Changes In Quantitative Sensory Testing Research Articles

Changes in quantitative sensory testing and patient perspectives following spinal cord stimulation for persistent spinal pain syndrome: An observational study with long-term follow-up.

BackgroundSpinal cord stimulation (SCS) can impact sensory, pain and tolerance thresholds in various ways, which can be accessed via quantitative sensory testing (QST). The objectives of this study were to (1) assess the subjective sensory responses using QST in patients following SCS therapy for PSPS and (2) to get a clinical impression of the results of SCS during an interview of these patients with PSPS and SCS during long term follow‐up.MethodsForty patients with PSPS who received SCS treatment underwent QST via electrical and mechanical pressure stimuli. QST was performed at four different moments (1) pre‐implantation SCS, (2) two weeks postoperatively, (3) three months after permanent SCS implantation and (4) six months after permanent SCS implantation. Patients’ perspectives on pain, use of drugs and quality of life were assessed via semi‐structured interviews during a follow‐up between 5 and 11 years.ResultsWe found statistical significant differences in the changes of sensory, pain and tolerance thresholds. A decrease in pain complaints and analgesics use were reported by the patients during follow‐up. The quality of life in patients increased from three to eight (NRS 0 [worst QoL imaginable] ‐10 [best QoL imaginable]) after receiving SCS.ConclusionsThe increased thresholds on areas without pain or being covered by the SCS induced paresthesias may indicate that there are central changes contributing to these deviations in thresholds. The overall QoL in patients improved greatly after receiving SCS.SignificanceThis study provides an overview of the effect of SCS on sensory, pain and tolerance thresholds in patients with PSPS throughout the SCS treatment process. In addition, this study presents data from 40 patients with PSPS treated with SCS, analysing several long‐term patient‐reported outcome measures. The results serve to give more insight into the mechanism of SCS and document SCS as a possible treatment for PSPS.

Multimodal sensory evaluation of neuropathic spinal cord injury pain: an experimental study

Study designAn experimental study.ObjectivesTo investigate the changes in somatosensory functions using the combined application of quantitative sensory testing (QST), contact heat-evoked potentials (CHEPs) and laser-evoked potentials (LEPs) studies in individuals with spinal cord injury (SCI) in relation to neuropathic pain (NeP).SettingCentre for Pain Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland.MethodsIndividuals with SCI were compared: 12 with NeP (SCI NeP) and 12 without NeP (SCI no NeP). Tools used were QST, CHEPs, LEPs and self-reported questionnaires. Tests were applied to the control (hand) and test (dermatome of altered sensation) sites, and compared to the able-bodied group.ResultsQST, LEPs and CHEPs assessments showed abnormalities both on the test and control sites, which did not differ between the groups with SCI. QST showed higher prevalence of allodynia in SCI NeP. CHEPs and LEPs demonstrated diminished amplitudes in both groups with SCI in comparison to able-bodied individuals. Only reaction time (RT) analysis revealed the difference of SCI NeP from the other two groups, expressed in partially preserved responses to the laser C-fibre stimulations.ConclusionsCombination of assessments in our study allowed to examine spinothalamic and dorsal column functions in individuals with SCI. Changes in QST, CHEPs and LEPs were detected below the level of injury independent of NeP and at the control site indicating modifications in sensory processing rostral to the spinal lesion. Analysis of RT during laser stimulation could be an essential component when evaluating the somatosensory functions related to NeP in persons with SCI.

Incidence of contralateral neurosensitive changes and persistent postoperative pain 6 months after mastectomy: A prospective, observational investigation.

Mirror image sensory dysfunction (MISD) after breast surgery has not yet been studied. This prospective observational study aimed to determine the incidence of MISD, persistent postoperative pain (PPP) and mirror image pain (MIP) during 6 months after total unilateral mastectomy.Visual analogue scale (VAS), Neuropathic Pain Symptom Inventory (NPSI), Pain Catastrophizing Scale (PCS), Hospital Anxiety and Depression Scale (HADS), Life orientation test (LOT) and Quantitative Sensory Testing (QST) (in ipsi and contralateral breast, axilla and thigh) were recorded. VAS > 3 at 1, 3, and 6 postoperative months was considered PPP. Contralateral changes of QST at any time was considered indicative of MISD and spontaneous contralateral VAS ≥ 1 as MIP.Sixty-four patients were included. PPP at 1, 3 and 6 months was 18.8%, 56.2%, and 21.3%, respectively Ten patients presented MIP. MISD was detected in 79.7% patients in contralateral breast and 62.5% in contralateral axilla. Furthermore, changes in QST were present in 39.1% of patients in thigh. Electronic Von Frey (EVF) changes in both contralateral breast and axilla, and in thigh significantly diminished at all postoperative times. Changes of postoperative EVF ≥ 20% in contralateral breast were associated to higher VAS values. NPSI scores were significantly higher at all postoperative times. At 1 month, PCS, depression HADS subscale and LOT scores were significantly worse than all the other periods.MISD incidence was almost 80%, and 15.6% of patients showed spontaneous contralateral VAS ≥ 1. At 6 months 21.3% of patients manifested PPP. The worst alteration of factors related to PPP occurred at 1 postoperative month. Most consistent QST was EVF.

