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Three Part Question

Does [benztropine] [improve pain scores] for patients with [acute musculoskeletal pain]?

Clinical Scenario

You see a 32-year-old man in the rapid assessment zone of your emergency department with acute neck pain a few hours after helping his friends move to their new apartment. There was no direct trauma and he has no neurological deficits and no bony tenderness. He has tried acetaminophen and ibuprofen but he continues to have limited range of motion and significant pain on the left side of his neck.

Search Strategy

OVID Medline and EMBASE
(benztropine.mp or exp Benztropine OR cogentin.mp) AND (back pain.mp or exp Back Pain OR spasm.mp or exp Spasm OR msk pain.mp or exp Musculoskeletal Pain OR exp Acute Pain or pain.mp or exp Low Back Pain or exp Neck Pain or exp Pain or exp Pain Management)

Search Outcome

716 studies imported for screening
28 duplicates removed
688 studies screened
673 studies irrelevant
15 full texts assessed
13 studies excluded
2 relevant studies were identified

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Epstein NL 2001 Canada	Eight emergency department patients (16-42 yo) with acute onset spasmodic neck and back pain. Benztropine 2-4 mg IM.	Case series	Pain (using ten-point visual analog scale)	All patients had improvement in pain scores after treatment	Small, single investigator, single-arm, case series Unclear if consecutive enrolment
Asha, S.E., Kerr, A., Jones, K., & McAlpine, A 2014 Australia	Thirty emergency department patients with acute, non-traumatic neck pain. Benztropine 2mg IM vs placebo IM injection.	Placebo-controlled, randomized-controlled trial	Mean pain (using ten-point verbal numeric rating scale) at 30 min after treatment	No significant difference in pain scores between groups (5.6 v 6.2, p = 0.40)	Compared post-treatment scores of benztropine v placebo, rather than change in scores pre to post-treatment between groups Small study, underpowered

Comment(s)

There is limited evidence on the use of benztropine for acute musculoskeletal pain. Our only high-quality evidence shows no evidence of benefit for treating acute spasmodic neck pain, and increased adverse events, when administering benztropine. The results of this study are limited by it’s small sample size.

Clinical Bottom Line

Benztropine should not be routinely used in the treatment of acute musculoskeletal pain.

References

1. Epstein, N.L. Benztropine for acute muscle spasm in the emergency department. Canadian Medical Association Journal 2001 164(2):203-204
2. Asha, S.E., Kerr, A., Jones, K., & McAlpine, A. Benztropine for the relief of acute non-traumatic neck pain (wry neck): A randomised trial. Emergency Medicine Journal 2014 32(8):616-619