Anatomical aspects of iatrogenic nerve injury

Abstract

Iatrogenic nerve injury causes distress and disability, often leading to litigation. To date, the scale and profile of these injuries can only be estimated from published case reports or series, and medico-legal claims analyses. Some iatrogenic nerve injuries may be avoidable, but without understanding their spectrum and circumstances, the development or wider implementation of preventive strategies is limited. A systematic review was undertaken to analyse recently published literature on iatrogenic nerve injury, selecting one major upper and lower limb nerve as examples. The databases MEDLINE, PubMed, Cochrane Library, and Google Scholar were searched for relevant reports published between January 2000 and October 2012, focusing on injury context, mechanism, and frequency. Case reports and series of specific nerve injuries accounted for most publications. Most injuries occurred in the context of surgery. An observational study was undertaken to determine the contemporary spectrum of iatrogenic nerve injury in New Zealand, by analysing treatment injury claims accepted by the Accident Compensation Corporation (ACC) during 2009. The hypothesis was that this spectrum of nerve injury is different to that reported in the recent literature. Of 5,227 treatment injury claims examined, 313 were for iatrogenic nerve injury. Two-thirds occurred in surgical patients. Leading causes of injury were patient malpositioning under general anaesthesia and venepuncture, most often affecting the ulnar and median nerves, respectively. Both leading contexts were underreported in the literature. On the basis of these findings two further studies were performed. The first investigated ulnar nerve blood supply in relation to upper limb positioning in supine adults. Colour Doppler ultrasound was used to assess the effect of elbow flexion (~120°) and shoulder hyperabduction (120°) on arterial resistance in two arteries supplying the ulnar nerve at the elbow, in 38 healthy adults. Both positions affected arterial resistance, but resistance in the posterior ulnar recurrent artery was significantly increased with elbow flexion. These findings provide novel insights into the potential mechanisms of ulnar nerve ischaemia secondary to upper limb positioning.

There were 26 claims for venepuncture-related nerve injury in the ACC analysis, mainly for median nerve damage, prompting the question whether phlebotomists have an adequate knowledge of anatomy. A questionnaire was sent to 49 registered phlebotomists in seven community laboratories in New Zealand, to survey their knowledge, education and experience of venepuncture-related nerve injury. Thirty-seven (76%) returned questionnaires, 29 of whom reported some education about nerve injury. Symptoms of injury were well described but knowledge of nerve anatomy in the cubital fossa was limited; only 25% of respondents recognised the median nerve as being at risk from venepuncture. Phlebotomists may benefit from further information about peripheral nerve injury, especially in relation to avoiding median nerve injury. Iatrogenic nerve injury occurs in a wide range of contexts, and affects a variety of nerves. Some may be unavoidable, but many cases might be preventable by a better knowledge of relevant anatomy and a greater awareness of the contexts in which specific nerves are vulnerable. Educating healthcare professionals on this subject may help to reduce the frequency of this distressing iatrogenic complication.