Moyamoya disease is a rare, progressive cerebrovascular disorder caused by narrowed or blocked arteries supplying the brain. The name refers to the appearance of net-like collateral blood vessels that develop in response. Its incidence is significantly higher in East Asian countries and primarily affects children in the first decade of life, although it can also occur in older individuals. The disease may cause ischaemic or haemorrhagic strokes that are considered the two main types of moyamoya disease presentation, varying in prevalence in the population of children and adults. Other symptoms include headache, epilepsy, and transient ischaemic attack. Treatment remains mainly surgical, as no medication has yet been found to cure or slow down the progression of the disease. The pathogenesis remains unclear, although it is most likely multifactorial, including modifiable risk factors such as obesity, but also unmodifiable risk factors, like genetic predisposition. At the same time, moyamoya syndrome, also known as quasi-moyamoya disease, is a moyamoya-like vasculopathy associated with various systemic diseases or conditions, such as atherosclerosis or brain tumours. However, many studies do not distinguish moyamoya disease from moyamoya syndrome. Still, both conditions present with the same symptoms, and the management approach is generally the same.