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Objective:
Spontaneous CSF rhinorrhea accounts for 10–30% of all CSF rhinorrhea cases. These patients do not have any history of trauma, skull base surgery, or mass lesions. Studies have suggested increased intracranial pressure as a possible cause, and spontaneous CSF leak is considered as a manifestation of chronic idiopathic intracranial hypertension (IIH). Typical signs and symptoms of intracranial hypertension are not present in most of these patients, owing to decompression by CSF leak. Some of these patients show sign of intracranial hypertension only after CSF leak repair. These patients have also shown higher rate of recurrence after endoscopic repair as compared to those due to trauma or surgery. However, success rate is higher if intracranial pressure is actively controlled postoperatively. Hence it is important to identify imaging features of chronic intracranial hypertension in these subgroups of patients. The purpose of our study was to evaluate various MRI findings suggestive of long-standing intracranial hypertension in patients with spontaneous CSF rhinorrhea.

Materials and Methods:
All patients who had MRI brain and MR cisternography study for CSF rhinorrhea were retrieved from the archives. Patients with previous history of trauma, surgery, tumor, or skull base congenital anomalies were excluded. Three patients with CSF rhinorrhea were diagnosed to have chronic hydrocephalus on MRI (one postinfection, two showed mass lesion). Seventeen patients who met our inclusion criteria were analyzed for location of CSF leak and imaging features of IIH. MR venography was available in 14 patients, which was also evaluated for venous sinus stenosis or hypoplasia.

Results:
The mean age of our patients was 45 years (age range 32–67 years) with female predominance (94%). Duration of CSF rhinorrhea varied between few days to 6 years. Most common site of CSF leak was ethmoid air cells through defect in cribriform plate (70%), followed by sphenoid sinus. Eighty-eight percent of these patients had features of IIH, 76% had grade 3 or higher partially empty sella, 47% had prominent Meckel’s cave, 76% had prominent perioptic space, and 35% had tortuosity of optic nerve, and 43% had small meningeal out pouching through the skull defects, predominantly along the cribriform plates. Among 14 patients who had MR venography, six (43 %) patients had unilateral transverse sinus stenosis and contralateral hypoplastic transverse sinus. All our patients had right-sided stenosis and left-sided hypoplastic sinus.

Conclusion:
Our study showed strong association of imaging features of IIH and spontaneous CSF rhinorrhea. As classic signs and symptoms of IIH is lacking in these group of patients, imaging features should be taken into consideration for diagnosing IIH in patients with CSF rhinorrhea. This will prompt the treating physician to include ICP lowering treatment in the management protocol of these patients. MR venography may be included in the evaluation of these patients for planning better management.