Puff of smoke appearance on contrast CT angiography is seen -

Ans. is 'a' i.e., Moya Moya Disease Movamova diseaseo Moyamoya disease is an idiopathic, non inflammatory, non atherosclerotic progressive vasculo-occlusive disease involving the circle of Willis, typically the supraclinoid internal carotid arteries.Epidemiologyo Moyamoya is a disease of children and young people, with a bi-modal age distribution:1) Early childhood: peak ~4 years of age (two-thirds)2) Middle age: 30-40 years of age (one-third)o The condition was initially described in Japanese patients, where it is still most common, in which 7-10% of cases are familial.Clinical presentationo Presentation is to some degree age dependent. In children hemispheric ischaemic strokes are most pronounced, whereas in adults haemorrhage from the abnormal vessels is more common . Watershed infarcts are also very commonly identified.Radiographic featureso Moyamoya disease affects the bilateral distal ICAs and circle of Willis. Up to 18% of patients with moyamoya may present with unilateral angiography-documented disease8. o Small abnormal net-like vessels proliferate giving the characteristic "puff of smoke" appearance on direct angiography. CTA and MRA is not always able to demonstrate this appearance on account of lower flow and spatial resolution.o Although classically described affecting the ICA, over 50% of patients also have involvement of the posterior cerebral arteries.Treatment and prognosiso Bypassing the occlusive segments is the aim of most surgical therapy.o In adults external carotid artery to middle cerebral artery (ECA-MCA) anastomoses can be performed as the vessels are larger. One of the surgical option is superficial temporal artery to middle cerebral artery (STA-MCA) bypass.o Encephaloduroarteriosynangiosis is the treatment of choice in paediatric patients as their vessels are too small to allow direct anastomosis.