To report a case of bilateral trochlear nerve palsy following cisternography.

A 43-year-old male with intermittent watery rhinorrhea persisting for 3 months visited the neurosurgery department of our institute. His past medical history included removal of a pituitary adenoma 22 years prior to presentation. Cerebrospinal fluid leakage was suspected and cisternography was performed. The patient was referred to our ophthalmology department for diplopia 3 days after the cisternography. An alternate prism cover test showed 5 prism diopter (PD) right hypertrophia in the primary position, and underaction of bilateral superior oblique muscles and overaction of the left inferior oblique muscle. A positive Bielschowsky test with the head tilted to either side was observed and excyclotorsion was 9° on the double Maddox rod test. The patient was diagnosed with bilateral trochlear nerve palsy. After 2 years of follow-up, diplopia persisted and recession of the bilateral inferior oblique muscles was performed. After the surgery, diplopia disappeared, the fundus photography showed no excyclotorsion, and the double Maddox rod test indicated 3° of excyclotorsion.

Cisternography should be carefully performed due to the possibility of bilateral trochlear nerve palsy, an extremely rare but possible occurrence following the procedure.