Ectatic vertebral artery associated medullary compression treated with microvascular decompression: a case report and review of literature.

BACKGROUND: Vertebral artery compression syndrome is a rare condition defined as the clinical presentation of dizziness, vertigo, ataxia, dysarthria, dysphagia, progressive or acute paralysis, hemisensory loss, and cervical myelopathy secondary to compression of the medulla and upper spinal cord by the vertebral artery. CASE DESCRIPTION: Here we describe a 57-year-old Mexican-American male with bulbar symptoms, positional vertigo, and diplopia. The patient's symptoms were managed through microsurgical decompression of the medulla utilizing a far lateral transcondylar approach. The patient reported clinical improvement on follow-up. CONCLUSION: This case underscores the clinical complexity and heterogeneity of this rare neurovascular pathology and the importance of elucidating the pathophysiological mechanisms underlying the symptomatic presentation of vertebral artery compression syndrome.

The surgical role of C1 nerve root identification for the disconnection of the spinal dural arteriovenous fistula at the craniocervical junction: a single center restrospective experience.

This study aims to discuss the identification of the C1 nerve root as an effective surgical approach to successfully locate the shunting point of craniocervical junction spinal dural arteriovenous fistula (CCJ-SDAVF) intraoperatively. This study included all patients with CCJ-SDAVF who underwent surgical treatment using the far-lateral transcondylar approach at a single institution from January 2017 to June 2023. Data on patient demographics, clinical and angiographic characteristics of CCJ-SDAVF, surgical details, and treatment outcomes were collected. Follow-up assessments were conducted for all patients until December 31, 2023. The study included a total of 7 patients, comprising 5 men(71.4%) and 2 women (28.6%), with an average age of 57.6 years. Among them, 4 patients (57.1%) developed diffuse subarachnoid hemorrhage(SAH), while 2 patients (28.6%) experienced progressive cervical myelopathy. The shunting points of all CCJ-SDAVFs, which exhibited engorged veins, were identified next to the C1 root. Complete obliteration of CCJ-SDAVFs was successfully achieved in all patients, as confirmed by postoperative angiography one month later. No recurrent CCJ-SDAVFs were observed two years after the operation. Among the patients, 5 (71.4%) experienced good functional recovery, as indicated by an mRS score ranging from 0 to 1, while the remaining 2 patients (28.6%) showed incomplete functional recovery. The surgical interruption of CCJ-SDAVFs is the preferred treatment option, given its high obliteration rate and favorable functional recovery outcomes. We advocate the identification of C1 spinal nerve root as a crucial surgical step to identify the shunting points of CCJ- SDAVFs.

Accessory Nerve Schwannoma with Medulla Oblongata Compression: Microsurgical Resection by Far Lateral Suboccipital Transcondylar Approach: 2-Dimensional Operative Video.

Schwannomas overall account for approximately 8% of primary brain tumors, with the majority of them arising from the vestibular nerves.1,2 Non-vestibular schwannomas are considered rare, particularly ones arising from the accessory nerve, constituting only around 4% of craniovertebral junction schwannomas.3,4 The far lateral approach and its variations is an important tool in the armamentarium of skull base neurosurgeons. It allows adequate exposure for accessing ventral and ventrolateral lesions of the craniocervical junction.5-13 A 60-year-old female patient presented with a 3-month history of difficulty walking and progressive right-sided weakness. Magnetic resonance imaging demonstrated an extra-axial solid lesion at the craniocervical junction with significant enhancement on post-contrast imaging. The lesion was ventrolateral to the medulla, causing compression, displacement, and peritumoral edema. The patient consented to the procedure and underwent a far lateral suboccipital craniotomy with C1 hemilaminectomy in a lateral position. Tumor origins were identified at the left accessory nerve rootlet. The patient's postoperative course was uneventful. Follow-up magnetic resonance imaging revealed gross total resection and complete resolution of hemiparesis 3 months after the surgery. Microsurgical resection of tumors at the craniocervical junction is challenging. Preoperative planning and tailoring the approach are essential in the decision-making process to safely perform surgery. This video demonstrates, in detail, the steps, relevant anatomy, and technical nuances for accessory nerve schwannoma ressmoval. To the best of our knowledge, this is the first operative video showing the resection of a pure accessory nerve schwannoma with compression of the medulla. Under our institutional ethical review board regulations, approval was not necessary.

