EFFECT OF ACETAZOLAMIDE IN MOYAMOYA DISEASE

Objectives: Acetazolamide (AZD) can ameliorate transient neurologic symptoms that are seen in some patients with moyamoya disease (MD), and this may be related to its effects on cerebral blow flow (CBF). In order to further understand the mechanisms we examined the effects of AZD clinically and hemodynamically in a patient with MD.

Methods: A 14 year old male with episodes of left hemichorea and weakness was found to have MD on investigation. There was occlusion at the terminal portion of the right ICA with moderate narrowing on the left. Hemodynamic reactivity (HR) was assessed with BOLD MRI using breath-holding (BH) which has been found in normals to produce increased MR signal (probably CBF) by increasing CO2. Motor cortex activation was assessed for each hand using fMRI and a finger-tap motor task. Duplicate studies were performed with the patient off and on AZD.

Results: The patient improved clinically on the AZD. HR studies revealed the expected increased signal with BH but this was impaired in the right hemisphere compared to the left. There were similar findings when AZD was present but the percentage increase in signal was less (1.6% vs. 2.5%). The right hand motor task produced the expected activation in the left hemisphere and this was unchanged by AZD. The left hand task produced a decreased signal (deactivation?) in the motor cortex on the right suggesting increased deoxyHb production without the associated increase in CBF. This was also seen after AZD.

Conclusion: The abnormal hemodynamic reactivity to BH, which can be seen in MD, was not lost in the presence of AZD. Percentage of signal change with BH was less when AZD was present. The fMRI motor activations were unchanged by AZD. Thus the vascular reactivity abnormalities in MD could still be demonstrated in the presence of AZD.