Recently the extra-intracranial (EC/IC) arterial bypass operation has been introduced in the treatment of Moyamoya disease and excellent postoperative outcomes have been reported. To assess the cerebral hemodynamic changes after the bypass surgery, ultrasonic Doppler flowmetry was performed in 10 children with Moyamoya disease. Their surgical treatments included superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis or encephalo-duro-arterio-synangiosis. The flow velocity and pattern of the major cerebral arteries and STAs, the donor artery of the bypass, were studied both before and after the operation. The results of Doppler flowmetry were compared with clinical symptoms and angiographical findings. Though the Doppler sonography of the major cerebral arteries showed little change, the flow velocity of the STAs revealed a pronounced and rapid increase after the bypass surgery. The flow pattern of the STAs, which was of the external carotid type preoperatively, changed to the internal carotid type postoperatively. These ultrasonic Doppler findings were thought to be due to a decrease in the peripheral vascular resistance, and suggested a good patency of the bypass arteries. These results of the Doppler flowmetry were in good agreement with clinical and EEG improvement and the findings of the postoperative cerebral angiography. It is suggested that ultrasonic Doppler flowmetry is a noninvasive and reliable method of assessing the function of the EC/IC bypass in children with Moyamoya disease.
Background and Purpose To elucidate the pathogenic role of vascular involvement such as mitochondrial angiopathy in patients with mitochondrial encephalomyopathy (MEM), we used the transcranial Doppler sonography (TCD) method to detect impairment of cerebrovascular CO 2 reactivity. Methods The cerebral perfusion reserve in 13 MEM patients, including 6 with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) was studied by TCD for different CO 2 partial pressures. For the parameter of mean flow velocity, the mean spatial Doppler frequency (fm) was obtained from the right and left middle cerebral arteries and basilar artery under conditions of normocapnia, hypercapnia, and hypocapnia in cases in which hyperventilation was possible. By fitting the obtained fm and the end-tidal CO 2 partial pressure (P etco 2 ) to the exponential formula fm=a×e (K×P etco 2 ) , where a is the theoretical fm at a P etco 2 of 0 mm Hg, the parameter K, an index of CO 2 reactivity, was calculated. Results The K value was lower than control values at at least one site of the middle cerebral arteries and basilar artery of all patients with MELAS as well as the other MEM patients except for one patient with myoclonic epilepsy with ragged-red fiber and one with Kearns-Sayer syndrome. Conclusions Our results suggest that there is a high incidence of impairment of cerebrovascular CO 2 reactivity in MEM patients. Moreover, the noninvasive TCD method was found useful for evaluation of cerebral hemodynamics in MEM patients.
We report a 9 year-old boy with MELAS. High dosed oral thiamine administration and high fat diet induced remarkable neurological and biochemical improvement. His mother had episodic headaches and hemiplegia, probably MELAS. He complained muscle weakness and repeated episodes of vomiting started from 2 years of age. High levels of serum lactate and pyruvate were recognized, but with no metabolic acidosis. He developed generalized muscle weakness, growth retardation, generalized convulsions and stroke-like episodes at 5 years old. Optic nerve atrophy and mental retardation gradually appeared. A muscle biopsy at 5 years old revealed numerous ragged-red fibers with excess accumulation of lipid droplets and glycogen particles. Scattered fibers had no cytochrome c oxidase (CCO) activity representing focal CCO deficiency. An electron microscopy showed markedly increased number of giant mitochondria filled with markedly proliferated complicated cristae. Pyruvate dehydrogenase complex level in the fibroblasts was within normal ranges. Serum carnitine level was normal. With oral administration of thiamine hydrochloride (1000 mg) and high fat diet (60-70%), muscle weakness improved, and lactate and pyruvate levels in the serum reduced to normal ranges, whereas the mental deterioration, muscle atrophy, pes cavus progressed very slowly. He died from cardiac and renal failures at 9 years old. Autopsied muscles showed a marked decrease in cytochrome c oxidase activity (biochemically 12.8% of the normal level), and almost all muscle fibers had no cytochrome c oxidase activity histochemically. The progression of the MELAS was probably in parallel with the decrease in CCO activity.
