Pure endoscopic endonasal odontoidectomy: anatomical study

Different disorders may produce irreducible atlanto-axial dislocation with compression of the ventral spinal cord. Among the surgical approaches available for a such condition, the transoral resection of the odontoid process is the most often used. The aim of this anatomical study is to demonstrate the possibility of an anterior cervico-medullary decompression through an endoscopic endonasal approach. Three fresh cadaver heads were used. A modified endonasal endoscopic approach was made in all cases. Endoscopic dissections were performed using a rigid endoscope, 4 mm in diameter, 18 cm in length, with 0 degree lenses. Access to the cranio-vertebral junction was possible using a lower trajectory, when compared to that necessary for the sellar region. The choana is entered and the mucosa of the rhinopharynx is dissected and transposed in the oral cavity in order to expose the cranio-vertebral junction and to obtain a mucosal flap useful for the closure. The anterior arch of the atlas and the odontoid process of C2 are removed, thus exposing the dura mater. The endoscopic endonasal approach could be a valid alternative to the transoral approach for anterior odontoidectomy.     

Odontoid process and clival regeneration with Chiari malformation worsening after transoral decompression: an unexpected and previously unreported cause of “accordion phenomenon”

Purpose

Transoral odontoidectomy followed by occipito-cervical fixation is a widely used approach to relieve ventral compressions at the craniovertebral junction (CVJ). Despite the large amount of literature on this approach and its complications, no previous reports of odontoid process and clival regeneration following transoral odontoidectomy are present in the English literature.

Methods

We report the case of odontoid process and clival regeneration following transoral odontoidectomy.

Results

A 7-year-old boy presented with symptoms of brainstem and upper cervical spinal cord compression due to a complex malformation at the CVJ including a basilar invagination with Chiari malformation. A successful transoral microsurgical endoscopic-assisted odontoidectomy extended to the clivus was performed along with occipito cervical instrumentation and fusion. Clinical and radiological resolution of the CVJ compression was evident up to 2 years post-op, when the child had a relapse of some of the presenting symptoms and the follow-up CT and MRI scans showed a quite complete regrowth of the odontoid process, clival partial regeneration and recurrence of preoperative Chiari malformation.

Conclusions

Besides the need of an accurate complete resection of the periosteum, which apparently was incompletely performed in our case, our experience suggests the need of resection of the odontoid down to the dentocentral synchondrosis and an accurate lateral removal of the bone surrounding the anterior tubercle of the Clivus is advised when an anterior CVJ decompression is required in children presenting a still evident synchondrosis at neuroradiological investigation.

     

前后路联合手术治疗颅底陷入症合并小脑扁桃体下疝畸形

目的：探讨颅底陷入症合并小脑扁桃体下疝畸形的手术治疗方法及效果。方法：8例颅底陷入症合并小脑扁桃体下疝畸形患者，术前均有不同程度四肢痉挛性瘫痪及感觉障碍，均行CT、MRI检查并测量有关数值：Klaus高度指数、齿状突尖到脑桥延髓交界处的距离及小脑扁桃体下疝深度。所有患者均首先接受后路减压、枕颈钛板固定、植骨融合，然后再经口咽行齿状突磨除术。结果：术后症状均得到缓解，随访8个月至2年，平均1．5年，术后半年8例患者生活均能自理，术后1年，4例患者能参与一般的体育活动，另4例患者也能进行较轻的劳动。MRI示内固定稳固，延颈髓角度明显增大，脊髓压迫解除，植骨融合。结论：对颅底陷入症合并小脑扁桃体下疝畸形的患者先行后路减压固定、植骨融合，再行前路经口咽人路磨除齿状突的联合手术，安全可靠、效果好。     

Endoscopic transnasal odontoidectomy to treat basilar invagination with congenital osseous malformations

Purpose

Transoral resection of the odontoid has been accepted as a standard procedure to decompress the cervicomedullary junction during the past several decades. The endoscopic transnasal odontoidectomy is emerging as a feasible surgical alternative to conventional microscopic transoral approach. In this article, we describe several operative nuances and pearls from our experience about this approach, which provided successful decompression.

