[The significance of preoperative evaluation for atlantoaxial reducibility should be reevaluated].

For treatment of atlantoaxial dislocation, the evaluation of reducibility used to be the main basis for its classification. In recent years, with the development of posterior reduction techniques, the treatment paradigm for atlantoaxial dislocation is gradually changing from a combined anterior and posterior approach to a direct posterior approach. Through posterior intra-articular release and distraction, part of atlantoaxial dislocation which is irreducible in traditional concept can become reducible. With the new proposed strategy based on posterior reduction techniques, the significance and necessity of preoperative evaluation for atlantoaxial reducibility should be reevaluated. Based on our clinical experience, we put forward our views on this hot topic for peer reference and criticism.

[Surgical treatment strategy for difficult-reducible atlantoaxial dislocation].

Objective: To discuss the surgical strategy for difficult-reducible atlantoaxial dislocation. Methods: Clinical data of 82 patients with difficult-reducible atlantoaxial dislocation underwent surgical treatment in the Department of Neurosurgery, Xuanwu Hospital from January 2018 to February 2019 were retrospectively reviewed. Total of 32 men and 50 women were included, with a mean age of (41.8±12.9) years. Most cases (n=80) were treated with one-staged posterior atlantoaxial joint distraction and cage implantation, a few (n=2) underwent ventral decompression. All cases were followed up, postoperative improvement of clinical symptoms and radiology parameters were analyzed. Results: Of the patients, 80 cases (97.6%) received one-staged posterior atlantoaxial joint distraction and cage implantation; lateral facet joint bony fusion was found in 4 patients and was cut off with an osteotome. Transoral odontoidectomy was performed in 2 cases (2.4%) with fused atlanto-odontoid joint. All the patients were followed-up for (18.6±7.3) months. Postoperative CT showed complete reduction of ADI was achieved in 60 patients (75.0%). The ADI decreased significantly after the operation [(2.1±1.4) mm vs (5.0±1.5) mm, P<0.05]. The postoperative vertical distance between odontoid process and the Chamberlain line decreased significantly when compared with that before the operation [(3.9±3.8) mm vs (10.2±5.2) mm, P<0.05]. The mean JOA score at 6 months post operation improved significantly than that before the operation (13.7±1.5 vs 11.2±1.7, P<0.05). Seventy-five patients (93.8%) had atlantoaxial intra-articular bony fusion at 1 year follow-up. Conclusion: Most difficult-reducible atlantoaxial dislocations can be managed well by posterior one-staged atlantoaxial joint distraction and Cage implantation.

[Posterior atlanto-axial intraarticular distraction technique as revision surgery to treat atlanto-axial dislocation associated with basilar invagination].

Objective: To examine the effect of posterior atlanto-axial intraarticular distraction technique as revision surgery for failed posterior fossa decompression in patients with basilar invagination(BI) and atlanto-axial dislocation(AAD). Methods: The clinical data of 13 cases of AAD accompanied with BI treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical University were retrospectively analyzed. There were 3 males and 10 females,aged (42.6±9.5) years (range:30 to 63 years). All cases had assimilation of atlas and once underwent posterior fossa decompression. Anterior tissue was released through posterior approach followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line(DCL),clivus-canal angle(CCA) and the length of syrinx were collected. Paired sample t test was used to compared the data before and after operation. Results: All patients underwent surgery successfully, the mean surgical time was (187.7±47.4) minutes (range from 116 to 261 minutes). Twenty occipital condyle screws, 26 C2 pedicle screws and 3 occipital plates were implanted. Clinical symptoms improved in all patients. Twelve patients had complete reduction of basilar invagination and atlanto-axial dislocation, 1 achieved near completely reduction of basilar invagination. The postoperative ADI, DCL and CCA significantly improved((4.3±1.1) mm vs. (1.8±0.8) mm, (11.7±5.0) mm vs. (6.4±2.8) mm, (142.4±7.9)° vs. (133.3±7.9)°, all P<0.01).There were 5 cases with syringomyelia before surgery, and shrinkage of syrinx was observed 1 week after surgery in all cases. Eight patients achieved bone fusion 3 months after surgery, all patients achieved bone fusion 6 months after surgery. The JOA score increased from 12.8±2.3 before surgery to 14.8±1.3 one year after surgery, with statistically significant difference (t=4.416, P<0.01).No implant failure, spacer subsidence and infection were observed. Conclusion: In cases of failure posterior fossa decompression of basilar invagination and atlanto-axial dislocation, using posterior atlanto-axial intraarticular distraction and cantilever technique with cage implantation could achieve complete reduction and symptomatic relief.

[Percutaneous endoscopic transforaminal discectomy for L5~S1 disc herniation].

Objective: To evaluate the clinical results of percutaneous endoscopic transforaminal discectomy (PETD) for L5~S1 lumbar disc herniation (LDH). Methods: One hundred and two cases of L5~S1 LDH from April 2016 to June 2018 were retrospectively analyzed, including 13 patients with high iliac crest. Pre-and postoperative pain was measured by Visual Analog Scale (VAS) and functional status was assessed by Oswestry Disability Index (ODI). Results: All the operations were successful and no severe complications occurred such as hemorrhages, infections, injury of nerves. The operation time was (87.6±21.0) min; the frequencies of intraoperative fluoroscopy were 29.1±11.7; the postoperative bedridden time was (4.6±1.1) hours and the hospital stay was (3.6±0.5) days. The mean VAS and ODI scores were significantly improved (P<0.01) postoperatively. The efficiency of 102 cases were excellent in 89 cases (87.3%), good in 8 cases (7.8%), fair in 4 cases (3.9%) and poor in 1 cases (1.0%). One patient (1.0%) relapsed at 6 months after surgery. Conclusions: PETD is a safe and effective method for treatment of L5~S1 LDH. The "transverse process localization method" might be an effective technique for patient with high iliac crest and/or hypertrophic transverse process.

[Reduction of the atlantoaxial dislocation associated with basilar invagination through single-stage posterior approach: using Xuanwu occipital-cervical reduction surgical suite].

Objective: To examine the effect of posterior reduction in atlantoaxial dislocation (AAD) associated with basilar invagination(BI) using Xuanwu occipital-cervical fusion system in single stage. Methods: Thirty-seven AAD accompanied with BI cases treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical Universiy and the Second Hospital of Hebei Medical University were retrospective analyzed. There were 15 males and 22 females with age of (42.3±12.3)years (range: 18-69 yars). All the cases had congenital osseous abnormalities, such as assimilation of atlas and abnormal cervical fusion. Anterior tissue was released through posterior route followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including anterior atlantodental interval (ADI),the distance of odontoid tip above Chamberlain line,clivus-canal angle (CCA) and the length of syrinx were collected.The preoperative and postoperative JOA score and radiological measurements were compared by paired t-test. Results: The mean JOA score of the patients increased from 10.5 to 14.4 at the one-year follow-up(t=14.3,P=0.00).Complete reduction of AAD and BI was achieved in 34 patients.The mean clivus-canal angle improved from 118.0 degrees preoperative to 143.7 degrees postoperative(t=6.2,P=0.00). Shrinkage of the syrinx was observed 1 week after surgery in 24 patients, and 6 months in 31 patients. Twenty-eight patients achieved bone fusion 6 months after surgery. All the patients achieved bone fusion 12 months after surgery. One-side vertebral artery occlusion was diagnosed in 1 case postoperatively for transient dizziness, and relieved in 2 weeks. Two patients developed moderate neck pain after surgery, and relieved in 1 month. No implant failure, spacer subsidence or infection was observed. Conclusions: The treatment of AAD associated with BI using Xuanwu occipital-cervical fusion system from posterior approach in single stage is effective and safe. Cage implantation intraarticularly and fixation with cantilever technique achieve complete reduction in most cases.

Cavernous angioma of the cauda equina: a case report and systematic review of the literature.

Cavernous angioma is an uncommon vascular malformation of the central nervous system with a tumoural aspect. Spinal cavernous angioma mainly occurs within vertebral bodies; only 3-5% of tumours are located entirely in the vertebral canal. This case report describes a case of cavernous angioma, originating from the nerve roots of the cauda equina at the L1 level, in a 57-year-old woman presenting with acute lower back pain. The lesion was surgically resected 6 months after symptom onset and the structural integrity of the nerve root was maintained. Histopathological examination confirmed the diagnosis of cavernous angioma. The patient experienced no postoperative neurological deficit or recurrence. The diagnosis, histopathological features and surgical treatment of this case are presented, together with a literature review of clinical details and surgical procedures undertaken in cases of cavernous angioma of the cauda equina.

A vertebral artery tortuous course below the posterior arch of the atlas (without passing through the transverse foramen). Anatomical report and clinical significance.

A vertebral artery (VA) coursing below the posterior arch of the atlas (C1) without passing through the transverse foramen of C1, combined with a tortuous course within the spinal canal has rarely been reported in the literature. This article describes a case encountered during an anatomical study of the far-lateral approach, and reviews its embryonic development and clinical significance. The suboccipital triangle was filled with numerous venous plexures. After exiting from the transverse foramen of C2, instead of passing upwards through the transverse foramen of C1, the VA turned directly medially towards the spinal canal. At the spinal canal, it first formed an angle downwards, then turned upwards, piercing and entering the lateral part of the dura at C1 level. The diameter of this VA seemed to be within its normal limits. The course of the contralateral (right) VA was normal but with a small caliber and mainly supplied the posterior inferior cerebellar artery (PICA); after PICA, it became much thinner and dysplastic, the basilar artery was mainly supplied by the left VA. The bilateral posterior communicating arteries were large in diameter but there was dysplasia of the P1 segment of the posterior cerebral arteries bilaterally. Marked tortuosity of the bilateral intracavernous internal carotid artery (ICA) was also found. We did not find any osseous abnormality in the occipito-axial region or of C1-C2 joint. An abnormal course of the VA should be kept in mind during exposure of the craniocervical junction, especially in the variety of lateral approaches; due to compression of the nerve roots or the spinal cord, this abnormal course of the VA could give rise to clinical symptoms, which could be resolved by microvascular decompression technique.

Frontotemporal orbitozygomatic craniotomy to exposure the cavernous sinus and its surrounding regions. Microsurgical anatomy.

BACKGROUND: The microsurgical anatomy of the cavernous sinus and its surrounding regions were examined via frontotemporal orbitozygomatic (FTOZ) craniotomy. Combined with other deep osteotomies, the possibility of exposing the petroclival region and basilar artery was also explored. METHODS: The study was made on 20 sides of 10 cadaveric specimens fixed with formalin, with the help of the surgical microscope (magnification 5-15). RESULTS: The FTOZ was performed with frontotemporal and orbitozygomatic flaps. Extradurally, V2, V3, the trigeminal ganglion, the posterior vertical segment of the intracavernous ICA and the VI nerve were exposed by FTOZ craniotomy. By further removal of the petrous apex (Kawase's triangle), exposure could be extended to the petroclival region; with anterior modification of the microscopic light, in 50% of the specimens, exposure reached as low as the convergence of the vertebral arteries. The anterior part of the cavernous sinus and the orbital apex were examined by removing the anterior clinoid process, orbital roof and unroofing the optic canal. Intradurally, the intrapeduncular fossa (upper 1/3 of the clivus) was examined. The intracavernous cranial nerves and vessels were studied via lateral and superior wall approaches. By removing both the anterior and posterior clinoid processes together, in 80% of the specimens, the exposure could be carried as far as the midpoint of the basilar artery. CONCLUSIONS: FTOZ craniotomy could be used to treat lesions involving the cavernous sinus and its surrounding regions. Incorporated with the petrous apectomy, it could be used to expose the petroclival region and, in selected cases, exposure could be extended to the convergence of the vertebral arteries. Combined with anterior and posterior clinoidectomies, it could also be used to treat midpoint regions of the basilar artery.