Meckel's Cave Research Articles

Single Fraction Radiosurgical Tolerance of Brainstem, Trigeminal Nerve, and Meckel's Cave for Facial Numbness

IntroductionThe purpose of this article is to review toxicity outcomes for a series of patients treated with stereotactic radiosurgery (SRS) for trigeminal neuralgia, focusing on dose to the brainstem, trigeminal nerve, and Meckel's cave as possible explanatory variables for the development of the most common post-treatment neuropathy, facial numbness. MaterialsA retrospective review of 136 cases treated with Cyberknife radiosurgery for trigeminal neuralgia was performed. Dose was initially (cohort 1) prescribed to 57 to 64 Gy covering a 6mm cylindrical shaped target volume at least 2mm from the dorsal root entry zone (DREZ). Subsequently a deliberate change to isocentric treatment planning occurred, resulting in delivery of 85 Gy to a spherical target (cohort 2). Brainstem, trigeminal nerve, and Meckel's cave were contoured and a variety of dosimetric and clinical factors were analyzed for association with development of treatment related facial numbness. ResultsTreatment-related numbness occurred in 59/136 (43%) patients and did not differ between the treatment cohorts. Fifty-two patients experienced BNI grade II toxicity, and 7 patients experienced BNI grade III toxicity. Time to numbness was 16.0 months for cohort 1 and 10.4 months for cohort 2 (p=0.184). The median brainstem maximum dose was 26.1 Gy, ranging from 4.2 Gy to 57.3 Gy. Maximum dose to the trigeminal nerve was 85 Gy. Mean trigeminal nerve dose was 47.3 Gy. The median Meckel's cave maximum and mean doses were 26.0 Gy and 6.8 Gy, respectively. No definitive upper limit dose threshold was detected for the structures analyzed, but trends were noted for maximum trigeminal nerve dose of 85 Gy (p=0.083) and for prescription dose (p=0.057) and trigeminal nerve V40 (p=0.077) in the Type I subset. ConclusionsBrainstem, trigeminal nerve, and Meckel's cave tolerated doses within the range delivered. Discussion of the literature is provided to guide treatment planning and management.

A narrative review of magnetic resonance imaging findings in pediatric idiopathic intracranial hypertension.

Idiopathic intracranial hypertension (IIH) is a rare neurological disorder in the pediatric population which is defined as an increase in intracranial pressure (ICP) without the presence of brain parenchymal lesions, hydrocephalus, or central nervous system infection. In this study, we have determined the magnetic resonance imaging (MRI) findings in IIH patients. A comprehensive literature search was conducted using the electronic databases including Web of Sciences, Scopus, and Pubmed to identify suitable and relevant articles using keyword search methods. The search included keywords such as "idiopathic intracranial hypertension," "pseudotumor cerebri," "MRI," and "pediatrics." The search was limited to the available publications up to January 2024. MRI plays a crucial role in diagnosing IIH by excluding secondary causes and revealing neuroimaging findings associated with elevated ICP. Despite fewer studies in children compared to adults, MRI serves as a cornerstone in identifying traditional neuroradiological markers such as empty sella turcica, posterior globe flattening, optic nerve tortuosity, optic nerve sheath distension, and transverse venous sinus stenosis. Additional subtle markers include increased Meckel's cave length, cerebellar tonsillar herniation, and slit-like ventricles, although these are less reliable. Diffusion-weighted imaging does not typically show cerebral ADC value changes indicative of cerebral edema in pediatric IIH. MRI findings provide valuable non-invasive diagnostic indicators that facilitate early detection, clinical management, and potential surgical intervention in pediatric IIH. The reliability of these MRI markers underscores their importance in clinical practice.

Neurosarcoidosis of the trigeminal nerve: clinical accompaniments, radiographic findings, and association with neuralgia.

