Neuropathic pain: symptoms, causes and treatment
Neuropathic pain is the term for pain that originates in the nervous system. Although it can arise in the central nervous system (spinal cord and brain), neuropathic pain usually originates in the peripheral nerves.
Neuropathic pain from compression neuropathies (compression by a neighbouring structure) has many causes. In the upper limb these include the median nerve in the carpal tunnel, the radial nerve at the arcade of Frohse, and the ulnar nerve in Guyon's canal or the cubital tunnel at the elbow, among others. In the lower limb they include the sciatic nerve at the piriformis muscle or the hamstring tendons, the peroneal nerve at the neck of the fibula and the sural nerve where it crosses the superficial fascia. Treatment usually involves relieving the nerve compression, with ultrasound-guided peripheral nerve hydrodissection (separating the nerve from the surrounding structures), botulinum toxin injections (where a muscle is involved) or even image-guided ligament release.
There are other causes of neuropathy, such as trigeminal neuralgia and varicella zoster (shingles) infection, among others. In these cases, as well as medication, several procedures may be used, such as peripheral nerve blocks, pulsed or ablative radiofrequency, cryoablation or even implanted peripheral or spinal cord stimulators.
How to recognise neuropathic pain
Neuropathic pain has its own characteristics, different from muscle or joint pain:
burning, electric shocks, stabbing or tingling;
numbness or altered sensation in the skin of the affected area;
pain triggered by things that don't normally hurt, such as clothes touching the skin;
a distribution that follows the path of a nerve, for example from the spine into the arm or leg;
worsening at night or in certain positions that compress the nerve.
How we diagnose it
At a pain medicine consultation, a neurological examination shows which nerve is involved and where along its path. Ultrasound lets us see the nerve, measure its thickness and identify the structure compressing it, such as a ligament, muscle or cyst. When nerve damage needs confirming, an electromyography (EMG) may be requested.
This precise diagnosis is what guides treatment: the same tingling in the hand can come from the carpal tunnel, the elbow or the neck, and each is treated differently.
Treatment
Medication for neuropathic pain: ordinary painkillers are usually not very effective; there are specific drugs, which the doctor adjusts to each case.
Ultrasound-guided procedures: nerve hydrodissection, peripheral nerve blocks, pulsed radiofrequency and botulinum toxin when a muscle compresses the nerve.
Physiotherapy: neural mobilisation and correction of the posture or movement that maintains the compression.
Frequently asked questions about neuropathic pain
Is tingling in the hand always carpal tunnel syndrome?
No. It can come from the median nerve at the wrist, the ulnar nerve at the elbow or a nerve root in the neck. Clinical examination and ultrasound tell these apart.
Can neuropathic pain be cured?
It depends on the cause. With nerve compression, freeing the nerve often resolves the pain. With other causes, such as post-herpetic neuralgia, the aim is to control pain and maintain quality of life.
When should I see a doctor?
If the pain lasts more than a few weeks, if there is loss of strength or numbness that doesn't go away, or if the pain wakes you at night.
Dr. Miguel Reis e Silva
Doctor at Sport Lisboa e Benfica
Medical Director and Founder of Clínica Myalgia
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