Snapshot A 28-year-old woman is referred to a headache neurologist for throbbing left-sided headaches that are refractory to numerous analgesics. Her headache is associated with episodes of double vision and "vision blurriness." She also endorses worsening headache with a cough and has experienced nausea. Her BMI is 32 kg/m2. Neurological examination is notable for a left-sided sixth nerve palsy, decreased visual fields, and papilledema on fundoscopy. She undergoes an MRI brain with MR venography, which is unremarkable. A lumbar puncture demonstrates a significant opening pressure with normal protein, glucose, and cells. She is started on acetazolamide and is referred to an Ophthalmologist for possible optic nerve sheath fenestration. Introduction Definition signs and symptoms consistent with increased intracranial pressure without an identifiable cause a diagnosis of exclusion Epidemiology Risk factors female gender in childbearing age obesity oral contraceptive pills vitamin A (isotretinoin) Pathogenesis Believed to be due to reduced cerebrospinal fluid absorption Presentation Symptoms headache typically lateralized and pulsatile in nature nausea and vomiting pulsatile tinnitus diplopia Physical exam papilledema (hallmark) sixth nerve palsy visual field loss Imaging MR brain with MR venography indication preferred initial imaging choice to exclude secondary causes of increased intracranial pressure findings typically normal; however, there are findings suggestive of idiopathic intracranial hypertension posterior sclera flattening vertical tortuosity of the orbital optic nerve perioptic subarachnoid space distension Studies Lumbar puncture most accurate diagnostic test for IIH indication performed after secondary causes of increased intracranial pressure has been excluded on neuroimaging findings elevated opening pressure otherwise normal CSF profile (protein, cells, and glucose) method perform in the lateral decubitus position with the legs extended Ophthalmic examination indication to determine the extent of optic nerve damage from the increased intracranial pressure Differential Migraine differentiating factor no papilledema on fundoscopy Secondary causes of increased intracranial pressure differentiating factor the presence of a malignancy, cerebral sinus thrombosis, or other space occupying lesions on neuroimaging Treatment Medical carbonic anhydrase inhibitors indication first-line treatment for idiopathic intracranial hypertension medication acetazolamide a loop diuretic can also be added as adjunctive therapy mechanism decreases the rate of CSF production Operative optic nerve sheath fenestration indication in patients who fail medical management Complications Blindness