Suboccipital Retrosigmoid Approach Research Articles

Microvascular decompression for intermediate nerve neuralgia: a case report and literature review

Intermediate nerve neuralgia (INN) is a rare craniofacial pain syndrome. The diagnosis of INN is challenging because of the complex ear sensory innervation that results in a clinical overlap with both trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GPN). A 76-year-old woman with a remarkable medical history presented with right otalgia and mandibular pain for 7 years. Neurological examination revealed a diminished sensation in the distribution of the intermediate nerve (IN). Magnetic resonance imaging demonstrated an impression of the anterior inferior cerebellar artery (AICA) on the facial–vestibulocochlear nerve complex (VII/VIII complex). The patient underwent microvascular decompression (MVD) after long-term oral medication. We confirmed that the responsible vessel was close to the VII/VIII complex and isolated the vessel under the microscope via a right-sided suboccipital retrosigmoid approach. The patient's otalgia and mandibular pain disappeared after the operation. There were no additional neurological deficits. In conclusion, MVD is a safe and feasible option for patients with INN who fail to respond to adequate pharmacotherapy.

Surgical Outcome of Vestibular Schwannoma in a Tertiary Care Hospital, Dhaka

Background: Presenting symptoms, treatment considerations, and outcome are strongly related to the extension of vestibular schwannomas (VS). The aim of the current retrospective study was to analyze the clinical features, microsurgical treatment, and outcome of VS with brainstem compression. Methods: 130 patients presented with VS who had undergone operative procedures performed in our unit from Jan, 2017 to may, 2022. The facial nerve function and hearing assessment was done according to House-Brackmann [HB] grading and pure tone audiometry (PTA) respectively. All patients were operated by retro-sigmoid retromastoid sub-occipital approach. Results: Most patients had large tumors and had no useful hearing (75.38%), had disabling cerebellar ataxia (84.61%) and presented with features of raised intracranial pressure (46.15%). Complete tumor excision was carried out 92.30% and anatomical preservation of facial nerve was achieved in 87.50% cases. Hearing preservation was achieved in eight patients. Cerebrospinal fluid leak with or without meningitis and transient lower cranial nerve paresis were common complications. The mortality rate was 7.69% Conclusions: Complete tumor excision with good facial nerve preservation can be achieved in large vestibular schwannomas. Hearing preservation is difficult in larger tumors. Primary microsurgical resection is an appropriate management option for large VS. In our experience, this goal can be achieved safely and successfully by using the retromastoid retrosigmoid sub-occipital approach. Bang. J Neurosurgery 2023; 12(2): 86-93

Quality of life in patients after vestibular schwannoma surgery

AimTo evaluate the most important factors of quality of life in patients after vestibular schwannoma surgery.Materials and methodsPatients with unilateral sporadic occurrence of vestibular schwannoma who underwent surgery via suboccipital-retrosigmoid approach were included in the prospective study (2018–2021). Patients after previous Leksell gamma knife irradiation (or other methods of stereotactic radiosurgery) were excluded. Quality of life was assessed using 10 validated questionnaires that were distributed preoperatively, 3 months and 1 year after the surgery.ResultsA total of 76 patients were included in the study, complete data were analysed in 43 of them (response rate 57%). Grade III and IV represented up to 70% of all tumors. Patients with larger tumors had a significantly higher risk of postoperative facial nerve paresis, liquorrhea and lower probability of hearing preservation. Patients with smaller tumors and those, who suffered from headaches before surgery had more frequent and severe headaches after surgery. Postoperative headaches were associated with higher incidence of anxiety and tinnitus. More frequent anxiety was also identified in patients with preoperative serviceable hearing who became deaf after surgery. Nevertheless, tinnitus and hearing impairment appeared to have less impact on overall quality of life compared to headaches and facial nerve function.ConclusionAccording to our results, tumor size, postoperative function of the facial nerve and occurrence of postoperative headaches had the greatest influence on the overall postoperative quality of life in patients after vestibular schwannoma surgery.

Microvascular Decompression for Hemifacial Spasm without the Use of Neuromonitoring and Fix Retraction: A Single-Center Experience.

