Traumatic atlanto-occipital dislocation: presentation of a new posterior occipitoatlantoaxial fixation technique in an adult survivor: technical case report.

OBJECTIVE AND IMPORTANCE: More survivors of traumatic atlanto-occipital dislocation (AOD) in adults have recently been reported. Surgical management options are therefore of increasing interest. We present a new technique of posterior C0-C1-C2 fixation. CLINICAL PRESENTATION: A 29-year-old motorcyclist survived a traumatic vertical AOD of 15 mm. No spinal cord or medullary lesion was present. Brain contusion and diffuse axonal injuries led to a cortical biplegia, which recovered progressively over a period of 6 months. Twelve months after surgery, no neurological deficit was present except for slightly increased deep tendon reflexes. INTERVENTION: Posterior C0-C1-C2 fixation was performed with two bicortical occipital screws, one bicortical lateral mass screw in the atlas, and one monocortical pars screw in the axis on each side, connected to a plate-rod on the right and left sides. Fusion was performed with monocortical bone graft from the posterior iliac crest. CONCLUSION: The surgical technique described was thought to be safe to perform and resulted in immediate stability without external immobilization. Solid fusion was achieved 6 months after surgery.

Propagation of interictal epileptiform activity can lead to erroneous source localizations: a 128-channel EEG mapping study.

The relationship between interictal epileptiform activity and the epileptogenic zone is complex. Despite the fact that intraspike propagation may occur, the peak of the spike is often used as indicator of the site of ictal onset. In this investigation, spatio-temporal segmentation was used to demonstrate this intraspike propagation and to determine at which time point the voltage pattern corresponded best to the epileptogenic zone. Sixteen patients with focal epilepsy were recorded with 125-channel EEG. Between one and five different map topographies were identified during the rising phase of the spike. A distributed source model (EPIFOCUS) was used to localize the source of each map, and the distance from the EPIFOCUS maximum to the anatomic lesion was calculated. In only 3 of 16 cases was the entire rising phase of the spike accounted for by one single map. In another five patients, several maps were obtained, although all were located within the epileptogenic lesion. In the remaining eight patients, however, parts of the rising phase had locations outside the epileptogenic lesion. On the average, 80% of the rising time had within lesion locations the most reliable time period being halfway between onset and peak. The results illustrate that intraspike propagation has to be considered in source localizations, and they also illustrate the usefulness of spatio-temporal segmentation for visualizing this propagation.