Methods

From September 2009 to April 2010, three consecutive patients with basilar invagination, of which the etiology was congenital osseous malformations, underwent endoscopic transnasal odontoidectomy. All patients presented with myelopathy. The last two cases also received occipitocervical fixation and bone fusion during the same surgical episode to ensure stability.

Results

All the patients were extubated after recovery from anesthesia and allowed oral food intake the next day. Cerebrospinal fluid rhinorrhea was found in the second case and cured by continuous lumber drainage of cerebrospinal fluid. No infection was noted. The average follow-up time was more than 24 months. Remarkable neurological recovery was observed postoperative in all patients.

Conclusion

The endoscopic transnasal odontoidectomy is a feasible approach for anterior decompression of pathology at the cervicomedullary junction. The advantages over the standard transoral odontoidectomy include elimination of risk of tongue swelling and teeth damaging, improvement of visualization, alleviation of prolonged intubation, reduction of need for enteral tube feeding and less risk of affecting phonation. The minimally invasive access and faster recovery associated with this technique make it a valid alternative for decompression of the ventral side of the cervicomedullary junction.     

Transoral-transpharyngeal approach to the anterior craniocervical junction. Ten-year experience with 72 patients

The anterior transoral-transpharyngeal operation to correct ventral irreducible compression of the cervicomedullary junction was utilized in 72 individuals. The patients' ages ranged from 6 to 82 years, and 29 were children. The pathology encountered was primary basilar invagination, rheumatoid irreducible cranial settling, secondary basilar invagination due to migration of odontoid fracture fragments, dystopic os odontoideum, granulation masses, clivus chordoma, osteoblastoma, and chondroma of the atlas. Fifteen patients had associated Chiari malformation with basilar invagination. Fifty-two patients required subsequent atlantoaxial or occipitocervical fusion. Neurological improvement was the rule. There were two deaths within 30 days of surgery: one from myocardial infarction 4 weeks after surgery and one from Gram-negative septicemia of urinary tract origin. There was one pharyngeal wound infection. The ventral transoral approach provides a safe, rapid, and effective means for decompression of the abnormal craniovertebral junction.     

Combined anterior and posterior approach for managing basilar invagination associated with type I Chiari malformation

Ventral brainstem compression is common in patients with basilar invagination associated with type I Chiari malformation. The aim of this study was to investigate the reliability of a combined one-session anterior-posterior surgical approach for these patients. Nine patients underwent transoral odontoidectomy, posterior foramen magnum decompression, occipitocervical fixation, and bone grafting. All but two patients had ventral and dorsal operations in one surgical sitting. One of these two individuals had previously undergone posterior decompressive surgery at another hospital, but his condition had deteriorated rapidly afterward. The mean follow-up time was 19 months (range, 14-30 months). There was no mortality and no significant morbidity in this series. All but one of the patients showed significant improvement in their symptoms. Chiari malformations have a surprisingly high association with basilar invagination, and patients may have symptoms in both conditions. If there is a marked anterior compression, anterior transoral and posterior decompression, fusion, and instrumentation is an optimal strategy for treating patients with basilar invagination associated with type I Chiari malformation.     

Endoscopic endonasal resection of the odontoid peg for paediatric basilar invagination

Osteogenesis imperfecta (OI) is a genetic disorder whose primary manifestations are fractures, bone deformity and bone pain. Brainstem compression due to basilar invagination is a rare and potentially life-threatening complication of OI. Children with this condition often require significant medical input and multiple admissions to hospital. Traditionally, anterior decompression is carried out through an open trans-oral route. We describe an endoscopic endonasal approach for resection of the peg in a child with OI and basilar invagination. We believe this approach provides an excellent alternative with minimal morbidity and decreased length of stay especially in the paediatric population.     

