Trochlear nerve schwannoma removed by combined petrosal approach.

Trochlear nerve schwannoma is an extremely rare intracranial tumour. It is a benign tumour often presenting late with the involvement of neighbouring structures and potentially life threatening complications. We report a case of this condition, which is the first to be treated by surgery via a presigmoid 'combined petrosal approach' with follow-up by magnetic resonance imaging (MRI) for 6 years. The advantages of the presigmoid combined petrosal approach for this type of tumour are described. Early investigation of patients with unexplained trochlear nerve palsy by MRI will facilitate the management of these rare tumours.