Lower Cranial Nerve Research Articles

The Far-Lateral Suboccipital Approach to the Lesions of the Craniovertebral Junction

The far-lateral suboccipital approach and its variants, including the transcondylar, supracondylar, and paracondylar approaches, are essential skull base techniques for the neurosurgeon to expose and treat pathologies located at the ventral and ventrolateral craniovertebral junction. An understanding of the surgical anatomy and technical nuances of these approaches is vital for preventing catastrophic brainstem or spinal cord injury, neurovascular injury, and/or cranial nerve injury. This is achieved by carefully studying the location, the rostral-caudal and lateral extents of the lesion itself, and the anatomy of the surrounding structures on preoperative imaging. The amount of bony exposure should be tailored to each specific lesion to avoid unnecessary bone drilling and therefore decrease the risk of potential craniocervical instability. Minimizing retraction of the cerebellum, brainstem, and spinal cord is important for preventing neurologic injury; therefore, appropriate intraoperative head positioning and adequate bony exposure should be ensured, especially for more ventrally located lesions. A thorough knowledge of the anatomy of the extradural and intradural segments of the vertebral artery, and the lower cranial nerves, in relation to the lesion is also critical. For almost all lesions, the far-lateral suboccipital route with no or minimal condylar drilling is more than adequate for removing the most ventral lesions. Herein, we discuss the indications, general and preoperative considerations, and surgical anatomy and technical nuances of this approach.

Comparison of Lower Cranial Nerve Function Between Tympanojugular Paraganglioma Class C1/C2 With and Without Intracranial Extension: A Four-Decade Experience.

To compare preoperative and postoperative lower cranial nerve (LCN) function between Class C1 and C2 tympanojugular paraganglioma (TJP) with/without intracranial intradural (Di)/extradural (De) extensions, according to the experience of a single surgeon over four decades. Retrospective review. Quaternary referral center for otology and skull base surgery. A chart review was conducted of all the patients operated for C1/C2 TJPs from September 1983 to December 2018. The tumors were classified as: Limited-Group (C1/C2 without Di/De extensions) and Extended-Group (C1/C2 with Di/De extensions). Of 159 patients, 107 (67.3%) were women; the mean age at surgery was 46.5 years. The Limited-Group (56.6%) comprised C1 (41.1%) and C2 (58.9%) tumors; the Extended-Group (43.4%) comprised C1+Di/De (14.5%) and C2+Di/De (85.5%) tumors. The prevalence of preoperative LCN palsy was 11.9 times higher in Extended than Limited tumors: 61.9% versus 4.9% (p < 0.05). The risk for postoperative LCN palsy was 4.7 times greater in Extended than Limited tumors: 29.2% versus 12.9%, p = 0.01. Especially in younger patients, complete removal of Limited C1/C2 tumors, before they extend intracranially, reduces the risk of dysfunctionality of LCNs and the burden of residual tumor. The incidence of new tumors increased over four decades. However, new-postoperative LCN palsy did not occur in any Limited C1/C2 tumors operated after the year 2000, and declined to less than 10% of Extended C1/C2 tumors.

Surgical treatment of dumbbell-shaped jugular foramen schwannomas via two-piece lateral suboccipital approach: Report of 26 patients

BackgroundDumbbell-shaped jugular foramen schwannomas (JFS) are rare but challenging for the treatment. Surgical resection is believed to be the optimal therapy; however, postoperative dysfunction of the lower cranial nerves (CNs), tumor residual, cerebrospinal fluid (CSF) leakage, and subcutaneous hydrops are common. The current study's objectives were to describe the optimal surgical strategies for the total removal of dumbbell-shaped JFS, the functional preservation of lower CNs, and the prevention of postoperative CSF leakage. Methods26 consecutive patients with dumbbell-shaped JFS were surgically treated between January 2014 and June 2019. All patients were operated on via two-piece lateral suboccipital approach, vascularized muscle flap was used for the repair of the dural defect after an operation. The clinical information and radiological data of these patients were retrospectively reviewed, and the optimal surgical strategies were further evaluated and discussed. ResultsThe tumor was completely removed in all 26 patients, one patient developed new CN Ⅶ paralysis, and 2 developed new CN IX and Ⅹ paralysis after an operation, all patients were significantly relieved during follow up. None of them developed subcutaneous hydrops and postoperative CSF leakage. No tumor recurrence was observed during a mean follow up of 38.8 (16–69) months. ConclusionsDumbbell-shaped JFS could be safely and completely removed via the two-piece lateral suboccipital approach. Postoperative CSF leakage could be effectively prevented by careful repair of the dural defect in the jugular foramen (JF) and filling the mastoid cavity with a vascularized muscular flap.