Soft Tissue Dissection in the Transcondylar Approach: A Modified Layered Technique to Maximize Lateral Access.

Objective While the transcondylar approach is technically challenging, it provides generous ventral and caudal exposure to the craniovertebral junction. This approach requires navigation around multiple eloquent neurovascular structures including the lower cranial nerves, vertebral artery and its branches, and the brainstem. Superficial exposure, including incision location and muscle dissection, can dramatically affect the surgical angle and maneuverability at depth. Methods We demonstrate the transcondylar approach in a step-by-step fashion in a formalin-embalmed, latex-injected cadaver head. Dissection within each layer of the suboccipital muscles was performed. A small cohort with an illustrative case is also included herein. Results The sternocleidomastoid (SCM) muscle was retracted anteriorly; the splenium capitis, semispinalis capitis, and longissimus capitis muscles were disconnected from the superior nuchal line and reflected inferomedially. The suboccipital muscle group was fully exposed. The superior and inferior oblique muscles were disconnected from the transverse process of C1. The superior oblique and the rectus capitis posterior major muscles were then dissected off the inferior nuchal line, and the suboccipital muscle group was retracted inferomedially en bloc . The greater auricular nerve was retracted laterally with the SCM, and the greater occipital nerve was retracted inferomedially with the suboccipital muscle group. Conclusion This technique avoids the obstructive muscle bulk that results from a myocutaneous approach while maximizing deep exposure. Understanding the detailed muscular anatomical relationship with the insertion location and suboccipital nerves is key to complete and safe extracranial dissection. Diligent dissection helps minimize postoperative pain and muscle spasm while optimizing the closure technique.

[Electrophysiological diagnostics in choosing treatment strategy for neuropathies in children with transcondylar fractures]. / Rol' elektrofiziologicheskoi diagnostiki v vybore taktiki lecheniya neiropatii u detei s chrezmyshchelkovymi perelomami.

BACKGROUND: A common complication of transcondylar fractures (TCF) in children is neuropathy requiring not only therapeutic but also surgical treatment. Despite numerous reports, clear criteria for selecting patients for surgical treatment have not been defined. OBJECTIVE: To clarify the role of clinical and electrophysiological diagnostics in choosing treatment tactics for neuropathies in children with TCF. MATERIAL AND METHODS: There were 20 patients with neuropathies after TCF between 2020 and 2022. Of these, 10 ones were selected for surgical treatment according to electrophysiological diagnostic data. Inclusion criteria: age 6-12 years, closed TCF within previous 3-12 months, symptoms of neuropathy confirmed by electroneuromyography (ENMG), no nerve disruption according to ultrasound data. Exclusion criteria: elbow joint contracture and post-traumatic ulnar nerve dislocation. All patients underwent needle myography with functional assessment of motor and sensory fibers, spontaneous activity in muscles, recruitment pattern and motor unit potentials. Intraoperative electrophysiological diagnostics included stimulation of motor fascicles with registration of M-responses from the target muscles. The follow-up period was 3-6 months. RESULTS: The study included 20 patients aged 6-12 years without peripheral nerve disruption. A group of 10 patients who required surgical treatment was identified. The control group consisted of 10 patients who did not require surgical treatment. To choose treatment tactics, we considered ENMG data. Surgical procedure was determined according to intraoperative neuromonitoring (IONM) data. CONCLUSION: When choosing treatment strategy, surgeons should consider objective ENMG and IONM criteria, as well as fascicular anatomy.

Risk factors for nonunion in patients with transcondylar fracture of the distal humerus after open reduction and internal fixation.

