Pain is a widespread and debilitating symptom of multiple sclerosis (MS), a chronic inflammatory demyelinating disease of the central nervous system. Although central neuroinflammation and demyelination have been implicated in MS-related pain, the contribution of peripheral and central mechanisms during different phases of the disease remains unclear. In this study, we used the animal model experimental autoimmune encephalomyelitis (EAE) to examine both stimulus-evoked and spontaneous pain behaviors, and neuroinflammatory changes, over the course of chronic disease.
We found that mechanical allodynia (increases sensitivitiy to movement/touch when it was not sensitive in the healthy animal) of the hind paw preceded the onset of clinical EAE but was unmeasurable at clinical peak (Not surprising as they can't feel anything because the limb is anaesthetic because nerves aren't signalling). This mechanical hypersensitivity coincided with increased microglial activation confined to the dorsal horn (The nerves that detect sensations enter the spinal cord through the dorsal horn.
The development of facial mechanical allodynia also emerged in preclinical EAE, persisted at the clinical peak, and corresponded with pathology of the peripheral trigeminal afferent pathway (The face also becomes sensitive to touch before signs of movement disease). This included T cell infiltration, which arose prior to overt central lesion formation and specific damage to myelinated neurons during the clinical peak. Measurement of spontaneous pain using the mouse grimace scale, a facial expression-based coding system, showed increased facial grimacing in mice with EAE during clinical disease.
So more evidence for the Home Office to say this is a nasty, procedure that needs limiting.
Trust me in the UK they are doing this.
However, the problem with the acute EAE model is that it is not really a model of neuropathic pain as found in MS, because when they are detecting sensory problems the animals have not the experienced nerve damage that damage the neuropathic problems that are so difficult to treat.
We and the Home office have looked for the Grimace faces following the development of chronic disability and they are not there. Therefore, we think that these faces are only able to detect acute pain effects, which will respond to routine analgesics.
We need something in addition to deal with the neuropathic pain condition in MS.