The condylus occipitalis fracture is rare and present in only 0.4% of all trauma patients. Neurological deficits are extremely rare but can develop over time in the form of mono-, para-, or tetraparesis or plegia. Hypoglossal nerve palsies have also been described.
Epidemiology
The fracture is extremely rare. The incidence is only 0.4% in a series of 24,745 trauma patients from 2009 (Maserati et al.).
Clinical presentation
Patients usually have neck pain and/or restricted head mobility (flexion, extension, rotation, lateral bending). Very rarely, a hypoglossal nerve palsy or swelling in the retropharyngeal space may occur. More severe deficits such as mono-, para-, or tetraparesis/plegia are usually associated with additional fractures.
Radiological findings
The imaging modality of choice is computed tomography with bone window settings. The occipital condyle fracture is not visible on standard X-rays. An indirect sign can be an increased distance (>2 mm) between the occipital condyle and C1 (atlanto-occipital interval – AOI). Additional MRI is useful for assessing ligamentous structures (alar ligament, transverse ligament, apex dentis ligament, tectorial membrane).
Points to consider
Classifications
There are several classification systems for fractures of the occipital condyles. The most widely used is that of Anderson & Montesano (1988); other systems such as the “Tuli”, “Maserati” or “Harborview” classification are also common.
Anderson & Montesano classification
- Type I: Comminution of the occipital condyle
- Type II: Fracture of the occipital condyle as an extension of a fracture at the foramen magnum
- Type III: Avulsion of the occipital condyle caused by the alar ligament
Indication for surgery
Normally, there is no indication for surgery. Type I/II fractures can be treated with or without a rigid cervical collar. Type III fractures should be immobilized for 6–8 weeks (rigid collar or halo). In cases of bilateral condylus occipitalis fractures, unilateral fracture with ligamentous involvement, or proven instability, immobilization is also indicated for type I/II fractures.
Outcome
The outcome for isolated condylus occipitalis fractures is very good. In the series by Maserati et al. with 100 patients, none of the non-operated patients (n=97) showed neurological deficits, instability, or misalignment in the long-term follow-up.