BACKGROUND: Transcondylar fractures have been reported to rarely occur in the distal humerus, and stable fixation is difficult because of the unique fracture pattern. However, few studies have reported the risk factors for nonunion after open reduction and internal fixation (ORIF). This study aimed to evaluate the demographic and surgical risk factors for nonunion in patients who had undergone ORIF for transcondylar fractures. METHODS: We retrospectively reviewed 68 patients who underwent ORIF for transcondylar fractures. Preoperative demographic factors, including diabetes mellitus (DM) and smoking, and operative factors, including fixation methods (eg, dual plate/single plate/tension band wiring [TBW]) were assessed as risk factors for nonunion. RESULTS: Nonunion occurred in 8 out of 68 patients (11.8%). Univariate analysis revealed that among the demographic factors, DM (4/8 [50%] vs. 8/60 [13.3%], P = .028) and smoking (3/8 [37.5%] vs. 4/60 [6.7%], P = .031) were significantly different between nonunion and union patients. Regarding operative factors, the fixation method (dual plate/single plate/TBW; 2 [25.0%]/2 [25.0%]/4 [50%] vs. 29 [48.3%]/25 [41.7%]/6 [10.0%], P = .033) showed significant differences between nonunion and union patients. Multivariate regression analysis showed that DM (odds ratio [OR], 10.560; 95% confidence interval [CI], 1.308-85.247; P = .027), smoking (OR 22.371; 95% CI, 2.111-237.081; P = .010), and TBW (OR 15.390; 95% CI, 1.348-175.666; P = .028) were independent risk factors for nonunion. CONCLUSIONS: Nonunion occurred in approximately 12% of the patients who underwent ORIF in the transcondylar region of the distal humerus. The risk of nonunion was higher in patients with DM than those who smoked. In addition, among the fixation methods, the TBW technique was a significant risk factor for nonunion.

A morphometric and morphological analysis of the foramen magnum, hypoglossal canal and occipital condyles in a select South African population.

BACKGROUND: The foramen magnum is a centralised structure found at the base of the skull. This orifice is a passageway that allows secondary structures, such as the medulla oblongata and meninges, to pass through. The occipital condyles is a small structure on either side of the foramen magnum, forming the craniovertebral joint. The hypoglossal canal is an orifice located on the occipital canal, providing a passageway for hypoglossal nerves. The study aimed to document the morphology and morphometry of the foramen magnum, occipital condyles and hypoglossal canals within a South African population. MATERIALS AND METHODS: Fifty skulls (n=50) were randomly selected from the Department of Clinical Anatomy, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal. This study investigated the morphological and morphometric parameters of the foramen magnum, occipital condyles and hypoglossal canal. The morphometric parameters were measured using a digital Vernier calliper. The data was statistically analysed using SPSS, and a p-value of <0.05 was deemed statistically significant. RESULTS: The mean length and width of the foramen magnum was found to be 35.19mm and 27.77mm, respectively. The mean index of the foramen magnum was 1.3, which indicated that the foramen magnum was predominantly oval-shaped within the selected sample. The occipital condyles have a mean length and width of 21.73mm and 12.87mm, respectively. Furthermore, the most prevalent shape of the occipital condyles was oval. The mean length and width of the hypoglossal canals were 5.14mm and 3.87mm, respectively. While the most prevalent shape of the hypoglossal canal was oval and round on the right and left sides, respectively. CONCLUSIONS: The findings of this study may assist in reducing the risk of injury and mortalities during trans-condylar approach procedures.

Bicolumnar 90-90 Locking Plate Fixation Through a Posterior Approach for the Treatment of Low Distal Humeral Fracture in Elderly Patients.

Background and objective Treating transcondylar humeral fractures in elderly individuals remains a challenge in trauma surgery, with plate fixation being one potential treatment method. This retrospective study was conducted to assess the effectiveness of plate fixing through a posterior approach in elderly individuals suffering from distal humeral fractures. Methods This retrospective study involved 28 older participants aged ≥65 years with low transcondylar fractures of the humerus (AO/OTA 13A2-3 fractures). We used the 90-90 orthogonal method for treatment. The inclusion criteria were as follows: (1) low transcondylar type of distal humeral fractures (13A2-3 according to the AO/OTA classification system), (2) patients aged ≥65 years, and (3) a follow-up period of at least 12 months. The exclusion criteria were as follows: polytrauma, pathological injuries, chronic elbow osteoarthritis or degenerative arthropathy, and fractures impacting the articular surface of the distal humeral. Clinical outcomes were assessed in terms of the visual analog scale (VAS) score, Mayo Elbow Performance Score (MEPS), and range of motion (ROM) of the elbow joint. Results The mean age of the patients was 72.25 years (range: 65-81 years), of which 14 (50%) were female and 14 (50%) were male. The mean VAS score for pain was 2.7 (range: 0-6). The mean angle of flexion was 130.6o (range: 115-140o), and the mean angle of the extension was -27.7 (range: -21 to -34). Regarding MEPS, 23 patients had an excellent score, four patients had a good score, and one patient had a poor score. There were four complications (two major and two minor) in the patients involved in the study. Conclusion Based on our findings, 90-90 plate fixation for low distal humeral fractures is associated with a high union rate and satisfactory clinical outcomes. Although we found complications in four patients, their healing was not affected. Therefore, we concluded that through improved monitoring and care, we could overcome such complications, and they did not affect the healing of the bone.

