Neuropathic Pain

In this episode of PodMD, Specialist Pain Medicine Physician and Specialist Anaesthetist Dr Liam Ring will be dicussing the topic of neuropathic pain, including what neuropathic pain is, how to properly diagnose it, the management options, any warning signs to look out for, when to refer and more.

  • Transcript
    Please note this is a machine generated transcription and may contain some errors.
    *As always, all in this PODMD podcast is intended for health professionals and the comments are of a general nature. Information given is not intended as specific medical advice pertaining to any given patient. If you have a clinical issue with one of your patients please seek appropriate advice from a colleague with expertise in the area.

    Today I’d like to welcome to the PodMD studio Dr Liam Ring

    Dr Liam Ring is an Australian trained Specialist Pain Medicine Physician. He has a special interest in multidisciplinary and interventional pain medicine.

    Today, we’ll be discussing the topic of neuropathic pain.

    *We do hope you enjoy this podcast but please remember that the advice here is of a general nature and is not intended as specific advice about a given patient. The views and opinions expressed in this podcast are those of the doctor, not PodMD.
    If you do have a patient on whom you require specific advice, then please seek advice from a colleague with appropriate expertise in that area.

    Liam, thanks for talking with us on Pod MD today.

    Liam: Thanks for having me.

    Question 1
    The topic of today’s discussion is neuropathic pain. Can you describe for our listeners what neuropathic pain is?

    Liam: Neuropathic pain is defined by the international association for the study of pain, neuropathic pain, special interest group. That’s a bit of a mouthful, um, as pain arising as a direct consequence of a lesion or disease affecting the somatosensory nervous system.

    As your listeners would be familiar with. A lot of patients describe, uh, neuropathic pain with descriptors like pain that is electric shock shooting, ants crawling painful hot, painful cold. It’s important for clinicians to understand that patients don’t always describe neuropathic pain with those words. Um, neuropathic pain can be described with new, uh, nociceptive descriptors like aching or nagging types of pain. The key way to diagnose neuropathic pain is to assess both symptoms and signs as well as identify mechanism. And it’s really important that you do all three of those things. Um, commonly, uh, from what I see in, uh, in, in my practices, a lot of patients, if they describe their pain in terms of electric shock shooting, most clinicians here that go, I know what that is, that’s neuropathic pain. And then they put them on a medication, uh, for neuropathic pain. Uh, but a lot of those patients actually don’t have neuropathic pain. Uh, also I see a lot of patients who do have neuropathic pain where no one’s delved into the symptoms or delved into the symptoms properly, or the signs, uh, or looked into a mechanism. And in fact that person does have definite neuropathic pain.

    Question 2
    How do you properly diagnose neuropathic pain?

    Liam: So identifying descriptors, like I was just describing electric shock shooting, hot burning, uh, hot, uh, painful, cold, painful, hot, uh, but also, uh, an prickling or ants crawling. Uh, but also, uh, patients will often report symptoms of Allodynia. So certain sensory stimuli will trigger their pain and they’ll be avoiding introducing those in that area. Uh, the other thing that’s also important to delineate is, uh, the nature of their pain. So it’s relatively common for patients with neuropathic pain to have spontaneous pain, so pain that can just completely come out of the blue with no obvious mechanical or any other obvious trigger. Uh, and usually that’s very brief, uh, but in some instances in say spinal cord injury, it can actually be quite prolonged. But it often is something that the patient is very confused about because they will report “I did nothing, I was just sitting there and then boom all of a sudden it was there and then all of a sudden it was gone”. Uh, so if it’s got a mind of its own is another really important symptom that you need to tease out with respect to signs, you need to identify obvious neurological change. Uh, whether that be, uh, hypoesthesia hyperesthesia, uh, allodynia being pain in response to non painful stimuli.

    But assessing that with, uh, all the different sensory modalities, the simplest way to do that is with light touch, which, uh, assesses a beta fibers, uh, using a pinprick we’d like a tooth peak, uh, that assesses a Delta fibers and then a patient’s description of what happens when cold water runs over it will assess C fibres. The final thing you need to be looking for is a mechanism that could lead to a person developing neuropathy, whether that be, you know, a diagnosis of diabetes or previous exposure to chemotherapy, uh, or alternatively, uh, some neuro compressive lesion or some, uh, surgery that could have compromised a nerve and, uh, whether or not there’s any need to do any appropriate investigations to confirm that like nerve conduction studies or an MRI scan, um, in a setting where you’ve got positive symptoms, positive signs and a different mechanism, well that’s defined as definite neuropathic pain. Uh, if you’ve only got two of those being positive, that’s probable neuropathic pain, uh, and if you’ve only got one of those positive that’s possible neuropathic pain and the neuropathic pain special interest group would encourage clinicians to treat definite neuropathic pain, whereas probable neuropathic pain and possible neuropathic pain well, um, I wouldn’t necessarily be introducing medications in those patients. Uh, you’ve got a very low likelihood of benefit.

    Question 3
    What are the management options?

    Liam: Well, most clinicians would be aware of medication, but there are other management techniques. Um, if we look at through a bio-psychosocial model, well, there is psychological desensitization. There is education and reassurance. There’s also, um, physical desensitization and then there’s medications. Uh, and I would generally only be introducing first-line medications for neuropathic pain.

