Appliance of preoperative diffusion tensor imaging and fiber tractography in patients with brainstem lesions

Background: Surgical resection of brainstem lesions has a high risk of morbidity, because vital fasciculi in the brainstem can be damaged along the entry routes. Diffusion tensor imaging (DTI) is an in vivo method for mapping white matter fiber tracts in the brain. Objective: To summarize the experience of surgical treatment of brainstem lesions with the assistance of DTI and fiber tractography. Materials and Methods: A retrospective analysis clinical data of nine patients with brainstem lesions were investigated between July 2007 and September 2009. The analysis included age distribution, clinical presentation, pre- and postoperative modified Rankin score (mRS), and surgical approach. DTI and fiber tractography were used to reconstruct the corticospinal tracts and the medial lemnisci. Results: DTI and fiber tractography showed that most of the corticospinal tracts were compressed anteriorly or anterolaterally, except for one case (posteriorly). All the medial lemnisci were displaced posteriorly or posterolaterally. Individualized surgical approaches were designed according to the information provided by DTI and fiber tractography. Total resection was achieved in two patients with brainstem cavernomas and two patients with pilocytic astrocytoma. Partial resection was performed in the other patients. The neurological functional status was better than preoperative period in eight patients, one patient with medulla oblongata astrocytoma deteriorated. The preoperative average mRS score was 2.22 points. At the time of the last follow-up, the average postoperative score had improved by 0.56 to 1.66 points. Conclusions: DTI and fiber tractography can provide valuable information regarding the relationship between the principal fiber tracts and brainstem lesions, which is useful in neurosurgical planning.