Surgical management of embolized jugular foramen paragangliomas without facial nerve transposition: Experience of a public tertiary hospital in Brazil.

Background: Jugular foramen paragangliomas (JFP) treatment represents a challenge for surgeons due to its close relationship with facial nerve (FN), lower cranial nerves (LCN), and internal carotid artery. Due to its hypervascularization, preoperative tumor embolization has been indicated.Methods: Retrospective analysis of the clinical evolution of 26 patients with JFP class C/D previously embolized treated through infratemporal/cervical access without FN transposition.Results: Total and subtotal resections were 50% each, regrowth/recurrence were 25%, and 23%, respectively, and mortality was 3.9%. Postoperatively, 68.4% of patients had FN House and Brackmann (HB) Grades I/II. New FN deficits were 15.4% post embolization and 30.7% postoperatively. Previous FN deficits worsened in 46.1%. Tumor involved the FN in 30.8% and in 62.5% of them these nerves were resected and grafted (60% of them had HB III). Lateral fall, ear murmur, and vertigo improved in all patients. Tinnitus improved in 77.8% and one patient developed tinnitus after surgery. Hearing loss did not improve, eight partial hearing loss remained unchanged and four worsened. New postoperative LCN deficits were 64.3%. Postoperative KPS between 80 and 100 dropped 8.3%. Two patients with secretory paragangliomas with arterial hypertension difficult to control had better postoperative blood pressure control.Conclusion: Although still with significant morbidity due to FN and LCN injuries, the treatment of patients with JFP Fisch C/D has good long-term results. Surgical techniques without FN transposition have less intraoperative nerve damage, lower rates of total resection, and higher recurrence. Preoperative embolization of JFP reduces the intraoperative blood loss but can cause FN deficit.

Predicting Outcome in Skull Base Osteomyelitis: An Assessment of Demographic, Clinical, and Pathological Attributes.

Objective Skull base osteomyelitis (SBO) is an enigmatic clinical diagnosis which is difficult to decipher and is associated with poor outcomes. The study aims to examine the demographic and clinical characteristics of patients with SBO and its outcomes. Materials and Methods Medical records of 30 patients with diagnosis of SBO over past 5 years were assessed for demographic and clinical characteristics, type of SBO, radiological parameters, treatment received, procedure performed, microbiological profile, comorbidities, and complications including cranial nerve (CN) palsies. These factors were analyzed for prediction of outcome (death or survival). Statistical Analysis Microsoft Office Excel 2010 SAS 10.0 for Windows was used. Student's t -test for continuous variables (age, duration of symptoms, number of days of hospitalization, and treatment duration) and chi-square test for categorical variables (imaging findings, symptomatology, presence of comorbidities, surgical procedure, complications, and type of antibiotics) were utilized. Results We found SBO was the disease of elderly population (64.07 ± 6.13 years) with male predominance (83.3%) highly associated with uncontrolled diabetes status (93.3%). Headache (100%) and CN palsy (80%) were the most common neurological presenting complaints followed by stroke (17%) and encephalopathy (10%). Pathological and radiological correlation showed that fungal infection ( Aspergillus ) was associated with anterior SBO (10%), while bacteria ( Pseudomonas ) was cultured from posterior SBO (30%). Fifty per cent of patients were alive after 1 year out of which 33% had good functional outcome. The mortality rate was 33.3% in our cohort and multiple lower CN palsies ( p = 0.04), suboptimal duration of medical treatment ( p = 0.03), surgical intervention during clinical course ( p = 0.02), and development of intracranial or extracranial complications ( p = 0.03) were the predictors of mortality. Conclusion Early diagnosis including identification of pathogenic organisms and optimal duration of treatment are crucial factors for improved outcomes in SBO.

Transcondylar Approach for Resection of Medullary Cavernous Malformation: 2-Dimensional Operative Video.

