Transventricular Transvelar Approach to Trochlear Nerve Schwannoma: Novel Technique to Lesions of Inferior Pineal Region.

Abstract

The schwannoma of the trochlear nerve is rare and originates mostly from the distal parts in the interpeduncular cistern. A lesion on the proximal segment in the inferior pineal region is extremely rare. Because of the rarity of the disease, the surgical approach to this region for the resection of trochlear nerve schwannoma has not been well documented in the literature. We herein describe a novel approach to successfully resect the trochlear nerve schwannoma. A 12-year-old boy presented with occipital headache, abnormal gait, and disturbed conjoined eye movement. He was diagnosed with a lesion in the inferior pineal region compressing the superior medullary velum into the roof of the fourth ventricle. A bilateral midline suboccipital craniotomy was performed, and the fourth ventricle was exposed. The lesion was approached through the fourth ventricle superior medullary velum (transventricular transvelar approach). The lesion was totally resected, and his histopathology examination revealed trochlear schwannoma. The patient's symptoms resolved, and he had no recurrence at 12-year follow-up with normal eye movement and vision. The transventricular transvelar approach is feasible and safe to treat a lesion of the lower part of the pineal region being pushed through the superior medullary velum.