Search Results

Object.This study was designed to examine the effect on target localization of removing one fixation pin or post.

Methods.A stereotactic frame was applied to a head phantom by using four fixation pins. Contiguous axial computerized tomography (CT) slices (1 mm thick) were obtained through the head phantom. Using clinical treatment planning software, a marker was identified and its coordinates were determined. The imaging procedure and point localization were repeated independently seven times in the control configuration, after four-pin fixation, to study reproducibility.

Standard deviations in marker coordinates were 0.013, 0.046, and 0.039 mm along the x, y, and z axes, respectively, indicating excellent reproducibility. Each of the four pins was then removed separately, leaving three pins providing fixation to the skull. Imaging was repeated for each three-pin configuration. To simulate the forces at each pin-skull interface, a lever arm was connected to the head phantom allowing application of variable torque to the system. The CT scans were obtained for each torque strength and pin removal combination. Marker coordinates were compared with the control.

Conclusions.In most cases, it was found that accurate target positioning could be achieved after removal of a single pin and/or post. When high torque was used, however, removal of a pin resulted in up to a 1.2-mm error. The findings may be significant for clinical practice, depending on the condition being treated.

Object.The purpose of this study was to assess the durability and completeness of pain relief in patients treated using stereotactic gamma knife surgery (GKS) for trigeminal neuralgia (TN).

Methods.Thirty-eight patients with refractory TN were treated with stereotactic GKS. All patients received a prescription radiation dose of 35, 40, or 45 Gy to the 50% isodose surface through a 4-mm collimator helmet. The group was assessed regularly based on physician-directed interviews for a median follow up of 24 months (range 6–27 months). Pain relief was classified as excellent (no pain without medication), good (well-controlled pain with continued medication), fair (decreased but residual pain with continued medication), or poor (unimproved or increased pain with the same or increased medication).

Three months after treatment, pain relief was good or excellent in 71% of patients. By 24 months post-GKS, 50% of the original cohort had poor pain relief, 21% continued to have either excellent or good relief, 3% had fair relief, and 26% had not reached the 24-month follow up. Based on their status at the last follow up, 29% of patients had excellent and 16% had good pain relief. Thirty-seven percent experienced facial numbness, which was dose related. In addition, there was a significantly higher rate of complete pain relief in patients who had facial numbness following treatment (p = 0.003).

Conclusions.立体定向pati门将是一种有效的治疗ents with TN; however, the durability of pain relief and the time to treatment response are limiting factors. As with other types of ablative treatment, facial numbness is strongly associated with better treatment response.