To report a rare case of spontaneous cerebrospinal fluid rhinorrhea as the sole presentation of Idiopathic Intracranial Hypertension, along with its diagnostic challenges and management.

Spontaneous CSF rhinorrhea is an uncommon, often associated with idiopathic intracranial hypertension (IIH) or skull base defects. Unlike post-traumatic or iatrogenic causes, spontaneous leaks may be overlooked, leading to delayed diagnosis and risk of meningitis. Current literature suggests an underrecognized link between IIH and spontaneous CSF leakage.

A 30-year-old female presented with complaints of clear discharge from the left nostril for 3 weeks, accompanied by dull, pressure-like headaches. She denied any history of head trauma, meningitis, or sinus surgery. Her BMI was 30. Neurological examination revealed no focal deficits or cranial nerve abnormalities, while ophthalmologic examination showed papilledema. Discharge examination showed β-2 transferrin. CT scan showed a bony defect in the anterior cranial fossa, involving the roof of the ethmoid sinus. MRI revealed CSF leakage noted in right anterior ethmoid air cells (Abnormal T2 hyperintense MR signals seen returning from right anterior ethmoidal air cells), along with partially empty sella and prominent optic nerve sheath CSF space, likely representing CSF Rhinorrhea due to benign intracranial hypertension. No evidence of venous sinus thrombosis was observed on MR venography. Lumbar puncture revealed CSF pressure of 28 cm H2O, with other parameters within range. Imaging was suggestive of IIH. The patient underwent surgical repair of the defect, which resulted in improvement of symptoms. She was discharged after 4 days. On follow-up after 3 months, there was normalization of intracranial pressure parameters and complete resolution of symptoms.

Spontaneous CSF rhinorrhea can be the only presenting feature of IIH and should prompt evaluation for elevated intracranial pressure. Early surgical intervention, and management of intracranial hypertension, is key to preventing recurrence and infectious complications.