A less invasive operative method using a medial cannulated cancellous screw and single plate fixation for the treatment of transcondylar fracture of the humerus in elderly patients in multicenter (TRON group) study.

BACKGROUND: Double plate fixation for transcondylar fracture (TCF) tends to be more invasive to the soft tissue, and often carries a higher risk of postoperative complications, including ulnar nerve neuropathy. This study presents the outcomes of TCF of the distal humerus between patients treated with a single plate and cannulated cancellous screw fixation and patients treated with double plate fixation. METHODS: Between 2011 and 2021, 371 cases involving treatment of distal humeral fracture were recorded in our multicenter (named TRON group) database. Patients of ≥ 65 years of age with TCF treated with opeb n reduction and internal fixation were included. Clinical outcomes were assessed by the Mayo elbow performance score, range of motion, and total elbow arc joint. Complications included fracture-related infection (FRI) and ulnar neuropathy. RESULTS: There were significant differences in the average operative time (CCS group vs. Plate group: 119.0 min vs. 186.5 min; p < 0.001) and average tourniquet time (CCS group vs. Plate group: 91.5 min vs. 121.0 min; p < 0.001). FRI occurred as a complication in the Plate group (n = 6). The rates of FRI did not differ to a statistically significant extent (CCS group vs. Plate group: 0% vs. 9.2%; p = 0.477). No patients underwent reoperation. The rate of sensory symptoms in the Plate group was higher than that in the CCS group (CCS group: none [n = 25], numbness [n = 1] vs. Plate group: none [n = 57], numbness [n = 15], sensory depression [n = 2]; p = 0.039). DISCUSSION: Among patients of ≥ 65 years of age with TCF, the clinical outcomes of patients treated with medial CCS and lateral/posterolateral plate did not differ from those of patients who received double plate fixation, and the former treatment was associated with significantly fewer complications, including ulnar nerve palsy. In addition to double plate fixation, this less invasive method of medial CCS and single plate fixation should be considered as a treatment option for TCF in elderly patients.

Biomechanical comparison of three internal fixation configurations for low transcondylar fractures of the distal humerus.

BACKGROUND: We aimed to evaluate the biomechanical stiffness and strength of different internal fixation configurations and find suitable treatment strategies for low transcondylar fractures of the distal humerus. METHODS AND MATERIALS: Thirty 4th generation composite humeri were used to create low transcondylar fracture models that were fixed by orthogonal and parallel double plates as well as posterolateral plate and medial screw (PPMS) configurations (n=10 in each group) using an anatomical locking compression plate-screw system and fully threaded medial cortical screws. Posterior bending (maximum 50 N), axial loading (maximum 200 N) and internal rotation (maximum 10 N·m) were tested, in that order, for each specimen. Stiffness under different biomechanical settings among different configurations were compared. Another 18 sets of fracture models were created using these three configurations (n=6 in each group) and the load to failure under axial loading among different configurations was compared. RESULTS: Under posterior bending, the stiffness of parallel group was higher than orthogonal group (P<0.001), and orthogonal group was higher than PPMS group (P<0.001). Under axial loading, the stiffness of parallel group was higher than orthogonal group (P=0.001) and PPMS group (P<0.001); however, the difference between orthogonal and PPMS group was not statistically significant (P>0.05). Under internal rotation, the stiffness of parallel group was higher than orthogonal group (P=0.044), and orthogonal group was higher than PPMS group (P=0.029). In failure test under axial loading, the load to failure in the orthogonal group was lower than parallel group (P=0.009) and PPMS group (P=0.021), but the difference between parallel group and PPMS group was not statistically significant (P>0.05). All specimens in orthogonal group demonstrated "distal medial failure"; most specimens had "distal medial and trochlear failure" in the parallel group; most specimens exhibited "contact failure" in the PPMS group. CONCLUSION: For treating low transcondylar fractures, the overall stiffness and strength of the parallel configuration were superior to those of the orthogonal and PPMS configurations. Nevertheless, the PPMS configuration can provide adequate stability and stiffness comparable to double-plate configurations under axial loading. Therefore, the PPMS construct may have certain clinical value.

