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Katharine A Wallis, Thomas Hills and S Ali Mirjalili

Minimising iatrogenic nerve injury in primary care

Nerve injuries usually present as pain, NERVE ANATOMICAL COURSE numbness, or weakness, and can have Sciatic nerve in the gluteal region devastating consequences for patients. Sciatic nerve injury in the buttock may Procedures that are common in primary result in numbness, and weakness of the care can cause nerve injury. Iatrogenic hamstrings and all muscles below the nerve injuries are largely preventable by knee. The upper outer quadrant of the understanding nerve anatomical course buttock (dorsogluteal region) remains and , and the risky one of the most common sites for interventions and regions. Most knowledge intramuscular injection worldwide.2 Recent of nerve anatomical course is derived cross-sectional imaging studies in living from early work on cadaver dissection, adults and children have led to a revision of but modern imaging techniques more the surface anatomy of the sciatic nerve.3 accurately map nerve anatomical course This evidence suggests that the safe zone in living bodies. for injection is not the upper outer buttock We provide an overview of nerve injuries but the gluteal triangle (ventrogluteal in primary care, discuss updated nerve region). The gluteal triangle is located by anatomical course and surface anatomy placing the palm of the opposing hand on based on modern radiological evidence, the greater trochanter and the index finger and make recommendations to guide safer on the anterior superior iliac spine, forming interventions in primary care. a triangle with the middle finger pointing towards the iliac crest, as demonstrated NERVE INJURIES IN PRIMARY CARE in Figure 1.3 The recommended injection In New Zealand’s primary care treatment site is the centre of the triangle with the injury claims dataset there were 69 nerve needle inserted at 90° to the skin surface. injuries over 4 years (2% of primary care Supplementary material in the form of injuries).1 Venepuncture was the leading short educational videos on nerve anatomy cause of nerve injury (27; 39%), followed to guide safer interventions in primary care by intramuscular injection (17; 25%), and are available on request from authors. steroid injection (15; 22%). Venepuncture injured the cutaneous nerve of the Axillary nerve in the deltoid region KA Wallis, MBHL, PhD, FRNZCGP, DipObst, (14), and the median (9) and radial (4) nerves; Damage to the axillary nerve can result senior lecturer, Department of General Practice intramuscular injections injured the sciatic in shoulder abduction weakness and and Primary Health Care; SA Mirjalili, PhD, (11), lateral cutaneous (3), and axillary (3) numbness.4 Many immunisation guidelines MD, PGDipSurg, PGCertCPU, PGDipSci, senior lecturer, Department of Anatomy and Medical nerves; steroid injections injured the median recommend that the anterolateral thigh be Imaging, University of Auckland, Auckland. (12, carpal tunnel) and ulnar (3, medial used for intramuscular injection in infants, T Hills, MSc, DPhil, registrar, Department of epicondyle) nerves; intravenous cannulation and the deltoid region or anterolateral Medicine, Auckland Hospital, Auckland. in the forearm injured the superficial radial thigh in older children. However, current Address for correspondence nerve (4); and minor surgical procedures anatomical knowledge suggests that the S Ali Mirjalili, Department of Anatomy and Medical Imaging, University of Auckland, injured the spinal accessory (3), common deltoid region is problematic because of Grafton 505/185, 85 Park Rd, Auckland 1023, fibular (1), sural (1), and ilioinguinal nerves the highly variable anatomical course of New Zealand. (1). Most nerve injuries were minor, but the axillary nerve.4 Given readily accessible Email: [email protected] 17 (25%) were assessed as having major alternative injection sites, the deltoid region Submitted: 22 January 2018; Editor’s or serious potential consequences. These is best avoided for intramuscular injection. response: 25 January 2018; final acceptance: severe injuries were caused by steroid If selected, the safest zone is the lateral 21 February 2017. ©British Journal of General Practice 2018; injections (9), intramuscular injections (4), aspect no more than 4 cm below the lower 5 68: 392–393. minor surgery (3), and venepuncture (1). border of the acromion. DOI: https://doi.org/10.3399/bjgp18X698273 There were no claims for nerve injuries in Modern radiological evidence suggests patients younger than 17 years old. that the safest sites for intramuscular

392 British Journal of General Practice, August 2018 ASIS of hamate can be used as a palpable landmark. The safe zone lies radial (lateral) to the hook, but not more than 5 mm radial to it. The ulnar and nerve lie ulnar (medial) to the hook Supplementary IC material in the form of short educational videos on nerve anatomy to guide safer interventions in primary care are available on request from authors.

