Proprioception, Emotion and Social Responsiveness in Children with Developmental Disorders: An Exploratory Study in Autism Spectrum Disorder, Cerebral Palsy and Different Neurodevelopmental Situations.

Proprioception has long been linked with emotional dysregulation in neurotypical adults. Neuropediatric disorders such as autism spectrum disorder (ASD) and cerebral palsy (CP) are distinct entities and yet both present with deficits and challenges in sensory processing and the regulation of emotions. This study aimed to explore the relationship between proprioception and emotional-social performance in children and to compare proprioception and emotional-social performance in different underlying neurodevelopmental conditions. For this purpose, this cross-sectional study included 42 children with ASD, 34 children with CP and 50 typically developing peers. Proprioceptive acuity, proprioceptive reactive behavior as well as emotion regulation and social responsiveness were assessed. The results show a significant correlation between proprioceptive deficits and emotional difficulties in this pediatric sample, with distinct proprioceptive impairment patterns according to the underlying neurological disorder. Children with CP showed significant emotional knowledge deficits, while children with ASD predominantly showed challenges in social responsiveness. These data thus suggest a differentiated impact of proprioception on emotional-social performance in neurodevelopmental disorders and highlight proprioception as a potential therapeutic target for balancing emotion regulation in children with neurodevelopmental conditions.

The diagnostic value of physical examination tests in adhesive capsulitis: a systematic review.

INTRODUCTION: Adhesive capsulitis, a condition marked by pain and stiffness of the shoulder, can have a frustrating clinical course for patients and health care professionals. Despite huge research interest, a universally accepted and used definition of clinical criteria for the diagnosis of adhesive capsulitis is currently still lacking. This systematic review aimed to identify diagnostic values for clinical examinations tests used in the diagnosis of adhesive capsulitis. EVIDENCE ACQUISITION: A total of 5 electronic databases (PubMed, Web of Science, Embase, Cochrane Central Register of Controlled Trials [CENTRAL] and PEDro) were searched for relevant studies from 2002 until October 2022 using the terms: "adhesive capsulitis AND diagnosis" and "frozen shoulder AND diagnosis." The Downs and Black Checklist (modified) was used to assess the risk of bias. The study protocol was prospectively registered at the International prospective register of systematic reviews (PROSPERO, CRD42022365993). EVIDENCE SYNTHESIS: The initial database search identified 1799 studies, of which 9 (0.50%) were eventually included in the systematic review. Non-intrusive shoulder range of motion measurements in patients with adhesive capsulitis using the Kinect for Windows (Microsoft, Redmond, WA, USA) showed high correlation with clinical range of motion measurement. Two specific clinical tests, the affected-unaffected shoulder approach of the Coracoid Pain Test and the Distension Test in Passive External Rotation, were identified and presented excellent sensibility and specificity in the diagnosis of adhesive capsulitis, in their original study. Comparison between clinical tests was not possible due to the heterogeneity in clinical tools. CONCLUSIONS: This systematic review identified several physical examination tests developed for the diagnosis of adhesive capsulitis but could not compare them nor advance a set of clinical diagnostic tests that are scientifically validated. Further research is warranted to obtain validation of clinical diagnosis tools for adhesive capsulitis.

A multidimensional investigation of the relationship between skin-mediated somatosensory signals, emotion regulation and behavior problems in autistic children.

Introduction: Autistic children may have abnormal sensory perception, emotion dysregulation and behavior problems. The aim of this cross-sectional study was to explore the relationship between skin-mediated somatosensory signals and emotion/behavior difficulties in autistic children and adolescents, in comparison typically developing peers (TDP). Methods: Thirty-eight autistic children and adolescents and 34 TDP completed a multidimensional assessment consisting of the measurement of somatosensory thresholds of touch, pain and temperature, a task on emotion knowledge and parent-reported questionnaires on sensory reactivity, emotion regulation and behavior. Results: Autistic children had higher pain sensitivity, less sensory reactive behaviors and more behavior problems than their TDP. In contrast to TDP, several somatosensory thresholds of autistic children correlated with emotion regulation and behavior problems. Discussion: Sensory dysfunction may affect the development of emotional processing and behavior in autistic children and adolescents. This knowledge can lay the foundation for future studies on co-occurring alterations in corresponding neural networks and for the implementation of early interventions, including sensory rehabilitation therapy, for promoting regulated behaviors in autistic children and adolescents.