Cranial neuropathy is a principal disease manifestation of neurosarcoidosis, but many forms remain poorly described, including trigeminal nerve disease despite its frequency in reported cohorts (5-12%). Herein, we characterize the clinical course of patients with neurosarcoidosis involving the trigeminal nerve. A single-center retrospective cohort analysis of patients with biopsy-proven sarcoidosis involving the trigeminal nerve was conducted between 1/1/2000-3/7/2023. The trigeminal nerve was affected in 14/245 (5.7%) patients, being clinically symptomatic in 5/245 (2.0%) and asymptomatic with radiographic involvement in 9/245 (3.7%). 14/14 (100.0%) patients had systemic sarcoidosis. In the symptomatic group, trigeminal neuropathy was an inaugural feature in 4/5 (80.0%), unilateral in 5/5 (100.0%) with the V1 subdivision most affected (4/5, 80.0%), and associated with neuralgia in 2/5 (40.0%). On MRI, the cisternal nerve roots (9/14, 64.3%), Meckel's cave (7/14, 50.0%), and cavernous sinus (5/14, 35.7%) were most commonly affected, and 14/14 (100.0%) patients had extra-trigeminal neuroinflammation on cranial MRI. CSF was abnormal in at least one dimension in 11/12 (91.7%) tested. All three treated patients with symptomatic trigeminal neuropathy responded to immunomodulatory treatment, and symptomatic treatments for trigeminal neuralgia were helpful in two patients. After a median follow-up period of 63 months, the median modified Rankin scale score was 1 for both subgroups. Neurosarcoidosis may involve any portion of the trigeminal apparatus, and when affected, it frequently demonstrates a mismatch in radiographic involvement from its clinical manifestations of facial numbness and pain, and typically occurs in association with other clinical or radiographic manifestations of neurosarcoidosis.

Is It Time for a Paradigm Shift in the Surgical Management of Trigeminal Schwannomas? Evaluating the Role of the Transorbital Approach: An Anatomo-Clinical Study and Systematic Literature Review

BackgroundEndoscopic transorbital approach emerged in recent years as an effective, minimally invasive route to access Meckel’s cave area. Several case series proved its effectiveness in the surgical treatment of trigeminal schwannomas. Nonetheless, this route provides the advantages of a minimally invasive approach associated with low morbidity rates. In this anatomo-clinical study we illustrate the usefulness of the superior eyelid transorbital approach for the surgical treatment of trigeminal schwannoma guiding the clinical applicability of the anatomical findings into the real surgical practice. MethodsSuperior eyelid transorbital endoscopic approach was performed on eight cadaveric specimens, and the surgical results were confirmed in a retrospective review of all the surgical cases of transorbital surgery performed by the senior authors providing an illustrative case. Finally, we performed a literature review of all the case series of trigeminal schwannomas operated through an endoscopic transorbital approach. ResultsStepwise dissection was divided in 3 phases: skin, endo-orbital and endocranial. The illustrative case provided demonstrate gross total resection of a cavernous sinus type trigeminal schwannomas treated through this route. Literature review revealed 68 cases of trigeminal schwannomas that were successfully treated using the transorbital approach. ConclusionsThe endoscopic transorbital approach may offer a valuable alternative for the surgical treatment of trigeminal schwannomas. This technique provides a minimally invasive, direct and natural “interdural” route to the lateral wall of the cavernous sinus and Meckel's cave.

Role of neuroimaging markers on predicting of idiopathic intracranial hypertension.

The goals of neuroimaging in idiopathic intracranial hypertension (IIH) are the exclusion of mimickers and effective management of disease. In recent studies, several imaging markers have been identified as potential predictors of IIH. To investigate the predictive roles of novel radiological markers as the Meckel's cave area, alongside classical radiologic markers in identifying IIH such as the empty sella. The patients were classified according to cerebrospinal fluid (CSF) opening pressure as the IIH group and control group. The observational, case-control study included 22 patients with IIH and 22 controls. Groups were compared for presence of empty sella, Meckel's cave area, fat area of posterior neck, fat thickness of scalp, presence of transverse sinus stenosis, and ophthalmic markers, such as increase of optic nerve (ON) sheath diameter. In the IHH group, higher occurrences of increased ON sheath diameter, ON tortuosity, flattening of the scleral surface, and transverse sinus stenosis were observed (P < 0.001, P < 0.001, P = 0.046, and P = 0.021, respectively). Meckel's cave area and fat area of posterior neck were similar in both groups (P = 0.444 and P = 0.794). Ophthalmic markers and transverse sinus stenosis could be utilized as radiologic features supporting early and precise diagnosis of IIH. However, enlargement of Meckel's cave area and measurements of fatty area of posterior neck are not helpful for diagnosis of IIH.

Anatomical Features and Morphometric Characteristics of the Sphenoidal Sinus in MRI Studies.