To evaluate outcome of patients with hemifacial spasm surgically treated by microvascular decompression without the use of neuromonitoring and fix retraction. Of the 78 patients with hemifacial spasm operated by the senior author of this study between 2016 and 2020, 60 patients who were followed up were included and retrospectively investigated. The female:male ratio was 32:28, and the mean age was 42.5 ± 11.5 years (range 23?71 years). All the patients were operated via the lateral retrosigmoid suboccipital infrafloccular approach, and no permanent retractor was employed during the procedures. Additionally, intraoperative neuromonitoring was not performed for any of the patients. Single vessel compression was observed in 77% of the patients, whereas 16% and 6% experienced compression in two and three vessels, respectively. Immediate recovery was achieved in 70% of the patients. Half of the remaining 30% fully recovered within 6 months?2 years. Furthermore, the complaints of 5% of the patients were alleviated, whereas no improvement was observed in 10% of the patients. One patient developed a recurrence. Microvascular decompression is a highly effective method for the treatment of hemifacial spasm. In this study, we did not resort to intraoperative neuromonitoring and observed that our postoperative complication rates were consistent with the existing literature.

Analysis of the influencing factors of short-term and long-term facial nerve function after vestibular schwannoma resection via suboccipital retrosigmoid approach

Objective: To summarize the experience of facial nerve(FN) preservation in microsurgical treatment of vestibular schwannoma (VS) resection via suboccipital retrosigmoid approach and to analyze the influencing factors of facial function prognosis in short-term and long-term period. Methods: Patients with VS who underwent microsurgery via suboccipital retrosigmoid approach by the skull base surgery team in Huashan Hospital from January 2013 to February 2018 were enrolled. A total of 308 patients were included in this study, including 132 males and 176 females. The average age was 47.9 year-old (Range: 17-79 year-old). The patient's clinical data and FN function prognosis were recorded. Univariate and multivariate analysis by SPSS 23.0 statistical software were performed to evaluate the factors affecting facial function prognosis and its recovery. Results: Gross total resection was achieved in 304 cases, and subtotal resection was in 4 cases. The facial nerve preservation rate anatomically was 99.4%. The facial nerve of 2 cases was thin due to large tumor compression and severed, and a one-stage reconstruction was performed during surgery.Of the 308 patients, 300 cases were successfully followed up, and 8 cases were lost to follow-up. The mean follow-up time was 52 months. In short-term (2 weeks after surgery), satisfactory facial nerve function (House-Brackmann (H-B) grade Ⅰ-Ⅱ) was achieved in 96 cases, and 212 cases were unsatisfactory function (H-B grade Ⅲ-Ⅵ). After 1 year, 198 were satisfactory function and 97 were unsatisfactory. After 3 years, 219 were satisfactory function and 75 were unsatisfactory. Five years later, 155 were satisfactory function and 34 were unsatisfactory. According to the results of logistic regression analysis, the impact factors of FN function in short-term were tumor size (P=0.011) and stimulation threshold (ST) of EMG monitoring (P<0.001). The impact factors in long-term were tumor size (P=0.005), ST of EMG monitoring (P=0.005) and FN rehabilitation training. Conclusions: Tumor diameter is an independent factor related to FN function, and the larger the tumor, the worse the postoperative FN function. The ST of EMG (ST≤0.05 mA) can predict short-term and long-term FN function. The systematic facial rehabilitation training can effectively promote the recovery of FN after surgery.

Analysis of Nonvestibular Cranial Nerve Schwannomas

Background and Aim: Cranial nerve (CN) schwannomas other than the eighth nerve schwannoma are called nonvestibular cranial nerve schwannomas (NVCNS). This study aims to analyze the clinical profile, distribution, and surgical outcome of the NVCNS. Methods and Materials/Patients: This is a retrospective study analyzing the NVCNS conducted between January 2007 and December 2021. VIIIth cranial nerve schwannomas and conservatively managed NVCNS were excluded from the study. Results: This study included 25 patients with NVCNS. Ten patients (40%) had trigeminal schwannomas, 3(12%) facial nerve schwannomas, 9 (36%) lower cranial nerve (LCN) schwannomas, 1 (4%) vagal schwannoma in neck and 2(8%) hypoglossal schwannomas. Eight patients (32%) were male and 17(68%) were female. The age of the patients ranges from 13 to 62 years (mean 39 years +/- 14 SD). Findings of cerebellar involvement, VIIIth CN involvement, and headache are the most common clinical features. The posterior cranial fossa is the most common location of the tumors. Thirteen patients (52%) underwent gross total resection (GTR), 7(28%) underwent neartotal resection (NTR) and 5(20%) underwent subtotal resection (STR). All the patients improved in the postoperative period. Facial nerve palsy is the most common cranial nerve palsy occurring in the postoperative period. Conclusion: Trigeminal and lower cranial nerve (LCN) schwannomas are the most common NVCNS. The retrosigmoid suboccipital approach is the most commonly used surgical approach for tumors located in the posterior cranial fossa. Since NVCNS are benign lesions, postoperative clinical improvement along with decreased complications should be the goal of the surgery. Hence, gross total resection is the most commonly achieved extent of resection, near-total or subtotal resection can be done wherever gross total resection (GTR) is not possible in NVCNS.

