Neuropathic pain and its management

Neuropathic pain is defined by the International Association for the Study of Pain (IASP) as pain arising as a direct consequence of a lesion or disease affecting the somatosensory system.¹

Clinical features²

Neuropathic pain is characterised by continuous or intermittent spontaneous pain, typically described as burning, aching or shooting in nature. The pain may be provoked by normally innocuous stimuli (allodynia). Neuropathic pain is also commonly associated with hyperalgesia (increased pain intensity evoked by normally painful stimuli), paraesthesia and dysaesthesia.

Prevalence³

There are no accurate figures for the overall prevalence of neuropathic pain.

• The prevalence of neuropathic pain has been estimated to be between 6% and 8%.

• A large study of computerised records in primary care from the Netherlands estimated the annual incidence of neuropathic pain in the general population to be almost 1%.

• Painful diabetic neuropathy is estimated to affect between 16% and 26% of people with diabetes.

• Prevalence estimates for postherpetic neuralgia range from 8% to 19% of people with herpes zoster when defined as pain at one month after rash onset, and 8% when defined as pain at three months after rash onset.

• The development of chronic pain after surgery is also fairly common, with estimates of prevalence ranging from 10% to 50% after many common operations. This pain is severe in between 2% and 10% of these patients, and many of the clinical features closely resemble those of neuropathic pain.

Neuropathic pain causes (aetiology)

Common causes of neuropathic pain include:¹

Peripheral

• Painful diabetic neuropathy.

• Postherpetic neuralgia.

• Trigeminal neuralgia.

• Lumbar radiculopathy.

• Nerve damage, including postoperative.

• Pain because of cancer tumour infiltration.

• Alcohol neuropathy.

Central

• Post-stroke pain.

• Multiple sclerosis.

• Chemotherapy-induced pain.

• Neuropathic contributions to other painful conditions.

Neuropathic pain treatment and management

• The treatment of the underlying causative condition is central to the management of neuropathic pain but is outside the scope of this article. Neuropathy caused by mechanical pressure, for example, may require surgical and other interventional procedures.

• The main role of the GP in the management of neuropathic pain is in the control of symptoms where the underlying cause is medical, where the condition is of a chronic, recurring or acute self-limiting nature, or whilst awaiting specialist intervention.

• Prescribing of therapy with little evidence of efficacy in neuropathic pain is still common in the UK and consequently treatment is often not in line with current guidance.⁴

• When selecting a particular medication, NICE recommends considering comorbidities, safety considerations, contra-indications, patient preference, lifestyle factors, any history of mental health problems (eg, anxiety, depression) and existing medication history.

• Clear advice should be given about dosage instructions, preferably in writing.

• Consider overlapping old and new treatment to prevent deterioration in pain control.

• Review the patient early after starting or changing treatment.

• Review the patient regularly, covering such aspects as pain control, side-effects, effect on daily living (eg, driving, working), mood, sleep and overall improvement.

Referral

Consider referring the person to a specialist pain service and/or a condition-specific service at any stage, including at initial presentation and at the regular clinical reviews, if:³

• They have severe pain; or

• Their pain significantly limits their lifestyle, daily activities (including sleep disturbance) and participation; or

• Their underlying health condition has deteriorated.

Non-pharmacological measures

• Psychological techniques - cognitive behavioural therapy has shown some benefit in the treatment of chronic pain.⁵

• Studies of chronic pain management suggest that a combination of psychological, pharmacological and physical therapies, tailored to the needs of the individual patient, may be the best approach.⁶

• Percutaneous electrical nerve stimulation (PENS) has shown evidence of short-term benefit for refractory neuropathic pain.⁷

• NICE recommends the use of spinal cord stimulation in patients who have had chronic pain for six months (measuring at least 50 mm on a 0-100 mm visual analogue scale) despite conventional medical management (providing a prior trial of stimulation has proved to be effective).⁸

• There is no good evidence supporting the efficacy of other non-drug measures, such as acupuncture, homeopathy or transcutaneous electrical nerve stimulation (TENS) for neuropathic pain.⁹

Pharmacological measures^{3 10}

All neuropathic pain (except trigeminal neuralgia):

• Offer a choice of amitriptyline, duloxetine, gabapentin or pregabalin as initial treatment for neuropathic pain (except trigeminal neuralgia).

• If the initial treatment is not effective or is not tolerated, offer one of the remaining three drugs, and consider switching again if the second and third drugs tried are also not effective or not tolerated.

• Consider short-term tramadol only if acute rescue therapy is needed.

• Consider capsaicin cream for people with localised neuropathic pain who wish to avoid, or who cannot tolerate, oral treatments.

• Patients with localised pain who are unable to take oral medicines may benefit from topical local anaesthetic preparations, such as lidocaine hydrochloride- medicated plasters, while awaiting specialist review.

• Combining two or more different drugs may improve analgesic efficacy and, in some situations, reduce overall side-effects. However, there is insufficient evidence to recommend any one specific drug combination for neuropathic pain.¹¹

Do not start the following to treat neuropathic pain in non-specialist settings, unless advised by a specialist to do so: cannabis sativa extract, capsaicin patch, lacosamide, lamotrigine, levetiracetam, morphine, oxcarbazepine, topiramate, long-term tramadol, venlafaxine.

Trigeminal neuralgia
See the separate article on Trigeminal Neuralgia.