The patient should be treated with acetazolamide. Although the headache described has many features of a tension-type headache, the findings of papilledema, partial left palsy of the abducens nerve (cranial nerve VI), and a cerebrospinal fluid (CSF) opening pressure of 350 mm H₂O suggests the presence of a secondary headache syndrome. Documentation of an elevated CSF opening pressure without evidence of a space-occupying lesion on neuroimaging confirms the diagnosis of idiopathic intracranial hypertension (IIH). This condition is most frequently seen in young women with an elevated BMI. The use of a combined oral contraceptive is an additional risk factor. Headache is the most common symptom, and papilledema is the most common physical examination finding. Carbonic anhydrase inhibitors, such as acetazolamide, are the only reliably effective medications for IIH. These inhibitors have been shown to reduce headache and improve visual impairment in patients with IIH.

Amitriptyline is an effective preventive medication for migraine or tension-type headache but would not address this patient's elevated intracranial pressure and thus is inappropriate.

An epidural blood patch is used in the treatment of intracranial hypotension arising spontaneously or occurring after lumbar puncture. This patient has intracranial hypertension.

Optic nerve sheath fenestration involves an incision in the meninges surrounding the optic nerve (cranial nerve II) to relieve elevated intracranial pressure. Optic nerve sheath fenestration can be used in the treatment of IIH but only after the failure of medical management. If acetazolamide does not relieve this patient's symptoms, then optic nerve fenestration may be appropriate.

Spironolactone is a recognized therapy for polycystic ovary syndrome but has no reported effect on headaches or intracranial pressure.