Differential access to pathological sellar processes and adjacent regions is determined by the anatomic structures identified through diagnostic imaging. Both direct endonasal access (microscopic or endoscopic) and sublabial access utilize the sphenoid sinus (SS) as the primary surgical pathway. Critical factors include the pneumatization of the sinus, its intermediate septa, and the presence of a double wall, consisting of a connective tissue membrane along the dorsal wall of the SS. The present study aims to demonstrate the significance of the size and type of the SS based on MRI measurements. The type of SS, its pneumatization, and the proximity of adjacent brain structures are crucial for different surgical approaches to the SS and pituitary fossa. In neurosurgical practice, six main types of sinuses are recognized: sphenoid body type, lateral type, clival type, lesser wing type, anterior type, and combined type. Failure to consider these variations can lead to damage to the cavernous sinus, Meckel's cave, nerve structures in the middle cranial fossa, planum sphenoidale, suprasellar region, and vital brainstem structures located on the clivus. Randomly included MRI measurements were conducted on 112 patients from Pulmed University Hospital, Plovdiv, Bulgaria, categorized into two cohorts based on gender, with mean ages of 51 years for men and 47.8 years for women. The measurements, recorded in centimeters, were obtained using two imaging software programs, RadiAnt DICOM Viewer (Medixant, Poznan, Poland) and Weasis DICOM Viewer (Nicolas Roduit, https://github.com/nroduit/Weasis). No statistically significant differences were observed between the measurements produced by the two programs. Measurements of the SS were taken in two equal groups, using three different projections: axial, sagittal, and coronal. The results for height, width, and depth showed average sizes of 2.73-3.04 cm in axial projections, 1.70-2.64 cm in sagittal projections, and 2.86-3.03 cm in coronal projections. The minor differences between axial and coronal measurements of the same parameters (height and width) are statistically acceptable and attributed to the varying angles of the MRI scans. These measurements are crucial for planning surgical access to the sellar and parasellar regions, determining the necessary bony resection of the posterior wall of the SS, and preventing complications from excessive bony trepanation.

Biportal Endoscopic TransOrbital and transMaxillary Approach to the Cranio-Orbital Region and Middle Cranial Fossa: A Preliminary Analysis of Maneuverability.

Traditional and well-established transcranial approaches to the spheno-orbital region and middle cranial fossa guarantee optimal intracranial exposure, and additional orbital and zygomatic osteotomies provide further control over extracranial components to be resected; however, these techniques come at the cost of additional morbidity. The introduction of minimally invasive endoscopic approaches and the conceptualization of the so-called "multiportal" paradigm might provide an alternative route. This preliminary study investigates the feasibility of the combined Biportal Endoscopic TransOrbital and transMaxillary Approach (bETOMA) approach to the spheno-orbital and middle cranial fossa regions. Using 4 silicon-injected adult cadaver heads (8 sides; 16 approaches), we systematically dissected through superior eyelid ETOA and endoscopic TMA approaches. The analysis focused on pterygopalatine, infratemporal, anterior and middle cranial fossae, Meckel cave, and cavernous sinus access. We evaluated the feasibility of bETOMA using linear distances, angles of attack, and exposure areas. We also introduced volume of operative maneuverability, its standardized derivative (sVOM), target distance, visuo-operative angle, and working zone volume as novel metrics. The analysis revealed comparable angles of attack between approaches. ETOA and TMA exposure areas were 918.38 ± 223.93 mm2 and 257.07 ± 86.07 mm2, respectively. TMA showed a larger VOM in the greater sphenoid wing, but ETOA offered superior distal maneuverability (sVOM: 5.39 ± 1.94 vs 2.54 ± 0.79 cm3) and closer intracranial space access (27.45 vs 50.83 mm). The combined approaches yielded a mean working zone volume of 13.75 ± 3.73 cm3 in the spheno-orbital interface. The bETOMA approach provides adequate neurovascular exposure and maneuverability to the spheno-orbital region, infratemporal, and anterior and middle cranial fossae, addressing significant limitations of previously investigated monoportal techniques (ie, optic nerve decompression, hyperostotic bone resection, and infratemporal exposure). This combined minimally invasive approach might help manage lesions harbored within the cranio-orbital interface region invading the extracranial space.

Comparative Analysis of Patients Undergoing Microvascular Decompression for Trigeminal Neuralgia Caused by Solely Arterial or Solely Venous Compression

Trigeminal neuralgia (TN) due to venous compression is far less common than that due to arterial compression, and its pathogenesis is less clear. We investigated the clinical and imaging features of TN caused by solely venous compression by measuring the morphologies of the posterior cranial fossa (PCF) and the trigeminal nerve. We retrospectively reviewed records of TN patients who underwent microvascular decompression at our institution and extracted cases with solely arterial or solely venous compression. Preoperative magnetic resonance imaging was used to find the length (Y), width (X), height (Z), and volume (V) of the PCF, the angle between the trigeminal nerve and pons, and the distance between Meckel's cave and the root entry zone of the trigeminal nerve. Of 152 patients, 24 had TN caused solely by venous compression. The value of Y was significantly smaller in the venous group than the arterial group (P < 0.01). The trigeminal nerve and pons was significantly smaller in the venous group (P < 0.01). We hypothesized that TN patients with solely venous compression had a characteristic PCF morphology with a short anteroposterior diameter (Y), such that age-related changes in brain morphology could alter the course of the trigeminal nerve and cause compression by a vein. The morphological features of the PCF differed between patients with TN of venous and those with TN of arterial etiology. Age-related changes in brain morphology and changes of course of the trigeminal nerve may also add to the possibility of developing TN, especially of venous etiology.