Cavernous malformations located within the brainstem present with a high rate of neurological symptoms and carry a more aggressive course in both pediatric and adult populations.1,2 Cavernomas within the medulla are the rarest form, representing only 5% of all brainstem lesions.3 Repeated hemorrhage of brainstem cavernomas is associated with significant and cumulative neurological deficits and thus requires treatment.4 Microsurgical resection has become the optimal mode of treatment with the aim of resecting the live malformation and not merely the multiaged, organized hematoma.4 This is best achieved by approaching the cavernoma at the location where it projects to the surface and entering the lesion through a safe brainstem anatomic zone. For ventrally located lesions in the medulla, a transcondylar skull base approach provides a direct trajectory to the entry zone through a short surgical distance without the need to manipulate or retract neurovascular structures.5-8 Neuronavigation and intraoperative neurophysiological monitoring of somatosensory evoked potential, motor, and lower cranial nerves are adjuncts to increase patient safety. Radiosurgery for the treatment of brainstem cavernous malformations has been proposed; however, it demonstrates high risk and variable and often poor response rates.9 We present a surgical video demonstrating the transcondylar approach and resection of a medullary cavernoma in a 54-yr-old woman who has had multiple known prior hemorrhages and presented with a new onset of facial numbness and weakness, ataxia, and left body sensory loss. The patient consented to surgery and to photograph publication. Images at 1:28, 1:43 (left), 2:02 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997,5 with permission. Images at 1:43 (right) from Arnautovic et al,8 with permission from JNSPG.

The Asterion-to-Transverse Process of the Atlas Line as a Surgical Landmark.

Introduction Proposed landmarks to predict the anatomical location and trajectory of the sigmoid sinus have varying degrees of reliability. Even with neuronavigation technology, landmarks are crucial in planning and performing complex approaches to the posterolateral skull base. By combining two major dependable structures-the asterion (A) and transverse process of the atlas (TPC1)-we investigate the A-TPC1 line in relation to the sigmoid sinus and in partitioning surgical approaches to the region. Methods We dissected six cadaveric heads (12 sides) to expose the posterolateral skull base, including the mastoid and suboccipital bone, TPC1 and suboccipital triangle, distal jugular vein and internal carotid artery, and lower cranial nerves in the distal cervical region. We inspected the A-TPC1 line before and after drilling the mastoid and occipital bones and studied the relationship of the sigmoid sinus trajectory and major muscular elements related to the line. We retrospectively reviewed 31 head and neck computed tomography (CT) angiograms (62 total sides), excluding posterior fossa or cervical pathologies. Bone and vessels were reconstructed using three-dimensional segmentation software. We measured the distance between the A-TPC1 line and sigmoid sinus at different levels: posterior digastric point (DP), and maximal distances above and below the digastric notch. Results A-TPC1 length averaged 65 mm and was posterior to the sigmoid sinus in all cadaver specimens, coming closest at the level of the DP. Using the transverse-asterion line as a rostrocaudal division and skull base as a horizontal plane, we divided the major surgical approaches into four quadrants: distal cervical/extreme lateral and jugular foramen (anteroinferior), presigmoid/petrosal (anterosuperior), retrosigmoid/suboccipital (posterosuperior), and far lateral/foramen magnum regions (posteroinferior). Radiographically, the A-TPC1 line was also posterior to the sigmoid sinus in all sides and came closest to the sinus at the level of DP (mean, 7 mm posterior; range, 0-18.7 mm). The maximal distance above the DP had a mean of 10.1 mm (range, 3.6-19.5 mm) and below the DP 5.2 mm (range, 0-20.7 mm). Conclusion The A-TPC1 line is a helpful landmark reliably found posterior to the sigmoid sinus in cadaveric specimens and radiographic CT scans. It can corroborate the accuracy of neuronavigation, assist in minimizing the risk of sigmoid sinus injury, and is a useful tool in planning surgical approaches to the posterolateral skull base, both preoperatively and intraoperatively.

