Application of Leksell Stereotactic Frame Using External Landmarks in Stereotactic Surgery

ABSTRACT

OBJECTIVE: This study is designed to evaluate the usefulness of the cutaneous external landmarks in the application of a Leksell stereotactic frame for functional stereotactic surgery. METHODS: Surgical procedures included thalamotomy in 12 and pallidotomy in 4. Thalamotomy and later pallidotomy were performed in one. In application of the Leksell stereotactic frame, the authors used the cutaneous external landmarks including (1) the pupil and the external acoustic meatus in group I, (2) the pupil and the crus of the helix in group II, (3) the lateral canthus, the crus of the helix, and inferior crura of antihelix in group III. This procedure was done for obtaining magnetic resonance(MR) images showing anterior and posterior commissure in the same axial scan. The targets were Vim for thalamotomy and GPi for pallidotomy. RESULTS: All MR images in group I, II, and III showed anterior and posterior commissures in the same axial scans except for two patients (17.7%) in group I. The MRI coordinate was accurate to localize the target within 1mm of the difference from electrophysiologic target in 76% of the patients. After surgery, a significant improvement was noticed in tremor scale and global outcome scale (p0.05). Transient postoperative complications including motor aphasia and hemihypesthesia were noticed in one each, which returned normal in 3 months. CONCLUSION: The cutaneous external landmarks are of value in applying Leksell stereotactic frame for obtaining magnetic resonance images, essentially showing anterior and posterior commissure. This method is also useful in saving total operation time, making patients comfortable, as well as cost effectiveness.