Severe lumbar pain in an adolescent due to idiopathic vena cava thrombosis: a case report.

BACKGROUND: Lumbar back pain in an adolescent is generally musculoskeletal, that is, due to a muscle strain or scoliosis. This case describes a young individual without any previous health issues who rapidly developed a life-threatening condition, though initially presenting with "only" back pain. CASE PRESENTATION: A 16-year-old Caucasian male patient was admitted twice to the emergency department with debilitating lumbar pain without neurological or vascular symptoms. Imagery showed an extensive thrombosis of the inferior vena cava. No external cause, structural abnormality, or any systemic disease were found that predisposed the patient to this highly unusual vaso-occlusive incident. CONCLUSION: Thrombosis of the inferior vena cava is a rare but life-threatening entity. It is underrecognized and associated with serious short- and long-term morbidity and mortality. Increased awareness is essential because deep vein thrombosis in children seems to cause atypical symptoms, such as spinal pain or the absence of edema of the lower limbs, as in the present case.

Association between Experimental Pain Measurements and the Central Sensitization Inventory in Patients at Least 3 Months after COVID-19 Infection: A Cross-Sectional Pilot Study.

Fatigue, pain, headache, brain fog, anosmia, ageusia, mood symptoms, and sleep disorders are symptoms commonly experienced by people with post-COVID-19 condition. These symptoms could be considered as manifestations of central sensitization. The aim of this study is to evaluate whether there are indicators of central sensitization by using experimental pain measurements and to determine their association with patient-reported outcome measures (PROMs). A cross-sectional study including 42 patients after COVID-19 infection was conducted. The central sensitization inventory (CSI) was administered as a PROM to evaluate central-sensitization-associated symptoms. Pressure pain thresholds (PPT), temporal summation, and descending nociceptive pain inhibition (CPM) were assessed as experimental pain measurements. The median score on the CSI was 46.5 (Q1-Q3: 33-54). The presence of central-sensitization-associated symptoms was seen in 64.3% of patients based on the CSI (≥40/100 points). A deficient CPM was seen in 12% and 14% of patients when measured at the trapezius and rectus femoris, respectively. A negative correlation between pressure sensitivity on the rectus femoris and the CSI score (r = -0.36, 95%CI -0.13 to -0.65, p = 0.007) was observed. Central-sensitization-associated symptoms were present in up to 64.3% of patients post-COVID-19 infection, based on a PROM, i.e., the CSI. A more objective evaluation of nociceptive processing through experimental pain measurements was less suggestive of indicators of central sensitization. Only a small negative correlation between pressure sensitivity and the CSI was observed, thereby pointing towards the discrepancy between the CSI and experimental pain measurements and presumably the complementary need for both to evaluate potential indicators of central sensitization in this population.

Impact of early brain lesions on the optic radiations in children with cerebral palsy.

Due to their early brain lesion, children with unilateral spastic cerebral palsy (USCP) present important changes in brain gray and white matter, often manifested by perturbed sensorimotor functions. We predicted that type and side of the lesion could influence the microstructure of white matter tracts. Using diffusion tensor imaging in 40 children with USCP, we investigated optic radiation (OR) characteristics: fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). First, we compared the OR of the lesional and non-lesional hemisphere. Then we evaluated the impact of the brain lesion type (periventricular or cortico-subcortical) and side in the differences observed in the lesional and non-lesional OR. Additionally, we examined the relationship between OR characteristics and performance of a visuospatial attention task. We observed alterations in the OR of children with USCP on the lesional hemisphere compared with the non-lesional hemisphere in the FA, MD and RD. These differences were influenced by the type of lesion and by the side of the lesion. A correlation was also observed between FA, MD and RD and the visuospatial assessment mainly in children with periventricular and right lesions. Our results indicate an important role of the timing and side of the lesion in the resulting features of these children's OR and probably in the compensation resulting from neuroplastic changes.

Randomized controlled trial of suprascapular nerve blocks for subacute adhesive capsulitis.