RARE-09. POORLY DIFFERENTIATED CLIVAL CHORDOMA IN EXTREME YOUNG AGE; CASE ILLUSTRATION AND REVIEW OF LITERATURE

Abstract Chordomas are rare tumors believed to be originated from notochordal remnants. Of all intracranial neoplasms, the incidence of cranial chordomas is less than 1%1. The youngest patient with an intracranial chordoma reported in the literature was a newborn in the first few days after birth9. Intracranial chondroma are more predominant in males compared to females1. The clinical features of intracranial chondroma in the pediatric age group commonly include increased Intracranial pressure, lower cranial nerves palsy, and torticollis2. There is no optimum treatment, however, surgical resection of the tumor followed by radiation therapy reported successful outcome3. This is a case of a poorly differentiated clival chordoma of a 23-month old boy. The clinical features, pathological, radiological findings, and surgical technique are discussed with an elaboration of the current review of the literature of clival chordoma in the extreme young age group. To the best of our knowledge, this is the youngest age of clivus chordoma reported in Saudi Arabia.

English

Schwannomas are relatively rare benign neoplasms of neurogenic origin from the neural sheath of peripheral nerves occurring more commonly in the head and neck. Mandibular bone is the commonest site of occurrence of these nerve lesions. Radiographically, intraosseous schwannoma of mandible is very difficult to differentiate from other bony pathologies such as neurofibroma, ameloblastoma, fibrous dysplasia, myxoma, central giant cell lesion, or periapical lesion, so it should be included in the differential diagnosis of lower jaw swelling. Schwannoma as a pathologic entity was first reported in 1910 by Verocay. Schwannoma (also known as neurinoma, neurolemmoma, neurilemmoma, perineural fibroblastoma, and peripheral nerve sheath tumour) is a rare, slowgrowing, benign neurogenic neoplasm that originated from Schwann cells. Schwann cells cover myelinated sheath of nerve fibres.1 These intraosseous schwannomas account for not more than 1 % of the central neoplasms. More than one third of all schwannomas are found in the head and neck region. 2 Most of these originate from the lower cranial nerve and sympathetic nervous system. Schwannomas from the upper cranial nerves such as trigeminal nerve and its branches are less common. Other commonly reported sites include the vertebra, clavicle, ribs, sacrum, humerus, ulna radius, etc. This painless slow-growing neoplasm may develop at any age.

Tension-Free Anterior Rerouting of the Facial Nerve in Management of Jugular Foramen Paragangliomas.

Tension-Free Anterior Rerouting of the Facial Nerve in Management of Jugular Foramen Paragangliomas.

Endoscopic-Assisted Resection of Anterior Foramen Magnum Meningiomas through a Midline Suboccipital Subtonsillar Approach.

Objective This study was aimed to demonstrate the resection of anterior foramen magnum meningiomas through an endoscopic-assisted posterior midline suboccipital subtonsillar approach. Design This study was designed with illustration of the surgical steps and safety of this approach. Setting Evidence of cerebrospinal fluid (CSF) cleft between the tumor and brainstem on MRI was studied ( Fig. 1A and B ). Preoperative tracheotomy was considered in cases of preoperative dysphagia to prevent any further neurological deterioration due to the bilateral access through the lower cranial nerves corridors. Semisitting position with extensive electrophysiological neuromonitoring and transesophageal echocardiogram was adopted. A standard midline incision with bilateral suboccipital craniotomy and C1-laminotomy was performed ( Fig. 2A ). After partial resection and elevation of the tonsils, tumor was debulked unilaterally around the lower cranial nerves and the vertebral artery, devascularized from the clival dura and then dissected from the brainstem ( Fig. 2B, C ). Endoscopic-assisted removal of its anterior portion followed. The same procedure was repeated from the opposite site for the contralateral portion, before approaching the purely anterior part with endoscope assistance ( Fig. 2D ). Participants Four consecutive patients were included in the study. Main Outcome Measures Grade of tumor resection and outcome (mRS) were primary measurement of this study. Results Clinical outcome and grade of resection are comparable to other series of patient treated with other foramen magnum approaches ( Fig. 1C and D ). Conclusion Anterior foramen magnum meningiomas can be safely removed through this relatively faster midline suboccipital approach with bilateral exposure of lower cranial nerves (CNs) and vertebral arteries and lower approach-related morbidity (no condyle drilling). The surgical corridor is created by the tumor during debulking reducing need for brain retraction and the removal of the anterior dural attachment coagulated under the microscope is verified and completed endoscopically with pituitary curettes (Simpson's grade II) ( Fig. 1C and D ). The link to the video can be found at: https://youtu.be/9eACAJVwQBs .

