Assessment of Temporal Somatosensory Discrimination in Females with Fibromyalgia: Reliability and Discriminative Ability of a New Assessment Tool.

We assessed the test-retest reliability and discriminative ability of a somatosensory temporal discrimination (SSTD) assessment tool for fibromyalgia syndrome (FMS) and determined if pain-related variables were associated with SSTD performance. Twenty-five women with FMS and twenty-five asymptomatic women were assessed during two sessions 7 to 10 days apart. The proportion of correct responses (range 0-100) was calculated. Sociodemographic information was collected for both groups. The participants with FMS also completed the widespread pain index and the Brief Pain Inventory. Test-retest reliability was verified by calculating intraclass correlation coefficients. Discriminative ability was verified by a between-group comparison of scores using a t-test. Associations between SSTD score and pain variables were tested using Pearson or Spearman correlation coefficients. The test-retest reliability of the SSTD score was excellent (ICC > 0.9, CI: 0.79-0.96) for the asymptomatic group and good for the FMS group (ICC: 0.81, 95% CI: 0.62-0.91). The median (Q1-Q3) test session SSTD score differed significantly between the FMS 84.1 (71-88) and the asymptomatic 91.6 (83.4-96.1) groups (p < 0.001). Only pain duration was associated with the SSTD score. In conclusion, the new SSTD test seems reliable for people with FMS and is discriminative. Further studies should examine its sensitivity to change and correlations with other SSTD tests.

Action observation plus motor imagery and somatosensory discrimination training are effective non-motor approaches to improve manual dexterity.

BACKGROUND: Action observation plus motor imagery (AOMI) and somatosensory discrimination training (SSDT) represent sensory input-based approaches to train the motor system without necessarily asking subjects to perform active movements. PURPOSE: To investigate AOMI and SSDT effects compared to no intervention on manual dexterity in healthy subjects. STUDY DESIGN: Randomized controlled study. METHODS: Sixty healthy right-handed participants were randomized into AOMI, SSDT or Control (CTRL) groups. AOMI observed video-clips including right-hand dexterity tasks and concurrently performed motor imagery, SSDT performed surfaces recognition and 2-point distance discrimination tasks with the right hand, whereas CTRL underwent no intervention. A blinded physiotherapist assessed participants for manual dexterity using the Purdue Pegboard Test (Right hand-R, Left hand-L, Both hands-B, R+L+B and assembly tasks) at baseline (T0) and training end (T1). A mixed-design Analysis of Variance with Time as within-subject factor and Group as between-subject factor was used to investigate between-group differences over time. RESULTS: A Time by Group interaction and Time effect were found for R task, which increased from T0 to T1 in all groups with very large effect sizes for SSDT (d = 1.8, CI95 2.4-1.0, P < .001) and AOMI (d = 1.7, CI95 2.5-1.0, P < .001) and medium effect size for CTRL (d = 0.6, CI95 1.2-0.2, P < .001). Between-group post-hoc comparison for deltas (T1-T0) showed large effect size (d = 1.0, CI95 1.6-0.3, P = .003) in favor of SSDT and medium effect size (d = 0.7, CI95 1.4-0.1, P = .026) in favor of AOMI compared to CTRL. Time effects were found for L, B, R + L + B and assembly tasks (P < .001). CONCLUSIONS: AOMI and SSDT induced greater manual dexterity improvements than no intervention. These findings supported the role of visual and somatosensory stimuli in building a motor plan and enhancing the accuracy of hand movements. These non-motor approaches may enhance motor performance in job or hobbies requiring marked manual dexterity.

Pupillary Dilations of Mice Performing a Vibrotactile Discrimination Task Reflect Task Engagement and Response Confidence.

