Incidence of ponticulus posterior of the atlas in migraine and cervicogenic headache.
BACKGROUND: The clinical significance of the ponticulus posticus is far from clear. It has been associated with headaches, Barré-Lieou syndrome, photophobia, and migraine. However, little epidemiologic evidence for this exists. OBJECTIVE: This study investigated the relationship of ponticulus posticus on x-ray studies and headache symptoms in a series of chiropractic patients. METHODS: Eight hundred ninety-five patients who visited a chiropractic clinic for the first time and whose conditions required cervical spine x-ray examinations were studied. Complaints were categorized as migraine with aura, migraine without aura, cervicogenic headache, neck pain only, and other conditions. The presence or absence of the ponticulus posticus (whether partial or complete) was determined by means of a lateral cervical film and noted as a positive or negative finding. The data were analyzed by frequency analysis and Pearson's chi 2 test. RESULTS: Forty-six percent of the sample were men and the predominant complaint was neck pain (33%). Most patients were in the fourth decade of life. The frequencies of the other complaints were migraine with aura (7%), migraine without aura (4%), cervicogenic headache (22%), other conditions (33%). An 18% prevalence of ponticulus posticus was found. This finding was significantly associated with migraine without aura (chi 2 = 4.97; P = .03) and not with any other conditions. CONCLUSION: In a chiropractic patient population that required cervical x-ray examinations, a significant association was found between ponticulus posticus and migraine without aura, with an odds ratio of 2.19:1 in favor of this complaint being present with the osseous anomaly. The mechanism for this remains obscure but may be related to ischemic compression of the vertebral artery or by dural tension at the craniocervical junction.