Neuropathic pain

Definitions

Dysesthesia	Any abnormal, unpleasant sensation
Hyperalgesia	Exaggerated pain response from normally painful stimulus
Hyperpathia	Same as Hyperalgesia
Hyperesthesia	Exaggerated perception of touch stimulus
Allodynia	Abnormal perception of pain from a normally non-painful stimulus
Hypoalgesia	Decreased sensitivity to pain
Analgesia	Loss of sensation to pain
Anaesthesia	Reduced sensation of all sensation
Pallanaesthesia	Loss of vibration sensation
Paraesthesia	Spontaneous, prickling sensation, usually described as pins and needles
Causalgia	Burning pain in the distribution of one or more peripheral nerves

•

Epidemiology

Pathogenesis

Clinical manifestations

Diagnosis

Treatment

Most studies have been done in setting of a specific type of neuropathic pain (e.g. postherpetic or diabetic peripheral neuropathy)

Painful polyneuropathy

• TCA’s (Amitriptyline)
• Multiple trials showing efficacy
• NNT ~2.5
• Anti-cholinergic SE
• SNRI
• Venlafaxine mildly effective
• SSRIs – not effective
• Carbamazepine
• Effective, NNT 2.3
• Gabapentin
• Some evidence, NNT 3.7
• Pregabalin
• Some evidence NNT 4.0
• Lamictal, topiramate and valproate – not effective
• Opioids and tramadol effective – but high SE and minimal improvement in QOL
• Capsaicin
• Topical treatment
• Effective but NNT 8

Post-herpetic neuralgia

· Amitriptyline effective as are

· Anticonvulsants - phenytoin, carbamazepine and gabapentin as well as valproate are effective

· Clonidine provides some small effect

· Opioids, including tramadol were also effective

· Capsaicin effective

Prognosis

•