Transoral digital reduction of complete anterior odontoid dislocation followed by fiducial-based navigated transcondylar screw fixation: illustrative case.

BACKGROUND: Posterior atlantoaxial dislocations (i.e., complete anterior odontoid dislocation) without C1 arch fractures are a rare hyperextension injury most often found in high-velocity trauma patients. Treatment options include either closed or open reduction and optional spinal fusion to address atlantoaxial instability due to ligamentous injury. OBSERVATIONS: A 60-year-old male was struck while on his bicycle by a truck and sustained an odontoid dislocation without C1 arch fracture. Imaging findings additionally delineated a high suspicion for craniocervical instability. The patient had neurological issues due to both a head injury and ischemia secondary to an injured vertebral artery. He was stabilized and transferred to our facility for definitive neurosurgical care. LESSONS: The patient underwent a successful transoral digital closed reduction and posterior occipital spinal fusion via a fiducial-based transcondylar, C1 lateral mass, C2 pedicle, and C3 lateral mass construct. This unique reduction technique has not been recorded in the literature before and avoided potential complications of overdistraction and the need for odontoidectomy. Furthermore, the use of bone fiducials for navigated screw fixation at the craniocervical junction is a novel technique and recommended particularly for placement of technically demanding transcondylar screws and C2 pedicle screws where pars anatomy is potentially unfavorable.

Bi-columnar locking plate fixation through a combined medial and lateral approach for the treatment of low transcondylar fractures of the distal humerus in the elderly.

BACKGROUND: Low transcondylar fractures (LTFs) of the distal humerus are relatively uncommon elbow injuries in elderly patients after low-energy injuries. Although there is still debate regarding the method of fixation, several surgeons prefer bi-columnar fixation using pre-contoured locking plates. However, posterior approaches, which are usually used to perform the above procedure, have disadvantages, such as ulnar nerve neuropathy, damage to the extensor mechanism, and the need for general anesthesia. To solve these problems, the authors designed a combined medial and lateral approach. The purpose of this study was to present the outcomes of bi-columnar internal fixation through a combined medial and lateral approach for the treatment of LTFs of the distal humerus in the elderly.  METHODS: A total of 46 patients diagnosed with distal humeral fractures between May 2017 and April 2020 were included. Thirty patients were excluded, and 16 patients who underwent open reduction and internal fixation by the medial and lateral approach were selected. We carried out all the surgeries under brachial plexus anesthesia. The clinical outcomes were assessed based on the visual analog scale (VAS) score, Mayo elbow performance score (MEPS), disabilities of the arm, shoulder, and hand (DASH) score, and range of motion (ROM) of the elbow joint. Standardized radiographs were obtained at 3, 6, and 12 months after surgery and at the last follow-up visit to evaluate for bony union and to check for complications, such as ulnar nerve neuropathy and heterotopic ossification. RESULTS: The mean age was 81 years (range, 65-91 years). Bony union was achieved in 15 out of 16 patients. The mean VAS score was 2.1 (range, 0-6), the mean MEPS was 84.4 (range, 70-100), and the mean DASH score was 20.6 (range, 9.5-33.6). There were three complications including reduction loss, skin necrosis, and stiffness of the elbow. There was no ulnar nerve neuropathy. The post-operative ROM was 100 degrees or higher in all cases, which did not cause any impairment in daily life. CONCLUSION: LTFs of the distal humerus in the elderly can yield satisfactory results with bi-columnar internal fixation through a combined medial and lateral approach.

Meningiomas Involving the Hypoglossal Canal: A Case Report and Literature Review.

We report a rare case of hypoglossal canal meningioma in a 65-year-old woman who presented with dysphagia. Neurological examination revealed left hypoglossal nerve palsy. Head computed tomography and magnetic resonance imaging revealed a lesion around the left hypoglossal canal. She underwent a total resection with a midline suboccipital transcondylar approach. There were no postoperative complications, and the hypoglossal nerve palsy improved. There was no recurrence nine months after the surgery. Choosing a surgical approach that considers the site of origin and extent of tumor extension is important.

Basilar decompression via a far lateral transcondylar approach: technical note.

