assess the nature of the stenosis, we performed venous sinus pressure monitoring with concurrent CSF drainage (5 ml at one minute intervals) through a lumbar drain with continuous mean sinovenous pressures recording. We observed a progressive decline in the pressure recording while draining CSF, after draining 40 ml of CSF, the final pressure gradient recording of the TS-SS trans-stenotic was (7 mm Hg from 27 mm Hg), mean SSS pressure (37 mm Hg from 60 mm Hg), and mean TS pressure (35 mm Hg from 56 mm Hg). The mean SS pressure remained relatively unperturbed. CONCLUSION: Our findings indicate that the cerebral sinovenous pressure response to CSF removal generally conforms to a monophasic exponential decay model.

Failure of tandem flow diversion for intracranial aneurysms: Literature review and illustrative case.

Background: Flow diverters are becoming one of the main endovascular procedures used to treat aneurysms. Flow diverter devices (FDDs) have multiple types approved for endovascular procedure use. Although their indications are not well described, they are usually used for large or giant, wide-necked, and recurrent aneurysms. Multiple FDDs can be deployed to treat giant aneurysms to ensure and accelerate aneurysm occlusion and mitigate complications. We report a case of endovascular treatment of an intracranial aneurysm using three silk FDDs complicated by a delayed migration of the stents along the parent artery, along with a literature review of the related cases. Methods: We conducted a PubMed Medline database search by the following combined formula of subjects headings: ((((((intracranial aneurysm[MeSH Terms]) AND (endovascular procedure[MeSH Terms])) OR (endovascular technique[MeSH Terms])) AND (endovascular[Title/Abstract]) AND (Flow diverter[Title/ Abstract])) OR (flow diversion[Title/Abstract])) OR (Pipeline[Title/Abstract])) AND (Multiple[Title/Abstract]). Results: The result was eight cases of endovascular treatment of intracranial aneurysms with multiple FDD. The male-to-female ratio in these cases was 5:3, and there is a wide age range from 22 months to 69 years old. The cases differed in the type and number of FDDs used, yet, they all had similar results with aneurysm occlusion and recovery of the patient with no observed complications. Conclusion: Tandem flow diverter deployment has technical challenges and complications such as complete obstruction can occur. Planning and learning from experience with those new technologies are the typical way to overcome such complications in the future.

Predictors of the Size and Surgical Freedom of the Trans-Cribriform and Trans-Clival Corridors, a Radiographic Analysis.

Introduction The transcribriform and transclival corridors are endoscopic endonasal approaches used to treat pathologies of the skull base. We present a predictive model that uses the clival length and ethmoidal width to predict the size and surgical freedom (SF) of these corridors. Methods Adult facial computed tomography scans were reviewed. Exclusion criteria included patients <18 years of age or radiographic evidence of trauma, neoplasm, or congenital deformities of the skull base. The images were analyzed using OsiriX MD (Bernex, Switzerland). Patients' demographics, clival length, ethmoidal width, surface area, and others were collected. Linear regression was used to create prediction models for the size and SF of the transclival and transcribriform corridors. Results A total of 103 patients were included with an average age of 44.9 years and 47% males. Females had a smaller clival surface area (8 vs. 9.2 cm 2 , p = 0.001). For transclival corridor, clival length correlated positively with SF in the sagittal plane (rho = 0.44, p < 0.05) and negatively with SF in the coronal plane (rho = - 0.2, p < 0.05). For transcribriform corridor, ethmoidal width correlated positively with SF in the coronal plane (rho = 0.74, p < 0.05), and negatively with SF in the sagittal plane (rho = - 0.2, p < 0.05). Conclusion A significant variability of the bony anatomy of the anterior and central skull base was found. The use of clival length and ethmoidal width as part of preoperative surgical planning might help to overcome the anatomical variability which could affect the adequacy of surgical corridors.

A case series of crossbow injury to the head highlighting the importance of an interdisciplinary management approach.

BACKGROUND: Penetrating crossbow head injuries are rare with no clear consensus regarding the optimal management paradigm for such injuries. We present three cases of crossbow injury to the head, with emphasis on the need for a comprehensive multidisciplinary management plan. CASE DESCRIPTION: Three cases are presented of patients presenting with self-inflicted penetrating crossbow to head injuries. All three patients presented with intact neurological exam. A comprehensive multidisciplinary plan was created for all three cases with subsequent successful removal of the arrows. All three patients were discharged home with modified Rankin scale score of <2. CONCLUSION: Penetrating crossbow brain injuries are rare and require complex management. A comprehensive management strategy is necessary to manage these injuries. Moreover, careful consideration of factors such as the arrow trajectory, complexity of the injuries, and availability of the required expertise is important to increase the chances of success.

Incidence and Long-Term Health Care Utilization Associated With Pseudomeningocele Repair Following Vestibular Schwannoma Resection: A National Database Analysis.

