ISOLATED BASILAR TRAUMATIC SUBARACHNOID HEMORRHAGE - AN OBSERVERS 25-YEAR REEVALUATION OF THE PATHOGENETIC POSSIBILITIES

This paper was inspired by Leadbeatter's recent review [1] on the subj ect, and consists primarily of a recapitulation of this author's obser vations in the 25 years since publication of his paper [2] describing three cases of traumatic basilar subarachnoid hemorrhage resulting fro m direct trauma to the upper lateral neck. Those observations include personal experience and case reports personally communicated or publis hed. Leadbeatter's analysis makes the following three salient points t o which the author considers a response to be appropriate: 1. For the ten years following Contostavlos' paper, all traumatic basilar subarac hnoid hemorrhages were considered to have resulted exclusively from di rect extracranial trauma to the vertebral artery. That belief has sinc e gradually been eroded. 2. The mechanisms of injury and hemorrhage ha ve been inadequately explored and demonstrated due to absence of appro priate and adequate anatomic dissection. 3. Attention has been increas ingly turned toward other factors besides direct arterial injury such as indirect mechanisms of injury, hyperextension of head on neck, hemo dynamic effects and congenital anomalies of the craniocervical articul ation, This author responds to these assertions thus: 1. Traumatic sub arachnoid hemorrhages do not have one mechanism only, The lesion descr ibed in Contostavlos' paper merely represents one commonly observed sy ndrome, as supported by the numerous case reports which have followed and also preceded his account. There may have been a tendency to 'pige on-hole' too many cases into that category but this author's personal experience in the past 25 years has shown that similar to 50% of traum atic isolated basilar subarachnoid hemorrhage fall into that category (direct trauma to lateral or posterolateral neck). 2. The anatomic loc ation of the injury virtually prevents effective demonstration by diss ection, and the possibilities of misleading artefacts incurred during the autopsy are such that many erroneous conclusions are reached by pr osectors, as well as many sites of significant trauma remaining undisc overed. Accordingly, empirical factors have to be considered for a dia gnosis in most cases, Four diagnostic criteria have been established f or a firm conclusion of death due to traumatic basilar subarachnoid he morrhage. 3. While over half of traumatic basilar subarachnoid hemorrh ages involve a completely different site of trauma, and many indirect mechanisms of injury may come into play, the author still considers th at in the commonly observed syndrome as described by him in 1971, dire ct trauma to the vertebral artery is the primary causative factor.