Topical anaesthesia degree is reduced in temporomandibular disorders patients: A novel approach to assess underlying mechanisms of the somatosensory alterations.

Changes in quantitative sensory testing (QST) parameters following topical anaesthesia could contribute to better elucidate underlying mechanisms of somatosensory alterations in temporomandibular disorder (TMD) pain patients. This placebo-controlled crossover investigation compared the somatosensory profile following topical anaesthesia between TMD patients (n=20) and healthy participants (n=20). Cold detection threshold, warm detection threshold, cold pain threshold, heat pain threshold, mechanical detection threshold, mechanical pain threshold, wind-up ratio and pressure pain threshold were assessed on the skin overlying the masseter at three consecutive days (baseline and immediately after lidocaine 4%/placebo cream). Mixed ANOVA and a coding system that accounts for the diversity of types of peripheral axons associated with the somatosensory parameters were applied for data analysis. The lidocaine application caused no changes in the somatosensory sensitivity in the masseter region in TMD patients (P>.050), but sensitivity to cold, cold pain, touch and pinprick stimuli were reduced after topical anaesthesia in healthy participants (P<.050). Also, the degree of topical anaesthesia was greater in healthy participants (P=.008). The coding system suggested that TMD patients presented only Aδ-fibre block, whereas a combination of either Aβ- and/or C-fibre block was observed in 35% of healthy participants in addition to Aδ-fibre block following lidocaine application. Quantitative sensory testing can be successfully applied to identify meaningful differences in the degree of hypoalgesia and hypoesthesia following short-time topical anaesthesia.

A randomized trial to assess the immediate impact of acupuncture on quantitative sensory testing, pain, and functional status.

In this randomized clinical trial, we examined whether the effect of true acupuncture can be differentiated from sham acupuncture (pain and functionality) by analyzing quantitative sensory testing (QST) profiles in chronic pain participants. We recruited 254 healthy or chronic back and neck pain participants. Healthy subjects were included to control for a possible effect of acupuncture on baseline QST changes. Study participants received 6 sessions (twice weekly) of true acupuncture, sham acupuncture, or no acupuncture treatment (routine care). Quantitative sensory testing profiles, pain scores, and functionality profile were obtained at baseline (visit 1) and after 3 (visit 4) or 6 sessions (visit 7). A total of 204 participants were analyzed. We found no QST profile changes among 3 groups (P = 0.533 and P = 0.549, likelihood ratio tests) in either healthy or chronic pain participants. In chronic back and neck pain participants, true acupuncture reduced pain (visit 4: difference in mean [DIM] = -0.8, 95% confidence interval [CI]: -1.4 to -0.1, adjusted P = 0.168; visit 7: DIM = -1.0, 95% CI: -1.7 to -0.3, adjusted P = 0.021) and improved functional status including physical functioning (DIM = 14.21, 95% CI: 5.84-22.58, adjusted P = 0.003) and energy/fatigue (DIM = 12.28, 95% CI: 3.46-21.11, adjusted P = 0.021) as compared to routine care. Our results indicate that QST was not helpful to differentiate between true acupuncture and sham acupuncture (primary outcome) in this study, although true acupuncture reduced pain and improved functionality (secondary outcomes) when compared with routine care.

Chronic Opioid Therapy Modifies QST Changes After Ketamine Infusion in Chronic Pain Patients.

The presented data further our understanding of modulation of sensory perception in the setting of chronic opioid use and the role of the N-methyl-D-aspartate receptor. The use of low-dose ketamine infusions may be useful for the treatment as well as diagnosis of opioid-related neuropathic conditions.

Thermal QST Phenotypes Associated with Response to Lumbar Epidural Steroid Injections: A Pilot Study.

