The craniovertebral region is the region where the lower part of the occipital bone forms the C-1 (atlas) and C-2 (axis) vertebrae. This region is the region where the spine is most active, such as the lumbosacral region at the waist. Many congenital and acquired diseases of this region cause advanced neurological deficits. Platibasi and basilar invagination anomalies were first described by Meckel and Glad Stone in 1815. However, after the Chamberline classical radiological study in 1939, the treatment protocol developed gradually. The basal angle is the line joining the plane of the clivus to the anterior fossa ( Mc rae 120-140 C, Boogard 118-147 C. There are two types of basilar invagination. In the anterior type, the basioccipit is short and the clivus is bedded together with platibasi. Paramedian basilar, the second type of basilar invagination. Invagination usually shows developmental disorder of the occipital bone and occiptal condylar hypoplasia.Therefore, the clivus is displaced towards the posterior fossa.
Surgical treatment of this type of anomalies in the early 1900’s was posterior decompressions and the posterior parts of the atlas and axis vertebrae were removed and at the same time. Fusion surgeries were performed with bone graft. However, post-operative death and disability were observed in a significant number of patients who were not resected by this type of surgery and when anterior bone compression occurred.In recent years, innovations in neuroradiology and neuroanesthesia and the development of microsurgical techniques have been used in the surgical treatment of skull base and cranio-vertebral junction anomalies. Significant contributions have been made.
Factors related to treatment
1: Reductability
2: Mechanics of compression and direction of pressure
3: cause of lesion (basilar invagination, rheumatoid arthritis, paget’s disease) )
4: Ephyseal growth in presence of ossification and prominent congenital anomalies
Description
Basilar invagination is a primary developmental disorder, which is the eastern displacement of the neck vertebrae to the skull base. Sometimes it is associated with developmental anomalies of the region such as fusion defects of the atlas or block veretebrae. Medical terms such as basilar invagination, basilar impression, and platibase are not synonymous.
After basilar invagination is a developmental defect, there is displacement of the upper cervical spines into the skull base. In these developmental bone anomalies, occipitalization of the atlas and block are seen together with vertebral anomalies. Cerebellum prolapse and syringomyelia are seen together in 25-30% of craniovertebral junction anomalies.
The term basilar impression is the medical name given to secondary or subsequent events due to softening of the skull bones. In diseases such as spasmodic torticollis and osteomalacia and rheumatoid arthritis, basilar impression occurs after erosions in the lateral mass of the atlas. Other than these diseases, hyperparathyroidism, Paget’s disease and osteogenesis imperfakta, rickets disease, inflammatory diseases that affect or do not affect the stability of the spine are among the causes.
The term platybasis is the term given to the abnormal basal angle formed by the anterior skull base plan and the clivus. Platabasi on its own is not to give any complaints or findings. Platybaceous coexistence with basilar impression. Some reference points are defined on direct cervical lateral radiographs. The odontoid process bi-mastoid line should not exceed more than 10 mm. The chamberline is the line that extends from the hard palate to the posterior margin of the foramen magnunum. The chamberline line should not exceed 2.5 mm from the odontoid process. Neurological deficits are seen when the effective sagittal diameter of the foramen magnum is less than 19 mm. Cerebellum prolapse is common with basilar invagination. Young adolescents aged 12-14 years have reductable craniovertebral junction anomalies. For the first time in cerebellum prolapse with irreductable basilar invagination, it was operated with oral decompression. However, in patients who underwent posterior decompression without this surgery, additional new neurological deficits emerged instead of recovery. Therefore, posterior fossa decompression and CSF circulation should be corrected after ventral pressure is removed first. Paget’s disease co-occurrence of basilar impression is quite high and they usually present after the age of 40.
Rheumatoid arthritis causes occipito atlanto-axial instability in patients with rheumatoid arthritis after the lateral atlanto-axial joints slide into the skull. Here, the odontoid process slides vertically upwards. Other causes include psoriasis, systemic lupus erythematosus, spasmatic torticollis, and chronic traumas.
Diagnosis
Cervical MRI is an important test method primarily in the evaluation of the cranio-cervical junction. However, MRI is insufficient for the evaluation of bone structures in this region. Dynamic radiographs of the cervical region such as flexion and extension should be performed. In the reduction of neck bones, MR compatible halo devices and neck traction are very important in correcting the alignment of the vertebrae. Computerized Tomography test of the neck region with 3D thin sections is important in diagnosis.
Treatment
Treatment principles of anomalies of craniocervical vertebrae, reduction and stabilization of reducible lesions should be performed. In non-reducing lesions, decompression of normal tissues and stabilization should be done for the instability that may occur. Immobilization alone is sufficient in acute traumatic atlanto-axial dislocations, ligament tears and post-inflammatory instability. If traction or halo traction is used, if fusion occurs within 2-3 months with immobilization, there is no need for further treatment, but if fusion does not occur, posterior surgery should be planned.
Transoral and transpharyngeal approach is an effective way in patients with anterior compression. Posterior occipito-cervical fusion surgeries are required in most patients undergoing such an operation. If the odontoid process herniates more than 20 mm into the foramen magnum in a patient with rheumatoid arthritis, since the alignment of the craniovertebral junction vertebrae with cervical traction will not be corrected, reduction of the spine should be performed first with halo-skeletal traction accompanied by narcosis.
In conclusion
craniovertebral junction anomalies are quite complex diseases. First of all, it is necessary to distinguish congenital or acquired diseases very well. The direction and type of bone compressions should be eliminated very well. Each patient should be examined in detail and a decision should be made, depending on whether they have clinical complaints or not. If patient evaluations are made without adequate examination and examination, it will be insufficient. Complaining basilar invaginations should be treated.
