Cranial nerve ischaemic arterial syndromes. A review.

Topographical vascular disorders involving combinations of cranial nerves are reviewed in this study. These are indicated by the correspondence between groupings of clinical manifestations and anatomical vascular distributions. Confirmatory evidence is provided by mishaps, following diagnostic or therapeutic angiography. Three systems play a role in the vascularization of cranial nerves: the inferolateral trunk (ILT), most often arising from the internal carotid artery, the middle meningeal system (MMS), and the ascending pharyngeal system (APS); the latter two are both derived from the external carotid artery. Conclusions concerning the ILT are least definite because of variations in vascular territory and the lack of confirmation from embolic events in a vascular region that is rarely the site of embolization. The specific ILT territory includes cranial nerve III and also nerves IV, VI and V1. Knowledge of the vascularization of nerve III may furnish explanations as to its different modes of involvement in diabetes mellitus. For the MMS, the cranial nerves concerned are V2, V3 and VII. Two vascular territories for the intrapetrous portion of nerve VII are defined: the first (stylomastoid artery) is limited to nerve VII; the second (MMS) supplies VII and V. Two examples of involvement of VII and V following selective MMS embolization are presented. A study of Bell's palsy associated with nerve V impairment is summarized. The APS supplies nerves IX, X, XI and XII; XI has a dual vascularization which explains why it can either be spared (as was the case in an angiographic accident) or involved (as in a case of herpes zoster). A vascular mechanism should be considered when cranial nerve lesions occur in the syndromes described here.