Clinical and Radiological Findings in Children with Anomalous Pontine Cranial Nerves.

We retrospectively reviewed the clinical and radiologic findings in 17 children with an aberrant cisternal CN7 and found that these patients had additional anomalies involving other pontine cranial nerves. The hallmark imaging feature identified in all patients was aberrant cisternal segment of an enlarged appearing CN7. The abnormal nerve coursed anteriorly towards the Gasserian ganglion where it fanned out towards the internal auditory canal, Meckel's cave or both. This finding was accompanied by a small cisternal CN5 which often had a lateral bowed appearance. CN5 and CN7 were abnormally close to each other. Meckel's cave appeared widened posteriorly and often was close to or merged with the internal auditory canal. Other abnormalities in the pontine cranial nerves included CN8 deficiency in the majority of children and variable CN6 deficiency. This constellation of findings was most often discovered in children having MR evaluation for sensorineural hearing loss and the majority of patients had preserved facial nerve function. In patients with available genetic testing, no pathogenic variants were observed. Interestingly, in 13 children with available birth history, 9 were notable for maternal or gestational diabetes (69%), suggesting a possible early intrauterine insult to the developing nerves.ABBREVIATIONS: CN= cranial nerve; OAVS= Oculo-Auriculo-Vertebral Spectrum; IAC= Internal Auditory Canal; PTCD= Pontine Tegmental Cap Dysplasia; EMR= Electronic Medical Record; SNHL= sensorineural hearing loss.

Trigeminal Microvascular Decompression and Meckel's Cave Tumor Resection via Retrosigmoid Approach With Suprameatal Extension: 2-Dimensional Operative Video.

The leading cause of trigeminal neuralgia (TGN) relies on the microvascular conflict between the superior cerebellar artery (SCA) loop and the dorsal root entry zone of the trigeminal nerve (TN). However, lesions along the TN have been described as a possible cause of TGN for direct mass effect or indirect vascular transposition. Thus, the surgical approach to TGN in patients harboring cerebellopontine angle or Meckel's cave tumor should be methodically chosen. The retrosigmoid (RS) approach with suprameatal extension offers direct access to the TN in both its cisternal and Meckel's cave segment, allowing optimal TN decompression from vascular and tumoral components. Although the RS approach with suprameatal extension has been described in numerous studies,1-4 videos detailing its key steps in addressing a multicomponent TGN are lacking. In this video, we highlight the case of a 46 year-old woman with 6 months of medically refractory typical TGN with a right en plaque meningioma involving the petrous bone, petroclival junction, Meckel's cave, and tentorium. In addition, magnetic resonance imaging was suspicious for a compressive SCA loop over the dorsal root entry zone. The patient underwent a RS approach with suprameatal extension for subtotal resection of the tumor and microvascular decompression of the TGN. The patient recovered with no complications and TGN resolved.

Multi-metric predictors of radiofrequency-treated trigeminal neuralgias.