内镜辅助经高颈前咽后入路治疗颅颈交界区脊椎病变

目的 探讨内镜辅助下经高位颈前咽后入路治疗颅颈交界区脊椎病变的可行性和临床疗效.方法 2007年4月至2009年10月,治疗19例颅颈交界区脊椎病变患者,男9例,女10例;年龄16～62岁,平均41.6岁;陈旧性齿突骨折合并脱位5例,单纯寰椎脱位2例,游离齿突6例,Marfan综合征1例,Kippel-Feil综合征合并颅底凹陷1例,枢椎肿瘤3例,寰枢关节类风湿关节炎1例.均采用内镜辅助下经高位颈前咽后人路完成前路手术操作,其中8例行寰枢关节前路松解复位,8例行齿突切除减压,3例行肿瘤全切与重建.同时一期行后路固定植骨融合术,其中13例采用寰枢椎椎弓根钉固定融合,4例行枕颈融合,2例行C1～C3椎弓根固定融合.结果 8例复位患者均获得解剖复位,8例齿突切除患者行部分或全部齿突切除,3例肿瘤病灶均完全切除.随访6～36个月,平均14个月,全部病例均获骨性融合.14例术前有脊髓症状者末次随访时日本矫形外科学会(Japanese Orthopaedic Association,JOA)评分从术前(9.1±3.3)分提高到术后(14.1±2.9)分JOA改善率优7例,良5例,可1例,差1例.术中出现硬膜破裂1例,经生物蛋白凝胶封堵及术后腰椎蛛网膜下腔置管引流1周后治愈;术后出现吞咽障碍3例,均静脉应用地塞米松及甘露醇,术后3个月内均恢复正常.末次随访时,无一例患者发生感染及内固定松动.结论 内镜辅助经高位颈前咽后入路是治疗颅颈交界区病变的安全、有效、微创的方法.

Abstract：

Objective To assess the feasibility and clinical results of video-assisted high anterior transcervical approach (Smith-Robinson) in treatment of spinal lesions of the craniovertebral junction. Methods Between April 2007 to October 2009, nineteen consecutive patients with spinal lesions of the craniovertebral junction were included in the study. There were 9 males and 10 females aged from 16 to 62 years old with a mean of 32 years. The primary pathologies included 4 cases with chronic odontiod fracture, 2 cases with purely irreducible atlantoaxial dislocation, 6 cases with os odonteideum, 1 case with Marfan synd rome, 1 case with primary basilar invagination from Kippel-Feil syndrome, 3 case with axis tumor and 1 case with irreducible rheumatoid atlantoaxial dislocation. All of the patients underwent combined video-assisted high anterior transcervical procedure and posterior fixation at one-stage. The anterior procedure included atlantoaxil release and reduction (8 cases), odontoidectomy (8 cases), and intralesional extracapsular excision and reconstruction (3 tumor cases). The posterior technique were C1-C2 pedicle screw fixation (13 cases), C1-C3 pedicle screw fixation (2 cases), and occipitalcervical fusion (4 cases). Results Anatomical reduction was achieved in eight cases with anterior release and reduction. Tumors were completely removed in three cases with axial tumor. The mean follow-up was 14 months (6-36 months). All of them achieved solid bone fusion. In the 14 patients with symptoms of spinal cord dysfunction, the average Japanese Orthopaedic Association (JOA)score had improved from 9.1±3.3 preoperatively to 14.1±2.9 postperatively. The improvement rate was excellent for 7 cases, good for 5 cases, fair for lcase and poor for 1 case. One patient experienced leakage of cerebrospinal fluid which was resolved by bioprotein gelatin blocking and lumbar subarachnoid continuous drainage within 1 week. Dysphagia which occurred in 3 cases responded well to dexamethason and mannitol.No infection and hardware failure were observed. Conclusion Video-assisted high anterior transcervical procedure is a safe and effective alternative for treating spinal lesions in the craniovertebral junction.     

Treatment of basilar invagination with atlantoaxial dislocation: atlantoaxial joint distraction and fixation with transoral atlantoaxial reduction plate (TARP) without odontoidectomy

Purpose

Although direct transoral decompression and one-stage posterior instrumentation can obtain satisfactory cord decompression for the treatment of basilar invagination with atlantoaxial dislocation, surgical injuries run high as combinative anterior-posterior approaches were necessary. Furthermore, the complications will rise notably when involvement of dens and/or clivus in the decompression necessitates relatively complicated surgical techniques. First initiated in 2005, transoral atlantoaxial reduction plate (TARP) works as an internal fixation for the treatment of basilar invagination with irreducible atlantoaxial dislocation. Therefore, this article aimed to describe several operative experiences about this approach, which has delivered successful decompression, fixation and fusion.