Cerebellopontine angle tumours: clinico-radiological features and surgical outcome

Object. Our aim is to demonstrate the various aspects of clinical-Radiological presentation and surgical Outcome with association to the tumour size concerning cerebellopontine angle (CPA) tumours.&#x0D; Materials and method. This is a prospective study of 40 patients at the Department of Neurosurgery, Jayarogya Group of Hospitals, GRMC Gwalior, M.P. India. All of the patients were pre-operatively evaluated with either non-enhanced and enhanced computerized tomography (CT) or Magnetic-resonance (MR) imaging or both.CPA tumours (predominantly acoustic neuroma) that underwent surgical removal using a suboccipital retro sigmoid approach over a 2-year period (June 2019 to May 2021).&#x0D; Results. There was a female preponderance. The most common presentation was Sensorineural hearing loss (90%) followed by Headache (67.5%). The majority of cases of Vestibular Schwannoma have heterogenous enhancement with cystic component.65% of patients have large (26-40mm) size tumours and facial nerve preservation is 86.4% in medium size tumours (10-25 mm).and Incidence of post-postoperative of facial nerve palsy is more in Giant size tumour (&gt; 40mm) so Positive association between size of lesion and Incidence of Post-operative facial nerve palsy. CSF leak occurs in 6 patients and postoperative Hydrocephalus occur in 2 patients and Mortality occurs in 3 patients.&#x0D; Conclusion. CP angle Tumor was common in middle age group, with the incidence in females slightly more than in males. The majority of lesions were of large size (26-40mm). Most of the patients on admission had a non-serviceable hearing. Heterogeneous enhancement with cystic components was found in most of the lesions. Gross-total excision was one in the majority of cases and vestibular schwannoma was the most common histopathological lesion obtained. Facial nerve palsy was the most complication and as the size of the lesion increased, the possibility of facial nerve palsy also increased post-operatively. Overall mortality is 7.5%.

Pediatric internal auditory canal cavernous hemangioma with rapid progression of sensorineural hearing loss: illustrative case.

Cavernous hemangioma of the internal auditory canal is extremely rare and is characterized by symptoms such as vertigo, sensorineural hearing loss, and facial nerve dysfunction. A health examination on an 11-year-old female in the fifth grade revealed hearing loss in the left ear. She also had dizziness that had persisted for approximately 1 year. Pure-tone audiometry revealed sensorineural hearing loss in her left ear. Rightward horizontal and rotatory nystagmus was detected. Facial paralysis was not present. Magnetic resonance imaging showed a lesion that was suspected to be hemangioma. The authors selected a left suboccipital retrosigmoid approach. The tumor showed a berry-tufted appearance throughout the cerebellopontine angle. The seventh cranial nerve penetrated the tumor and partly circulated outside the tumor with marked adhesion. The authors partially resected the tumor to avoid damaging the facial nerve. A histological examination identified cavernous hemangioma. The fundamental treatment for cavernous hemangioma of the internal auditory canal is complete surgical removal; however, any surgical intervention may result in hearing loss and facial paralysis. The extent of surgery needs to be decided intraoperatively based on the balance between preoperative symptoms and postoperative complications.

Radical resection of trigeminal schwannoma at the cerebellopontine angle with support of the digital robotic exoscope Synaptive Modus V system: A case report and literature review

We report on a 67-year-old woman who experienced drowsy mental status, facial numbness, and hearing loss on the right side; the symptom gradually worsened over the last 4 years. Brain magnetic resonance imaging revealed a 4.8 × 1.8 × 2.6 cm lesion located in the right cerebellopontine angle. She underwent surgery with the retrosigmoid suboccipital approach and support from the digital robotic exoscope Synaptive Modus V system. To the best of our knowledge, this is the first reported case that used the robotic exoscope system in Vietnam, and also in Asia. We performed radical resection of the tumor, the surgery position and the pathology result concluded the diagnosis was trigeminal schwannoma. After 30 months of follow-up, she fully recovered and the magnetic resonance imaging showed radical resection of the tumor. The aim of this study is to share our experience with the robotic exoscope system, which can improve optical field and image resolution, hence creating an opportunity for surgery that otherwise is impossible. The application of this robotic exoscope system is a breakthrough in neurosurgery in developing countries, such as Vietnam.

