Neuropathic Pain: Diagnosis and Treatment
Medicinewise News 5 February 2018: Modified by Helen Potter FACP 22nd February 2018
Neuropathic pain occurs when your nervous system becomes hypersensitised.
If you imagine listening to your favourite piece of music playing softly then increase the volume, it becomes irritating. Eventually the music is painful to hear. When acute pain becomes chronic the brain becomes over-sensitive.
What is Neuropathic Pain?
Neuropathic pain results from a neurological lesion or a somatosensory system disease. It is different to acute nociceptive pain as it is associated with nervous system changes. Fibromyalgia, and chronic regional pain syndrome are examples of neuropathic pain.
Testing finds little in terms of nerve damage but pressure tests show increased feeling.
- Neuropathic pain and nociceptive pain are treated differently.
- A history and a physical examination are important.
- A diagnosis proceeds choice of medication and the physiotherapy approach.
- A physical examination establishes the link between the pain and a lesion or disease in the brain.
- Australian guidelines use a stepwise approach to build evidence for a neuropathic pain diagnosis.
- Teaching understanding pain and the underlying pathology precedes addressing the pain itself.
- The clinical history and examination confirm that the location of the pain is anatomically consistent with a neurological lesion.
- Pain descriptors that include burning, shooting, prickling, or tingling contribute towards the diagnosis of neuropathic pain.
- Pain due to radiculopathy is slower to recover than other pain.
Neuropathic Pain is graded as:
Neuropathic pain is a possible diagnosis if there is:
- A history suggestive of a relevant neurological lesion (like herpes zoster or a traumatic nerve injury)
- Pain descriptors are (burning, shooting, pricking and pins and needles)
- There are non-painful sensations like numbness or tingling
- A pain distribution is explainable by a lesion or disease in the somatosensory system, or typical of an underlying neuropathic disorder
A clinical examination needs to reach a ‘probable’ level of certainty. Toothpicks, brushes or cotton wool can detect sensory changes that help further differentiate neuropathic from non-neuropathic pain.
Hypoalgesia to pinprick, hypoesthesia to tact buile stimuli, and allodynia to brush and cold are particularly discriminant.
Sensory changes should also lie within a plausible neurological distribution. (MRI) can confirm a stroke, multiple sclerosis or spinal cord injury and a skin biopsy showing reduced nerve fibre density.
Start treatment once probable the diagnosis of neuropathic pain is reached. Use further investigations only if these tests inform treatment.
The treatment of neuropathic pain remains challenging – partial pain relief is usually considered a good result. Pharmaceutical pain relief is part of a total plan for living with pain, which focuses on improving the patient’s quality of life and ability to function. Non-pharmacological treatment such as physical exercise, cognitive behavioural therapy (CBT) and meditation can help in accepting and coping with the pain.
‘There is little evidence to support the use of specific drugs in specific neuropathic pain conditions’, says Professor Siddall. ‘Usually the choice is determined by the general evidence in neuropathic pain as well as the likelihood of side effects in a particular person and the cost.’
Research recommends four medicines for treatment of neuropathic pain:
- Amitriptyline, duloxetine and gabapentin and pregabalin
- Other medicines recommended as second- or third-line options include Tramadol, lignocaine, capsaicin and botulinum toxin A.
- There is a limited role for opioids in the treatment of neuropathic pain because of safety concerns and poor evidence of long-term efficacy.
- There is little evidence that paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs) are effective.
Most patients’ expectations of an analgesic medicine are something that does or doesn’t work almost immediately. Neuropathic pain analgesics, act slowly. Start low, go slow is the best way to find the balance between the analgesic benefit and the side effect burden.
Unfortunately, only partial relief is possible in many cases. Some people will need support and strategies to help them understand, accept, and live with their pain.
A clear and targeted diagnosis, tackling the source of the pain where possible, and a treatment plan are essential.
Neuropathic Pain: Useful links