Chronic pain in multiple sclerosis is common, and difficult to treat. Its mechanisms remain incompletely understood. Dysfunction of the descending pain modulatory system is known to contribute to human chronic pain conditions. However, it is not clear how alterations in executive function influence this network, despite healthy volunteer studies linking function of the descending pain modulatory system, to cognition. In adults with multiple sclerosis-associated chronic neuropathic limb pain, compared to those without pain, we hypothesised altered functional connectivity of the descending pain modulatory system, coupled to executive dysfunction. Specifically we hypothesised reduced mental flexibility, because of potential importance in stimulus reappraisal.
To investigate these hypotheses, we conducted a case-control cross-sectional study of 47 adults with relapsing remitting multiple sclerosis (31 with chronic neuropathic limb pain, 16 without pain), employing clinical, neuropsychological, structural and functional MRI measures. We measured brain lesions and atrophy affecting descending pain modulatory system structures.
Both cognitive and affective dysfunction were confirmed in the chronic neuropathic limb pain group, including reduced mental flexibility (Delis Kaplan Executive Function System card sorting tests p < 0.001). Functional connectivity of rostral anterior cingulate and ventrolateral periaqueductal gray, key structures of the descending pain modulatory system, was significantly lower in the group experiencing chronic neuropathic pain. There was no significant between-group difference in whole-brain grey matter or lesion volumes, nor lesion volume affecting white matter tracts between rostral anterior cingulate and periaqueductal gray. Brainstem-specific lesion volume was higher in the chronic neuropathic limb pain group (p = 0.0017). Differential functional connectivity remained after correction for brainstem-specific lesion volume. Gabapentinoid medications were more frequently used in the chronic pain group.
We describe executive dysfunction in people with multiple sclerosis affected by chronic neuropathic pain, along with functional and structural MRI evidence compatible with dysfunction of the descending pain modulatory system. These findings extend understanding of close inter-relationships between cognition, function of the descending pain modulatory system, and chronic pain; both in multiple sclerosis, and more generally in human chronic pain conditions. These findings could support application of pharmacological and cognitive interventions in chronic neuropathic pain associated with multiple sclerosis.
Traditional Thai massage (TTM) is a unique form of whole body massage practiced to promote health and well-being in Thailand since ancient times. The goal of the present study was to create a standardised TTM protocol to treat office syndrome (OS) diagnosed based on the identification of the palpation of at least one so-called myofascial trigger point (MTrP) in the upper trapezius muscle. The new 90 min TTM protocol, which was developed following appropriate review of the literature and in consultation with relevant experts, has 25 distinct steps (20 pressing steps, 2 artery occlusion steps, and 3 stretching steps). Eleven TTM therapists treated three patients each using the new 90 min TTM protocol. All of the therapists reported scores greater than 80% in respect to their satisfaction and confidence to deliver the protocol, and all of the patients gave the treatment a satisfaction score of greater than 80%. The treatment produced a significant reduction in pain intensity measured on a Visual Analogue Scale (VAS), with minimum and maximum values of 0 and 10 cm, of 2.33 cm (95% CI (1.76, 2.89 cm), p < 0.001) and significant increase in pain pressure threshold (PPT) of 0.37 kg/cm2 (95% CI (0.10, 0.64 kg/cm2), p < 0.05). The protocol was revised based on the feedback and the results obtained, and the new standardised TTM protocol will be applied in a randomised control trial (RCT) to compare the efficacy of TTM and conventional physical therapy (PT) for treating OS.
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