Neuropathic pain and its assessment

Neuropathic pain, i.e., pain arising as a direct consequence of a lesion or disease affecting the somatosensory system, is a frequent complaint in the elderly. The frequency of herpes zoster and peripheral neuropathy, the commonest diseases that cause neuropathic pain, increases with age. More than half of all persons in whom herpes zoster develops are older than 60 years and about 30% of these patients will ultimately suffer from chronic postherpetic neuralgia. The prevalence of peripheral neuropathy rises from 2.4% in the general population to 8% in subjects older than 55 years.With advancing age, the nociceptive pathway undergoes degenerative changes, mainly consisting of axonal loss. This age-related nociceptive pathway degeneration probably explains why elderly patients tend to under-report pain in many medical conditions including myocardial infarction, fractures, and arthritis. This age-related impairment probably plays a key role in the development of neuropathic pain. In this report we describe the most reliable methods for assessing neuropathic pain such as laser evoked potential (LEP) recordings and skin biopsy, procedures that selectively assess nociceptive pathways in order to obtain a rapid diagnosis and hence determine treatment.