BACKGROUND: Shoulder pain and loss of function remain a therapeutic challenge in adhesive capsulitis. Suprascapular nerve blocks, a common treatment in adhesive capsulitis, are considered a safe and effective method for the resolution of pain and restoration of shoulder range of motion (ROM). To our knowledge, no data are available on the use of suprascapular nerve blocks in adhesive capsulitis in the subacute phase. AIM: The aim of this study was to compare the efficacy of ultrasound-guided suprascapular nerve blocks versus saline injections for treating adhesive capsulitis in the subacute phase. DESIGN: Randomized double-blinded controlled trial; level of evidence 2. SETTING: Out-patient consultation of Physical and Rehabilitation Medicine in a general hospital. POPULATION: Thirty-five patients with subacute adhesive capsulitis. METHODS: Patients were randomly allocated to receive either 3 successive (1-week interval) ultrasound-guided suprascapular nerve blocks with ropivacaine 5 mL 2 mg/mL (intervention group) or ultrasound-guided injections of 5 mL sterile saline solution (NaCl 0.9%) (control group), at the floor of the suprascapular fossa. Primary outcome was shoulder function assessed by the Constant-Murley Score. Secondary outcomes were shoulder ROM and shoulder pain intensity. Assessments were performed before each injection and 4 weeks after the last injection. RESULTS: A significant increase of Constant-Murley Score (P<0.001), increase of shoulder ROM (all directions: P<0.011) and decrease of pain (P<0.001), were observed over time in both study groups. However, no significant differences were observed between the intervention and the control group. CONCLUSIONS: Three successive suprascapular nerve blocks did not provide a better outcome than saline injections on shoulder function, ROM, and pain in subacute adhesive capsulitis. These negative findings warrant some considerations on the natural history of adhesive capsulitis, as well as timing, type, and placebo effects of injections. CLINICAL REHABILITATION IMPACT: The current place of suprascapular nerve blocks in the treatment strategy of adhesive capsulitis needs to be rediscussed.

Hospital at Home for Intrathecal Pump Refills: A Prospective Effectiveness, Safety and Feasibility Study.

Continuous Intrathecal Drug Delivery through an implanted pump is a well-known therapeutic option for the management of chronic pain and severe disabling spasticity. To have a successful therapy, pump refills need to be performed at regular time intervals after implantation. In line with the increased applications of Hospital at Home, these refill procedures might be performed at the patient's home. The aim of this pilot study is to evaluate the feasibility, safety, and effectiveness of intrathecal pump refill procedures at home. Twenty patients were included whereby pump refill procedures were conducted at the patient's home. To enable contact with the hospital, a video connection was set-up. Tele-ultrasound was used as post-refill verification. All procedures were successfully performed with complete patient satisfaction. Ninety-five percent of the patients felt safe during the procedure, and 95% of the procedures felt safe according to the physician. All patients indicated that they preferred their next refill at home. The median time consumption for the physician/nurse at the patient's home was 26 min and for the researcher at the hospital 15 min. In light of quality enhancement programs and personalized care, it is important to continue urgent pain management procedures in a safe way, even during a pandemic.

Fibromyalgia syndrome-A laser-evoked potentials study unsupportive of small nerve fibre involvement.

BACKGROUND: Fibromyalgia syndrome (FMS) is a chronic pain syndrome characterized by widespread pain and a variety of non-pain symptoms. Central sensitivity phenomena are found consistently in FMS. Additionally, several researchers proclaimed that a subgroup of FMS patients may present with unrecognized peripheral small fibre neuropathy (SFN). Laser-evoked brain potentials (LEP) are considered as a reliable method for the functional assessment of the thermo-nociceptive system, including the evaluation of SFN. OBJECTIVES: The aim of this retrospective study was to estimate the prevalence of thermo-nociceptive system dysfunction based on LEPs in FMS. METHODS: LEP recordings of 92 FMS patients and 39 age and gender-matched healthy controls were selected from a database collected between 2003 and 2012 with standardized settings for laser stimulation and EEG recording. The N1, N2 and P2 LEP components were identified and characterized by peak latency and amplitude. RESULTS: None of the FMS patients showed signs of loss of function of the nociceptive responses evoked by A δ-nociceptor activation, compared to healthy controls. 6.5% of the FMS patients had N2-P2 peak-to-peak amplitudes above the upper limit of the 99%-confidence interval. N2-P2 peak-to-peak amplitudes were negatively correlated with age, without age-related differences between groups. CONCLUSIONS: The characteristic signs of a damaged thermo-nociceptive system as revealed by LEPs were absent in this large cohort of FMS patients. SIGNIFICANCE: The present research does not support the hypothesis that small fibre neuropathy is a significant contributor to the pathophysiology of FMS.

