CT study of craniovertebral rotation in whiplash injury

The present study investigates the diagnostic value of rotatory computed to mography (CT) examinations in normal subjects and patients with whiplash as sociated disorders (WAD), with the aim of reproducing earlier findings of r otatory CT studies. Forty-seven WAD patients with persistent complaints aft er a rear-end collision (non-cranial contact acceleration/deceleration trau ma) were enrolled in this study. To guarantee a maximally homogeneous study population, only WAD patients with a marked passive cervical retroflexion restriction were included. Transversal CT slices in left and right rotation were made for all cervical levels (the skull included). CT slices in neutr al position were used to reconstruct partially depicted vertebrae. Absolute rotatory values were estimated according the method of Penning and Dvorak. For all levels the relative rotatory (RR) value was calculated by dividing absolute rotation values of a particular cervical level by the correspondi ng total cervical rotation. The measuring error was estimated by comparing the findings of two separately performed measuring procedures. Two age grou ps of WAD patients were formed. A younger group was matched for age with 26 normal healthy volunteers (the original data of an earlier study). The use of neutral CT slices for reconstruction of a partially depicted cervical v ertebra resulted in a measurement error of 1.9 degrees at the level of C0/C 1 (occiput/atlas) and 3.5 degrees at C1/C2. Suspected hypermobility as defi ned by Dvorak was rare in our WAD patients (6.4% C0/C1 and 10.6% C1/C2). RR values at C0/C1 were significantly larger in 79% of the WAD patients. Disc riminant analysis of the RR values showed 80% correctly classified WAD pati ents. Only 11.5% of the normal subjects were classified as false-positive. Since no hypermobility was found at C1/C2, a traumatic lesion of the alar l igaments is less likely. It was concluded that the use of absolute rotation values in rotatory CT scan procedures has a low diagnostic value in WAD pa tients. Excessive RR values were only found at C0/C1. A traumatic lesion of the ligaments at C0/C1, which prevent vertical translation of the skull wi th regard to the atlas, is hypothesised. The results of the discriminant an alysis of the RR values make this method applicable for the individual WAD patient in daily practice.