sCAD begins in the outer artery wall layers
MedWire News: Pathologic changes in the arterial walls of patients with spontaneous cervical artery dissection (sCAD) are confined mainly to the outer layers, shows research published in the journal Neurology.
The findings, which were obtained in specimens of distal superficial temporal arteries (STAs), "are important because they confirm the existence of an underlying systemic arteriopathy in patients with sCAD," said editorialists Wouter Schievink (Cedars-Sinai Medical Center, Los Angeles, California, USA) and Stephanie Debette (Salpêtrière Hospital, Paris, France).
Ralf Dittrich (University Hospital of Münster, Germany) and colleagues found pathologic changes in the adventitial and medial layers of biopsy STA specimens taken from 14 sCAD patients, aged an average of 45.5 years.
They detected vacuolar degeneration and fissuring of the medial and adventitial tissue (termed foamy medial adventitial border - FOMAB) in all but one of the sCAD specimens. Similar, but very mild changes were found in one of nine control specimens, which were obtained from accident victims who were free of clinical vascular disease.
The control specimen with mild FOMAB also had mild erythrocyte extravasation into the connective tissue and neoangiogenesis of capillaries. These features were mildly to severely present in most of the sCAD specimens, as were capillary defects.
Four sCAD specimens had lymphocytes or macrophages present and also exhibited microhematomas, which were visible at low magnification and contained necrotic cells and clotted blood.
"Our results suggest that sCAD is due to an 'outside-in' process starting in the TA [tunica adventitia] and TM [tunica media] and not an 'inside-out' injury starting from the endothelium leading to endothelial rupture as the primary event," say Dittrich et al.
They believe that FOMAB is the initial event, followed by leakage of neoangiogenetic capillaries, leading eventually to microhematomas. As these increase in size, a trigger event such as mild neck trauma results in full sCAD.
In their editorial, Schievink and Debette noted that while the overall risk for recurrent sCAD is low, the short-term risk is high. They said: "Identifying the initial events in the pathophysiology of cervical artery dissections may lead to the development of new therapeutic approaches that could effectively minimize the risk of a recurrent dissection."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Eleanor McDermid