Response to lumbar epidural steroid injection in lumbar radicular pain varies. The purpose of this study is to characterize the changes in quantitative sensory testing (QST) phenotypes of subjects and compare the QST characteristics in patients who do respond to treatment of radicular pain with a lumbar epidural steroid injection (ESI). Prospective, observational pilot study. Outpatient pain center. Twenty subjects with a lower extremity (LE) radicular pain who were scheduled to have an ESI were recruited. At the visit prior to and four weeks following an ESI, subjects underwent QST measurements of both the affected LE and the contralateral unaffected UE. Following an ESI, nine subjects reported a greater than 30% reduction in radicular pain and 11 reported a less than 30% reduction in radicular pain. Subjects who had less than 30% pain reduction response (nonresponders) to an ESI had increased pre-injection warm sensation threshold (37.30 °C, SD = 2.51 vs 40.39, SD = 3.36, P = 0.03) and heat pain threshold (47.22 °C, SD = 1.38, vs 48.83 °C, SD = 2.10, P = 0.04). Further, the nonresponders also showed increased pre-injection warm sensation threshold as measured in the difference of warm sensation detection threshold difference in the affected limb and the unaffected arm (2.68 °C, SD = 2.92 vs 5.67 °C, SD = 3.22, P = 0.045). Other QST parameters were not affected. The results show that the nonresponders to ESIs have increased detection threshold to heat pain and warm sensation, suggesting that a preexisting dysfunction in the C fibers in this group of subjects who can be detected by QST. Such altered QST characteristics may prognosticate the response to ESIs.

Prognosis After Surgical Treatment of Trigeminal Neuropathy with a PGA-c Tube: Report of 10 Cases.

Although surgery using a polyglycolic acid-collagen (PGA-c) tube is effective for peripheral nerve injury-induced chronic hand pain, it has not been applied to trigeminal nerve lesions because of the difficult approach. We used a PGA-c tube during surgery for trigeminal neuropathy and evaluated its prognosis based on the outcomes. Case report. In the dental anesthesia division of a university hospital, 11 patients with severe dysesthesia underwent surgical repair of a damaged lingual nerve (LN) or inferior alveolar nerve (IAN). One patient was lost to follow-up. Changes in quantitative sensory testing (QST) and the presence of dysesthesia as a treatment outcome were compared preoperatively and postoperatively in 10 patients. Two surgical treatments, bridging or encircling peripheral nerves, were applied. Bridging of both stumps was selected when neurotmesis was detected or the nerve was lacerated during surgery (N = 4). Otherwise, a longitudinal PGA-c tube was used to encircle the lesion (N = 6). Outcomes were evaluated 2 months to 8 years postoperatively. Both methods improved the patients' condition based on QST results (brush stroke perception, mechanical touch threshold, sensitivity to cold/hot stimuli). Preoperative allodynia or dysesthesia was resolved in six patients and greatly reduced in four. Two patients (one with inflammation-induced pain, one with implant-related pain) developed prolonged postoperative allodynia requiring pain-relief medication. Use of a PGA-c tube for surgical treatment of intractable pain due to LN or IAN neuropathy helps alleviate sensory impairment. The possibility of new dysesthesias emerging postoperatively, however, should be noted.

Chronic sensory stroke with and without central pain is associated with bilaterally distributed sensory abnormalities as detected by quantitative sensory testing.

Approximately 20% of patients suffering from stroke with pure or predominant sensory symptoms (referred to as sensory stroke patients) develop central poststroke pain (CPSP). It is largely unknown what distinguishes these patients from those who remain pain free. Using quantitative sensory testing (QST), we analyzed the somatosensory profiles of 50 patients with chronic sensory stroke, of which 25 suffered from CPSP. As compared with reference data from healthy controls, patients with CPSP showed alterations of thermal and mechanical thresholds on the body area contralateral to their stroke (P < 0.01). Patients with sensory stroke but without CPSP (non-pain sensory stroke [NPSS] patients) exhibited similar albeit less pronounced contralesional changes. Paradoxical heat sensation (PHS) and dynamic mechanical allodynia (DMA) showed higher values in CPSP, and an elevated cold detection threshold (CDT) was seen more often in CPSP than in patients with NPSS (P < 0.05). In patients with CPSP, changes in CDT, PHS, dynamic mechanical allodynia, and temporal pain summation (wind-up ratio) each correlated with the presence of pain (P < 0.05). On the homologous ipsilesional body area, both patient groups showed additional significant abnormalities as compared with the reference data, which strongly resembled the contralesional changes. In summary, our analysis reveals that CPSP is associated with impaired temperature perception and positive sensory signs, but differences between patients with CPSP and NPSS are subtle. Both patients with CPSP and NPSS show considerable QST changes on the ipsilesional body side. These results are in part paralleled by recent findings of bilaterally spread cortical atrophy in CPSP and might reflect chronic maladaptive cortical plasticity, particularly in patients with CPSP.

