Craniovertebral Junction

24 Craniovertebral Junction

Anatomy

See Chapter 2.9, page 57.

Embryology

See Chapter 4, page 98.

Pathology

Table 24.1 summarizes the main pathologies of the craniovertebral junction (CVJ).¹

Signs and Symptoms

• Pain is the most typical symptom in CVJ pathologies.

• Compressive myelopathy: weakness and clumsiness of the hands with or without spasticity of the extremities, sensory abnormalities.

• Classically, the sensory and/or motor findings start in the ipsilateral arm and then in the ipsilateral leg, followed by the contralateral leg and finally the contralateral arm.

Examination Pearl

To identify CN XI palsy, determine the presence of sternocleidomastoid and trapezius muscles atrophy. Note that slowly progressive pathologies provide time for the patient to compensate for shoulder movement by muscle groups innervated by nerves other than CN XI.

Table 24.1 Main Pathologies* of the Craniovertebral Junction

Developmental	• Malformations of the C0–C2 complex • Basilar invagination • Basilar impression in Paget’s disease, osteogenesis imperfecta • Rheumatoid arthritis • Deformities related to hyperparathyroidism, arthropathies, osteomyelitis, tuberculosis, and other conditions • Chiari malformation
Neoplastic	• Meningioma, schwannoma, neurofibroma, arachnoid cyst • Benign primary osseous lesions: aneurysmal bone cyst, benign giant cell tumor, osteoblastoma, osteochondroma, osteoid osteoma, eosinophilic granuloma, solitary plasmacytoma, hemangioma • Malignant lesions: chordoma, myeloma, lymphoma, chondrosarcoma, osteosarcoma, Ewing’s sarcoma, fibrosarcoma, hemangiopericytoma • Metastases • Central nervous systems tumors: astrocytomas, ependymomas
Traumatic	Fractures of the clivus, occipital condyles, odontoid, hangman’s fracture, C2 vertebral body; atlanto-occipital dislocation; ligamentous disruptions
Vascular	Spinal arteriovenous malformations, vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms, cavernous malformations of the cervicomedullary junction

*Congenital and acquired.

• Lower cranial nerve deficits, especially in CNs XI and XII.

• Internuclear ophthalmoplegia, downbeat nystagmus.

• Sleep apnea.

• Vertebrobasilar ischemia.

Surgical Approaches

The goals of surgery in the CVJ are (1) to decompress neurovascular structures; (2) to alleviate pain and stop the progression of neurologic deterioration; (3) to restore, whenever indicated, the stability of the junction; and (4) in the case of neoplastic disease, to resect the lesion as completely as possible and make a tissue diagnosis.

Table 24.2 Approaches to the Craniovertebral Junction

Anterior/anterolateral

• Transoral (± extensions/variants, e.g., ± transmaxillary, translabiomandibular, transpalatal, transglossal, etc.)

• Transnasal endoscopic

• Combined endoscopic transoral-transnasal

• Retropharyngeal

Lateral/posterolateral

• Subtemporal with anterior petrosectomy

• Posterior or extended transpetrosal

• Retrosigmoidal

• Far lateral transcondylar transtubercular

Posterior

• Suboccipital ± upper cervical laminectomy

• According to the nature and localization of the disease (e.g., ventral compression of the cervicomedullary junction caused by chordoma or dens displacement), the CVJ can be approached via anterior/anterolateral, lateral/posterolateral, and posterior approaches 1 (Table 24.2).

Extended Endonasal Transclival Approaches to the CVJ

See Chapter 16, page 426.

Transoral Odontoidectomy:

The use of self-retaining retractors enables greater spreading of the space and better access to the clivus, the anterior arch of C1, and C2, and is highly recommended.