The Two-Arm Coordination Test: Maturation of Bimanual Coordination in Typically Developing Children and Deficits in Children with Unilateral Cerebral Palsy.

Background: Tools to assess bimanual coordination are scant. We aimed to: 1) provide normative data of maturation of bimanual coordination in tipically developing (TD) children measured by the Two Arm Coordination Test (TACT), and 2) validate the TACT as an instrument to specifically discriminate impairment of bimanual coordination in children with unilateral cerebral palsy (UCP). Procedure: Cross-sectional observational study. 252 TD children and 26 children with UCP performed 8 trials of TACT (following a star pattern with a pointer steered by coordinated movements of both arms). Number of errors and time were combined in a performance index of motor learning.Results: In TD children, bimanual coordination improved with age (F(7,244)=36.888, p<.001). Children with UCP had a poorer bimanual coordination than TD children (all t>24.25, all p<.01). TACT scores were correlated moderately to manual dexterity and manual ability (all r>-.452, all p<.039), showing the capacity of the TACT to provide information on different aspects of hand function. Conclusion: TACT is a valid instrument to assess bimanual coordination.

Reduction of Pain Sensitivity after Somatosensory Therapy in Children with Autism Spectrum Disorders.

Children with autism spectrum disorders (ASD) often present with somatosensory dysfunction including an abnormal reactivity to tactile stimuli and altered pain perception. A therapy based on somatosensory stimuli has shown effectiveness in reducing pain sensitivity among adults with cerebral palsy. The present study aims at exploring the influence of somatosensory therapy on somatosensory parameters in children with ASD. Children with high-functioning ASD were randomly assigned to either the intervention (n = 29) or the control group (n = 30). The intervention group received a somatosensory therapy consisting of four types of exercises (touch, proprioception, vibration, stereognosis). Somatosensory function (pressure pain thresholds, tactile thresholds, stereognosis, proprioception) was assessed before and immediately after the therapy. Children in the intervention group showed a significant reduction of pain sensitivity and increase of tactile sensitivity after treatment, whereas children in the control group displayed increased pain sensitivity in the absence of changes of tactile sensitivity. No changes were observed for proprioception or stereognosis. The repetitive somatosensory stimulation therapy led to a decrease of pain sensitivity and an increase of tactile sensitivity. These findings may have important research and clinical implications, as promoting early tactile interventions in children with ASD may lead to a more adequate development of somatosensory processing and less somatosensory abnormalities upon adult life.

Cerebral Blood Flow and Heart Rate Variability in Chronic Fatigue Syndrome: A Randomized Cross-Over Study.

BACKGROUND: Pain, fatigue, and concentration difficulties are typical features of chronic fatigue syndrome (CFS). The exact underlying mechanisms of these symptoms are still unknown, but available evidence suggests an important role for impaired pain modulation. As evidence also suggests that pain modulation is related to cardiovascular mechanisms, it seems logical to investigate whether cerebral blood flow (CBF) and heart rate variability (HRV) are altered in these patients. OBJECTIVES: We aimed to investigate the role of the cardiovascular system in pain modulation and symptoms of CFS; the response of CBF and HRV to physical stress and their relation to the change in temporal summation (TS) of pressure pain and self-reported symptoms was evaluated. STUDY DESIGN: A controlled, randomized cross-over trial. SETTING: University Hospital Brussels. METHODS: Twenty CFS patients and 20 sedentary healthy controls were included in this study. In both of the groups, the change in TS of pressure pain, CBF (using transcranial Doppler), and HRV (using finger plethysmography) was examined during physical and emotional stress (to control for potential bias), as well as their association mutually and with self-reported symptoms of pain, fatigue, and concentrations difficulties. RESULTS: There was no significant interaction or group (F-values ranging from .100 to 1.862, P-values ranging from .754 to .181) effect in CBF or HRV parameters. HRV and CBF did change during physical exercise, but the changes did not differ between patients and controls. While pain scores during TS at the trapezius site reduced in the control group after the physical exercise protocol (P = .037), they did not change in the CFS group (P = .108), suggesting impaired pain modulation. There were no significant correlations between CBF, HRV, TS, and self-reported symptoms (all P-values of correlation analyses > .01). LIMITATIONS: Although effect sizes were medium to large, the study sample was relatively low. Also, the mild nature of the exercise bout is discussable. Nonetheless, this mild exercise was able to provoke endogenous pain modulation in the control group, which endorsed a proper execution of the cycling exercise. Moreover, mild exercises are more applicable to daily physical activities in CFS patients than vigorous exercises. CONCLUSION: These results seem to refute the previously suggested alterations of CBF/HRV in CFS patients. These cardiovascular parameters appear not to explain pain before, during, and following exercise. KEY WORDS: Chronic pain, physical exercise, emotional stress, pain modulation, cardiovascular systems, temporal summation, pain pressure thresholds, transcranial Doppler, plethysmography.

