Transtubular Transoral Approach for Irreducible Ventral Craniovertebral Junction Compressive Pathologies: Surgical Technique and Outcome

@#Introduction: To investigate the use of a tubular retractor to provide access to the craniovertebral junction (CVJ) sparing the soft palate with the aim of reducing complications associated with traditional transoral approach but yet allowing adequate decompression of the CVJ. Materials and methods: Twelve consecutive patients with severe myelopathy (JOA-score less than 11) from ventral CVJ compression were operated between 2014-2020 using a tubular retractor assisted transoral decompression. Results: All patients improved neurologically statistically (p=0.02). There were no posterior pharynx wound infections or rhinolalia. There was one case with incomplete removal of the lateral wall of odontoid and one incidental durotomy. Conclusions: A Tubular retractor provides adequate access for decompression of the ventral compression of CVJ. As the tubular retractor pushed away the uvula, soft palate and pillars of the tonsils as it docked on the posterior pharyngeal wall, the traditional complications associated with traditional transoral procedures is completely avoided.

Anatomy of endoscopic odontoidectomy via submandibular approach / 解剖学报

Objective To provide the basis for endoscopic craniocervical junction surgery through cervical CT image and endoscopic odontoid process anatomy of atlas, axis and odontoid. Methods A total of 150 cases of cervical vertebrae were selected for high resolution thin slice plain CT measurement to evaluate the atlantoaxial structure and its adjacent structure, and to estimate the safe boundary of odontoid process resection. The atlantoaxial odontoid process was anatomized on 3 cadaver head specimens under endoscope through the submandibular approach using STORZ endoscopy system and endoscopic surgical instruments. Results The average length of atlas anterior arch and other anatomical marks were measured by CT, and the safety boundary area of odontoidectomy was estimated to be（240.9 ± 39.92）mm~2, male:（248.3 ± 49.64）mm~2, Female:（233.2 ± 24.54）mm~2. Through the submandibular endoscopic approach, the atlantoaxial anatomy and odontoidectomy anatomy made a transverse incision at the midpoint of the connecting line between one mandibular angle and hyoid bone to expose the submandibular triangle area. Under the endoscope, the digastric muscle and the greater angle of hyoid bone were exposed through the submandibular triangle area, and the retropharyngeal space was passively separated layer by layer to the prevertebral space to expose the prevertebral fascia. After removing the prevertebral tissue, the atlas, the dentate process of the axis, the atlantooccipital joint, the atlantoaxial joint, and part of the foramen magnum were fully exposed. Conclusion Estimating odontoid resection safety boundary area by CT image, in combination with endoscopic odontoidectomy anatomy via sunbmandibular approach, we can perform the surgery safely and efficiently under the bright of endoscope with surgical instruments, which can significantly reduce the incidence of cerebrospinal fluid leakage and postoperative infection while decompressing.

Feasibility of full-endoscopic posterolateral odontoidectomy / 西安交通大学学报(医学版)

【Objective】 To investigate the feasibility of full-endoscopic posterolateral odontoidectomy through morphological analysis and cadaver specimen surgery. 【Methods】 We collected the DICOM data of 20 normal cervical CT patients （10 males and 10 females） from the PACS Image Library of our hospital. The Mimics software was used for cervical CT reconstruction and anatomical measurements were made to measure the maximum sagittal diameter， coronal diameter and height of the odontoid process. The C1 lateral mass could provide the maximum working height and width of endoscopic operation with a diameter of 7 mm， as well as the angle between the anchor point of C1 lateral mass and the notch on both sides of the odontoid process. The feasibility of endoscopic surgery was analyzed based on the measured data. The fresh frozen corpse was used for the operation in prone position under the guidance of C-arm. Kirschner wire was anchored at the midpoint of the lower surface of the C1 lateral mass. Part of the C1 lateral mass was removed by the grinding drill and endoscopic tools， and then the odontoid process and adjacent ligaments were removed. 【Results】 The maximum sagittal diameter， coronal diameter and height of the odontoid process were （11.73±0.74）mm， （10.97±0.71）mm and （14.51±0.91）mm， respectively. The working height and width of the C1 lateral mass were （13.53±0.57）mm and （10.00±1.27）mm， respectively. The angle between the anchor point and the double-edge notch of the odontoid process was （28.3±3.1）°， with no statistical difference between the male and female patients （P>0.05）. All the measurements met the requirements of 7 mm endoscopic implantation and surgical operation， and the space for swing could be provided for complete or partial removal of the odontoid process to meet the requirements of ventral spinal decompression. In cadaver surgery， a fully endoscopic posterolateral approach enabled complete removal of the odontoid process by grinding part of the C1 lateral mass. Postoperative cervical CT confirmed that the odontoid process had been completely resected， and there were no signs of dural sac or vertebral artery injury. 【Conclusion】 The odontoid process can be completely resected through a posterolateral endoscopic approach via the lateral mass approach of C1， providing a new surgical method for clinical odontoidectomy to decompress the spinal cord in craniovertebral junction.

