The Mystery of a Unilateral Headache Ultimately Diagnosed as Moyamoya Disease.

Moyamoya disease (MMD) is a rare chronic cerebrovascular occlusive disease characterized by progressive stenosis or occlusion of the intracranial internal carotid arteries and their proximal branches, with subsequent abnormally formed collateral vessels. Moyamoya disease is typically found in children of East Asian descent and is the most common pediatric cerebrovascular pathology in East Asian populations. However, moyamoya disease can be present without any predisposing factors, and this is what distinguishes the disease from the syndrome. Moyamoya syndrome is typically associated with other conditions such as sickle cell disease or neurofibromatosis. The syndrome can also be seen in patients who have had exposure to cervical or neck radiation. We present a rare case of an adult Peruvian woman who initially presented with a severe right hemispherical headache, which was ultimately diagnosed as MMD. This report and the discussion aim to provide more understanding of moyamoya disease and how it can be incidentally discovered in an unsuspected patient without any predisposing factors. The fact that the patient lacked any predisposing factors makes moyamoya disease, and not the syndrome, the diagnosis. Currently available treatments are limited. One specialized therapeutic approach is a procedure called encephaloduroarteriosynangiosis (EDAS), which aims to involve the transposition of a segment of a scalp artery onto the surface of the brain to permit the additional formation of collateral arteries. We aim to highlight the management and treatment of a case of moyamoya presenting as a severe right hemispherical headache in a patient without any predisposing factors.