Expert Opinion Section Editor: Steven Mandel, MD Isolated Palsy Secondary to Influenza Vaccination: A Case Report with Imaging Correlation

This report presents the first case of an injection to the radial nerve caused by inappropriately placed intramuscular Influenza vaccination, documented with advanced imaging.

By Pedro K. Beredjiklian, MD; Levon N. Nazarian, MD; Michael J. Bercik, MD;

Matthew Gorski, MD; and Steven Mandel, MD

e present a case of an injection injury to the to its abundant vascularity, this injection site optimizes the radial nerve caused by inappropriately placed immunogenicity of the vaccine while also minimizing the intramuscular injection. This patient’s symp- adverse reactions at the injection site.3 Generally, the vac- toms and corresponding images suggest the cination is well tolerated, and there are few side effects. The Wnerve palsy developed secondary to an inflammatory reac- most common side effects include injection site soreness, tion induced by the injectate into the nerve sheath. This redness, or swelling. Rarely, severe allergic reactions or auto- case report provides some understanding of the mechanism immune manifestations have been observed.4 involved in injection injury to the radial nerve. There are several reports of peripheral nerve fol- lowing intramuscular vaccine injection.5 The most recent Background of these come from countries with developing health care The Centers for Disease Control and Prevention (CDC) systems in which the staff were most likely improperly recommends vaccination against the Influenza virus for all trained.6-8 We present an unusual case of a patient who suf- health-care personnel. Vaccinations have been shown to fered a radial nerve motor palsy secondary to inappropriate protect health-care workers from viral infection and its co- placement of the Influenza vaccination. morbidities,1 while also decreasing mortality rates amongst hospital patients by reducing the rates of nosocomial infec- Case Report tion.2 Many institutions now mandate that all hospital The patient is a 26-year-old male who presented personnel be vaccinated. Complications are rare and often to an outpatient hand clinic with a chief complaint symptomatically negligible, making this a relatively uncon- of left . The patient indicated that he had received troversial health policy. an Influenza vaccination into his left arm approximately In adults older than 19 years of age, the recommended one day prior to presentation. While the patient did not site for intramuscular injection is the deltoid muscle. Due experience any or other symptoms at the time

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of injection, 16 hours later the patient began to develop progressively worsening weakness over his distal left upper extremity. After 20 hours, the patient had total weakness in the affected muscles. The patient had no past medical history and the review of systems was unremarkable. Physical examination revealed a small puncture wound in the posterolateral portion of his mid- arm, approximately 2.5cm distal to the clinically identifiable deltoid tuberosity. His motor exam demonstrated 4/5 strength in his triceps, 2/5 Figure 1. Sagittal STIR (TE 4716, TR 50) MR image demonstrates edema strength in his brachioradialis and 0/5 strength (arrows) along course of the radial nerve. in wrist extension, finger extension and thumb extension. No sensory abnormalities were noted. The remainder of the neurovascular exam was within normal limits. Magnetic resonance (MR) imaging of the left upper arm on the day after the injection, revealed edema along the course of the radial nerve without focal collection. The nerve itself was not grossly enlarged or damaged. (Figure 1) (US) examination of the patient’s arm on the day after the injection demonstrated swelling of the radial nerve in the distal third of the arm starting approximately 3cm distal to the injection site. At the center of the swollen seg- ment, an adhesive band was identified as com- pressing the nerve, likely an incidental finding Figure 2. Sagittal US image shows fusiform swelling of the radial nerve since the band was not near the site of injection (arrows), with an adhesive band (arrowhead) constricting the midportion of and the nerve was found to be swollen proximal- the swollen segment. H= . ly and distally to the band. (Figure 2) Given the results of the MR and the US, the impression was that the nerve palsy was secondary to a demy- elinating process related to inflammation around the nerve and not to axonal damage. A splint and a steroid taper were prescribed. Surgery in the form of a neurolysis was offered, but the patient elected nonoperative management. One month following the injury, the patient underwent nerve conduction studies and elec- tromyography (EMG) study to assess his periph- eral nerve function. This study demonstrated a severe left radial neuropathy with total motor axonal loss with sparing of the radial sensory nerve. A follow-up US obtained at the same time revealed progression of the swelling of the radial nerve in both size and craniocaudal extent, with involvement of the posterior interosseous nerve Figure 3. Transverse US image obtained two months after the vaccination and signs of supinator atrophy. This swelling and shows a markedly enlarged posterior interosseous nerve (arrowhead) after it atrophy were absent on the US evaluation on the has pierced the atrophic fibers of the supinator muscle. R = radius. On the ini- day after the injury. (Figure 3) tial study (not shown), the posterior interosseous nerve had been normal.

