From the Guidelines
Allodynia is an abnormal state of pain responsiveness that can be elicited by innocuous stimuli, such as food in the stomach or urge to have a bowel movement, as defined in the 2024 study by Gastroenterology 1. This condition occurs when the nervous system becomes hypersensitive, causing non-painful touch, pressure, or temperature to trigger pain signals.
- Key characteristics of allodynia include:
- Pain from stimuli that are not normally painful
- Hypersensitivity of the nervous system
- Can be elicited by innocuous stimuli
- Allodynia can be classified into different types, including:
- Tactile allodynia (pain from light touch)
- Mechanical allodynia (pain from pressure)
- Thermal allodynia (pain from mild temperature changes)
- According to the 2024 study by Ophthalmology 1, allodynia can occur in conditions like fibromyalgia, migraines, neuropathy, and complex regional pain syndrome. Treatment typically involves addressing the underlying condition and may include medications such as anticonvulsants (gabapentin, pregabalin), antidepressants (amitriptyline, duloxetine), topical agents (lidocaine patches), and in some cases, opioids for severe cases, as suggested by the 2016 study by Stroke 1. Non-pharmacological approaches like physical therapy, cognitive behavioral therapy, and stress management can also help manage symptoms. It is essential to note that allodynia differs from hyperalgesia, which is an increased pain response to stimuli that are normally painful, though both represent abnormal pain processing in the nervous system, as highlighted in the 2024 study by Gastroenterology 1.
From the Research
Definition of Allodynia
- Allodynia is characterized by a painful response to a non-noxious stimulus 2.
- It is a debilitating condition that can be difficult to treat, with limited diagnostic modalities and treatment options 2.
Clinical Manifestations
- Allodynia and hyperalgesia are prominent symptoms in patients with neuropathic pain, affecting 15-50% of patients 3.
- Allodynia can be classified according to the sensory modality (touch, pressure, pinprick, cold, and heat) that is used to elicit the sensation 3.
- Allodynia is a common clinical feature in various pain syndromes, including migraine 4.
Pathophysiology
- Peripheral sensitisation and maladaptive central changes contribute to the generation and maintenance of allodynia, with separate mechanisms in different subtypes of allodynia and hyperalgesia 3.
- Allodynia is a marker for sensitization of central trigeminal neurons in migraine patients 4.
Treatment
- Gabapentin and pregabalin have been shown to suppress tactile allodynia and potentiate spinal cord stimulation in a model of neuropathy 5.
- Morphine, pregabalin, gabapentin, and duloxetine have been found to attenuate mechanical allodynia in a dose-dependent manner, but their efficacy on neuroma pain is different 6.
- Treatment with cyclooxygenase inhibitors and dihydroergotamine may be able to reverse allodynia in migraine patients 4.