Injury of the Spino-Thalamo-Cortical Pathway Is Necessary for Central Post-Stroke Pain

Abstract

Objectives: We investigated the relationship between injury of the spino-thalamo-cortical pathway (STP) and central post-stroke pain (CPSP) in patients with intracerebral hemorrhage, using diffusion tensor tractography (DTT). Methods: 30 consecutive chronic patients, in whom integrity of the STP and the medial lemnisco-thalamo-cortical pathway (MLP) were spared in both hemispheres, were recruited. We classified the patients into two groups according to the presence of the CPSP. DTTs were obtained using the FMRIB Software Library. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured. A laterality index (LI) was used to determine asymmetry of DTT parameters between the hemispheres. Results: The LI for tract volume of the STP in the CPSP group was lower than that of the non-CPSP group (p = 0.000). However, there were no differences between the CPSP group and non-CPSP group for the LIs of FA or MD of the STP or for the LIs of FA, MD, or tract volume of the MLP (p > 0.05). Conclusions: Decrease of tract volume without changes in the STP FA or MD values in the CPSP group indicates partial injury of STP. Therefore, injury of the STP seems to be a requirement for the development of CPSP in patients with intracerebral hemorrhage.

Characteristics of the aberrant pyramidal tract in comparison with the pyramidal tract in the human brain

“…The FA value represents the degree of directionality of microstructures (e.g., axons, myelin, and microtubules), and the MD value indicates the magnitude of water diffusion [15-17]. In contrast, the tract volume was determined by the number of voxels contained within the neural tract [18]. Changes in DTI parameters observed in the APT, that is, decreased FA value and tract volume with unchanged MD value, suggest less directionality and fewer neural fibers than in the PT.…”

Persistent shoulder pain after stroke

“…Many stroke survivors are left with permanent disabilities, including (partial) paralysis 22 , somatosensory deficits 43 , speech and language problems 11 , cognitive deficits 6,30 , fatigue 24 and emotional 46 or personality changes 23 . In addition, pain is common after stroke.…”

“…CPSP 24 , wide-spread pain or shoulder-hand syndrome). Healthy control subjects had to be free of any neurological or psychiatric disorder, diabetes mellitus, psychotropic medication or long-lasting (> 1 week in the last 3 months) pain complaints.…”

“…41 In addition, loss of sensory function, and specifically loss of spinothalamocortical tract function, has been implicated in mechanisms of central pain 24 and is considered a prerequisite for the development of central neuropathic pain. In a sub-analysis, in which the PSSP patients from the present study were classified on the basis of their score on the neuropathic pain diagnostic questionnaire 5 , it was shown that loss of spinothalamocortical tract function was more frequently present in the patients classified as having a possible neuropathic component to their pain.…”

“…42 Moreover, the evidence-base for therapeutic interventions is lacking or inconsistent. 24,71 In addition, in the case of successful treatment, it often remains unclear how pain reduction has been achieved. For example, neuromuscular electrical stimulation, aimed at reducing glenohumeral subluxation, provided pain relief in patients with PSSP while the degree of subluxation remained unaltered 59 .…”