Headache due to an extra joint between head and neck

A girl, born in 1973, started having headache in preschool age. After a head trauma in 1985, there was a clear worsening of the headache, and the headache became chronic at around 14 years, making regular school attendance impossible. The headache was "symptom poor," bilateral-occipital, but with a clear left-sided preponderance and occasionally spreading to the forehead. The headache was always worst in the morning hours, easing up by noontime. Neck rotation to the right could provoke long-lasting exacerbations. Neck movement was restricted on rotation to the left. A sore bony structure was discovered on palpation just underneath the mastoid process of the left side. This proved to correspond to a bony "bridge" with an extra joint between the first vertebra on the left side and the skull, medially to the mastoid process that could be demonstrated on x-ray tomography and CT scanning. This bony bridge was removed surgically more than 2 years ago, and the pain disappeared on the day of operation and has not recurred in the intervening time. Such bony bridges have in the past been considered to be innocuous and not symptom producing. Although this may be the general rule, the present case tends to show that even to this rule, there are exceptions.