Moya moya disease, meaning “puff of smoke” in Japanese, is an idiopathic arteritis of young people, affecting the distal ICA and circle of Willis. Collateral vessels proliferate giving the puff appearance. The condition was initially described in Japanese patients, where it is still most common.

Most commonly it is idiopathic, although there is a familial component. (7% familial in Japan). Other aetiologies include:
1. radiotherapy
2. base of skull meningitis, eg TB
3. connective tissue disorders
4. Sickle cell disease
5. Neurofibromatosis type 1

The condition not surprisingly predisposes to strokes, and often results in frontal atrophy.

For more images and information on staging of moya moya, please visit here.
Credit: Dr Frank Gaillard