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Objective: The objective of this study was to test whether regenerating motor axons from a donor nerve can travel in a retrograde fashion using sensory branches to successfully reinnervate a motor nerve end organ., Methods: This study has two parts. In part I, rats (n = 30) were assigned to one of five groups for obturator nerve (ON)-to-femoral nerve transfer: group 1, ON-to-saphenous nerve (SN) distal stump; group 2, ON-to-SN proximal stump without femoral nerve proper (FNP) injury; group 3, ON-to-SN proximal stump with FNP crush injury; group 4, ON-to-SN proximal stump with FNP transection injury; and group 5, gold standard transfer, ON-to-motor femoral nerve (MFN) branch. At 8 weeks, retrograde labeling was done from the distal MFN, and the spinal cords were examined to assess the degree of obturator motor axon regeneration across the five groups. In part II, only group 4 was examined (n = 8). Through use of immunostaining and optical tissue clearing methods, the nerve transfer networks were cleared and imaged using light-sheet fluorescence microscopy to visualize the regeneration pathways in 2D and 3D models at 2- and 8-week time points., Results: Proximal FNP transection (group 4) enabled a significantly higher number of retrogradely regenerated motor axons compared with control groups 1-3. Moreover, group 4 had modest, but nonsignificant, superiority of motor neuron counts compared with the positive control group, group 5. Optical tissue clearing demonstrated that the axons traveled in a retrograde fashion from the recipient sensory branch to the FNP mixed stump, then through complex turns, down to distal branches. Immunostaining confirmed the tissue clearing findings and suggested perineurium disruption as a means by which axons could traverse across fascicular boundaries., Conclusions: Sensory branches can transmit regenerating axons from donor nerves back to main mixed recipient nerves, then distally toward target organs. The extent of retrograde regeneration is markedly influenced by the type and severity of injury sustained by the recipient nerve. Using a sensory branch as a bridge for retrogradely regenerating axons can open new potential horizons in nerve repair surgery for severely injured mixed nerves.

Background: Chordomas are rare but challenging neoplasms involving the skull base. A preoperative grading system will be useful to identify both areas for treatment and risk factors, and correlate to the degree of resection, complications, and recurrence., Objective: To propose a new grading system for cranial chordomas designed by the senior author. Its purpose is to enable comparison of different tumors with a similar pathology to clivus chordoma, and statistically correlate with postoperative outcomes., Methods: The numerical grading system included tumor size, site of the tumor, vascular encasement, intradural extension, brainstem invasion, and recurrence of the tumor either after surgery or radiotherapy with a range of 2 to 25 points; it was used in 42 patients with cranial chordoma. The grading system was correlated with number of operations for resection, degree of resection, number and type of complications, recurrence, and survival., Results: We found 3 groups: low-risk 0 to 7 points, intermediate-risk 8 to 12 points, and high-risk ≥13 points in the grading system. The 3 groups were correlated with the following: extent of resection (partial, subtotal, or complete; P < .002); number of operative stages to achieve removal (P < .014); tumor recurrence (P = .03); postoperative Karnofsky Performance Status (P < .001); and with successful outcome (P = .005). The grading system itself correlated with the outcome (P = .005)., Conclusion: The proposed chordoma grading system can help surgeons to predict the difficulty of the case and know which areas of the skull base will need attention to plan further therapy.

Background: Cerebral bypass has been an important tool in the treatment of complex intracranial aneurysms. The recent advent of flow-diverting stents (FDS) has expanded the capacity for endovascular arterial reconstruction., Objective: We investigated how the advent of FDS has impacted the application and outcomes of cerebral bypass in the treatment of intracranial aneurysms., Methods: We reviewed a consecutive series of cerebral bypasses during aneurysm surgery over the course of 10 years. FDS were in active use during the last 5 years of this series. We compared the clinical characteristics, surgical technique, and outcomes of patients who required cerebral bypass for aneurysm treatment during the preflow diversion era (PreFD) with those of the postflow diversion era (PostFD)., Results: We treated 1061 aneurysms in the PreFD era (from July 2005 through June 2010) and 1348 in the PostFD era (from July 2010 through June 2015). Eighty-five PreFD patients (8%) and 45 PostFD patients (3%) were treated with cerebral bypass. PreFD patients had better baseline functional status compared to PostFD patients with average preoperative modified Rankin Scale score of 0.55 in PreFD and 1.18 in PostFD., Conclusion: After the introduction of FDS, cerebral bypass was performed in a lower proportion of patients with aneurysms. Patients selected for bypass in the flow-diverter era had worse preoperative modified Rankin Scale scores indicating a greater complexity of the patients. Cerebral bypass in well-selected patients and revascularization remains an important technique in vascular neurosurgery. It is also useful as a rescue technique after failed FDS treatment of aneurysms., (Copyright © 2017 by the Congress of Neurological Surgeons)

Background: The resection of planum sphenoidale and tuberculum sellae meningiomas is challenging. A universally accepted classification system predicting surgical risk and outcome is still lacking., Objectives: We report a modern surgical technique specific for planum sphenoidale and tuberculum sellae meningiomas with associated outcome. A new classification system that can guide the surgical approach and may predict surgical risk is proposed., Methods: We conducted a retrospective review of the patients who between 2005 and March 2015 underwent a craniotomy or endoscopic surgery for the resection of meningiomas involving the suprasellar region. Operative nuances of a modified frontotemporal craniotomy and orbital osteotomy technique for meningioma removal and reconstruction are described., Results: Twenty-seven patients were found to have tumors arising mainly from the planum sphenoidale or the tuberculum sellae; 25 underwent frontotemporal craniotomy and tumor removal with orbital osteotomy and bilateral optic canal decompression, and 2 patients underwent endonasal transphenoidal resection. The most common presenting symptom was visual disturbance (77%). Vision improved in 90% of those who presented with visual decline, and there was no permanent visual deterioration. Cerebrospinal fluid leak occurred in one of the 25 cranial cases (4%) and in 1 of 2 transphenoidal cases (50%), and in both cases it resolved with treatment. There was no surgical mortality., Conclusion: An orbitotomy and early decompression of the involved optic canal are important for achieving gross total resection, maximizing visual improvement, and avoiding recurrence. The visual outcomes were excellent. A new classification system that can allow the comparison of different series and approaches and indicate cases that are more suitable for an endoscopic transsphenoidal approach is presented., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Spinal intradural arachnoid cysts (ACs) are found frequently in the thoracic region, and often extend over four or five vertebral levels. We present a 28-year-old patient who had a giant thoracic congenital intradural extramedullary AC (T1-T12) with a 10-month history of pain, paresthesia, paraparesis and gait ataxia. A T3 to T6 laminectomy was performed. After durotomy, the posterior wall of the AC was visualized compressing the spinal cord. We resected the cyst wall as widely as possible and connected the cyst to the subarachnoid space using a catheter. There were no postoperative complications. At 1-year follow-up, the patient presented with no motor deficits or pain, and had experienced progressive resolution of the gait ataxia. The treatment of giant intradural extramedullary ACs, especially for those that cannot be totally excised, should include generous fenestration and the insertion of a cyst-subarachnoid shunt.