Increased cerebral blood flow in MELAS shown by Tc-99m HMPAO brain SPECT

We report cerebral SPECT studies on two siblings with the syndrome of mitoc hondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), Tc-99m HMPAO brain SPECT was performed 8, 19 and 30 days after a stroke-like episode in one case and 10 days after a strokelike episode, 6 h after a partial seizure and as a follow-up study in the other. Increased b lood flow was seen in both these patients with strokelike episodes due to M ELAS. The cause of the increased blood now is uncertain, but it may be rela ted to the decreased pH created by local increase in lactic acid.