Prediction of Vestibular Schwannoma Surgical Outcome Using Deep Neural Network

To compare shallow machine learning models and deep neural network (DNN) model in prediction of vestibular schwannoma (VS) surgical outcome. 188 patients with VS were included, all underwent suboccipital retrosigmoid sinus approach, and preoperative MRI recorded a series of patient characteristics. Degree of tumor resection was collected during surgery and facial nerve function was evaluated on the 8th day after surgery. Potential predictors of VS surgical outcome were obtained by univariate analysis, including tumor diameter, tumor volume, tumor surface area, brain tissue edema, tumor property and tumor shape respectively. This study proposes a DNN framework to predict the prognosis of VS surgical outcomes based on potential predictors, and compares it with a series of classic machine learning algorithms including logistic regression. The results showed that three predictors of tumor diameter, tumor volume, and tumor surface area were the most important prognostic factors for VS surgical outcomes, followed by tumor shape, while brain tissue edema and tumor property were the least influential. Different from shallow machine learning models, such as logistic regression with average performance (area under the curve (AUC): 0.8263; accuracy: 81.38%), the proposed DNN shows better performance, where AUC and accuracy were 0.8723 and 85.64% respectively. Based on potential risk factors, DNN can be exploited to achieve preoperative automatic assessment of VS surgical outcomes, and its performance is significantly better than other methods. It is therefore highly warranted to continue to investigate their utility as complementary clinical tools in predicting surgical outcomes preoperatively.

Application of Preoperative Multimodal Image Fusion Technique in Microvascular Decompression Surgery via Suboccipital Retrosigmoid Approach

To explore the application value of preoperative multimodal image fusion technique in microvascular decompression (MVD) surgery via the suboccipital retrosigmoid approach. Comprehensive data of 13 patients with primary trigeminal neuralgia (TN) and 13 patients with hemifacial spasm (HFS) treated by microvascular decompression surgery via the suboccipital retrosigmoid approach at the Department of Neurosurgery in Zhuhai People's Hospital from January 2021 to December 2021 were retrospectively analyzed. Preoperatively, all patients underwent cranial thin-section computed tomography (CT) and magnetic resonance (MR) examinations. Three-dimensional (3D) digital images of the skull, brainstem, nerves, and blood vessels were constructed by the 3D-slicer software or RadiAnt DICOM Viewer, which were then applied to design the surgical approach and surgical plan. The multimodal image fusion results, clinical characteristics, intraoperative data, surgical outcomes, and complications of all patients were summarized. The 3D digital images after fusion reconstruction can vividly show the anatomical relationship between the skull, brainstem, nerves, and blood vessels, and was helpful to tailor the surgical strategy. All 26 patients underwent a smooth surgery. During the surgery, the key points were accurately located,the corner of the transverse sinus and sigmoid sinus were completely exposed, and no venous sinus injury occurred in all 26 patients. The key point was approximately located at the top point of the digastric groove, 12.3±0.46 mm vertically above and 6.3±0.6 mm laterally to the Frankfurt horizontal plane. The average cranial opening time was 30.4 (±3.6) min, and the mean operating time was 104.7 (±12.1) min. The diameter of the bone window was about 2.0-3.0 cm, and the bone flap was restored. Among the 13 patients with primary trigeminal neuralgia, 12 (92.3%) exhibited complete relief of pain and 1 had significant relief. Complications of surgery included facial sensory numbness in 1 case, vertigo in 2 cases, and herpes at the corners of the mouth in 1 case. Of the 13 patients with hemifacial spasm, 12 (92.3%) had complete relief of facial twitching symptoms, and 1 had significant relief, and the complications included mild facial palsy in 2 (15.4%) cases and facial sensory numbness in another 2 (15.4%) cases. The mean follow-up time after surgery ranged from 6-16 months, and 1 of 26 patients experienced recurrence of hemifacial spasm during the follow-up period. Preoperative multimodal image fusion technology can provide adequate preoperative assessment for patients and assistance in designing surgical approaches, which is an important guideline for microvascular decompression surgery via the suboccipital retrosigmoid approach for primary trigeminal neuralgia and facial muscle spasm.

