Low Dose Intravenous Midazolam Provides Significant Pain Relief During Leksell Frame Fixation

Chan K. F.1, Chung Ping Yu1, Robert T. K.1, Joel Y. C.2, Ben K. P.1

1Canossa 2Princess Margaret, Hong Kong.

Keywords: anesthesia, technique, gamma knife, radiosurgery, stereotactic frame

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     In the procedures of Gamma Knife Radiosurgery, Leksell Frame Fixation is the most stressful step experienced by the patients. It is mainly due to the pain and pressure exerted from the fixation pins, plus the
     anxiety thereof. We study the efficacy of low dose intravenous midazolam (dormicum) in providing further pain relief in addition to local anesthesia during Leksell Frame Fixation. Quantitative measurement of pain perception is assessed by NRS (Numerical Rating Scale).
     Two groups of patients (total 115) were studied. Group A (51 patients: 26 male/25 female; mean age is 52.7) were given intravenous midazolam of dosage 1mg before and titrated to maximum 2mg during frame fixation.
     Injection of local anesthesia at pin sites is a mixture of Xylocaine 2% with adrenaline 1:200,000 and Chirocaine 5mg/ml at 1:1 proportion. Group B (64 patients: 34 male/ 30 female; mean age is 54.8) were given local anesthesia only with the same preparation as in Group A. Assessment of Pain using Numerical Rating Scale (NRS) was done 5 minutes after completion of frame fixation. Patients usually forget the procedure soon after the administration of midazolam. Patients were asked about the intensity of pain rating from 0 to 10. Score 0 represents no pain while score 10 represents maximum intensity of pain that the patient ever experienced. Patients with history of allergy to the above stated medication were excluded in the test. Vital signs of blood pressure and pulse of the patient were carefully monitored during the frame fixation procedure for early detection of vasovagal shock.
     For Group A (midazolam group), the mean NRS was 3.1 (SD=2.48), and median being 3.0. Group B (without midazolam), the NRS was 4.92 (SD=2.23), and median being 5.0. The results of an unpaired t-test showed p = 0.0001. No patients in both group A and B suffered from hypotension, vasovagal attack or other adverse events during the frame fixation procedure.
     This is a retrospective study.
     Low dose IV midazolam is effective and safe for further pain relief during Leksell frame fixation.


Project Roles:

C. F. (), C. Yu (), R. K. (), J. C. (), B. P. ()