BACKGROUND: Treatments for symptomatic or unstable basilar invagination (BI) include posterior decompression, distraction/fusion, trans-nasal or trans-oral anterior decompression, and combined techniques, with the need for occipitocervical fusion based on the degree of craniocervical instability. Variations of the far lateral transcondylar approach are described in limited case series for BI, but have not been widely applied. METHODS: A single-institution, retrospective review of consecutive patients undergoing a far lateral transcondylar approach for odontoidectomy (± resection of the inferior clivus) followed by occipitocervical fusion over a 6-year period (1/1/2016 to 12/31/2021) is performed. Detailed technical notes are combined with images from cadaveric dissections and patient surgeries to illustrate our technique using a lateral retroauricular incision. RESULTS: Nine patients were identified (3 males, 6 females; mean age 40.2 ± 19.6 years). All patients had congenital or acquired BI causing neurologic deficits. There were no major neurologic or wound-healing complications. 9/9 patients (100%) experienced improvement in preoperative symptoms. CONCLUSIONS: The far lateral transcondylar approach provides a direct corridor for ventral brainstem decompression in patients with symptomatic BI. A comprehensive knowledge of craniovertebral junction anatomy is critical to the safe performance of this surgery, especially when using a lateral retroauricular incision.

Aberrant drainage of posterior condylar emissary vein and abnormal orifice of hypoglossal canal: surgical implications in the transcondylar fossa approach for VA-PICA junction aneurysm.

BACKGROUND: The posterior condylar emissary vein (PCEV) and posterior condylar canal (PCC) are anatomical landmarks for identifying important structures like jugular tubercle and occipital condyle in surgical approach to the foramen magnum and condylar fossa. Several anatomical variations have been described. Drainage into the jugular bulb is found to be commonest. METHOD: A 70-year-old patient with unruptured vertebral artery-posterior inferior cerebellar artery (PICA) junction aneurysm-underwent surgical clipping via transcondylar fossa approach. RESULT: Preoperative computed tomography demonstrated an abnormal communication existed between the left-sided PCC and hypoglossal canal (HC). The PCEV was identified draining into a dilated venous channel/pouch at the "hip" of sigmoid sinus (junction of sigmoid sinus and jugular bulb). Intra-operatively, an occipital artery-PICA bypass was performed. The PCEV was skeletonized, coagulated, and divided to achieve hemostasis. The lateral and cranial drilling around PCC was successful at safeguarding the underlying contents of HC (in medial and caudal extent). CONCLUSION: Preoperative angiography and detailed morphometric analysis of the PCC were helpful in planning surgical approach-identifying and controlling the PCEV, and skeletonization of the PCC without compromising the hypoglossal nerve and anterior condylar emissary vein.

Angulation Between the Occipital Condyle and the Hypoglossal Canal: An Anatomical Study With Application in Transcondylar Approaches and Occipital Condyle Screw Placement.

Background A detailed understanding of the relationship between the occipital condyle (OC) and the deeper-lying hypoglossal canal (HC) is necessary for surgeons who place screws into the OC or drill through or around the HC. Therefore, this anatomical study was performed. Methodology A total of 30 skulls (60 sides) underwent an analysis of the angle formed between the long axis of the OC and the HC, i.e., the OC/HC angle. Additionally, the lengths and widths of the OCs and foramen magnum (FM) of each skull were measured using a micrometer. Statistical analyses were performed between the left and right sides, and a Pearson's correlation coefficient was calculated between OC/HC angles and the sizes of the OCs and FM of the skulls. Results The OC/HC angle for the left and right sides ranged from 30 to 56 degrees (mean 46 degrees). The width of the OCs ranged from 9 to 18 mm (mean 13 mm). The length of the OCs was 18 to 31 mm (mean 24 mm). The mean length and width of the FM were 36 mm and 30 mm, respectively. There was no statistically significant difference between the OC/HC angle comparing left and right sides or male or female specimens. Additionally, no statistically significant differences were found between septated and non-septated HC. Pearson's correlation coefficient for left and right OC/HC angles and left and right OC lengths was r = 0.4056 and r = 0.2378, respectively. Pearson's correlation coefficient for left and right OC/HC angles and left and right OC width was r = 0.3035 and r = 0.3530, respectively. Pearson's correlation coefficient for left and right OC/HC angles and the width of the FM was r = 0.2178 and r = 0.2048, respectively. Pearson's correlation coefficient for left and right OC/HC angles and the length of the FM was r = 0.3319 and r = 0.2683, respectively. Conclusions The OC/HC angle as measured here was relatively consistent with no statistically significant differences between sides. We did not find a strong correlation between the width or length of the OC or the width or length of the FM and the OC/HC angles. Therefore, based on our study, surgeons can expect that this angle will range between 30 and 56 degrees (mean 46 degrees). Such knowledge might decrease patient morbidity following invasive procedures involving the OC.