Evaluation of neurovascular compression-related trigeminal neuralgia (NVC-TN) and its resolution through microvascular decompression are demonstrable by MRI and intraoperatively [Leal et al. (Atrophic changes in the trigeminal nerves of patients with trigeminal neuralgia due to neurovascular compression and their association with the severity of compression and clinical outcomes: Clinical article. J Neurosurg. 2014;120(6):1484-1495)]. Non-NVC-TNs treated by radiofrequency (RF) lack such detectable features. Multimodal integration of pre-surgical diffusion tensor imaging (DTI) and volumetry (VOL) with intraoperative neurophysiology (ION) could improve understanding and performance of RF among non-NVC-TN. We hypothesized that DTI disturbances' localization (central relay versus peripherally) rather than their values bares the most significant predictive value upon outcome and that ION could quantitatively both localize and assist RF of affected branches. The first pre-surgical step evaluated the differences between affected and non-affected sides (by DTI and VOL). Four TN's segments were studied, from peripheral to central relay: Meckel's cave-trigeminal ganglion (MC-TGN), cisternal portion, root entry zone (REZ) and spinal tract [Lin et al. (Flatness of the Meckel cave may cause primary trigeminal neuralgia: A radiomics-based study. J Headache Pain. 2021;22(1):104)]. In the second intraoperative step, we used both ION and patient's testimonies to confirm the localization of the affected branch, evolving hypoesthesia, pain reduction and monitoring of adverse effects [Sindou (Neurophysiological navigation in the trigeminal nerve: Use of masticatory responses and facial motor responses evoked by electrical stimulation of the trigeminal rootlets for RF-thermorhizotomy guidance. Stereotact Funct Neurosurg. 1999;73(1-4):117-121); Sindou and Tatli (Traitement de la névralgie trigéminale par thermorhizotomie. Neurochirurgie. 2009;55(2):203-210)]. Last and postoperatively, each data set's features and correlation with short-term (3 months) and long-term outcomes (23.5 ± 6.7 months) were independently analysed and blind to each other. Finally, we designed a multimodal predictive model. Sixteen non-NVC-TN patients (mean 53.6 ± SD years old) with mean duration of 6.56 ± 4.1 years (75% right TN; 43.8% V3) were included. After 23.5 ± 6.7 months, 14/16 were good responders. Age, gender, TN duration and side/branch did not correlate with outcomes. Affected sides showed significant DTI disturbances in both peripheral (MC-TGNs) and central-relay (REZ) segments. However, worse outcome correlated only with REZ-located DTI disturbances (P = 0.04; r = 0.53). Concerning volumetry, affected MC-TGNs were abnormally flatter: lower volumes and surface area correlated with worse outcomes (both P = 0.033; r = 0.55 and 0.77, respectively). Intraoperatively, ION could not differ the affected from non-affected branch. However, the magnitude of ION's amplitude reduction (ION-Δ-Amplitude) had the most significant correlation with outcomes (r = 0.86; P < 0.00006). It was higher among responders [68.4% (50-82%)], and a <40% reduction characterized non-responders [36.7% (0-40%)]. Multiple regression showed that ION-Δ-Amplitude, centrally located only REZ DTI integrity and MC-TGN flatness explain 82.2% of the variance of post-RF visual analogue score. Integration of pre-surgical DTI-VOL with ION-Δ-Amplitude suggests a multi-metric predictive model of post-RF outcome in non-NVC-TN. In multiple regression, central-relay REZ DTI disturbances and insufficiently reduced excitability (<40%) predicted worse outcome. Quantitative fine-tuned ION tools should be sought for peri-operative evaluation of the affected branches.

Combined Petrosal Intertentorial Approach: A Cadaveric Study of Comparison With the Standard Combined Petrosectomy.

The combined petrosal intertentorial approach (CPIA) has been proposed as an alternative to standard combined petrosal approach (SCPA). CPIA has been designed to maintain integrity of the temporal dura with a view to reduce temporal lobe morbidity and venous complications. This study has been designed to perform a quantitative comparison between these approaches. Five human specimens were used for this study. CPIA was performed on one side and SCPA on the opposite side. The area of exposure (petroclival and brainstem), surgical freedom, and angles of attack to a predefined target were measured and compared. SCPA provided a significantly larger petroclival area of exposure (6.81 ± 0.60 cm2) over the CPIA (5.59 ± 0.59 cm2), P = .012. The area of brainstem exposed with SCPA was greater than with CPIA (7.17 ± 0.84 vs 5.63 ± 0.72, P = .014). The area of surgical freedom was greater in SCPA rather than in CPIA (8.59 ± 0.55 and 7.13 ± 0.96 cm2, respectively, P = .019). There was no significative difference between CPIA and SCPA in the vertical angles of attack for the Meckel cave, Dorello canal, and root entry zone of cranial nerve VII. Conversely, the horizontal angles of attack permitted by the CPIA were significantly smaller for the Meckel cave (52.36° ± 5.01° vs 64.4° ± 5.3°, P = .006) and root entry zone of cranial nerve VII (30.7° ± 4.4° vs 40.1° ± 6.2°, P = .025). CPIA is associated with a reduction in terms of the area of surgical freedom (22%), skull base (18%), brainstem exposure (17%), and horizontal angles of attack (18%-23%) when compared with SCPA. This loss in terms of exposure is counterbalanced by the advantage of keeping the temporal lobe covered by an extra layer of meningeal tissue, thus possibly reducing the risk of temporal lobe injury and venous infarction. These results need to be validated with adequate clinical experience.

