Massive body-brain disconnection consequent to spinal cord injuries drives profound changes in higher-order cognitive and emotional functions: A PRISMA scoping review

Pain and the perception of space in fibromyalgia

The Economy of action hypothesis postulates that bodily states rescale the perception of the individual's environment's spatial layout. The estimation of distances and slopes in navigation space (i.e. the space reachable by locomotion) is influenced by sensations relating to body condition and the metabolic cost of the actions. The results of the studies investigating the impact of pain on distance estimation remain inconclusive. 28 women suffering from chronic pain and fibromyalgia (FM), and 24 healthy women (HC) were assessed for musculoskeletal, neuropathic, and visceral pain by means of the Widespread Pain Index, the Symptom Severity Scale and an ad-hoc devised questionnaire for pain (the Verona Pain Questionnaire). In a VR-mediated task, they observed a 3D scenario and estimated the distance of a flag positioned at different distances (1, 2, 3, 4 or 5 m) on virtual ramps with either a 4% or 24% inclination in two different conditions: sitting and standing. Overestimation of distances in the steeper ramp condition was expected, if participants executed the task by internally simulating the movement. The results showed a dissociation between the effects of musculoskeletal and visceral-neuropathic pain on distance estimations. While, according to the Economy of Action hypothesis, the HCs estimated the distances as being farther away when the ramp was more inclined (i.e. with a 24% inclination), there was no effect related to the different ramp inclinations in the FM group. Furthermore, visceral and neuropathic pain were found to affect the performance of the FM group. These results suggest that chronic and widespread pain conditions, that typically characterize fibromyalgia, can affect space representations. In line with the Economy of Action hypothesis, bodily based estimation of distances is compromised in these patients.

Cognitive assessment during inpatient rehabilitation after spinal cord injury, a retrospective cross-sectional study

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

Cognitive screening is underdeveloped in spinal cord injury (SCI). Therefore, the objectives of our study were: (1) to evaluate cognitive functioning of rehabilitation inpatients with recently acquired spinal cord injury (SCI) with the Montreal Cognitive Assessment (MoCA); (2) to analyse associations between patient and lesion characteristics and the MoCA scores and (3) to compare the MoCA with the cognitive domain of the Utrecht scale for Evaluation of Rehabilitation (USER).

SETTING

Inpatient rehabilitation in a specialized rehabilitation centre in the Netherlands.

METHODS

MOCA and USER data of inpatients between November 2020 and December 2021 were used. Correlation and regression analysis were used.

RESULTS

Included were 98 adults aged (median) 61.6 years (range 19.5-83.6), 66% male, 26.5% traumatic SCI, 63% persons with paraplegia. MoCA and USER scores were available for 83 and 92 individuals, respectively. In 44.6% of the participants, the MoCA score was below the cut-off. Age (r = 0.31, p = 0.005) and educational level (r = 0.54 P < 0.00) were significantly correlated to the MoCA score. The MoCA and the cognitive domain of the USER were moderately correlated (r = 0.25, p = 0.03).

CONCLUSIONS

Almost half of the inpatients scored below the cut-off score on the MoCA. Since the MoCA is a validated cognitive screening tool, the moderate correlation of the MoCA and the cognitive domain of the USER suggests that the USER alone is not sufficient in detecting cognitive deficits. We recommend to screen for cognitive deficits in all people with new SCI.

SPONSORSHIP

None.

How pain and body representations transform each other: A narrative review

Pain, as a multidimensional and subjective experience, intertwines with various aspects of body representation, involving sensory, affective and motivational components. This review explores the bidirectional relationship between pain and body representations, emphasizing the impact of the sense of ownership on pain perception, the transformative impact of pain on motor imagery, the effects associated with vicarious pain perception on body representations and the role of pain in the maintenance of body representations in specific clinical conditions. Literature indicates complex interactions between pain and body representations, with the sense of ownership inducing analgesic effects in some cases and hyperalgesia in others, contingent upon factors such as the appearance of the affected limb. Pain sensations inform the body on which actions might be executed without harm, and which are potentially dangerous. This information impacts on motor imagery too, showing reduced motor imagery and increased reaction times in tasks where motor imagery involves the painful body parts. Finally, contrary to the conventional view, according to which pain impairs body representation, evidence suggests that pain can serve as an informative somatosensory index, preserving or even enhancing the representation of the absent or affected body parts. This bidirectional relationship highlights the dynamic and multifaceted nature of the interplay between pain and body representations, offering insights into the adaptive nature of the central nervous system in response to perceived bodily states.

Topographic mapping of the sensorimotor qualities of empathic reactivity: A psychophysiological study in people with spinal cord injuries

The experience of empathy for pain is underpinned by sensorimotor and affective dimensions which, although interconnected, are at least in part behaviorally and neurally distinct. Spinal cord injuries (SCI) induce a massive, below-lesion level, sensorimotor body-brain disconnection. This condition may make it possible to test whether sensorimotor deprivation alters specific dimensions of empathic reactivity to observed pain. To explore this issue, we asked SCI people with paraplegia and healthy controls to observe videos of painful or neutral stimuli administered to a hand (intact) or a foot (deafferented). The stimuli were displayed by means of a virtual reality set-up and seen from a first person (1PP) or third person (3PP) visual perspective. A number of measures were recorded ranging from explicit behaviors like explicit verbal reports on the videos, to implicit measures of muscular activity (like EMG from the corrugator and zygomatic muscles that may represent a proxy of sensorimotor empathy) and of autonomic reactivity (like the electrodermal response and Respiratory Sinus Arrhythmia that may represent a general proxy of affective empathy). While no across group differences in explicit verbal reports about the pain stimuli were found, SCI people exhibited reduced facial muscle reactivity to the stimuli applied to the foot (but not the hand) seen from the 1PP. Tellingly, the corrugator activity correlated with SCI participants' neuropathic pain. There were no across group differences in autonomic reactivity suggesting that SCI lesions may affect sensorimotor dimensions connected to empathy for pain.

Predicting and coding sound into action translation in spinal cord injured people

Motor activation in response to perception of action-related stimuli may depend on a resonance mechanism subserving action understanding. The extent to which this mechanism is innate or learned from sensorimotor experience is still unclear. Here, we recorded EEG while people with paraplegia or tetraplegia consequent to spinal cord injury (SCI) and healthy control participants were presented with action sounds produced by body parts (mouth, hands or feet) that were or were not affected by SCI. Non-action sounds were used as further control. We observed reduced brain activation in subjects affected by SCI at both pre- and post-stimulus latencies specifically for those actions whose effector was disconnected by the spinal lesion (i.e., hand sound for tetraplegia and leg sound for both paraplegia and tetraplegia). Correlation analyses showed that these modulations were functionally linked with the chronicity of the lesion, indicating that the longer the time the lesion- EEG data acquisition interval and/or the more the lesion occurred at a young age, the weaker was the cortical activity in response to these action sounds. Tellingly, source estimations confirmed that these modulations originated from a deficit in the motor resonance mechanism, by showing diminished activity in premotor (during prediction and perception) and near the primary motor (during perception) areas. Such dissociation along the cortical hierarchy is consistent with both previous reports in healthy subjects and with hierarchical predictive coding accounts. Overall, these data expand on the notion that sensorimotor experience maintains the cortical representations relevant to anticipate and perceive action-related stimuli.