Impairments of Visuospatial Attention in Children with Unilateral Spastic Cerebral Palsy.

Aim: This observational study aimed at assessing the prevalence of visuospatial attention deficits in children with unilateral spastic cerebral palsy (USCP), taking into consideration the affected hemibody and the localization of the brain lesion. Method: Seventy-five children with USCP were assessed with four visuospatial attention tests: star cancellation, Ogden figure copy, line bisection, and proprioceptive pointing. Results: A majority (64%) of children with USCP presented a deficit in at least one test compared to the reference values. The alterations observed in children with left or right USCP were related to egocentric or allocentric neglect, respectively. Children with cortico/subcortical lesion presented more often visuospatial attention deficits than children with periventricular lesion. Visuospatial attention deficits were not associated with brain lesion locations. Interpretation: Visuospatial attention deficits are prevalent in children with USCP and should be taken into account during their rehabilitation process. The present results shed new light on the interpretation of motor impairments in children with USCP as they may be influenced by the frequent presence of visuospatial deficits.

Development of Visuospatial Attention in Typically Developing Children.

The aim of the present study is to investigate the development of visuospatial attention in typically developing children and to propose reference values for children for the following six visuospatial attention tests: star cancellation, Ogden figure, reading test, line bisection, proprioceptive pointing and visuo-proprioceptive pointing. Data of 159 children attending primary or secondary school in the Fédération Wallonie Bruxelles (Belgium) were analyzed. Results showed that the children's performance on star cancellation, Ogden figure and reading test improved until the age of 13 years, whereas their performance on proprioceptive pointing, visuo-proprioceptive pointing and line bisection was stable with increasing age. These results suggest that the execution of different types of visuospatial attention tasks are not following the same developmental trajectories. This dissociation is strengthened by the lack of correlation observed between tests assessing egocentric and allocentric visuospatial attention, except for the star cancellation test (egocentric) and the Ogden figure copy (ego- and allocentric). Reference values are proposed that may be useful to examine children with clinical disorders of visuospatial attention.

Rehabilitation of Motor Function after Stroke: A Multiple Systematic Review Focused on Techniques to Stimulate Upper Extremity Recovery.

Stroke is one of the leading causes for disability worldwide. Motor function deficits due to stroke affect the patients' mobility, their limitation in daily life activities, their participation in society and their odds of returning to professional activities. All of these factors contribute to a low overall quality of life. Rehabilitation training is the most effective way to reduce motor impairments in stroke patients. This multiple systematic review focuses both on standard treatment methods and on innovating rehabilitation techniques used to promote upper extremity motor function in stroke patients. A total number of 5712 publications on stroke rehabilitation was systematically reviewed for relevance and quality with regards to upper extremity motor outcome. This procedure yielded 270 publications corresponding to the inclusion criteria of the systematic review. Recent technology-based interventions in stroke rehabilitation including non-invasive brain stimulation, robot-assisted training, and virtual reality immersion are addressed. Finally, a decisional tree based on evidence from the literature and characteristics of stroke patients is proposed. At present, the stroke rehabilitation field faces the challenge to tailor evidence-based treatment strategies to the needs of the individual stroke patient. Interventions can be combined in order to achieve the maximal motor function recovery for each patient. Though the efficacy of some interventions may be under debate, motor skill learning, and some new technological approaches give promising outcome prognosis in stroke motor rehabilitation.