    Question 4
    Have there been any developments in management in the last years or are there any in trials or development now?

    Liam: The latest developments in terms of targeting focal neuropathic pain, uh, is, um, electrical neuromodulation of stimulation. Um, whether that be, uh, peripheral nerve stimulation, dorsal root ganglion stimulation, or epidural spinal cord stimulation. Um, there are more trials being done with positive results in patients with, uh, the classic being, um, peripheral neuropathy associated with diabetes, uh, using dorsal root ganglion, uh, stimulation. So leads that target L five S one will cover the foot and ankle, uh, where a lot of these patients will first start getting their symptoms, uh, in classic definite neuropathic pain, following surgery, uh, like inguinal hernia, like post inguinal hernia, surgery, pain, uh, post knee surgery pain, if they have features of definite neuropathic pain in those distributions well, um, dorsal root ganglion leads involving L three, uh, for the knee or, uh, T 12, uh, L1 involving the groin can be helpful or alternatively, uh, epidural spinal cord stimulation could help all those areas depending on the position of the lead. Um, that’s very much the latest, uh, developments. Uh, it’s being more and more widely applied, but it’s in the early days.

    Question 5
    Are there any warning signs a GP or their patient can look out for?

    Liam: I would be concerned if a patient’s having rapidly progressing symptoms. Uh, so if the distribution of the patient’s symptoms is rapidly changing, um, I have a very low threshold for investigating that. Um, and, uh, be concerned about some primary medical condition contributing to that, uh, that may not have been diagnosed.

    Question 6
    When should a GP refer?

    Liam: If the GPS assessment of, of the symptoms and signs and mechanism, uh, they’re very confident of that. Um, I wouldn’t be recommending, they refer them on, um, at that point I’d be wanting them to try and, uh, first of all, educate the patient about, uh, neuropathic pain, uh, link them up with providers that could train them in physical desensitization and psychological desensitization, uh, and they could consider a trial of a first-line agent for neuropathic pain. Um, and I would encourage them to just very slowly titrate that, evaluate that through the prism of either. Is it causing the desired effects of reducing pain, or is it causing undesired effects in terms of it causing intolerable side effects.

    If they reach a juncture where they’ve done all of those things and the patient’s still struggling well, then that will be the time to refer them on to a pain medicine physician. If the primary physician or the GP hasn’t confirmed in their own mind, uh, what the mechanism is, um, or the act, what the cause could be referring them on to a neurologist or a relevant specialist say if they are an endocrinologist or other discipline to better assess uh, what would be the, uh, primary condition causing the neuropathy, uh, would be indicated? Um, I guess also in that state depending on which specialist they’d refer them to appropriate investigations beforehand would be important.

    If they’re uncertain around the diagnosis, uh, appropriate early investigations and referral to a relevant specialist would be indicated if they’re certain of an investor of the diagnosis and they’ve tried simple strategies and one or two medications, and the patient’s still struggling then referring them on to a pain medicine specialist would be indicated.

    Question 7
    What role does the GP play in the treatment of the condition?

    Liam: The only thing that I might say with regards to the GPS role, uh, from my perspective, uh, I see my role as, uh, educating and guiding a GP with regards to medication management, uh, and also linking a patient up with appropriately trained, uh, allied health professionals, uh, and supporting a GP and trying to coordinate that team for the patient.

    Concluding Question
    Thank you for your time here today in the PodMD studio. To sum up for us, could you please identify the take home messages from today’s podcast on Neuropathic Pain?

    Liam: The first take home message, uh, would be the importance of properly assessing your patients, um, assessing both their symptoms, their signs, and hunting for a plausible mechanism, um, and diagnosing patients in accordance with the international association for the study of pain’s definitions of definite neuropathic pain, probable neuropathic pain, and possible unconfirmed neuropathic pain. Uh, and if all clinicians were talking about neuropathic pain with that nomenclature, that would be very helpful. Uh, and if we were introducing medical therapies like medications or interventions in only the group of patients with definite neuropathic pain, um, I guess the second point there would be, um, if we have established definite neuropathic pain, uh, management should always involve simple strategies of education, reassurance, uh, linking them up with appropriately trained allied health professionals to guide them in both physical desensitization and psychological desensitization.

    Something else that I’ve forgotten to mention is, uh, the importance of just broader pain management guidance in terms of greater exercise exposure, uh, in order to improve their functional capacity. Um, and in a setting of patients with definite neuropathic pain, uh, if they’re not responsive to self-management strategies and education, uh, that, that group, which is the group of patients where, uh, targeted medications or interventions are indicated. And, uh, I would have, uh, I would encourage my, uh, general practitioner colleagues to refer these patients early, particularly if they’ve tried one or two agents and that patient’s not responding as they would like.

    Thanks for your time and the insights you’ve provided.

    Liam: Thanks very much.

*As always, all in this PODMD podcast is intended for health professionals and the comments are of a general nature. Information given is not intended as specific medical advice pertaining to any given patient. If you have a clinical issue with one of your patients please seek appropriate advice from a colleague with expertise in the area.