Blurred by a “Puff of Smoke”—A Case-Based Review on the Challenging Recognition of Coexisting CNS Demyelinating Disease and Moyamoya Angiopathy

Moyamoya angiopathy (MMA) is a cerebrovascular disease determining chronic progressive steno-occlusion of the supraclinoid internal carotid arteries and their main branches. The pathogenesis of MMA remains largely unknown. Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the central nervous system characterized by the progressive accumulation of focal demyelinating lesions, whose pathophysiology has been theorized but still incompletely understood. Beyond misdiagnoses due to mimicking features among the two disorders, MS coexisting with MMA have been previously, rarely, reported. Herein, we present two other cases of patients with MMA with a concomitant, previously missed, diagnosis of MS and discuss their overlapping features as a hint for a potentially shared pathophysiology. The finding of typical angiographic features enables MMA diagnosis, yet it does not allow us to rule out other potentially concomitant disorders affecting the CNS. The association may be easily missed if the clinical/neuroradiological picture is not carefully assessed. Cerebral spinal fluid analysis and spine neuroimaging should be suggested in all MMA patients with atypical MRI lesions.