Surgical freedom of odontoidectomy via endoscopic endonasal approach / 西安交通大学学报(医学版)

【Objective】 To quantitatively analyze the surgical freedom of odontioectomy via endoscopic endonasal approach. 【Methods】 Seven adult head specimens were dissected by the endoscopic transnasal approach to the sellar region and craniocervical junction. The center of sellar floor (CenSF), opticocarotid recess (LOCR), foramen magnum, atlas, atlas-occipital joint and tip of odontoid process (TOP) were exposed. The surgical freedom of TOP was calculated by using the spatial coordinate positioning system of neuronavigation, and compared with that of LOCR and CenSF. 【Results】 CenSF and LOCR were common landmarks in the endonasal endoscopic approach. When the surgical freedom between TOP and CenSF and LOCR was compared, it indicated that ① The angle of attack on axial plane (AAAP):There was a significant difference among TOP, LOCR and CenSF (5.7 ° vs. 6.9 ° vs. 8.5 °, P=0.004). The comparison between the two groups showed that TOP was less than CenSF (P=0.003). ② The angle of attack on sagittal plane (AASP): There was a significant difference among TOP, LOCR and CenSF (6.3° vs. 7.0° vs. 9.5°, P=0.009). The TOP was less than CenSF (P=0.008). ③ There was no statistical significance between TOP and LOCR in surgical freedom (P=0.604, P=0.688). 【Conclusion】 Endoscopic transnasal approach can provide sufficient surgical freedom for odontoidectomy.

Endoscopic Endonasal Odontoidectomy: Nuances of Neurosurgical Technique / Odontoidectomia endoscópica endonasal: nuances da técnica cirúrgica

Odontoidectomy is the treatment of choice for some diseases that cause irreducible ventral compression of the brainstem. In this study, we present our series emphasizing the technical nuances of endoscopic endonasal odontoidectomy

Odontoidectomia é o tratamento de escolha para algumas doenças que cursam com compressão irredutível do tronco encefálico. Neste trabalho, apresentamos nossa série enfatizando as nuances da técnica cirúrgica da odontoidectomia por via endonasal endoscópica.

Transoral approach to the craniovertebral junction

The transoral approach provides a safe exposure to lesions in the midline and the ventral side of the craniovertebral junction. The advantages of the transoral approach are 1) the impinging bony pathology and granulation tissue are accessible only via the ventral route; 2) the head is placed in the extended position, thus decreasing the angulation of the brainstem during the surgery; and 3) surgery is done through the avascular median pharyngeal raphe and clivus. We analyzed the clinical effects of odontoidectomy after treating 38 patients with basilar invagination. The anterior transoral operation to treat irreducible ventral compression in patients with basilar invagination was performed in 38 patients. The patientsÆ ages ranged from 34 to 67 years. Fourteen patients had associated Chiari malformation and eight had previously undergone posterior decompressive surgery. The main indication for surgery was significant neurological deterioration. Symptoms and signs included neck pain, myelopathy, lower cranial nerve dysfunction, nystagmus and gait disturbance. Extended exposure was performed in 24 patients. The surgery was beneficial to the majority of patients. There was one death within 10 days of surgery, due to pulmonary embolism. Postoperative complications included two cases of pneumonia, three cases of oronasal fistula with regurgitation and one cerebrospinal fluid leak. In patients with marked ventral compression, the transoral approach provides direct access to the anterior face of the craniovertebral junction and effective means for odontoidectomy.

O acesso transoral é uma via direta e segura às lesões situadas na linha média e na face anterior da junção craniocervical. As vantagens do acesso transoral são as seguintes:1) a compressão óssea e o tecido de granulação localizam-se anteriormente e são accessíveis pela via anterior; 2) a cabeça do paciente é colocada em extensão, diminuindo a angulação do tronco cerebral durante a cirurgia; e 3) a cirurgia é feita através de um plano avascular na linha média faríngea e clivo. Analisamos os resultados obtidos após odontoidectomia por via transoral em 38 pacientes portadores de invaginação basilar. Trinta e oito pacientes com compressão ventral da junção craniocervical foram submetidos a odontoidectomia por via transoral. A idade dos pacientes variou de 34 a 67 anos. Quatorze pacientes apresentavam associação com malformação de Chiari tipo I e 8 já haviam sido submetidos à cirurgia descompressiva por via posterior. A maioria dos pacientes apresentou nucalgia, mielopatia, déficits dos nervos cranianos baixos, nistagmo, e distúrbio da marcha. Em 24 pacientes foi necessário ampliar o acesso transoral através de miotomia do palato mole, ou osteotomia do palato duro ou maxilotomia. A cirurgia proporcionou melhora dos sintomas na maioria dos pacientes. Um paciente faleceu no pós-operatório imediato por causa de embolia pulmonar. Dois pacientes tiveram pneumonia, três apresentaram fístula oronasal com regurgitação, e um teve fístula liquórica. Em pacientes com compressão ventral irredutível da junção craniocervical, a via transoral proporcionou uma abordagem direta e ampla ao processo odontoide.

A Case of Basilar Impression

A case of basilar impression surgically treated in a female patient aged 22 years is presented. A myriad of abnormal neurologic findings were present that were secondary to compression of neural tissue by anormalous bony structure at craniovertebral junction. Metrizamide computerized tomography with coronal and sagittal reconstruction identified bony abnomalities and displacement of the surrounding neural structures. The surgical intervention for the treatment of the basilar impression consisted of ventral decompression by transoral odontoidectomy and of dorsal decompression by an enlargement of foramen magnum and by laminectomy of C1, followed by occipito-atlanto-axial bony fusion.