The clivo-axial angle (CAA) is a key radiological measurement used to assess the alignment of the craniocervical junction, particularly in the context of conditions like platybasia and basilar invagination.

### Clivo-Axial Angle - It is the angle formed between the clivus (the slope of the skull base) and the axis of the odontoid process (C2 vertebra). - A normal clivo-axial angle is typically between 150° and 165°. - A reduced angle (less than 135°) is often associated with abnormalities in the craniocervical junction, such as brainstem compression or cervicomedullary compression.

### Platybasia Platybasia is a flattening or abnormal broadening of the skull base. This condition is often linked to: - A decreased clivo-axial angle. - Associated with conditions like Chiari malformation, basilar invagination, and other congenital or acquired craniovertebral junction abnormalities.

### Clinical Implications - A reduced clivo-axial angle in the context of platybasia can lead to brainstem compression and associated neurological symptoms like dysphagia, dysarthria, and upper motor neuron signs. - Imaging, including MRI and CT, is essential for accurately measuring this angle and evaluating the degree of compression.

Assessment of the clivo-axial angle in cases of platybasia is crucial for determining the need for potential surgical interventions like posterior fossa decompression or craniocervical stabilization.