Methods

21 consecutive patients with basilar invagination underwent the TARP operation. The pre- and postoperative medulla-cervical angles were measured and compared. The JOA scores of spinal cord function were calculated pre- and post-operatively. 20 cases (20/21) were followed up to average 12.5 months.

Results

Symptoms of all the 20 cases were relieved in different degrees. The postoperative imaging showed the odontoid processes obtained ideal reduction and the internal fixators were all in good position. The medulla-cervical angle was correctd from an average (± standard deviation) 128.7° + 11.9° (n = 20) before surgery to 156.5° + 8.1° (n = 20) after surgery (P < 0.01). The average preoperative and postoperative Japaneses Orthopedic Association scores were 11.25 (n = 20) and 15.9 (n = 20), respectively, indicating 76 % improvement. Screw-loosening was observed in one patient due to severe osteoporosis. After a revised operation with a TARP in another size, the neurological symptoms showed no obvious improvements. Then the treatment was terminated.

Conclusions

The TARP operation and intra-operative traction could reduce the odontoid process superiorly migrating into the foramen magnum, directly ease the ventral compression of spinal cord, and fix the reduced atlantoaxial joints through a single transoral approach without the need of a posterior operation. In this stury, 21 patients were evaluated and 20 did well with TARP operation. The preliminary clinical result was satisfactory.     

Basilar invagination: craniocervical instability treated with cervical traction and occipitocervical fixation. Case report

The upward odontoid displacement observed in basilar invagination (BI) is generally associated with a horizontal clivus and craniocervical kyphosis, conditions that exert ventral compression at the spinomedullary junction. Ventral brainstem decompression by reduction or elimination of the odontoid invagination is part of the desired treatment. The authors describe a case of BI in an adult, who was effectively treated with the easy and safe reduction of odontoid invagination via cervical traction. Normalization of kyphosis at the craniovertebral junction and the vertical position of both a previously horizontal clivus and the cerebellar tentorium demonstrated that these conditions were not part of the original malformation but instead were caused by a reducible craniovertebral instability.     

Halo traction in basilar invagination: technical case report

BACKGROUND: In the management of basilar invagination, traction therapy may help by pulling down the odontoid process away from the brain stem that may result in clinical and radiological improvement. We aimed to discuss the role of the halo vest apparatus traction on the reduction of severe anterior compression pathologies in basilar invagination. CASE DESCRIPTION: We describe a simple and safe cervical traction method by the halo vest apparatus that is followed by rigid posterior occipitocervical fixation and foramen magnum decompression in a patient who presented with basilar invagination and symptoms of severe brain stem compression. An MR-suitable halo vest apparatus was used for reduction of the deformity. The reduction of the basilar invagination was achieved gradually by distracting the halo crown in stages. CONCLUSION: The halo vest apparatus can be safely used in complex craniocervical junction anomalies. An effective cervical traction can be performed in basilar invagination, and reduction of the deformity may be achieved without the risk of overdistraction. In some cases, even partial reduction of the deformity may facilitate brain stem and spinal cord relief without any need of posterior decompression. Patients may benefit from ambulatory functions because bed rest is eliminated in this procedure. Neurovascular structures and the degree of the reduction can be observed on MRIs when an MR-suitable device is used.     

