Patients suffering from distortion of the cervical spine after an acceleration trauma present problems with respect to the correct diagnostic recognition of the existing injuries. To define instability of the craniocervical junction, attention should be given to the position of the dens and the dimension of its subarachnoid space during the entire rotational maneuver. Our diagnosis via functional magnetic resonance imaging (fMRI) with video did not focus on injuries to the ligamentous microstructure as visualized with high-resolution MRI. Our purpose was to demonstrate the cause of instability of the craniocervical junction by direct visualization during fMRI-video technique. Between December 1997 and March 1999, 200 patients were studied using fMRI on a 0.2-Tesla Magnetom Open. Routine evaluation of the extracranial vertebral circulation by MRI angiography as an additional preinvestigative requirement is recommended. The earliest examination time from injury to MRI evaluation was 3 months and the maximum, 5 years (average, 2.6 years). Among the 200 patients investigated, 30 showed instability of the ligamentous dens complex. Of the same 200, 8 (4%) had a complete rupture and 22 (11%) an incomplete rupture of the alar ligament, with instability signs. In another 45 patients (22.5%), fMRI-video showed evidence of instability, and all these patients had coexisting intraligamentous signal pattern variation, probably due to granulation tissue. Eighty patients of the 200 (40%) had signal indifference without demonstrable video instability signs, and 43 patients (21.5%) showed no evidence of instability and no signal variation in the alar ligaments. On the basis of recognition of instability and the malfunction of the ligaments, the fibrous capsula, and the tiny dens capsula, we now can distinguish between lesions caused by rotatory trauma to the craniocervical junction and those from classic whiplash injury.