Introduction
Iatrogenic injury is one directly caused by medical treatment or investigation. It was George Bonney who famously wrote that “when a patient enters hospital without a nerve lesion and emerges with one, it is seldom possible to resist an allegation of negligence.”1
The true incidence of iatrogenic nerve injuries is difficult to ascertain. Estimates suggest that up to 25% of all nerve injuries may result from some form of medical intervention.2 Many of these may be mild and self-limiting but severe injury to a major motor, sensory or mixed nerve trunk can be catastrophic for patients who may experience neuropathic pain, paralysis and sensory loss. Alongside this there is the added psychological distress caused by uncertainty over the diagnosis and a lack of clarity about prognosis.
Most clinicians rarely see nerve injuries, and many will never encounter an iatrogenic injury. Delay to diagnosis is therefore common, and this serves not only to increase the patient’s frustration but risks the development of pain syndromes including central sensitisation and type 2 complex regional pain syndrome, which can be notoriously difficult to treat. A delay to diagnosis may also worsen the outcome for a nerve that is acutely subject to local pressure or ischaemia. Delay may also reduce the chances of successful repair or reconstruction where a nerve injury has caused a time-critical motor deficit.3,4
The psychological burden carried by the clinician involved in an iatrogenic nerve injury can be significant, but seldom merits consideration. For peripheral nerve surgeons, an important part of our role is to offer ease of access for colleagues to seek advice, and a prompt clinical review when an iatrogenic nerve injury may be suspected. This also ensures that injuries requiring further intervention are picked up at an early stage.
Classification and Incidence of Nerve Injuries
Peripheral nerve injuries are commonly classified using Seddon’s system, which divides them into three categories:5
Neurapraxia: A temporary block in nerve conduction without structural damage. Recovery typically occurs within 2 to 12 weeks. The diagnosis should be approached with caution to avoid delays in treating more severe injuries.
Axonotmesis: Involves the disruption of the axon and myelin sheath, often due to severe compression or crush injuries. Wallerian degeneration occurs and recovery occurs via axonal regeneration, which proceeds at approximately 1-2 mm per day.
Neurotmesis: The nerve is completely severed. Recovery requires surgical intervention, such as nerve repair or grafting.
Mixed nerve injuries: Different fascicles are injured to different degrees and will recover at different rates. A mixed nerve injury can therefore have elements of a conduction block, but a significant part of the nerve may be carrying a more significant injury.
If an iatrogenic nerve injury is identified intra-operatively the patient should be discussed with the local peripheral nerve service. An immediate microsurgical repair of a divided nerve may avoid the need for a more difficult delayed repair that needs an interposition graft. In cases where motor recovery may be uncertain, for example due to long regenerative distances, the patient can be given clarity about the likely recovery process and the need for adjunctive techniques to upgrade motor function such as nerve transfer. If specialist input is not available intra-operatively, the standard advice is to tag the nerve ends to aid identification during re-exploration.6
More often, the injury is unrecognised during the procedure but is suspected in the early post-operative period. A significant nerve injury is marked by dense loss of motor and sensory function, loss of autonomic innervation (hyperaemia and dry skin) and severe unrelenting neuropathic pain. The severity and character of the pain is the most distinguishing feature of a high-grade injury.7,8
Obtaining a clear diagnosis can be compromised by the use of spinal and regional anaesthesia or where pre-operative documentation of nerve function has been missing or incomplete.
Nerve conduction studies and electromyography are an important part of diagnosing and grading these injuries. However, neurophysiology can be misleading in the first two weeks after nerve injury, as Wallerian degeneration will not yet be established. This can result in a degenerative nerve injury being incorrectly graded as a conduction block, potentially causing a delay to intervention.
Early Referral to a Peripheral Nerve Surgeon
The BOAST guidelines offer some clarity in the early management of a peripheral nerve injury and outline when to seek the involvement of a peripheral nerve surgeon.6 Failure to offer early diagnosis, specialist referral and treatment, may expose the patient to further deterioration and may close the window of opportunity for successful intervention.3
The guidelines emphasize that early intervention is particularly important in cases of suspected axonotmesis or neurotmesis, where timely surgical exploration and repair can significantly impact recovery. Early referral is also advisable where the complexity of the case adds to uncertainty regarding the diagnosis, or where the primary clinician lacks the necessary experience in assessing nerve injuries. By seeking advice early, the treating clinician can avoid delays in treatment that might otherwise result in poorer outcomes and an increased risk of litigation.9,6
Medico-Legal Considerations
Medico-legal claims related to iatrogenic nerve injuries are not uncommon.9,10
Iatrogenic nerve injuries may result from distorted anatomy, intra-operative positioning, traction to the limb, prolonged tourniquet usage, or direct trauma to the nerve from misplaced metal work, diathermy or power tools. Minimally invasive surgery or approaches with limited sight of local neurovascular structures may also carry additional risk.10
Causes of litigation include inadequate informed consent, delays in diagnosis or treatment, and mismanagement of the injury postoperatively. Poor assessment and poor documentation can be a contributing factor.