Pupillometry, the measure of pupil size and reactivity, has been widely used to assess cognitive processes. Changes in pupil size have been shown to correlate with various behavioral states, both externally and internally induced such as locomotion, arousal, cortical state, and decision-making processes. Besides, these pupillary responses have also been linked to the activity of neuromodulatory systems that modulate attention and perception such as the noradrenergic and cholinergic systems. Due to the extent of processes the pupil reflects, we aimed at further resolving pupillary responses in the context of behavioral state and task performance while recording pupillary transients of mice performing a vibrotactile two-alternative forced-choice task (2-AFC). We show that before the presentation of task-relevant information, pre-stimulus, pupil size differentiates between states of disengagement from task performance vs. engagement. Also, when subjects have to attend to task stimuli to attain a reward, post-stimulus, pupillary dilations exhibit a difference between correct and error responses with this difference reflecting an internal decision variable. We hypothesize that this internal decision variable relates to response confidence, the internal perception of the confidence the subject has in its choice. As opposed to this, we show that in a condition of passive performance, when the stimulus has no more task relevance due to reward being provided automatically, pupillary dilations reflect the occurrence of stimulation and reward provision but not decisional variables as under active performance. Our results provide evidence that in addition to reflecting attentiveness under task performance rather than arousal per se, pupil dilations also reflect the confidence of the subject in his ensuing response. This confidence coding is overlaid within a more pronounced pupil dilation that reflects post-decision components that are related to the response itself but not to the decision. We also provide evidence as to how different behavioral states, imposed by task demands, modulate what the pupil is reflecting, presumably showing what the underlying cognitive network is coding for.

Widespread impairment of tactile spatial acuity and sensory-motor control in patients with chronic nonspecific neck pain with neuropathic features.

OBJECTIVE: To assess differences in tactile spatial acuity and in sensory-motor control between patients with chronic nonspecific neck pain (CNSNP) with and without neuropathic features (NF), as well as asymptomatic. METHODS: 183 participants were included, 135 had CNSNP classified by the Self-report version of Leeds Assessment of Neuropathic Symptoms and Signs scale in order to identify pain with NF: (1) CNSNP with NF (n = 67), (2) CNSNP with No-NF (n = 68), and (3) asymptomatic subjects (n = 48). The following tests in the following order were assessed after determining the participants' clinical characteristics: 1) two-point discrimination, 2) joint position error, and 3) craniocervical flexion test. RESULTS: Both neck pain groups showed a significant reduction in their ability to discriminate two points in the trapezium and masseter, as well as a significant deficit of a moderate to large magnitude in craniocervical motor control compared with the asymptomatic group. However, only the CNSNP with NF group showed a significant impairment of the two-point discrimination in the tibia (d = 0.57) and a significant impairment of the kinesthetic sense (neck rotation, d = 0.73; neck lateroflexion, d = 0.69), compared with the asymptomatic group. Significant differences in pain intensity, disability and psychological factors between the CNSNP groups were also found, observing the poorest results in the NF group. CONCLUSIONS: Patients with CNSNP with NF have a greater sensory, motor and psychological impairment than those without NF, more pain intensity, disability and negative psychological factors, as well as more impaired tactile spatial acuity in areas remote to the pain and impaired cervical kinesthetic sense.

Experience of Engagement in a Somatosensory Discrimination Intervention for Children with Hemiplegic Cerebral Palsy: A Qualitative Investigation.

Background: To successfully modify an intervention from an adult population for use with children with cerebral palsy, it is important to understand the components that support a child's motivation and engagement. Method: Ten children who had participated in the Sense© intervention (mean age = 11 years 2 m [SD = 2 years]; four males; Manual Ability Classification System level I = 1, II = 9) and their primary caregivers (N = 11, 10 females) were interviewed. Transcripts were analyzed using framework analysis. Results: Key themes were identified in the core domains of the Synthesis of Child, Occupational Performance and Environment in Time model. Child: children's somatosensory discrimination ability improved; Motivation: incorporating child's goals was essential, as were real-world gains; Environmental: parents were interested in having more involvement in the intervention. Conclusion: The most engaging elements of the intervention for children were the attainment of their self-selected goals. Opportunities to modify the intervention for improved partnership with parents were identified.

