Mural Dissections of Brain-Supplying Arteries in a Chimpanzee (Pan troglodytes)

We describe the pathologic features of mural arterial dissection involving brain-supplying arteries in a 31-y-old female chimpanzee (Pan troglodytes). Several hours after examination for a possible respiratory tract infection, the chimpanzee became unresponsive, developed seizures, and died within 18 h. At necropsy, the occipital cortex of the brain had a small area of congestion, and the cerebellar cortex contained a small necrotic area. Histologic evaluation confirmed the cortical lesions and revealed an additional necrotic area in the medulla oblongata characterized by mural dissection of the brain-supplying vertebral and basilar arteries and subsequent branches. Lesions in the cortices and medulla were within areas supplied by the vertebrobasilar system. Dissection of brain-supplying arteries has been described in humans but not previously in chimpanzees (or any other NHP), suggesting that these species might be useful in understanding this condition in humans. In addition, the lesion should be added to the NHP clinician''s and pathologist''s differential diagnosis list for similar presentations in this species.Mural dissection of brain-supplying arteries is a well-recognized clinical problem in humans.² In fact, these dissections are a common lesion of these arteries, second only to atherosclerotic changes. Dissections of these arteries can cause pain and lead to tissue ischemia and infarction (stroke).²In our experience, the blood supply to the brain is similar between chimpanzees and humans. However, mural dissection of brain-supplying arteries in NHP species had not been described previously, and the apparent absence of information on this topic might reflect a low rate of occurrence for the condition or indicate that the condition has gone unrecognized. Regardless of the cause, similar vascular mural dissection in NHP might be expected to cause significant clinical problems for the affected animal, as well as diagnostic and management challenges for veterinary clinicians and pathologists.Here we describe the first documented occurrence of mural arterial dissection involving brain-supplying arteries in an adult chimpanzee. The objectives of this report are to make the laboratory animal community aware of this condition and to suggest that chimpanzees might help to increase our understanding of this condition in humans.