Inclusion Criteria:

Moyamoya Patient Inclusion Criteria:

   - Men and non-pregnant women, at least 21 years of age.

   - Outpatients seen at the Stanford Neurosurgery and Neurology Departments.

   - Ability to comply with all studies.

   - Inclusion of Moyamoya patients with Sulfa allergies.

   - Patients diagnosed with or suspected to have Moyamoya disease.

Stroke Patient Inclusion Criteria:

   - Men and non-pregnant women, at least 21 years of age.

   - Patients admitted to the inpatient Stanford Stroke Service for stroke-like symptoms,
   less than 24 hours from last time seen normal.

   - Ability to comply with all studies.

Clinical Patient Acetazolamide MRI Inclusion Criteria:

   - Men and non-pregnant women, at least 21 years of age.

   - Patients admitted to the inpatient Stanford Stroke Service or Neurosurgical -Service
   for symptoms compatible with cerebrovascular disease.

   - Ability to comply with all studies.

Normal Subject Inclusion Criteria:

   - Ability to comply with the MRI study.

Exclusion Criteria:

   - Level of consciousness score of 2 or greater as defined by the NIH stroke scale.

   - Symptoms likely related to psychoactive drugs or patients with symptoms related to an
   active inflammatory disease such as AIDS, meningitis, or cerebritis.

   - Psychiatric or substance abuse disorder or dementia that interferes with evaluation or
   interpretation of the neurologic and mental assessment of these patients.

   - Informed consent cannot be obtained either from the patient or legal representative.

   - Severe coexisting or terminal systemic disease that limits life expectancy or that may
   interfere with the conduct of the study.

   - Symptoms related to an alternative diagnosis such as seizures or migraine.

   - Patients receiving any thrombolytic agent or receiving acute stroke investigational
   drug therapies during the 30-day study.