Idiopathic CSF otorrhea is a relatively rare condition. The major site of leakage is the canopy of the tympanum and mastoid cavity, and the condition is often associated with idiopathic intracranial hypertension. A 62-year-old man presented with a 1-year history of left otorrhea. He was treated for exudative otitis media, but continued to have pulsatile serous otorrhea. He was referred to our hospital with suspected CSF otorrhea. Imaging showed a bone defect behind the lateral semicircular canal ridge, and we performed transmastoid closure. Using a combination of microscopy and endoscopy, we identified the fistula in the bony defect and dura and closed it with fascia, bone fragments, and a peroneal temporal muscle valve. A more detailed imaging study showed a bone defect in the same part of contralateral side, suggesting meningeal varus in a congenital bone defect; MRI showed an empty sella, and MR venography showed obstruction of the right transverse sinus. However, ophthalmologic examination did not reveal any papillary edema, and there was no evidence of increased CSF pressure at the time of surgery. As it was possible that intracranial pressure was regulated by the CSF otorrhea, we considered that there was a risk of increased CSF pressure with fistula closure. The patient will be followed up with special attention paid to visual symptoms and headache.