Introduction To compare the healthcare utilization in patients who presented with no pseudomeningocele (PSM) following vestibular schwannoma (VS) surgery (nd-PSM), PSM following VS surgery and required surgical repair (s-PSM) and those who presented with PSM and did not require surgical repair (ns-PSM). Methods MarketScan database was queried using the International Classification of Diseases, ninth and tenth revisions, and current procedural terminology four, from 2000 to 2018. We included patients ≥18 years of age with a PSM diagnosis with at least two years of continuous enrollment. The hospital admissions, outpatient services, medication refills, and associated payments were analyzed. Results Of 1,460 patients, 96.6% (n=1,411) had no PSM following surgery for VS, 2.4% (n=35) were in s-PSM and only 0.95% (n=14) were in ns-PSM cohorts. Patients in the s-PSM cohort incurred higher hospital readmission rate, outpatient payments compared to those in the nd-PSM and ns-PSM cohorts at six months, one-year, and two-years following the following VS resection. At one-year following VS resection, the median combined payments for the s-PSM cohort were $74,683 compared to $42,664 for the ns-PSM and $9,476 for the nd-PSM cohort, p<0.0001. Similarly, at two-years, median combined payments for s-PSM cohort were $83,351 compared to $63,942 for ns-PSM and $18,839 for the nd-PSM cohort, p<0.0001. Conclusion  Patients in the s-PSM cohort incurred eight times and 4.4 times the combined payments at one- and two-years, respectively, compared to the nd-PSM cohort. Also, patients in the ns-PSM cohort incurred 4.5 times and 3.4 times the payments compared to the nd-PSM cohort.

Morphometric Study of the Posterior Fossa: Identification of Practical Parameters for Tailored Selection of Surgical Routes to the Petroclival Region.

Introduction The petroclival region is an integral part of the skull base. It can harbor different pathologies and provides access to the petroclival junction and cerebellopontine angle. We present the results of the morphometric analysis of the posterior fossa and a prediction model to enable skull base surgeons to choose an optimal surgical corridor considering patient's bony anatomy. Methods Ninety patients (14 to assess interobserver reliability) with temporal bone computed tomography were selected. Exclusion criteria included patients <18 years of age, radiographic evidence of trauma, infection, or previous surgery. The images were analyzed using OsiriX MD (Bernex, Switzerland). We recorded clival length, vertical angle, and surface area, and petroclival angle, petrous apex, and translabyrinthine corridors volume. Results The average age was 49.5 years (55%) for males. The mean clival length and surface areas were 44.2 mm (standard deviation [SD] ± 4.1) and 8.1 cm 2 (SD ± 1.3). The mean petrous apex and translabyrinthine corridors volumes were 2.2 cm 3 (SD ± 0.6) and 10.1 cm 3 (SD ± 3.7). The mean petroclival angle at the internal auditory canal (IAC) was 154.9 degrees (SD ± 9). The clival length correlated positively with clival surface area (rho = 0.6, p <0.05), petrous apex volume (rho = 0.3, p < 0.05), and translabyrinthine volume (rho = 0.3, p < 0.05). Conclusion The petroclival region is complex and with high variability of surgical significance. The use of preoperative measurements of the clival length and petroclival angle as part of surgical planning that could help the surgeon to choose an optimal surgical corridor by overcoming the anatomical variability elements.

Complications associated with early cranioplasty for patients with traumatic brain injury: a 25-year single-center analysis.

OBJECTIVE: Cranioplasty is a technically simple procedure, although one with potentially high rates of complications. The ideal timing of cranioplasty should minimize the risk of complications, but research investigating cranioplasty timing and risk of complications has generated diverse findings. Previous studies have included mixed populations of patients undergoing cranioplasty following decompression for traumatic, vascular, and other cerebral insults, making results challenging to interpret. The objective of the current study was to examine rates of complications associated with cranioplasty, specifically for patients with traumatic brain injury (TBI) receiving this procedure at the authors' high-volume level 1 trauma center over a 25-year time period. METHODS: A single-institution retrospective review was conducted of patients undergoing cranioplasty after decompression for trauma. Patients were identified and clinical and demographic variables obtained from 2 neurotrauma databases. Patients were categorized into 3 groups based on timing of cranioplasty: early (≤ 90 days after craniectomy), intermediate (91-180 days after craniectomy), and late (> 180 days after craniectomy). In addition, a subgroup analysis of complications in patients with TBI associated with ultra-early cranioplasty (< 42 days, or 6 weeks, after craniectomy) was performed. RESULTS: Of 435 patients identified, 141 patients underwent early cranioplasty, 187 patients received intermediate cranioplasty, and 107 patients underwent late cranioplasty. A total of 54 patients underwent ultra-early cranioplasty. Among the total cohort, the mean rate of postoperative hydrocephalus was 2.8%, the rate of seizure was 4.6%, the rate of postoperative hematoma was 3.4%, and the rate of infection was 6.0%. The total complication rate for the entire population was 16.8%. There was no significant difference in complications between any of the 3 groups. No significant differences in postoperative complications were found comparing the ultra-early cranioplasty group with all other patients combined. CONCLUSIONS: In this cohort of patients with TBI, early cranioplasty, including ultra-early procedures, was not associated with higher rates of complications. Early cranioplasty may confer benefits such as shorter or fewer hospitalizations, decreased financial burden, and overall improved recovery, and should be considered based on patient-specific factors.