Analysis of Imaging Results for Semisitting Compared with Supine Positioning in the Retrosigmoid Approach for Resection of Cerebellopontine Angle Vestibular Schwannomas.

To compare the completeness of resection of vestibular schwannomas using three-dimensional segmented volumetric analysis of pre- and postoperative magnetic resonance imaging (MRI) of patients undergoing supine and semisitting positioning for the retrosigmoid approach. Retrospective chart review. Tertiary medical center. Patients with vestibular schwannomas undergoing surgical resection via the retrosigmoid approach. Tumor resection via the retrosigmoid approach with different patient positioning: standard supine versus semisitting. Preoperative versus postoperative three-dimensional segmented volumetric MRI analysis of vestibular schwannomas. A total of 43 patients (15 supine and 28 semisitting) underwent retrosigmoid craniotomy for resection of vestibular schwannomas. For the conventional supine and semisitting positioning, mean preoperative tumor volumes were 12.65 and 8.73 cm 3 ( p = 0.15), respectively. Postoperative mean tumor volumes for the supine and semisitting positions were 2.09 and 0.48 cm 3 ( p = 0.13), respectively. There were 11 cases of postoperative sigmoid sinus thrombosis, 3 in the conventional supine group and 8 in the semisitting groups, and there were 6 cases of postoperative cerebrospinal fluid leaks, all in the semisitting group. The mean House-Brackmann scores for the supine and semisitting groups were 2.9 and 2.3, respectively. There was no statistically significant difference between groups in the rates of these or any other postoperative complications. The semisitting position for the suboccipital retrosigmoid approach for vestibular schwannoma resection does not compromise the ability to adequately resect the tumor as seen by volumetric MRI results. Further studies are needed to establish the safety of this position compared with the traditional supine approach.

Schwannomas of Brain and Spinal Cord.

Schwannomas are benign tumors originating from the Schwann cells of cranial or spinal nerves. The most common cranial schwannomas originate from the eight cranial nervevestibular schwannomas (VS). VS account for 6-8% of all intracranial tumors, 25-33% of the tumors localized in the posterior cranial fossa, and 80-94% of the tumors in the cerebellopontine angle (CPA). Schwannomas of other cranial nerves/trigeminal, facial, and schwannomas of the lower cranial nerves/are much less frequent. According to the World Health Organization (WHO), intracranial and intraspinal schwannomas are classified as Grade I. Some VS are found incidentally, but most present with hearing loss (95%), tinnitus (63%), disequilibrium (61%), or headache (32%). The neurological symptoms of VSs are mainly due to compression on the surrounding structures, such as the cranial nerves and vessels, or the brainstem. The gold standard for the imaging diagnosis of VS is MRI scan. The optimal management of VSs remains controversial. There are three main management options-conservative treatment or "watch-and-wait" policy, surgical treatment, and radiotherapy in all its variations. Currently, surgery of VS is not merely a life-saving procedure. The functional outcome of surgery and the quality of life become issues of major importance. The most appropriate surgical approach for each patient should be considered according to some criteria including indications, risk-benefit ratio, and prognosis of each patient. The approaches to the CPA and VS removal are generally divided in posterior and lateral. The retrosigmoid suboccipital approach is a safe and simple approach, and it is favored for VS surgery in most neurosurgical centers. Radiosurgery is becoming more and more available nowadays and is established as one of the main treatment modalities in VS management. Radiosurgery (SRS) is performed with either Gamma knife, Cyber knife, or linear accelerator. Larger tumors are being increasingly frequently managed with combined surgery and radiosurgery. The main goal of VS management is preservation of neurological function - facial nerve function, hearing, etc. The reported recurrence rate after microsurgical tumor removal is 0.5-5%. Postoperative follow-up imaging is essential to diagnose any recurrence.