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.

Far Lateral Craniotomy Closure Technique for Preservation of Suboccipital Musculature.

The far lateral approach is used for accessing pathology at the craniovertebral junction but can be complicated by postoperative suboccipital muscle atrophy. In addition to significant cosmetic deformity, this atrophy can lead to head and neck pain and potentially could contribute to cranio-cervical instability. To address this issue, the senior author began using a single myocutaneous flap without a muscle cuff and securing it directly to the bone using predrilled holes in the bone that resemble a chevron. The method is described and illustrated with an example case. Results from seven consecutive cases are reported since the technique was adopted. Muscle atrophy was measured by calculating area at the level of the occipital condyle and compared with the contralateral side. No significant differences were noted. In conclusion, we have found this to be an excellent closure technique and wanted to present our initial results for consideration by other skull base surgeons.

Foramen Magnum Meningioma-The Attainment of the Intra-Arachnoidal Dissection: 2-Dimensional Operative Video.

Ventral foramen magnum meningiomas are a forbidding lesion. The stake is so high with a risk of devastating paralysis and respiratory failure. Careful preoperative clinical and radiological evaluation is necessary to implement the best treatment plan. Successful surgical intervention depends on paying high attention to minute details throughout the case, from intratracheal intubation to extubation. The neural head-on-neck position is critical to avoid further medullary compression at intubation and positioning.1 Extensive neurophysiological monitoring, including somatosensory, motor, brainstem evoked potential, and cranial nerves, during the positioning and throughout the case, is extremely helpful to detect early signs of dysfunction.1 To expose and access ventral tumors, partial condyle resection and vertebral artery transposition are invaluable techniques.2,3 Preservation and minute manipulation of the vital neurovascular structures at this junction that includes the medullar, anterior spinal artery, posterior inferior cerebellar artery, vertebral junction perforators, and lower cranial nerves are essential for good outcomes. This is achieved by microsurgical intra-arachnoidal dissection under high magnification and after debulking the tumor to establish that plane.1,3,4 The demonstration of this technique is the purpose of this article. We demonstrate these surgical tenets applied to the resection of a large ventral foramen magnum meningioma extending from the midclivus to the C3 vertebral body level in a 54-yr-old female presenting with swallowing difficulties. The patient consented to the surgical intervention and the publication of her images. Image at 1:38 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, © LWW, 1998.

Transcondylar Odontoid Resection and Stabilization for Craniovertebral Degenerative Compression: 2-Dimensional Operative Video.

Non-neoplastic craniovertebral junction lesions are well known with various etiologies.1,2 They are frequently associated with craniovertebral junction instability. Many require only stabilization for their management.2 However, when significant irreducible anterior compression is present, surgical decompression becomes necessary.2-4 The traditional decompression route is direct anterior, such as the transoral, transmaxillary, or endoscopic endonasal approaches with a separate posterior stabilization.1,2 The transcondylar approach offers a wide and direct exposure to the anterolateral foramen magnum and atlantoaxial space, allowing extensive decompression, total resection of the odontoid, and associated pannus, even with large lateral extension, as well as fusion in the same surgical setting.5 The surgical manipulation is parallel to the dural sac in the sagittal plane, which could be safer than perpendicular dissection.5 Understanding the regional anatomy allows safe exposure and transposition of the vertebral artery with the surrounding alveolar and venous plexus (suboccipital cavernous sinus).5-7 We present this technique's details in a case of a 72-yr-old female who presented with progressively worsening bilateral upper extremity weakness and significant anterior compression due to irreducible odontoid degenerative changes. We demonstrate the steps necessary to achieve adequate exposure and decompression. The patient agreed to the surgical intervention. Images at 2:46, 3:00, and 3:25 reused from Al-Mefty et al,5 by permission from JNSPG. Images at 9:28 from Symonds et al,3 by permission of Oxford University Press. Image at 2:15, © Ossama Al-Mefty, used with permission.