Discovering the sense of touch: protocol for a randomised controlled trial examining the efficacy of a somatosensory discrimination intervention for children with hemiplegic cerebral palsy.

BACKGROUND: Of children with hemiplegic cerebral palsy, 75% have impaired somatosensory function, which contributes to learned non-use of the affected upper limb. Currently, motor learning approaches are used to improve upper-limb motor skills in these children, but few studies have examined the effect of any intervention to ameliorate somatosensory impairments. Recently, Sense© training was piloted with a paediatric sample, seven children with hemiplegic cerebral palsy, demonstrating statistically and clinically significant change in limb position sense, goal performance and bimanual hand-use. This paper describes a protocol for a Randomised Controlled Trial of Sense© for Kids training, hypothesising that its receipt will improve somatosensory discrimination ability more than placebo (dose-matched Goal Directed Therapy via Home Program). Secondary hypotheses include that it will alter brain activation in somatosensory processing regions, white-matter characteristics of the thalamocortical tracts and improve bimanual function, activity and participation more than Goal Directed Training via Home Program. METHODS AND DESIGN: This is a single blind, randomised matched-pair, placebo-controlled trial. Participants will be aged 6-15 years with a confirmed description of hemiplegic cerebral palsy and somatosensory discrimination impairment, as measured by the sense©_assess Kids. Participants will be randomly allocated to receive 3h a week for 6 weeks of either Sense© for Kids or Goal Directed Therapy via Home Program. Children will be matched on age and severity of somatosensory discrimination impairment. The primary outcome will be somatosensory discrimination ability, measured by sense©_assess Kids score. Secondary outcomes will include degree of brain activation in response to a somatosensory task measured by functional MRI, changes in the white matter of the thalamocortical tract measured by diffusion MRI, bimanual motor function, activity and participation. DISCUSSION: This study will assess the efficacy of an intervention to increase somatosensory discrimination ability in children with cerebral palsy. It will explore clinically important questions about the efficacy of intervening in somatosensation impairment to improve bimanual motor function, compared with focusing on motor impairment directly, and whether focusing on motor impairment alone can affect somatosensory ability. TRIAL REGISTRATION: This trial is registered with the Australian New Zealand Clinical Trials Registry, registration number: ACTRN12618000348257. World Health Organisation universal trial number: U1111-1210-1726.

Two-point orientation discrimination versus the traditional two-point test for tactile spatial acuity assessment.

Two-point discrimination is widely used to measure tactile spatial acuity. The validity of the two-point threshold as a spatial acuity measure rests on the assumption that two points can be distinguished from one only when the two points are sufficiently separated to evoke spatially distinguishable foci of neural activity. However, some previous research has challenged this view, suggesting instead that two-point task performance benefits from an unintended non-spatial cue, allowing spuriously good performance at small tip separations. We compared the traditional two-point task to an equally convenient alternative task in which participants attempt to discern the orientation (vertical or horizontal) of two points of contact. We used precision digital readout calipers to administer two-interval forced-choice versions of both tasks to 24 neurologically healthy adults, on the fingertip, finger base, palm, and forearm. We used Bayesian adaptive testing to estimate the participants' psychometric functions on the two tasks. Traditional two-point performance remained significantly above chance levels even at zero point separation. In contrast, two-point orientation discrimination approached chance as point separation approached zero, as expected for a valid measure of tactile spatial acuity. Traditional two-point performance was so inflated at small point separations that 75%-correct thresholds could be determined on all tested sites for fewer than half of participants. The 95%-correct thresholds on the two tasks were similar, and correlated with receptive field spacing. In keeping with previous critiques, we conclude that the traditional two-point task provides an unintended non-spatial cue, resulting in spuriously good performance at small spatial separations. Unlike two-point discrimination, two-point orientation discrimination rigorously measures tactile spatial acuity. We recommend the use of two-point orientation discrimination for neurological assessment.