IgG4-related hypertrophic pachymeningitis with tumor-like intracranial and intracerebral lesions

ObjectiveIgG4-related hypertrophic pachymeningitis is a rare fibroinflammatory disorder that may cause localized or diffused thickening of the dura mater. Misinterpretations of the clinical and imaging findings are common. Clinical manifestations depend on the location of the inflammatory lesion and on compression of neural structures leading to functional deficits. A dural biopsy is commonly needed for a definitive diagnosis. Immunomodulatory therapy is considered the therapy of choice.MethodsFour patients with IgG4-related hypertrophic pachymeningitis were identified over a 5-year period. Patient-related characteristics including age, preoperative workup, signs and symptoms of patients, and diagnostic procedures were evaluated. Furthermore, the surgical treatment and 5-year follow-up outcomes were analyzed.ResultsThere were two adults and two adolescents (mean age 32 years; range 15 to 67 years). Two patients were male, and two were female. No history of disease was known in any of the patients. Clinical symptoms were epilepsy (n = 2), ataxia and nausea (n = 1), and facial nerve palsy (n = 1). MR imaging studies showed contrast enhancing lesions in the temporal region in two patients, and in the cerebellar region in the other two patients. Subtotal resection was performed in two instances and a biopsy via a suboccipital retrosigmoid approach was obtained in the other two patients. Histochemical and immunohistochemical investigations revealed an IgG 4 disease in all of these patients. Immunomodulatorry therapy led to clinical stability during follow-up of 5 years in all four cases.ConclusionThe diagnosis of IgG4-related hypertrophic pachymeningitis is challenging, but is of great relevance as treatment differs significantly from other forms of pachymeningitis and a specific therapeutic approach may avoid long-term neurological complications. Our series contributes to a better clinical characterization of this rare disease.

Beyond the observation of all or nothing: The clinical significance of the pre-decompression instability of abnormal muscle response in Microvascular decompression for Hemifacial spasm

BackgroundIn microvascular decompression (MVD) surgery, abnormal muscle response (AMR) monitoring was utilized to confirm sufficient decompression. However, the AMR seems to contain more information that could improve surgical results. MethodPatients’ records of HFS treated with MVD under AMR monitoring, from January 2018 to December 2019 in our centre, were retrospectively reviewed. MVD procedures were performed via a suboccipital retrosigmoid approach, and AMR monitoring was performed. Pre-Decompression Instability (PDI) of AMR before the final decompression, including amplitude inconsistency and waveform chaos, was inspected and notified to the surgeon. Result165 cases were found with full follow-up data. In these cases, PDI was recognized in 144 cases. And in the remaining 21 cases, the AMR disappeared abruptly or continued to exist to the end of the MVD surgery. When PDI appeared, the rate of electrophysiological relief was significantly higher (91.7 % vs 66.7 %, P = 0.001). In cases with PDI appearance during MVD procedure, the rate of neurological dysfunction was lower (13.2 % vs 38.1 %, P = 0.004). The relief rate the PDI group tended to be higher without statistical significance. ConclusionThe appearance and observation of pre-decompression instability of AMR monitoring made a positive impact on the surgical outcomes of MVD surgeries. The advent of PDI indicates that the key step of the procedure has arrived. The timely notification of the PDI advent improved the surgical outcomes of MVD surgery by increasing the electrophysiological relief rate, reducing the incidence of neurological dysfunction, and possible elevation of the relief rate. Therefore, continuous intra-operative communication between the surgeon and electrophysiological monitoring staff should be encouraged.

Ultrasound-guided superficial cervical plexus block reduces opioid consumption in patients undergoing craniotomy via suboccipital retrosigmoid approach: a randomized controlled trial

IntroductionThe effectiveness of superficial cervical plexus block (SCPB) at decreasing opioid use and improving hemodynamic stability during suboccipital retrosigmoid craniotomy has not been established. The aim of this study is...

Lateral Suboccipital Retrosigmoid and Far Lateral Approaches:Various Extensions for Schwannoma, Meningioma, and Epidermoid Cyst Surgery

The lateral suboccipital retrosigmoid approach is one of the most established approaches for accessing the posterior cranial fossa. In order to expand the surgical field, several extensions, including(1)extended craniotomy(e.g., far lateral, transcondylar, and transsigmoid approaches), (2)additional intradural osseous or bony drilling(e.g., transmeatal and suprajugular approaches), and (3)fissure dissection(e.g., suprafloccular and infrafloccular approaches), have been described. In this report, we introduce our technique for the retrosigmoid approach and review several extensions as illustrated by schwannoma, meningioma, and epidermoid cyst surgeries.

Precise Localization in Craniotomy With a Retrosigmoid Keyhole Approach: Microsurgical Anatomy and Clinical Study.

