Topical Anesthetic EMLA for Postoperative Wound Pain in Stereotactic Gamma Knife Radiosurgery: A Perspective, Randomized, Placebo-Controlled Study

The Effect of Pain Reduction during Headframe Fixation for Stereotactic Radiosurgery by the Preceded Local Anesthesia under the Needle Cap Guidance

Background

Gamma knife radiosurgery (GKRS) has become a major alternative in the neurosurgical field. However, many patients complained of considerable discomfort during the fixation of rigid headframe. This study investigated whether our modified procedure could reduce fixation-related pain.

Methods

Sixty-six patients who underwent GKRS were enrolled in this study. Thirty-one patients (Group A) underwent the conventional subcutaneous infiltration technique, and 35 patients (Group B) did the modified procedure. In group A, the headframe was held in position by an assistant, and local anesthetics were injected subcutaneously using a 23-gauge spinal needle at pinning sites. Subsequently, pins were applied according to measurements based on spinal needle depth. In group B, with the frame held in position by an assistant, pin sites were marked with a surgical pen under the guidance of needle cap placed on the pin holes. The head frame was then removed, and local anesthetics were injected subcutaneously and periosteally at each marked pin site using a 26-gauge needle. The headframe was then repositioned 5 minutes after local infiltration, and pins were applied according to measurements based on spinal needle depth. To evaluate pain severity during procedures, visual analogue scale (VAS) scores were recorded during local infiltration and frame placement with pins. The pain scores of the two groups were analyzed statistically.

Results

Group B had a significantly lower VAS score during frame placement than group A (7.26 vs. 3.61; p<0.001), and mean VAS score at local infiltration was also significantly lower in group B (4.74 vs. 3.74; p=0.008).

Conclusion

Patients in group B experienced significantly less pain than those in group A during pin placement. Pre-fixation time advanced local anesthesia might reduce pain during stereotactic procedures, and the use of a 26-gauge needle appeared in less pain during local infiltration.

A Randomized Trial on the Efficacy of Topical Anesthesia for Pain Reduction during Frame Placement for Gamma Knife Radiosurgery

BACKGROUND/AIMS

Frame application for gamma knife radiosurgery (GKR) may be perceived as painful by patients. This study was designed to assess the efficacy of EMLA (2.5% lidocaine/2.5% prilocaine) in pain reduction.

METHODS

This was a prospective, randomized, and controlled trial approved by our institutional review board. Fifty-four patients undergoing outpatient GKR were divided into EMLA and placebo groups. Prior to frame placement, EMLA/placebo was applied to the patient's forehead. A visual analog scale (VAS) was used to measure pain during 4 intervals: frontal injections, occipital injections, frontal screw insertion, and overall discomfort. This study was designed to observe a difference of 1.0 on the VAS at a power of 95%.

RESULTS

VAS for EMLA versus placebo for frontal injections (5.2 ± 2.7 vs. 5.7 ± 2.0, respectively; p < 0.45), back injections, (6.5 ± 2.2 vs. 5.9 ± 2.3, respectively; p < 0.30), frontal pins (4.6 ± 2.7 vs. 4.6 ± 2.2, respectively; p < 0.99), and overall discomfort (p < 0.29) were not significantly different. A comparison between back and frontal injections for EMLA (6.54 vs. 5.19, respectively; p < 0.16) and placebo (5.89 vs. 5.68, respectively; p < 0.69) showed no significant difference between group and location (p < 0.21).

CONCLUSION

Application of EMLA did not significantly reduce pain when used preoperatively for frame fixation. EMLA is no longer used as part of our routine for patients undergoing GKR.