Challenges in Using the Posterior Inferior Cerebellar Artery for Revascularization of the Anterior Inferior Cerebellar Artery: A Microsurgical Anatomic Study

A bypass is usually required to prevent ischemia during the treatment of anterior inferior cerebellar artery (AICA) aneurysms. The intracranial (IC)-to-IC bypass provides several advantages over the extracranial-to-IC bypass in the posterior fossa. However, there are only 2 case reports about AICA revascularization with the posterior inferior cerebellar artery (PICA). We aimed to investigate the microsurgical anatomical challenges for PICA to AICA anastomosis. Ten cadaveric heads injected with colored silicone were inspected on both sides using a lateral transcondylar approach. After the donor and recipient arteries were examined from the posterior side, neurovascular contents of the posterior fossa were excised and the origin, course, and variations of both arteries were investigated from the anterior view. The diameters of the AICA and PICA segments and the intersegment distance were measured. PICA variations and posteromedial origins from the vertebral artery were identified in 8 of the 20 right and 6 of the 20 left sides, and the first segment of the PICA was not present in 7 sides. Furthermore, in 18 sides, the PICA was trapped between the lower cranial nerves and dentate ligaments. Therefore the donor artery could not be brought closer than 1 cm to the recipient artery in 19 sides. Moreover, AICA variations were identified in 6 sides, and in 12 sides, the diameter of the recipient artery was <1 mm. The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.

English

BACKGROUND The craniovertebral junction is a complex articulation between occiput, atlas, axis and supporting ligaments enclosing the soft tissue structures of cervicomedullary junction which includes medulla, spinal cord and lower cranial nerves. The incidence of different types of CVJ anomalies varies with demographic environment &amp; ill-defined genetic factors. CVJ anomalies are more frequently found in Indian subcontinent than anywhere else in the world. Even in India, these anomalies are more frequently documented from Bihar, Uttar Pradesh, Rajasthan and Gujarat. The reason for this geographical clustering is more speculative. The CVJ anomalies can be either due to bony or soft tissue anomalies. They are common in all age groups and almost equal in both sex groups. The anomalies can be due to congenital or acquired causes. There has been a renewed interest in the normal anatomy &amp; pathological lesions of CVJ anomalies with dynamic xrays, computed tomography (CT) and magnetic resonance imaging (MRI). The clinical features are often delayed up to 2 nd or 3rd decade, since they are subtle and often missed. Various congenital anomalies and acquired disease processes can affect the craniovertebral junction. They often cause diagnostic dilemmas. Only few studies have been conducted in this regard. This study is an attempt to define importance of precise diagnosis for pre-treatment evaluation and systematic classification of CVJ abnormalities with MRI and multi-detector computed tomography (MDCT). METHODS We conducted this cross-sectional descriptive study with 55 patients, who had been referred to us for CT / MRI from Department of Neurology. 3 Tesla MRI (GE Healthcare) and 16 slice MDCT (Philips) were used in this study. RESULTS In our study, congenital anomalies were the most common type of CVJ abnormality followed by degenerative changes and trauma. MRI proved to be better at detecting soft tissue abnormalities and assessing spinal cord compression, although CT was very much accurate at demonstrating bony lesions with short scan times and ability to reconstruct in three orthogonal planes. CONCLUSIONS CT and MRI cannot be compared in imaging the craniovertebral junction and should be complementary to each other. KEYWORDS Craniovertebral Junction, MRI, MDCT

Microneurosurgical Management of Posterior Inferior Cerebellar Artery Aneurysms: Results of a Consecutive Series.

Aneurysms of the posterior inferior cerebellar artery (PICA) are uncommon. The complex anatomy of PICA and its intimate relationships with medulla, lower cranial nerves, and jugular tubercle makes the surgical treatment of these aneurysms fascinating. The reported isstudy aimed at a critical review of the overall results of a personal series of PICA aneurysms,treated by the senior author, R. Galzio. Demographics, charts, videos, outcome, and follow-up of a cohort of PICA aneurysms managed in the last 10years were retrospectively analyzed, focusing only upon those treated with microneurosurgery. Twenty-five patients, harboring a single aneurysm, were operated on. Fifteen aneurysms were ruptured. Nineteen were proximal, all of these being been treated through a far-lateral approach. Trans-condylar or trans-tubercular variants were rarely necessary and howeverreserved to peculiar cases. Twenty-three aneurysms underwent direct treatment consisting of clip ligation. At 6-month follow-up, 60% of patients had a modified Rankin Score (mRS) of 0-2. Given the high anatomical variability of both PICA and patients' bony anatomy, a case-by-case meticulous preoperative imaging evaluation is mandatory for the choice of the most suitableand tailored surgical corridor which, in turn, is pivotal to achievethe best outcome.

