Both the Immunization Bulletin from the Office of the Chief Medical Health Officer, Vancouver Coastal Health, dated 1 September 2015, and the Vaccine Administration and Pain Management Information Circular from the same source dated September 2015 advocate subcutaneous vaccine injection into the upper-outer triceps region for patients equal to or over 12 months of age. I recommend that Vancouver Coastal Health revise such a recommendation, and I advise immunizing health professionals about the hazards inherent to those 2015 recommendations.

Nerve injuries following injections have long been recognized to occur more frequently than was thought.[1] Indeed, inadvertent injury to the radial nerve continues to be reported following errant injections along the lateral arm.[2-4] Although subcutaneous injections should, in theory, avoid the radial nerve, the subcutaneous adipose in children and thin adults may be insufficient to safeguard the relatively superficial radial nerve. When the lateral triceps is advocated for subcutaneous vaccines, the popularity also spills over to use of that site for subcutaneous allergen desensitization injections. In my clinical experience I have seen patients present de novo with transient radial nerve pathology after either intramuscular or subcutaneous injections in that region. Effectively, the triceps region should be avoided given the underlying radial, brachial, and ulnar nerves and the profunda brachii artery.[5] There are many alternative safe sites for subcutaneous vaccination or allergen injection.

Furthermore, apart from excessively low intramuscular deltoid injections potentially affecting the radial nerve, other deltoid injections can be problematic. In particular, an excessively high deltoid placement can injure the anterior axillary nerve branch or enter accidentally into the subacromial space.[6,7] The upper third of the deltoid should be avoided, and placement should be made into the middle third of the deltoid muscle.
—Nevio Cimolai, MD, FRCPC
Department of Pathology and Laboratory Medicine
UBC Faculty of Medicine

References

1.    Hanson DJ. Intramuscular injection injuries and complications. Am J Nurs 1963;63:99-101.
2.    Ling CM, Loong SC. Injection injury of the radial nerve. Injury 1976;8:60-62.
3.    Taras JS, Donohue KW. Radial nerve motor palsy following seasonal influenza vaccination: A case report. J Surg Orthop Adv 2014;23:42-44.
4.    Beredjiklian PK, Nazarian LN, Bercik MJ, et al. Isolated radial nerve palsy secondary to influenza vaccination: A case report with imaging correlation. Pract Neurol 2012;September/October:14-16.
5.    Bergeson PS, Singer SA, Kaplan AM. Intra-muscular injections in children. Pediatrics 1982;70:944-948.
6.    Davidson LT, Carter GT, Kilmer DD, et al. Iatrogenic axillary neuropathy after intramuscular injection of the deltoid muscle. Am J Phys Med Rehabil 2007;86:507-511.
7.    Atanasoff S, Ryan R, Lightfoot R, et al. Shoulder injury related to vaccine administration. Vaccine 2010;28:8049-8052.