CRANIOCERVICAL JUNCTION SUBARACHNOID HEMORRHAGE ASSOCIATED WITH ATLANTOOCCIPITAL DISLOCATION

Study Design. The sensitivity of plain radiographs for diagnosing trau matic atlanto-occipital dislocation and its association with craniocer vical junction subarachnoid hemorrhage was examined in a retrospective review of seven patients. Objective. The purpose of this study was to demonstrate the frequency of nondiagnostic plain radiographs and the common association of craniocervical junction subarachnoid hemorrhage in the context of reported cases of atlanto-occipital dislocation to f acilitate better recognition of this injury. The use of sagittal recon structions of computed tomography or sagittal magnetic resonance imagi ng for diagnosis was evaluated. Summary of Background Data. Although t raumatic atlanto-occipital dislocation is a common cause of motor vehi cle fatalities, survival has been more common in the last 16 years. Ho wever, the diagnosis was missed on lateral cervical radiographs in 38% of children and 59% of adults; fewer than half were diagnosed subsequ ently with plain radiography. Moreover, the diagnosis of traumatic atl anto-occipital dislocation often was not considered, because more than half of the survivors had no neurologic abnormality or unilateral def icit. Consequently, more than one third of initially undiagnosed patie nts experienced neurologic deterioration due to inadequate cervical im mobilization. Additional radiographic studies allowing diagnosis were prompted by the neurologic worsening. Methods. The authors reviewed se ven patients treated with traumatic atlanto-occipital dislocation duri ng a 14-year period. Emergency department records were compared with r eexamination of initial cervical radiographs to determine the success in diagnosis by means of published methods. The frequency of cranio-ce rvical junction subarachnoid hemorrhage on computed tomography was det ermined, and the use of sagittal imaging for subsequent diagnosis was evaluated. Results. In the emergency department, only one patient's co ndition was diagnosed as atlanto-occipital dislocation. Review of the initial radiographs identified an additional four patients for whom at lanto-occipital dislocation could be diagnosed. Sagittal computed tomo graphy reconstruction or sagittal magnetic resonance imaging identifie d the remaining two. All but one patient had craniocervical junction s ubarachnoid hemorrhage. A review of reported cases revealed a common a ssociation of craniocervical junction subarachnoid hemorrhage with tra umatic atlanto-occipital dislocation but not with traumatic head injur y. Conclusions. The diagnosis of traumatic atlanto-occipital dislocati on is often missed in the emergency department, and current methods fo r evaluating the integrity of the atlanto-occipital joint on cervical radiographs fail to identify all patients with this injury. Although i nfratentorial subarachnoid hemorrhage is uncommon in traumatic head in jury, craniocervical junction subarachnoid hemorrhage is often associa ted with atlanto-occipital dislocation and should raise the suspicion of severe craniocervical ligamentous injury. Sagittal computed tomogra phy reconstructions or sagittal magnetic resonance imaging can allow f or the diagnosis when plain radiography is inconclusive.