Page created on April 5, 2022. Not updated since.
Neuropathic pain is pain which occurs due to injury or disorder of the somatosensory nervous system, either peripherally or sentrally. It’s usually chronic and debilitating, and unfortunately relatively prevalent (3 – 10% of population).
The neuralgias (postherpetic and trigeminal) are forms of neuropathic pain.
- Peripheral causes
- Polyneuropathy (like diabetes, cytostatic, vasculitis)
- Entrapment syndromes (like carpal tunnel)
- Post surgery (like phantom pain)
- Herpes zoster and postherpetic neuralgia
- Central causes
- Stroke, especially brainstem/thalamus
- Tramatic brain/spinal cord injury
- Multiple sclerosis
Neuropathic pain can be continous or intermittent and paroxysmal, and usually has a burning or electrical shock-like characteristic. Other features include:
- Hypoestesia – decreased sensibility to non-painful stimuli
- Hypoalgaesia – decreased sensibility to painful stimuli
- Paraesthesia – abnormal “pins and needles” sensation
- Allodynia – pain upon non-painful stimuli
- Hyperalgaesia – severe pain upon mild painful stimuli
Diagnosis and evaluation
The diagnosis of neuropathic pain is clinical. Screening questionnaires like DN4, PainDETECT and LANSS can be used to distinguish neuropathic pain from other types.
Following the diagnosis, appropriate neurological examination and investigations must be performed to determine the etiology.
Unfortunately, most patients can’t achieve a pain-free state, and it’s important to communicate this to the patient to not set their expectations too high. The evidence is not strong for non-pharmacological interventions like CBT, transcutaneous nerve stimulation, or physiotherapy, but it’s quite strong for pharmacological therapy.
The following are first choice drugs in the management of neuropathic pain:
- Gabapentin and pregabalin
- Tricyclic antidepressants
- Duloxetine and venlafaxine
- Carbamazepine and oxcarbazepine (mostly used for trigeminal neuralgia)
- Lidocaine patch
- Capsaicin patch
Opioids and botulinum toxin only have weak evidence of effect and are therefore second line drugs. Cannabinoids don’t have much evidence of effect but they have a good safety profile.