Endoscopic Transpterygoid Approach to Meckel’s Cave: Technical Considerations and Retrospective Analysis of a Clinical Series

ObjectiveTumors located within the Meckel's cave (MC) pose a significant surgical challenge. Although several corridors to access this complex region have been described, the endoscopic transpterygoid approach (ETPA) and the endoscopic transorbital superior eyelid approach (ETOA) have emerged in recent years, as viable alternatives to traditional microsurgical transcranial approaches (MTA). To date, there is a limited literature on surgical series considering endoscopic-assisted approaches to the MC. MethodsWe conducted a retrospective analysis of patients with primary MC tumors treated at our Institution between 2015 and 2022, specifically those managed via the ETPA assisted by intraoperative Endoscopic Diving Technique (EDT). Lesion resection extent was evaluated using pre- and post-intervention radiological images and surgical videos. Moreover, a literature review on ETPA was performed. ResultsThis series comprises 7 patients affected by 4 trigeminal schwannomas, 1 benign notochordal cell tumor, 1 dermoid cyst and 1 mesenchymal tumor. In 71 % of cases, trigeminal neuralgia was the presenting symptom. Post-operative clinical improvement was observed in all but one case. Notably, 85.7 % of patients achieved total or near-total resection (NTR), with the remaining case undergoing subtotal resection (STR). No significant intraoperative complications occurred, and no recurrences were observed during the mean follow-up period of 41 months. ConclusionsIn selected cases, the ETPA offers a direct and safe path to lesions located into the MC. This approach circumvents complications and constraints associated with ETOA or MTA. Moreover, the use of the EDT reduces manipulation of critical neurovascular structures, enhancing the efficacy of the ETPA.

Interdural extra-arachnoidal resection of fifth nerve schwannomas with tailored petrous drilling: Eliminating the blind spot

Background and objectives Around 20-40% of trigeminal schwannomas (TS) are dumbbell shaped, spanning the middle and posterior cranial fossa The petrous apex is often truncated in these patients, aiding surgical resection of both compartments through the middle fossa approach. However, a less eroded petrous creates a blind spot, making total resection difficult. This study describes the feasibility of an approach combining expanded Meckel cave access with tailored petrous bone drilling to optimize tumor visualization and resection. Methods Eleven patients with dumbbell TS and minimal petrous apex erosion underwent the described surgery. Surgical steps included temporo-orbito-zygomatic craniotomy, middle fossa floor drilling, navigation aided (tailored) extradural petrous bone drilling and extra-arachnoidal tumor excision. Extent of resection and postoperative outcomes were recorded. Results Patients presented with trigeminal nerve dysfunction (n = 9; sensory −9 and motor − 5), headache(8/11), ataxia (7/11) and pseudobulbar palsy (3/11). Complete tumor resection was achieved in all patients. Postoperatively, 8 out of 9 patients had transient increase in facial hypoesthesia with conjunctival injection in 3. It improved within 3-6 months, except in four cases wherein mild hypoesthesia persisted. Motor symptoms improved in 2 of 5 patients. Two developed transient 6th nerve paresis, that resolved in 2 months. Cerebellar and brainstem pressure symptoms resolved in all. No patients developed new onset permanent neurological deficit. Two patients reported mild post-craniotomy masticatory difficulty. Conclusions The additional tailored petrous bony drilling enhances the surgeon’s view, allowing a higher chance of total resection with no major operative morbidity.

Efficacy and safety of Dyna CT-assisted percutaneous balloon compression in the treatment of tumor-related trigeminal neuralgia: A single-center retrospective analysis

BackgroundPercutaneous balloon compression (PBC) has been widely used in the treatment of trigeminal neuralgia (TN). Patients with tumor-related TN are typically treated by tumor resection. However, when craniotomy is not feasible, PBC may serve as a simple and effective method for pain relief. Currently, there is limited literature on the use of this technique in treating patients with tumor-related TN. In this study, we aim to evaluate the efficacy and safety of Dyna CT-assisted PBC in the treatment of tumor-related TN. MethodsFrom January 2018 to December 2023, a total of 19 patients with tumor-related TN underwent Dyna CT-assisted PBC at our institution. The modified Barrow Neurological Institute Pain Intensity Grading Scale and sensory reduction scores were employed to assess treatment outcomes. A retrospective analysis was conducted on the clinical characteristics, surgical efficacy, postoperative complications, and follow-up results of all patients. ResultsImmediate and complete pain relief was observed in 18 patients following PBC, with one patient experiencing delayed recovery. Follow-up periods ranged from 4 to 62 months, revealing only 4 patients with pain recurrence at the last follow-up, and tumor-related TN patients with involvement of Meckel's cave were more prone to recurrence. No severe complications occurred throughout the follow-up period. Although facial numbness was reported in all 15 patients, jaw weakness in 8 patients, and postoperative headache in 7 patients, these symptoms resolved within a short period. There were no statistically significant differences in postoperative facial numbness and jaw weakness between tumor-related TN patients with or without Meckel's cave involvement. However, patients with Meckel's cave involvement were more likely to experience postoperative headaches. Patient satisfaction scores indicated a significant improvement in postoperative quality of life. ConclusionFor patients with tumor-related TN, when craniotomy is not feasible, Dyna CT-assisted PBC proves to be a safe and effective alternative treatment. Additionally, we observed varying postoperative clinical outcomes based on the different sites of tumor compression on the trigeminal nerve. Patients with tumor-related TN not involving Meckel's cave exhibited more enduring clinical efficacy compared to those with Meckel's cave involvement.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Translabyrinthine and Transcochlear Approaches

