Perspectives from Tara Renton

Understanding and managing Post Traumatic Neuropathic Pain

Over the last 15 years there is recognition that there are three main types of pain:

  • nociceptive (injury, injection and surgical pain) which is the healthy standard pain we all understand that protects us from harm.
  • neuropathic (caused by a lesion of the peripheral or central sensory nerve system) pain, due to disease (e.g. viruses [post herpetic pain), chemicals (chemotherapy), thermal insult (burns and frost bite) or trauma (accident or surgery) 
  • noci-plastic pain, which we currently believe to be centralised or dysfunctional pain, leading to chronic widespread pain and or fibromyalgia-type conditions.

The first two pains are undoubtedly preventable in the main. Perioperative acute nociceptive pain is not the focus of this blog. But Post Traumatic Neuropathic Pain (PTNP) is!

Up to 80% of patients attending chronic pain clinics have neuropathic pain, some due to past injury but mostly a result of surgery. Heinrich Kehlet highlighted the significant prevalence of chronic post-surgical pain after surgery[1]; including limb amputation, thoracotomy, cardiac and breast surgery over 30% of patients were affected - 10% of them significantly. Interestingly, dentistry has a much lower incidence of PTNP (5-8%) likely due to the use of local anaesthesia which may prevent central sensitisation leading to persistent pain. The problem with dentistry is that even though the post traumatic pain prevalence is low, a lot of dental procedures are carried out. Third molar surgery, dental implants, endodontics and block local anaesthesia are the main procedures leading to sensory nerve injury and PTNP after dentistry. These nerve injuries are avoidable in the main, by careful preoperative risk assessment, minimal access surgery and good perioperative pain management.

PTNP is characterised by ongoing and or elicited pain which onsets immediately after surgery. A demonstrable sensory neuropathic area within the dermatome of the previous surgery is present. The elicited pain, in the region, is usually allodynic (pain in response to a non-noxious stimulus) and/or neuralgic (pain in response to touch or cold). Neuralgic pain can also be spontaneous too.  Ongoing pain is usually characterised by burning pain that is less intense during or after sleep and worse towards the end of the day, or during illness and or stress.

Psychological factors including anxiety, depression, psychological vulnerability, catastrophising, introversion and neuroticism are predictors of PTNP. Fear of pain and surgery and comorbid pain conditions may also predispose patients to persistent post-surgical pain. Which may beg the question: Should routine psychological screening be undertaken to screen out patients at risk of PTNP prior to elective procedures?  Surgical factors include the site of surgery, duration, conventional access (not minimal access surgery), degree of tissue retraction and poor perioperative pain control. If some or all of these factors could be mitigated then prevention of PTNP may be possible.

I have spent most of my academic career highlighting the plight of patients with PTNP related to dentistry and the huge impact it has on their lives. The trigeminal nerve is the most important sensory nerve in the body, protecting our most important life sustaining structures (eyes, nose, mouth, meninges) providing life’s pleasures (smell, taste, speech, sexual interaction and sensation). Any patient with PTNP related to routine dentistry is massively impacted by the suddenness of it, the pain, and the functional and psychological impact, particularly as many of these patients will suffer pain for decades without fully understanding how it came about and are often resistant to treatment.

Management of PTNP is challenging. Explanation of the pathophysiology and prognosis of neuropathic pain is most important for the patient. They also need to understand that lessons have been learnt and inappropriate techniques or mistakes will not be repeated on future patients. Psychological interventions are crucial, allowing the patient to accept and come to terms with their predicament. Conventional surgical approaches do not work for neuropathic pain. Medical approaches include systemic medication, usually antiepileptics (pregabalin, gabapentin), tricyclic antidepressants (nortriptyline or amitriptyline) or topical medications including local anaesthetic patches, Botulinum toxin injections and capsaicin creams. But all barely touch the pain and present major side effects that are often intolerable for the patient. Overall management is deficient in so many ways and patients face significant challenges trying to lead normal lives.

This is why prevention of surgical-related sensory nerve injuries and the related post traumatic neuropathic pain is essential in preventing millions of patients facing lifelong preventable pain.

[1] Kehlet H, Jensen TS, Woolf CJ: Persistent postsurgical pain: Risk factors and prevention. Lancet 2006; 367:1618–25


Tara Renton is Professor Oral Surgery at Kings College London. Her maxillofacial training and PhD in neuroscience in Trigeminal nerve injuries has established her an international lead in orofacial pain and prevention of Trigeminal post traumatic neuropathic pain. She has two patient facing websites and that provide easy access information for clinicians and patients. Tara is also the Editor of a BDJ book in print on Pain Management for the Dental team.

undefined undefined

Tara Renton

Professor Oral Surgery at Kings College London, UK