颅底凹陷合并难复性寰枢椎脱位术后齿状突下移程度对神经功能影响的临床研究

目的分析颅底凹陷合并难复性寰枢椎脱位术后齿状突下移程度与术后神经功能恢复的关系。方法回顾性分析2010—2018年在我院诊断为颅底凹陷合并难复性寰枢椎脱位并行后路减压治疗的患者19例,其中男10例,女9例;平均(41.89±14.27)岁;病程持续(42.61±70.71)个月。10例合并寰枕融合,7例合并Klippel-Feil综合征,4例合并椎动脉发育畸形,无病例合并小脑扁桃体疝及脊髓空洞等。测量术前及末次随访寰齿前间隙(anterior atlantodental interval,AADI)、斜坡齿突角(clivo-axial angle,CXA)及齿状突上移程度(the distance of the tip of odontoid to the McRae line,McRL),采用日本骨科协会评分(Japanese orthopaedic association scores,JOA)评估神经功能。对JOA评分改善率与齿状突下移率(odontoid descent rate,ODR)、寰齿前间隙变化(△AADI)和斜坡齿突角变化(△CXA)进行相关性分析。结果本组患者获得随访时间10~79个月,平均随访时间(20.42±8.24)个月。术前JOA为(11.21±2.62)分,末次随访JOA为(14.53±2.19)分,平均JOA改善率为(58.75±24.43)%。JOA评分改善率与ODR存在相关关系(R=0.88,P<0.05),与△AADI(R=0.07,P=0.77)及△CXA(R=-0.04,P=0.98)无明显相关性。结论难复性寰枢椎脱位合并颅底凹陷的手术疗效与齿状突复位率相关。     

Noonan syndrome with occipito-atlantal dislocation and upper cervical cord compression due to C1 dysplasia and basilar invagination

A 11-year-old female with Noonan syndrome presented with occipito-atlantal dislocation and upper cervical cord compression due to C1 dysplasia and basilar invagination. Computed tomography (CT) of the cervical spine showed dysplasia of the C1 posterior arch and bilateral dislocation of the occipito-atlantal joints. Dynamic lateral radiography revealed no instability at the occipito-atlantal joints. CT also demonstrated basilar invagination. The tip of the odontoid process extended above the Chamberlain line by 9 mm and the McGregor line by 10 mm. Whole spinal radiography showed no scoliosis. C1 laminectomy was performed with instrumented occipito-C2 fixation. The postoperative course was uneventful, and magnetic resonance imaging revealed sufficient decompression of the upper cervical cord at 2 months after surgery. CT demonstrated solid bony fusion between the occipital bone and C2 at 8 months after surgery. Cervical neuraxial malformations are rare in patients with Noonan syndrome.     

Circumferential decompression of the foramen magnum for the treatment of syringomyelia associated with basilar invagination

Posterior fossa decompression utilizing suboccipital craniectomy and duraplasty remains the standard surgical treatment for Chiari-associated syringomyelia. In the presence of basilar invagination, anterior decompression, typically transoral odontoidectomy, or posterior decompression may be performed. We report two cases in which anterior and posterior (circumferential) decompression of the foramen magnum was used to treat cervical syringomyelia successfully. These cases demonstrate that circumferential decompression of the foramen magnum may be necessary in some cases of cervical syringomyelia associated with basilar invagination and Chiari malformation.     

前路经口减压后路固定和枕骨大孔减压治疗颅底凹陷症

目的 探讨前路经口寰枢关节松解减压后路固定融合术（TAAR）与后路枕骨大孔减压术（FMD）治疗颅底凹陷症的疗效.方法 对18例颅底凹陷患者采用TAAR治疗9例、FMD治疗9例.术前测量Chamberlain 线、McRae线、Wackenheim线、寰齿前间距（AID）、Klaus高度指数及延脊髓角;记录患者手术时间、术中出血总量.应用JOA颈椎病疗效判定标准,比较两种方式的疗效.结果 McRae线、Wackenheim线和AID值TAAR组均明显大于FMD组,差异有统计学意义（P＜0.05）.Chamberlain 线值、Klaus值和延脊髓角度指标两组间差异均无统计学意义（P＞0.05）.JOA评分：TAAR组优4例,良3例,好转1例,差1例;FMD组优7例,良1例,好转1例;两组比较差异无统计学意义（P＞0.05）.结论 对有固定寰枢关节脱位颅底凹陷症且齿状突高于McRae 线和Wackenheim线者行TAAR,对无寰枢关节脱位且齿状突低于McRae 线和Wackenheim线者行FMD,两种方法疗效相当.     

