The International Association for Study of Pain, the most authoritative organization in the filed of pain management, has revised the definition of Neuropathic pain. The new definition is:
Pain caused by a lesion or disease of the somatosensory system.
IASP offers the following footnote to the definition:
Neuropathic pain is a clinical description (and not a diagnosis) which requires a demonstrable lesion or a disease that satisfies established neurological diagnostic criteria.
The term lesion is commonly used when diagnostic investigations (e.g. imaging, neurophysiology, biopsies, lab tests) reveal an abnormality or when there was obvious trauma.
The term disease is commonly used when the underlying cause of the lesion is known (e.g. stroke, vasculitis, diabetes mellitus, genetic abnormality).
Somatosensory refers to information about the body per se including visceral organs, rather than information about the external world (e.g., vision, hearing, or olfaction).
The presence of symptoms or signs (e.g., touch-evoked pain) alone does not justify the use of the term neuropathic. Some disease entities, such as trigeminal neuralgia, are currently defined by their clinical presentation rather than by objective diagnostic testing.
Other diagnoses such as postherpetic neuralgia are normally based upon the history.
It is common when investigating neuropathic pain that diagnostic testing may yield inconclusive or even inconsistent data.
In such instances, clinical judgment is required to reduce the totality of findings in a patient into one putative diagnosis or concise group of diagnoses.
The previous definition by IASP (1994) had read:
Pain initiated or caused by a primary lesion, dysfunction or transitory perturbation of the peripheral or central nervous system.
The new definition takes away the word “dysfunction”.
In their editorial commentary, “A new definition of neuropathic pain” in Pain, 152 (2011) 2204-2205, Dr Troels S Jensen and colleagues explain why…
“Clinicians with neurological training and background have found it difficult to accept conditions in which symptoms and signs were not reflected in abnormal neuropathophysiology”
The new definition also specifies “somatosensory system” instead of the earlier more vague “nervous system”.