Abstract Introduction Skull base neuroanatomy is traditionally learned through two-dimensional anatomical atlases, which while are of unquestionable value, lack the nuanced association of three-dimensional relationships between fundamental anatomical structures relevant to surgical approaches. Surgically focused step-by-step anatomical dissections can augment trainee learning of complex skull base techniques, particularly multistep and nuanced techniques such as translabyrinthine and transcochlear approaches. Methods Translabyrinthine and transcochlear approaches were performed on six sides of three formalin-fixed latex-injected specimens. The study objective was the completion and photo documentation of the steps involved in the approach in order to provide a comprehensive, intelligible, and anatomically oriented resource for multilevel trainees. Illustrative case examples were prepared to supplement approach dissections. Results The translabyrinthine and transcochlear approaches offer unique lateral windows through the temporal bone into the posterior fossa, providing excellent access to pathology at the petrous apex, internal auditory canal, Meckel's cave, and anterolateral brainstem. The transcochlear approach, which is an anterior extension of the translabyrinthine, particularly provides excellent exposure of the prepontine region and clivus. Important surgical considerations include patient position, temporal bone drilling and identification of critical landmarks, dural opening and identification of neurovascular structures, and reconstruction/closure techniques. Conclusion The translabyrinthine and transcochlear approaches are fundamental techniques for lateral skull base and posterior fossa pathologies. Both approaches are hearing-sacrificing but often require minimal to no cerebellar retraction and deliver unique visualization of prepontine neurovascular structures. This step-by-step approach guide provides a unique practical and high-yield surgically oriented learning resource for neurosurgery and otolaryngology trainees.

Lateral Transorbital Endoscope-Assisted Resection of Anterior Temporal Lobe Neoplasm: 2-Dimensional Operative Video.

Transorbital neuroendoscopic surgery (TONES) is a minimally invasive approach, providing excellent access to extradural pathology of the sphenoid wing, orbital apex, Meckel's cave, and lateral cavernous sinus.1-10 Few cases of intradural pathology, such as gliomas or epileptic foci of the temporal lobe, have been described, apart from cadaveric anatomic studies.11-13 In this video, we present the case of a 63-year-old man with first time seizure. MRI demonstrated a fluid-attenuated inversion recovery hyperintense, noncontrast enhancing medial temporal lobe lesion consistent with low grade glioma. While frontotemporal craniotomy is the standard approach for this lesion, the TONES approach detailed in the video (the patient consented to the procedure and to the publication of his image) provided excellent access to the lesion, which minimized unnecessary trauma or removal of the lateral temporal lobe during the approach.4,14,15 The dura was closed primarily, overlayed with abdominal fat and fibrin glue, and a lumbar drain was left in place for 24 hours. The TONES approach avoided not only temporal lobe violation but also temporalis muscle disruption and any sort of external bone manipulation, which expedited the patient's recovery.16 The patient's eyelid incision was barely visible as early as postoperative day 7 with minimal ecchymosis. Postoperative MRI demonstrated a gross total resection. Pathology was consistent with a central nervous system World Health Organization grade 1 dysembryoplastic neuroepithelial tumor, a low-grade lesion with low risk of recurrence.17,18.

Purely endoscopic subtemporal keyhole anterior transpetrosal approach to access the petrous apex region: surgical techniques and early results.