Transoral operations for craniospinal malformations

The transoral approach to the lower third of the clivus and to the ventral aspect of the upper cervical spine is used in craniospinal malformations with or without dislocation as well as in basilar aneurysms, ventrally situated cranio-spinal tumours, fractures of the odontoid process, and in rheumatoid arthritis compressing the spinal cord. In consideration of the literature and ten personal cases the indications and techniques of the transoral approach in craniospinal malformations are discussed. According to our own experiences and those of other authors it is possible to expose the lower clivus and the cervical spine down to C2 by a midline incision of the pharyngeal wall using a mouth retractor and oral intubation. Splitting of the soft palate or resection of the hard palate are not necessary, a tracheotomy should be performed only in exceptional cases. In congenital craniospinal malformations without dislocation or instability causing a ventral compression of the spinal cord, for instance by the odontoid process, the transoral decompression is preferable to dorsal decompressing operations. In cases of pure instability without any space-occupying lesion the transoral and posterior approach are possible in order to perform a fusion. The last one seems more advantageous in these cases. In craniospinal malformations with dislocation causing a ventral and dorsal narrowing of the spinal canal, apart from the decompression a stabilization has to be achieved. In these usually complex malformations individual treatment is necessary. According to the rare cases in the literature and to our own experience a primary anterior decompression, followed by a most careful posterior stabilization seems to produce the most favourable results.     

Transoral approach for the treatment of atlanto-axial dislocation with the Os odontoideum and obstruction of the bilateral vertebral arteries (author's transl)]

The two approaches are well-known in the surgical treatment of atlanto-axial dislocation, the one is the anterior and the other is the posterior approach. The indication of these methods is still controversial. This report concerns with one case of atlanto-axial dislocation with the separate odontoid and bilateral obstruction of both vertebral arteries, which was successfully treated by transoral decompression and fusion between the bodies of the atlas and axis. The reasons why we chose this method were: (1) the spinal cord decompression was necessary because of the presence of compression of the cord by the separate odontoid process, (2) the spinal fusion had to be performed to stabilize the atlanto-axial articulation, (3) it was necessary to avoid the damage of collateral circulations to the brainstem through the deep cervical arteries demonstrated by bilat vertebral angiography. The posterior approach is highly susceptible to injure these collateral circulations.     

Endoscopic endonasal odontoidectomy for basilar invagination in children: Literature review and case report

BackgroundBasilar invagination (BI) is an uncommon clinical condition of the craniocervical junction (CCJ). Surgical management depends on 2 factors: mobility and reducibility; in cases of irreducible dislocation or persistent compression, odontoidectomy should be considered.Case discussionWe present the case of a 13-year-old boy with severe BI, causing cervical myelopathy with progressive gait disorder. The patient underwent cervical traction followed by posterior decompression and occipitocervical fusion. Postoperatively, symptoms initially improved, until new neurological deterioraton set in 4 months later. Follow-up neuroimaging showed compression of the bulbo-medullary junction, with severe brainstem kinking and appearance of a cervical syrinx. Secondary surgery via an endoscopic endonasal approach (EEA) was deemed necessary to relieve the compression. Postoperative course was unremarkable, with steady clinical improvement and a return to independent activities of daily living within 6 months.Literature reviewA systematic literature review indicated that EEA conserves the palate and oropharynx mucosae, thus causing less airway and swallowing complications than the transoral approach.ConclusionIn selected cases with persistent anterior compression, odontoidectomy on EEA is a safe, effective and valid alternative for managing CCJ pathology.     

Endoscopic transcervical anterior release and posterior fixation in the treatment of irreducible vertical atlantoaxial dislocation

Vertical atlantoaxial dislocation is a type of atlantoaxial instability with upper cervical spinal cord compression. The transoral ondontoid resection with posterior fixation is the gold standard for ventral decompression. Results are satisfying though surgery can be challenging due to its invasiveness. The endoscopic transcervical anterior release could provide sufficient ventral decompression with less collateral damage. In the illustrative case, anatomic reduction was achieved with significant improvement in neurological function and radiographic parameters. Endoscopic transcervical anterior release and posterior fixation appears to be a viable and interesting alternative for the treatment of vertical atlantoaxial dislocation in properly selected individuals, and its implementation could significantly reduce the post-surgical complications.