Dysphagia and Tongue Deviation: A Rare Case of Collett–Sicard Syndrome after Blunt Head Trauma

The jugular foramen and the hypoglossal canal are both apertures located at the base of the skull. Multiple lower cranial nerve palsies tend to occur with injuries to these structures. The pattern of injuries tend to correlate with the combination of nerves damaged. Case Report: A 28-year-old male was involved in an AVP injury while crossing the highway. Exam showed a GCS of 15 AAOx3, with dysphagia, tongue deviation to the right, uvula deviation to the left and a depressed palate. Initial imaging showed B/L frontal traumatic Sub-Arachnoid Hemorrhages (tSAH), Left Frontal Epidural Hematoma and a Basilar Skull Fracture. On second look by a trained Neuroradiologist c At 3 month follow up, patient’s tongue normalized to midline and his dysphagia resolved. Discussion: Collette-Sicard syndrome is a rare condition/syndrome characterized by unilateral palsy of CN: IX, X, XII. This condition has been rarely described as a consequence of blunt head trauma. In most cases, the condition is self-limiting with patients regaining most to all of their neurological functions within 6 months. Nerve traction injuries and soft tissue edema compressing the cranial nerves are the leading two hypothesis. In conclusion, injuries with focal neurological deficits which were not apparent on initial imaging should be reviewed by relevant experts with concomitant knowledge of the patient’s history.

Resection of Foramen Magnum Meningioma through Modified Far Lateral Approach: Surgical Principles and Technical Nuances.

Objectives Safe maximal resection is the basic principle of cranial base surgery and the grade of resection is an important factor influencing the prognostic outcome. This operative video highlights the surgical principles and technical nuances in the microsurgical resection of foramen magnum meningioma (FMM). Case Description The surgery was performed in a 45-year-old lady who presented with hoarseness of voice and spastic quadriparesis (grade 4/5). On imaging, FMM with mass effect on brainstem and spinal cord was identified. The tumor was gross totally resected through modified far lateral approach with minimal occipital condyle drilling. This video demonstrates the surgical techniques of tumor resection including early devascularization, operating in the arachnoid plane to dissect the neurovascular structures, piecemeal decompression, sharp dissection to separate tumor from lower cranial nerves (LCN), identifying the brainstem veins, and resecting the lesion from tumor–brainstem interface. Postoperatively, she had significant neurological improvement and the magnetic resonance imaging revealed excellent radiological outcome ( Figs. 1 and 2 ). Conclusion The surgery of FMM is challenging due to the deep surgical corridor, critical location, close proximity with various neurovascular structures, firm consistency, and high vascularity of the tumor. The modified far lateral approach by preserving the occipital condyle may prevent the postoperative incidence of craniovertebral junction instability. The key operative principles to achieve the best surgical outcome include careful dissection along the arachnoid plane, gentle handling of cranial nerves, veins, and perforator vessels, avoidance of traction on brainstem and spinal cord, intraoperative neurophysiological monitoring, proper hemostasis, and meticulous dural closure. The link to the video can be found at: https://youtu.be/1qvAeUmNIUw .

Clival Meningioma Removal through a Suboccipital Retrosigmoid Approach: Operative Video and Technical Nuances