Abnormal Pressure Pain, Touch Sensitivity, Proprioception, and Manual Dexterity in Children with Autism Spectrum Disorders.

UNLABELLED: Children with autism spectrum disorders (ASD) often display an abnormal reactivity to tactile stimuli, altered pain perception, and lower motor skills than healthy children. Nevertheless, these motor and sensory deficits have been mostly assessed by using clinical observation and self-report questionnaires. The present study aims to explore somatosensory and motor function in children with ASD by using standardized and objective testing procedures. METHODS: Tactile and pressure pain thresholds in hands and lips, stereognosis, proprioception, and fine motor performance of the upper limbs were assessed in high-functioning children with ASD (n = 27) and compared with typically developing peers (n = 30). RESULTS: Children with ASD showed increased pain sensitivity, increased touch sensitivity in C-tactile afferents innervated areas, and diminished fine motor performance and proprioception compared to healthy children. No group differences were observed for stereognosis. CONCLUSION: Increased pain sensitivity and increased touch sensitivity in areas classically related to affective touch (C-tactile afferents innervated areas) may explain typical avoiding behaviors associated with hypersensitivity. Both sensory and motor impairments should be assessed and treated in children with ASD.

Use of prism adaptation in children with unilateral brain lesion: Is it feasible?

INTRODUCTION: Unilateral visuospatial deficits have been observed in children with brain damage. While the effectiveness of prism adaptation for treating unilateral neglect in adult stroke patients has been demonstrated previously, the usefulness of prism adaptation in a pediatric population is still unknown. The present study aims at evaluating the feasibility of prism adaptation in children with unilateral brain lesion and comparing the validity of a game procedure designed for child-friendly paediatric intervention, with the ecological task used for prism adaptation in adult patients. METHODS: Twenty-one children with unilateral brain lesion randomly were assigned to a prism group wearing prismatic glasses, or a control group wearing neutral glasses during a bimanual task intervention. All children performed two different bimanual tasks on randomly assigned consecutive days: ecological tasks or game tasks. The efficacy of prism adaptation was measured by assessing its after-effects with visual open loop pointing (visuoproprioceptive test) and subjective straight-ahead pointing (proprioceptive test). RESULTS: Game tasks and ecological tasks produced similar after-effects. Prismatic glasses elicited a significant shift of visuospatial coordinates which was not observed in the control group. CONCLUSION: Prism adaptation performed with game tasks seems an effective procedure to obtain after-effects in children with unilateral brain lesion. The usefulness of repetitive prism adaptation sessions as a therapeutic intervention in children with visuospatial deficits and/or neglect, should be investigated in future studies.

Pain sensitivity and tactile spatial acuity are altered in healthy musicians as in chronic pain patients.

Extensive training of repetitive and highly skilled movements, as it occurs in professional classical musicians, may lead to changes in tactile sensitivity and corresponding cortical reorganization of somatosensory cortices. It is also known that professional musicians frequently experience musculoskeletal pain and pain-related symptoms during their careers. The present study aimed at understanding the complex interaction between chronic pain and music training with respect to somatosensory processing. For this purpose, tactile thresholds (mechanical detection, grating orientation, two-point discrimination) and subjective ratings to thermal and pressure pain stimuli were assessed in 17 professional musicians with chronic pain, 30 pain-free musicians, 20 non-musicians with chronic pain, and 18 pain-free non-musicians. We found that pain-free musicians displayed greater touch sensitivity (i.e., lower mechanical detection thresholds), lower tactile spatial acuity (i.e., higher grating orientation thresholds) and increased pain sensitivity to pressure and heat compared to pain-free non-musicians. Moreover, we also found that musicians and non-musicians with chronic pain presented lower tactile spatial acuity and increased pain sensitivity to pressure and heat compared to pain-free non-musicians. The significant increment of pain sensitivity together with decreased spatial discrimination in pain-free musicians and the similarity of results found in chronic pain patients, suggests that the extensive training of repetitive and highly skilled movements in classical musicians could be considered as a risk factor for developing chronic pain, probably due to use-dependent plastic changes elicited in somatosensory pathways.