The Montgomery ruling11 has emphasised the importance of obtaining detailed informed consent, particularly for procedures that carry a risk of nerve damage. Surgeons are advised to discuss potential risks with patients thoroughly and document these discussions, and this may serve to mitigate the risk of legal action.10
An analysis of litigation claims in trauma and orthopaedic surgery within the NHS from 2008/2009 to 2018/2019 revealed that nerve injuries accounted for 9.2% of claims. However, neurological injuries accounted for 24.5% of damages paid out, highlighting the significant, often lifelong impact of these injuries on patients.9
Role of a Peripheral Nerve Surgeon in Medico-Legal Settings
A peripheral nerve surgeon plays a crucial role in the medico-legal evaluation of nerve injuries in the realms of both negligence and personal injury.
There is frequently a lack of clarity over which nerve trunk has been injured and the depth and grade of injury. A careful review of the notes and an up-to-date assessment of the patient is usually enough to clarify the diagnosis and the extent of recovery, as well as the likely prospects for further spontaneous recovery.
Differentiating neuropathic pain from other types of pain is a particular challenge, particularly in a longstanding injury where nerve pain is established. Pain scoring, for example using the S-LANSS and NPQ systems, alongside careful clinical evaluation can be helpful, but the natural history of the nerve injury, and a thorough clinical evaluation for objective markers of nerve regeneration are also important.
Features of central sensitisation such as allodynia and hyperaesthesia are common findings and may be hallmarks of a wider pain syndrome.10
Where there is an ongoing pain driver from an injured peripheral nerve that has failed to respond to adequate therapy and neuropathic pharmacology, a strategy of ultrasound guided nerve blocks may be devised to determine whether surgical treatment of a painful neuroma can offer a reliable route to pain relief.4
Results can be unpredictable, however, particularly where there is an established pain syndrome or longstanding neuropathic pain. Where nerves are tethered in scar tissue, a local mechanical stimulus for pain may be a significant factor and needs addressing at the same time.8
Surgery may involve techniques such as, nerve wrapping, nerve reconstruction using allograft or autograft, nerve capping, targeted muscle reinnervation (TMR) or regenerative peripheral nerve interfaces (RPNI). When successful, the pain relief afforded can be life changing and have a significant impact on prognosis. Devices such as peripheral nerve stimulators and spinal cord stimulators have found some success in intractable pain but are expensive and require long term follow up and patient engagement.4,7,8,10
A peripheral nerve specialist is invaluable in determining whether late-stage or missed diagnoses still offer treatment options that could significantly alter the prognosis. Often there are a number of possible options available. A clear evaluation of each of these ensures that the involved parties have a clear understanding of the injury's implications and the realistic outcomes of potential treatments, thereby helping to shape the course of litigation or settlement discussions.10
Conclusion
Iatrogenic nerve injuries, though rare, remain a significant concern, both for their impact on patients and the potential for medico-legal repercussions. The rise in litigation claims over the past decade underscores the need for diligence in surgical practice, informed consent, and early recognition and intervention when injuries occur. Initiatives like GIRFT, and clear guidelines for specialist referral offer hope for reducing the frequency and cost of these claims, but ongoing efforts are needed to ensure that preventable injuries are minimised.
Recent research and technological advances in peripheral nerve surgery have increased the options available for treating nerve injuries, both in the acute setting, and where an injury has been missed or undertreated.
References:
[1] Bonney G. Iatrogenic injuries of nerves. J Bone Joint Surg [Br] 1986; 68-B: 9-13.
[2] Khan R, Birch R. Iatropathic injuries of peripheral nerves. J Bone Joint Surg [Br] 2001; 83-B: 1145-1148.
[3] Ross A. Medico-legal aspects of peripheral nerve injury. Bone & Joint Journal.
[4] Kretschmer T , Heinen CW , Antoniadis G , Richter HP , König RW . Iatrogenic nerve injuries. Neurosurg Clin N Am 2009; 20:73–90.
[5] Seddon HJ. Three types of nerve injury. Brain 1943; 66: 237-288.
[6] BOAST peripheral nerve injury guidelines. 3rd December 2021. BSSH, BAPRAS, OTS
[7] Dellon AL. Invited discussion: management strategies for iatrogenic peripheral nerve lesions. Ann Plast Surg 2005; 54: 140-142.
[8] Kyriacou S, Pastides PS, Singh VK et al. Exploration and neurolysis for the treatment of neuropathic pain in patients with a sciatic nerve palsy after total hip replacement. Bone Joint J 2013; 95-B: 20–22.
[9] Majeed H. Litigations in trauma and orthopaedic surgery: analysis and outcomes of medico-legal claims during the last 10 years in the United Kingdom National Health Service. EFORT Open Rev 2021;
6: 152-159.
[10] Bage T, Power D. Iatrogenic nerve injuries. EFFORT Open Rev. 2021 Aug10;6(8)607-617.
[11] Montgomery v Lanarkshire Health Board [2015] SC 11 [2015] 1 AC 1430.
Published by: