Basilar invagination

Basilar invagination is a rare but significant structural disorder where the tip of the odontoid process (the uppermost part of the second cervical vertebra) projects into the cranial cavity, causing impingement on the lower brainstem and upper spinal cord. This condition can lead to a variety of neurological deficits and symptoms due to the compression of neural structures. Basilar invagination can be congenital, resulting from developmental anomalies, or acquired, due to conditions such as rheumatoid arthritis, Paget's disease, or trauma.

Etiology

Basilar invagination can be classified into two main types based on its etiology: congenital and acquired.

• Congenital basilar invagination is often associated with other developmental anomalies such as Klippel-Feil syndrome, Chiari malformation, and syringomyelia. These conditions can contribute to the abnormal bone growth that characterizes basilar invagination.
• Acquired basilar invagination may develop as a result of bone diseases like Paget's disease, osteogenesis imperfecta, or inflammatory conditions such as rheumatoid arthritis. Trauma to the cervical spine can also lead to this condition.

Symptoms

Symptoms of basilar invagination vary depending on the extent of compression on the brainstem, spinal cord, and surrounding nerves. Common symptoms include:

• Neck pain
• Headaches, especially in the back of the head
• Weakness or numbness in the limbs
• Difficulty walking
• Dizziness or vertigo
• Visual disturbances
• Difficulty swallowing (dysphagia)
• Irregular breathing patterns

Diagnosis

Diagnosis of basilar invagination involves a thorough clinical evaluation and imaging studies. Magnetic resonance imaging (MRI) is the preferred method as it provides detailed images of the craniovertebral junction, allowing for the assessment of the extent of neural compression. Computed tomography (CT) scans are also useful in evaluating the bony structures and the degree of odontoid process invagination.

Treatment

Treatment of basilar invagination aims to relieve compression of the neural structures and stabilize the craniovertebral junction. Options include:

• Conservative management with medications to relieve symptoms such as pain and inflammation.
• Surgical intervention is considered for patients with significant neurological deficits or when conservative management fails. Surgical procedures may involve decompression of the neural structures and stabilization of the spine through fusion techniques.

Prognosis

The prognosis for individuals with basilar invagination varies. Early diagnosis and appropriate treatment can lead to significant improvement in symptoms and quality of life. However, untreated or severe cases may result in progressive neurological deficits and complications.

See also

• Cervical vertebrae
• Craniovertebral junction
• Neurological disorders