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• For adults, a 20- or 22-gauge needle that is 1 to 1.5 With training in the appropriate inches in length should be used. administration of an intramuscular • It should be injected at a 90 degree angle into the thick- injection and a basic est portion of the deltoid muscle. • A dose of no greater than 1cc should be administered. understanding of anatomy, It is unclear whether early surgical intervention to iatrogenic injury to nearby debride the nerve sheath or observation is the preferred peripheral nerves can be avoided. course of treatment. At the last office visit, one year after injury, the patient demonstrated near normal return of strength. The treatment strategy for nerve At approximately six months after the initial injury, the palsy remains controversial. Most radial nerve palsies patient reported progressive improvement in his motor are associated with humeral shaft fractures. In these symptoms beginning with the brachioradialis and progress- injuries, the palsy is often secondary to a neuropraxia ing inferiorly to his thumb extensor over time. At one and the nerve often will undergo a complete recovery.11 year post injury, physical exam revealed 5/5 strength in his In this case, as the inflammatory response waned, the triceps, 5/5 strength in his brachioradialis, and 4/5 strength nerve regenerated in the predicted proximal to distal in wrist extension, finger extension and thumb extension. fashion. He reported minimal functional limitations and was able to resume work in full. Conclusion We present the first case of an injection injury to the radial Discussion nerve caused by inappropriately placed intramuscular Significant peripheral nerve injuries may occur following Influenza vaccination with advanced imaging. The etiology improper administration of injected medications.5-8 A wide of injury—direct trauma to the nerve versus indirect injury range of injury patterns and recovery has been reported.6 via an inflammatory process—remains unclear. Routine vac- Whether an injection injury to a peripheral nerve is caused cination against the Influenza virus is warranted for health- by direct injury to the nerve or secondary to chemical care personnel. With training in the appropriate administra- insult is unclear. Experimental studies have shown direct tion of an intramuscular injection and a basic understanding toxicity to peripheral nerves with intraneural injection.9 of anatomy, iatrogenic injury to nearby peripheral nerves The imaging in this case suggests that his nerve injury can be avoided. With the large number of vaccinations given was caused by injection of the vaccination into the nerve annually, inadvertent injury may be inevitable. n sheath and not the nerve itself. Specifically, the MR dem- onstrated edema along the course of the radial nerve Pedro K. Beredjiklian, MD is Associate Professor, without distinct injury to the nerve. Early US showed Orthopaedic Surgery, Jefferson Medical College and nerve response distal to the injection site. We hypothesize Chief, Division of , The Rothman Institute, that the injectate dissected down the tissue planes along Philadelphia, PA. the radial nerve causing a chemical , leading to Levon N. Nazarian, MD is Professor of and axonal ischemia and loss. The progressive develop- Vice-Chairman for Education at Thomas Jefferson University ment of symptoms over time supports the notion that the Hospital in Philadelphia, PA. palsy developed secondary to an inflammatory process. 1. Wilde JA, McMillan JA, Serwint J, Butta J, O’Riordan MA, Steinhoff MC. Effectiveness of influenza vaccine in health care Alternatively, it is also possible that the total axonal loss professionals: a randomized trial. J Am Med Assoc 1999; 281:908-913. was due to ischemia from a chemical neuritis induced by 2. Potter J, Stott DJ, Roberts MA, Elder AG, O’Donnell B, Knight, PV, et al. Influenza vaccination of health care workers in long-term-care hospitals reduces the mortality of elderly patients. J Infect Dis 1997; 175:1-6. the injectate. 3. Zuckerman JN. The importance of injecting vaccines into muscle. Different patients need different needle sizes. Brit Med We believe that the reason for the palsy was inappropri- J 2000; 321: 1237-8. 4. Lasky T, Terracciano GJ, Magder L, Koski CL Ballesteros M, Nash D, et al. The Guillain-Barre syndrome and the 1992- ate location of the injection. The appropriate technique for 1993 and 1993-1994 influenza vaccines. N Engl J Med 1998; 339: 1797-1802. deltoid intramuscular injection is as follows.10 5. Broadbent TR, Odom GL, Woodhall B. Peripheral nerve injuries from administration of penicillin; report of four clinical cases. J Am Med Assoc 1949; 140:1008-1010. • The entire upper extremity should be exposed in 6. Gaur SC, Swarup A. Radial nerve palsy caused by injections. J Hand Surg Br 1996; 21: 338-340. order to identify the landmarks. The center of an 7. Pandian JD, Bose S, Daniel V, Singh Y, Abraham AP. Nerve injuries following intramuscular injections: a clinical and neurophysiological study from Northwest India. J Peripher Nerv Syst 2006; 11: 165-171. upside triangle is the target site. The acromion process 8. Ling CM, Loong SC. Injection injury of the radial nerve. Injury 1976; 8: 60-62. forms the base of the triangle, while the point of the 9. Hadzic A, Dilberovic F, Shah S, Kulenovic A, Kapur E, Zaciragic A, et al. Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs. Reg Anesth Pain Med 2004; 29: 417-423. triangle is located below the middle of the base at the 10. Covington TP, Trattler MR. Bull’s-eye! Finding the right target for i.m. injections. Nursing 1997; 27: 62-63. level of the axilla. 11. DeFranco MJ, Lawton JN. Radial nerve injuries associated with humeral fractures. J Hand Surg Am 2006; 31: 655-656.

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