Acetazolamide to Prevent Post Operative CSF Leak

Inclusion Criteria: * Elective transsphenoidal resection of a tumor expected to result in an intraoperative high flow CSF leak; such tumors include craniopharyngioma, meningioma, and Rathke cleft cyst. * Elective transsphenoidal resection of a pituitary adenoma, with BMI \>25, or with observed low or high flow CSF leak during surgery, conferring an elevated risk of postoperative CSF leak. * Patients who voluntarily sign Informed Consent * Male subjects and female subjects of childbearing potential and at risk for pregnancy must agree to use a highly effective method of contraception during study treatment and for at least 1 month after stopping study treatment. Male subjects should refrain from donating semen during treatment and 1 month after stopping treatment. Exclusion Criteria: * Adults unable to consent * Individuals who are not yet adults (infants, children, teenagers) * Pregnant women * Prisoners * Patients with prior adverse reactions to acetazolamide or who are taking aspirin concomitantly (which may increase the risk of adverse reactions to acetazolamide) * Patients with moderate to severe chronic obstructive pulmonary disease (which may increase the risk of adverse effects of acetazolamide) * Acetazolamide therapy is contraindicated in situations in which sodium and/or potassium blood serum levels are depressed, in cases of marked kidney and liver disease or dysfunction, in suprarenal gland failure, and in hyperchloremic acidosis. * It is contraindicated in patients with cirrhosis because of the risk of development of hepatic encephalopathy * Sulfonamide allergy * Pregnant females, breastfeeding females, and males and females of childbearing potential who are unwilling or unable to use a highly effective method of contraception