UNUSUAL INTRAMEDULLARY VASCULAR LESION - REPORT OF 2 CASES

OBJECTIVE AND IMPORTANCE: Spinal arteriovenous malformations have been divided by location into dural (Type I), intramedullary glomus (Type II), juvenile (Type III), and perimedullary direct arteriovenous fistu lae (Type IV). We report two cases of an unusual intramedullary prolif eration of hyalinized capillaries that do not fit into any of these ca tegories. CLINICAL PRESENTATION: A 27-year-old woman and a 62-year-old man presented with subacute progressive caudal myelopathy. Magnetic r esonance imaging revealed focal spinal cord enlargement, high signal o n Ta-weighted images, and patchy enhancement with gadolinium consisten t with tumor. No serpentine flow voids were visualized on the surface of the spinal cord. Spinal angiography revealed nothing abnormal. No a bnormal vasculature was grossly visible on open biopsy. Histological e xamination of the tissue specimens revealed a proliferation of capilla ry-sized vessels with varying degrees of vascular wall changes ranging from endothelial hyperplasia to concentric hyalinization, suggesting ongoing evolution of the lesion. Surrounding neural tissue demonstrate d ischemic changes characterized by myelin and axonal loss and astrocy tosis but no necrosis. INTERVENTION: Patients were treated with chroni c anticoagulation, which seemed to slow, but not halt, symptomatic dis ease progression. CONCLUSION:Although the pathological substrate seems to be an acquired intramedullary vascular lesion characterized primar ily by capillary proliferation, the cause of this lesion is unknown. T his disease differs from Foix-Alajouanine syndrome and subacute necrot izing myelopathy by an absence of abnormal surface vessels and a lack of intramedullary necrosis. The histological findings are reminiscent of the process that occurs in the kidney and various end organs from l ong-standing mild to moderate elevations in blood pressure or chronic diabetes. Tissue ischemia may result from luminal obstruction by sever e hyalinization and thrombosis. Because the natural history of this di sease is unknown, it is unclear whether anticoagulation slowed disease progression.