ObjectiveWe aimed to explore a method of precise localization within craniotomy based on skull anatomical landmarks via the suboccipital retrosigmoid approach.MethodCraniometric measurements were taken from 15 adult dry skulls and eight cadaver head specimens. In the anatomical study, the keypoint corresponded to the transverse-sigmoid sinus junction's corresponding point on the external surface of the temporal mastoid process, eight cadaveric heads underwent a simulated craniotomy using the suboccipital retrosigmoid approach. The center of the burr hole is precisely oriented 12 mm vertically above the top point of the mastoid groove based on the line between the infraorbital margin and the upper edge of the external auditory canal. Clinical application was verified in clinical surgery by evaluating the accuracy, safety, rapidity, and minimal invasiveness of the procedure in 29 patients.ResultNo venous sinus injuries were observed. Within clinical application, 29 patients underwent craniotomy using the suboccipital retrosigmoid approach. The operative area was clearly exposed in all patients and the microsurgical anatomy of the intracranial region after the dura mater incision was satisfactory. No venous sinus ruptures were observed. The average craniectomy time was 27.02 ± 0.86 min. The diameter of the bone window was 1.7–2.9 cm.ConclusionWe conclude that the method can ensure safe, accurate, and rapid craniotomy with good vision while avoiding injury to the venous sinus.

Dural sinus thrombosis after resection of vestibular schwannoma using suboccipital retrosigmoid approach-thrombosis classification and management proposal.

Dural sinus thrombosis is one of the complications after posterior fossa surgery. However, that topic is not described well with regard to vestibular schwannoma surgery using the unique suboccipital retrosigmoid approach. We analyzed retrospectively medical records and radiological investigations of 116 patients. The including criteria were histopathologically confirmed vestibular schwannoma operated on using the retrosigmoid approach, preoperative and postoperative contrast-enhanced MRI, and at least 1-year follow-up. The patient group included 36% males and 64% females. The average age was 47.3 ± 13.9years. Sixty percent of the tumors were classified as T4b according to the Hannover scale and their mean volume was 13.73 ± 10.28 cm3. There were no signs of thrombosis preoperatively. Postoperative changes in the dural sinuses were found in 26 (22%) cases. In 7 (27%) cases, there was an external compression by the hemostatic agent, and in 19 (73%) cases, a thrombus was visualized in the sinus lumen. The size of the sinus, age, and the tumor size were not risk factors for thrombosis, whereas an intraoperative sinus injury was a statistically significant risk factor (p = 0.0012). All of the patients diagnosed with thrombosis were in good clinical condition in long-term follow-up, except one fatal case. Complete recanalization was observed in 58% of cases after 1-year follow-up. Postoperative changes in the dural venous sinuses are a frequent finding after vestibular schwannoma surgery using the suboccipital retrosigmoid approach. Intraoperative dural injury is a risk factor for thrombosis. Thrombosis in that group of patients is usually asymptomatic and does not influence the prognosis.

Giant cerebellopontine Angle Tumor Surgery: Experience of a Tertiary Care Center in Lahore, Pakistan

Objectives: In this case series, we report our experience of microsurgical resection of large and giant CPA tumors at the Department of Neurosurgery, Punjab Institute of Neurosciences (PINS).&#x0D; Materials and Methods: This was a retrospective case series of 328 patients (mean age, 40 years) with large and giant CPA tumors (predominantly vestibular schwannomas) who underwent surgical removal using a retro sigmoid approach over 4 years.&#x0D; Results: In the study, there were 58% (190) females while 42% (138) were males. 60% (197) of the tumors were right – sided and 40% (131) left – sided. Hearing loss was the main presenting complaint with 73% of the patients having non-serviceable hearing. There were 14 (4.3%) deaths reported during the retrospective analytic study. There were 3 cases of postoperative hemorrhage, and 11 patients expired due to post-operative wound infection. There were 13 cases diagnosed as having post-operative bacterial meningitis. Gross total tumor excision was achieved in 98% of patients based on postoperative imaging. There were 26 cases (8%) with postoperative CSF leakage that was managed with LP drain (5 patients) and in the rest VP shunt was done. Facial nerve function was graded according to the House Brackmann system. It was recorded in all patients following surgery: There were 16% patients with HB grade IV and 216 (66%) patients with HB grade III facial palsy. &#x0D; Conclusion: Suboccipital Retrosigmoid approach is ideal for dealing with giant CPA tumors. Complication rates in our series were comparable with other reported literature.