Abstract Background Clival meningiomas are challenging lesions that need to be managed according to the displacement of the adjacent structures. Lateral skull base approaches are needed to achieve their radical removal; however, they are associated with significant morbidity, especially when the tumor involves the basilar artery, its perforators, brainstem, and lower cranial nerves. Design This is a case of a 79-year-old female patient, diagnosed with a large lower clival meningioma after suffering from headaches. It was offered a conservative treatment but on serial MRI, an increase in the meningioma's size was observed, so it was decided to remove the meningioma using a left suboccipital retrosigmoid approach. Settings On a left three-quarter prone position, with facial nerve, auditory brainstem response, lower cranial nerves, and motor-evoked potentials and somatosensory-evoked potentials neurophysiologic monitoring, a right suboccipital retrosigmoid craniotomy with opening of the foramen magnum was performed, giving enough lateral visualization of the tumor. Broad base tumor pushing backward and aside the vertebral and basilar arteries, cranial nerves (7th–12th), and the brainstem was exposed and removed. Results Near total resection of the meningioma was achieved, leaving a microscopic residual in the entry points of the low cranial nerves without complications. There was no neurological deficit after the surgery. Postoperative MRI revealed no signs of residual tumor. Conclusion: In this case, the regular retrosigmoid approach, extended into the foramen magnum was enough for the removal of this pure clival meningioma.The link to the video can be found at: https://youtu.be/3d6Uj4gjmDU.

Isolated Unilateral Vocal Fold Palsy following Skull Base Fracture: A Case Report

Isolated lower cranial nerve (CN) palsy affecting the CN X resulting from a skull base fracture is very rare. The clinical manifestation and natural history is related closely to the complex anatomy of this region and mechanism of injury. Here, we report a case of a 54 year-old man who presented with a delayed onset of dysphonia and dysphagia with aspiration following a closed head injury sustained from a motor vehicle accident. Injection laryngoplasty was implemented to alleviate symptoms of his CN X palsy, which eventually almost completely resolved. High index of suspicion should be maintained when investigating possible skull base fractures, especially with a suggestive clinical presentation of lower CN palsies affecting one or all the lower CNs. Delayed onset of these CN palsies are likely to have more favourable outcomes.

Neurenteric CYST of the craniocervical junction. Case report

Neurenteric cysts are uncommon benign endodermally-derived epithelial-lined cystic lesions of the central nervous system. We report a case of neurenteric cyst in the craniocervical junction and review of the literature.A 17-year-old boy complained of a 9-month history of progressive headaches. Neurological examination did not reveal any abnormalities. A computed tomography scan was performed demonstrating a hypodense lesion in the craniocervical junction and the magnetic resonance imaging (MRI) revealed an approximately 19 × 24 × 23 mm prebulbar cyst that induced posterior displacement of the medulla. Four months later, the patient developed right hemiparesis and limitation of his neck movements. Further MRI showed that the lesion had increased a little in size. Given this, a suboccipital craniotomy was performed with right C1 laminectomy, achieving complete excision of the cyst, and the peribulbar region and the lower cranial nerves were released. After 4 months, he was asymptomatic and playing football again, and 3 years later, MRI did not demonstrate any signs of growth.

Revascularization of the Posterior Inferior Cerebellar Artery Using the Occipital Artery: A Cadaveric Study Comparing the p3 and p1 Recipient Sites.

Revascularization of the posterior inferior cerebellar artery (PICA) is typically performed with the occipital artery (OA) as an extracranial donor. The p3 segment is the most accessible recipient site for OA-PICA bypass at its caudal loop inferior to the cerebellar tonsil, but this site may be absent or hidden due to a high-riding location. To test our hypothesis that freeing p1 PICA from its origin, transposing the recipient into a shallower position, and performing OA-p1 PICA bypass with an end-to-end anastomosis would facilitate this bypass. The OA was harvested, and a far lateral craniotomy was performed in 16 cadaveric specimens. PICA caliber and number of perforators were measured at p1 and p3 segments. OA-p3 PICA end-to-side and OA-p1 PICA end-to-end bypasses were compared. OA-p1 PICA bypass with end-to-end anastomosis was performed in 16 specimens; whereas, OA-p3 PICA bypass with end-to-side anastomosis was performed in 11. Mean distance from OA at the occipital groove to the anastomosis site was shorter for p1 than p3 segments (30.2 vs 48.5 mm; P<.001). Median number of perforators on p1 was 1, and on p3, it was 4 (P<.001). Although most OA-PICA bypasses can be performed using the p3 segment as the recipient site for an end-to-side anastomosis, a more feasible alternative to conventional OA-p3 PICA bypass in cases of high-riding caudal loops or aberrant anatomy is to free the p1 PICA, transpose it away from the lower cranial nerves, and perform an end-to-end OA-p1 PICA bypass instead.