Anesth Pain Med.  2016 Oct;11(4):393-398. 10.17085/apm.2016.11.4.393.

Comparison of 0.075% and 0.1% ropivacaine in terms of motor dysfunction after piriformis muscle injection

• Lee EJ
• Lee GG
• Baek SY

• KMID: 2358338
• DOI: http://doi.org/10.17085/apm.2016.11.4.393

Abstract

BACKGROUND
Motor weakness occurs frequently after piriformis injection and it could put patients at risk of falls. We investigated the appropriate concentration and volume of ropivacaine required to minimize motor dysfunction.
METHODS
A total of 120 patients who received piriformis injection were included in this study. Piriformis injections of triamcinolone 10 mg in various concentrations (0.1%, 0.075%) and volumes (8, 10, 12 ml) of ropivacaine were administered in 20 patients, respectively. One hour after the injection, we compared motor function according to the concentrations and volumes of ropivacaine.
RESULTS
There were significant differences (P < 0.05) in the occurrence of motor dysfunction according to body mass index (BMI) and the concentration of ropivacaine. No significant differences were found in terms of gender, age, weight, height, or the volume of ropivacaine. Logistic regression analysis showed that the likelihood of motor dysfunction with administration of 0.1% ropivacaine was 58.249 times greater than that with administration of 0.075% concentration (P < 0.001), while BMI did not have a significant effect on motor dysfunction.
CONCLUSIONS
According to the results of this study, 0.075% ropivacaine rather than 0.1% ropivacaine is appropriate in terms of reducing motor dysfunction after piriformis injection.

Keyword

Concentration; Piriformis injection; Piriformis syndrome; Ropivacaine; Volume

MeSH Terms

Accidental Falls
Body Mass Index
Humans
Logistic Models
Piriformis Muscle Syndrome
Triamcinolone
Triamcinolone

Figure

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  Fig. 1 Anatomical superficial references for classical posterior approach. (A) Greater trochanter. (B) Posterior superior iliac spine.

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  Fig. 2 Myogram of piriformis muscle with fluoroscopic and nerve stimulator localization.

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