allodynie

Allodynia is pain that is elicited by a stimulus that normally does not provoke pain. It is a feature of several chronic pain conditions and reflects abnormal processing of sensory information by the nervous system, often involving central sensitization of pain pathways.

Types commonly described include mechanical allodynia, in which light touch, brushing, or clothing causes pain; dynamic allodynia, where gentle movement of the skin or air currents evokes pain; and, less frequently, thermal allodynia, in which innocuous temperature changes produce pain. The term is often used in the context of neuropathic pain and migraine-related sensitivity.

Pathophysiology involves both peripheral and central mechanisms. Peripheral sensitization enhances responsiveness of damaged or irritated peripheral nerves, while central sensitization in the spinal cord and brain amplifies input from normally non-painful stimuli. Dysfunction in descending inhibitory pathways can also contribute. In conditions such as migraines, cutaneous allodynia is considered a sign of central sensitization.

Clinical contexts in which allodynia may occur include neuropathic pain syndromes (for example, diabetic polyneuropathy, postherpetic neuralgia, chemotherapy-induced neuropathy), complex regional pain syndrome, and migraine with aura. It can significantly affect quality of life and treatment outcomes.

Diagnosis is clinical, based on history and examination. Quantitative tools, such as von Frey filaments or brush tests, may help quantify sensitivity and distinguish allodynia from hyperalgesia.

Management focuses on treating the underlying condition and reducing pain sensitization. Pharmacologic options include gabapentinoids, certain antidepressants (e.g., SNRIs or TCAs), and topical anesthetics. Nonpharmacologic approaches such as graded desensitization, physical therapy, and psychological therapies may also be beneficial. Prognosis varies with the underlying disorder and response to treatment.