GT Spinal accessory nerve in the Accessory nerve injuries can be debilitating resulting in paralysis of the trapezius, drooping of the shoulder, loss of full Figure 1. The gluteal triangle (ventrogluteal injections in all age groups are the gluteal abduction, winging of the scapula, and pain. region).3 ASIS = anterior superior iliac spine. triangle and the anterolateral thigh. It is estimated that up to 8% of procedures GT = greater trochanter. IC = iliac crest. in the posterior triangle of the neck are at the antecubital associated with accessory nerve injury, The median nerve controls most of the mostly caused by skin lesion removal and muscles in the forearm and provides biopsy. The spinal accessory sensory input to the thumb, index and nerve has a superficial and highly variable 6 REFERENCES middle fingers. If damaged, patients may course in the posterior triangle of the neck. 1. Wallis K, Dovey S. No-fault compensation for Landmarks in this region cannot be relied treatment injury in New Zealand: identifying be unable to oppose the thumb and have threats to patient safety in primary care.BMJ weak wrist and finger flexion. The median on to avoid nerve injury. Patients requiring Qual Saf 2011; 20(7): 587–591. nerve enters the cubital fossa medial to the procedures in the posterior triangle of the 2. Mishra P, Stringer MD. Sciatic nerve injury palpable . neck should be referred. Supplementary from intramuscular injection: a persistent and material in the form of short educational global problem. Int J Clin Pract 2010; 64(11): videos on nerve anatomy to guide safer 1573–1579. at the antecubital fossa Damage to the radial nerve can leave interventions in primary care are available 3. Currin SS, Mirjalili SA, Meikle G, Stringer MD. on request from authors. Revisiting the surface anatomy of the sciatic patients unable to extend their wrist (wrist nerve in the gluteal region. Clin Anat 2015; drop). The radial nerve lies immediately at 28(1): 144–149. the lateral border of the cubital fossa, under Common fibular nerve in the leg 4. Davidson LT, Carter GT, Kilmer DD, Han the muscle. Injury to the fibular nerve can result in foot JJ. Iatrogenic axillary neuropathy after For venepuncture at the antecubital fossa, drop. The common fibular nerve is prone intramuscular injection of the deltoid muscle. to injury at the fibular neck as it curves Am J Phys Med Rehabil 2007; 86(6): 507–511. the lateral border of the cubital fossa should superficially lateral to the fibula. 5. Zhang J, Moore AE, Stringer MD. Iatrogenic be avoided. Blind attempts should also be nerve injuries: a systematic review. avoided. If it is not possible to identify the CONCLUSION AND RECOMMENDATIONS ANZ J Surg 2011; 81(4): 227–236. median cubital , for example, in obesity, 6. Mirjalili SA, Muirhead JC, Stringer MD. an alternative site should be considered or, Avoidable iatrogenic nerve injuries are a Ultrasound visualization of the spinal if available, ultrasound guidance used. persisting problem in primary care, most accessory nerve in vivo. J Surg Res 2012; commonly caused by venepuncture, 175(1): e11–e16. at the medial epicondyle intramuscular injection, and steroid injection. Nerve injuries may be difficult to Damage of the ulnar nerve can result in diagnose in babies and young children. claw hand deformity and loss of sensation Modern radiological evidence suggests to the little finger. The ulnar nerve can often that the safest sites for intramuscular be palpated as it runs behind the medial injections in all age groups are the gluteal epicondyle. If it is not possible to identify the triangle (ventrogluteal region) and the nerve or the tip of the medial epicondyle, anterolateral thigh. The lateral border of Competing interests steroid injections for medial epicondylitis the antecubital fossa should be avoided for The authors have declared no competing should be avoided or ultrasound guidance venepuncture, as should blind attempts. If interests. used. it is not possible to identify landmarks, for Acknowledgements example, in obesity, ultrasound guidance is Median nerve at the wrist (carpal tunnel) Sebastien Barfoot, Department of Anatomy recommended. At the distal forearm the median nerve and Medical Imaging, University of runs between the two visible tendons, the Auckland, New Zealand. Professor Mark palmaris longus and flexor carpi radialis. Stringer, Paediatric Surgeon, Wellington Funding The palmaris longus may be absent in up (Figure 1). Funded by School of Population Health, to 25% of people. The recommended safe University of Auckland. Discuss this article zone for carpal tunnel steroid injections is a Contribute and read comments about this 9 mm zone located 8 mm radially (laterally) Provenance article: bjgp.org/letters from the pisiform. Alternatively, the hook Freely submitted; externally peer reviewed.

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