The anterior transpetrosal approach using a microscope to provide wider access to the petrous apex region has been described for radical resection of lesions of the middle and posterior skull base. The microscopic anterior transpetrosal approach (mATPA) requires a wide craniotomy and meticulous epidural procedures to minimize temporal lobe retraction. Recently, the clinical application of transcranial endoscopic keyhole approaches for minimally invasive surgery has been steadily expanding. In this study, the details of the purely endoscopic subtemporal keyhole ATPA (eATPA) for petrous apex lesions are described and its initial results are reported. Between May 2022 and May 2023, the authors performed eATPA in 10 patients with petrous apex lesions, of which 6 were meningiomas, 3 were trigeminal schwannomas, and 1 was epidermoid cyst. The surgical procedure of the purely eATPA is as follows. After a small temporal craniotomy, the endoscopic procedure is started. The anterior rim of the petrous bone and Meckel's cave are exposed via an intradural subtemporal approach. The lesion is removed with additional drilling of Kawase's triangle, cutting the superior petrosal sinus, opening Meckel's cave, and cutting the tentorium. The authors also compared the outcomes of mATPA versus eATPA for consecutive cases of petrous apex lesions. Gross-total resection was achieved in 8 of the 10 patients. The average operative time was 4 hours 13 minutes. There were 3 cases of transient abducens nerve palsy and 1 case of trochlear nerve palsy in the postoperative period. No new-onset motor deficits or CSF leakage was noted in any of these patients. Only 1 patient exhibited postoperative asymptomatic temporal lobe edema. The Karnofsky Performance Scale (KPS) scores remained unchanged or improved for all patients postoperatively. Compared with mATPA, eATPA achieved a similar extent of resection and comparable postoperative KPS scores with a significantly shorter mean operative time, much smaller temporal craniotomy, and thus less mean blood loss during surgery with lower rates of new-onset temporal lobe edema in the postoperative period. An eATPA allows a direct route to access Meckel's cave and posterior cranial fossa lesions similar to conventional mATPA, with shortening the operative time and reducing the risk of postoperative temporal lobe edema. This eATPA is considered one of the new surgical techniques that can be expected to develop in the future.

The lateral retrocanthal transorbital endoscopic approach to the middle fossa: cadaveric stepwise approach and review of quantitative cadaveric data.

The lateral retrocanthal transorbital endoscopic approach (LRCTEA) facilitates trajectory to the middle fossa, preserving the lateral canthal tendon and thus avoiding postoperative complications such as eyelid malposition. Here, the authors sought to define the surgical anatomy and technique of LRCTEA using a stepwise approach in cadaveric heads and offer an in-depth examination of existing quantitative data from cadaveric studies. The authors performed LRCTEA to the middle cranial fossa under neuronavigation in 7 cadaveric head specimens that underwent high-resolution (1-mm) CT scans preceding the dissections. The LRCTEA provided access to middle fossa regions including the cavernous sinus, Meckel's cave, and medial temporal lobe. The trajectories and endpoints of the approach were confirmed using electromagnetic neuronavigation. A stepwise approach was delineated and recorded. The authors' cadaveric study delineates the surgical anatomy and technique of the LRCTEA, providing a stepwise approach for its implementation. As these approaches continue to evolve, their development and refinement will play an important role in expanding the surgical options available to neurosurgeons, ultimately improving outcomes for patients with complex skull base pathologies. The LRCTEA presents a promising advancement in skull base surgery, particularly for accessing challenging middle fossa regions. However, surgeons must remain vigilant to potential complications, including transient diplopia, orbital hematoma, or damage to the optic apparatus.

Giant Meningiomas Invading the Cavernous Sinus: The “Inevitable Ones”

Abstract Introduction Giant meningiomas invading the cavernous sinus (GMICSs) are a subgroup of challenging tumors due to their volume and the extent of neurological impairment. Preserving quality of life is one of the most relevant aspects of treating patients with GMICS. Methods A retrospective study was conducted for surgeries performed between 2012 and 2022, including 33 patients presenting meningiomas with the largest diameter of at least 5 cm invading the cavernous sinus. The data from surgical intervention, Simpson grade of resection, tumor location, and morbimortality related to the surgeries were reviewed. Results The group comprised 25 women and 8 men with a median age of 56 years. The mean follow-up period was 52 months. The tumors were in the sphenoid wing, anterior clinoid, spheno-orbital, spheno-petroclival, petroclival, and Meckel's cave. Simpson grade I, II, and III were obtained in 70% of cases. The meningiomas were classified as WHO grade 1 in 94%, grade 2 in 3%, and grade 3 in 3%. The overall mortality was 3%. Permanent cranial nerve deficits occurred in 21%, transient cranial nerve deficits in 42%, cerebrospinal fistula in 15%, and hemiparesis in 18%. The recurrence/regrowth rate was 6%. The Karnofsky Performance Status score of 100 and 90 was 82%. Conclusions The surgical treatment of GMICS is an effective treatment modality with acceptable morbimortality and good long-term control. Involvement of the internal carotid artery is essential to determine the extent of resection inside the cavernous sinus, and training in the microsurgical laboratory is mandatory for safe surgical treatment.