Value of quantitative sensory testing in neurological and pain disorders: NeuPSIG consensus.

Quantitative sensory testing (QST) is a psychophysical method used to quantify somatosensory function in response to controlled stimuli in healthy subjects and patients. Although QST shares similarities with the quantitative assessment of hearing or vision, which is extensively used in clinical practice and research, it has not gained a large acceptance among clinicians for many reasons, and in significant part because of the lack of information about standards for performing QST, its potential utility, and interpretation of results. A consensus meeting was convened by the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain (NeuPSIG) to formulate recommendations for conducting QST in clinical practice and research. Research studies have confirmed the utility of QST for the assessment and monitoring of somatosensory deficits, particularly in diabetic and small fiber neuropathies; the assessment of evoked pains (mechanical and thermal allodynia or hyperalgesia); and the diagnosis of sensory neuropathies. Promising applications include the assessment of evoked pains in large-scale clinical trials and the study of conditioned pain modulation. In clinical practice, we recommend the use QST for screening for small and large fiber neuropathies; monitoring of somatosensory deficits; and monitoring of evoked pains, allodynia, and hyperalgesia. QST is not recommended as a stand-alone test for the diagnosis of neuropathic pain. For the conduct of QST in healthy subjects and in patients, we recommend use of predefined standardized stimuli and instructions, validated algorithms of testing, and reference values corrected for anatomical site, age, and gender. Interpretation of results should always take into account the clinical context, and patients with language and cognitive difficulties, anxiety, or litigation should not be considered eligible for QST. When appropriate standards, as discussed here, are applied, QST can provide important and unique information about the functional status of somatosensory system, which would be complementary to already existing clinical methods.

Clinical, functional and structural determinants of central pain in syringomyelia.

The present study aimed to investigate the relationship between neuropathic symptoms (i.e. pain and paraesthesia/dysaesthesia) and structural damage and functional alterations of spinal sensory tracts in patients with syringomyelia. Three-dimensional fibre tracking of the cervical spinal cord (at level C3-C4), electrophysiological assessments of nociceptive (laser-evoked potentials) and non-nociceptive (somatosensory-evoked potentials) pathways and quantitative sensory testing were carried out in 37 patients with syringomyelia, 27 with neuropathic pain and 21 controls. Four regions of the body (both hands and shoulders) were systematically examined with laser-evoked potentials and quantitative sensory testing, and somatosensory-evoked potentials were induced from both hands. The diffusion tensor imaging variables investigated included the mean fractional anisotropy, the mean apparent diffusion coefficient and the number of reconstructed nerve fibres of the tracts located within three volumes of interest (full spinal section, anterior cord and posterior cord). Consistent with the results of previous studies, patients with or without neuropathic pain were indistinguishable on the basis of quantitative sensory testing, laser-evoked and somatosensory-evoked potentials and three-dimensional fibre tracking analyses. However, in patients with neuropathic pain, higher average daily pain intensity was correlated with greater structural damage to the spinal cord, as assessed by fractional anisotropy (Spearman's ρ = -0.64, P = 0.020) and the number of reconstructed nerve fibres (r = -0.75; P = 0.020) of the full spinal cord. The number of reconstructed nerve fibres was negatively correlated with two neuropathic dimensions, i.e. 'deep spontaneous pain' (r = -0.59, P = 0.040) and 'paraesthesia/dysaesthesia' (i.e. pins and needles/tingling) (r = -0.67, P = 0.020), suggesting that various pain descriptors have distinct underlying mechanisms. Patients with both spontaneous and evoked pain clearly differed from patients with spontaneous pain only. Patients with spontaneous pain only had more severe spinal cord damage, and the correlation between average daily pain intensity and fractional anisotropy of the full spinal cord was particularly strong in this subgroup of patients (Spearman's ρ = -0.93, P = 0.008). By contrast, patients with both spontaneous and evoked pain had not only less structural spinal cord damage, but also better preserved spinothalamic and lemniscal tracts on quantitative sensory testing and electrophysiological testing. These data showed, for the first time, a direct relationship between central neuropathic pain and objective markers of spinal cord damage, and confirmed the clinical relevance of 3D fibre tracking for the sensory assessment of patients with a spinal cord lesion.