Dynamic Pain Phenotypes are Associated with Spinal Cord Stimulation-Induced Reduction in Pain: A Repeated Measures Observational Pilot Study.

Spinal cord stimulation (SCS) has become a widely used treatment option for a variety of pain conditions. Substantial variability exists in the degree of benefit obtained from SCS and patient selection is a topic of expanding interest and importance. However, few studies have examined the potential benefits of dynamic quantitative sensory testing (QST) to develop objective measures of SCS outcomes or as a predictive tool to help patient selection. Psychological characteristics have been shown to play an important role in shaping individual differences in the pain experience and may aid in predicting responses to SCS. Static laboratory pain-induction measures have also been examined in their capacity for predicting SCS outcomes. The current study evaluated clinical, psychological and laboratory pain measures at baseline, during trial SCS lead placement, as well as 1 month and 3 months following permanent SCS implantation in chronic pain patients who received SCS treatment. Several QST measures were conducted, with specific focus on examination of dynamic models (central sensitization and conditioned pain modulation [CPM]) and their association with pain outcomes 3 months post SCS implantation. Results suggest few changes in QST over time. However, central sensitization and CPM at baseline were significantly associated with clinical pain at 3 months following SCS implantation, controlling for psycho/behavioral factors and pain at baseline. Specifically, enhanced central sensitization and reduced CPM were associated with less self-reported pain 3 months following SCS implantation. These findings suggest a potentially important role for dynamic pain assessment in individuals undergoing SCS, and hint at potential mechanisms through which SCS may impart its benefit.

Skin Biopsy in Complex Regional Pain Syndrome: Case Series and Literature Review

Background: Accumulating experimental and clinical evidence supports the hypothesis that complex regional pain syndrome type I (CRPS-I) may be a small fiber neuropathy. Objectives: To evaluate the use of commercially available standard biopsy methods to detect intradermal axon pathology in CRPS-I, and to ascertain if these structural changes can explain quantitative sensory testing (QST) findings in CRPS-I. Study Design: Retrospective review of charts and laboratory data. Setting: Outpatient clinic Methods: Skin biopsies from 43 patients with CRPS-I were stained with PGP 9.5, and epidermal nerve fiber density, sweat gland nerve fiber density and morphological abnormalities were evaluated. Thirty-five patients had quantitative sensory testing. Results: Alterations in skin innervation were seen in approximately 20% of CRPS-I patients with commercial processing. There were no patient characteristics, including duration of disease, that predicted a decreased epidermal nerve fiber density (ENFD). There was no consistent relationship between QST changes and ENFD measured by standard commercial skin biopsy evaluation procedures. Limitations: Commercial processing of tissue does not utilize stereologic quantitative analysis of nerve fiber density. Biopsy material is utilized from a proximal and distal source only, and differences in denervation of a partial nerve territory may be missed. The functional attributes of small fibers cannot be assessed. Conclusions: The negative results indicate that CRPS-I may be associated with changes in the ultramicroscopic small fiber structure that cannot be visualized with commercially available techniques. Alternatively, functional rather than structural alterations of small fibers or pathological changes at a more proximal site such as the spinal cord or brain may be responsible for the syndrome. Key words: Complex Regional Pain Syndrome, CRPS-1, CRPS, skin biopsy, epidermal nerve fiber density, sweat gland nerve fiber density, quantitative sensory testing.

Ultrasound-Guided Ilioinguinal/Iliohypogastric Nerve Blocks for Persistent Inguinal Postherniorrhaphy Pain

Ilioinguinal and iliohypogastric nerve blocks are used in the clinical management of persistent inguinal postherniorrhaphy pain, but no controlled studies have been published on the subject. In this controlled study, we investigated the analgesic and sensory effects of ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerves with lidocaine. A randomized, double-blind, placebo-controlled, crossover trial in 12 patients with severe persistent inguinal postherniorrhaphy pain, including a control group of 12 healthy controls, was performed. Assessments included pain ratings under standardized conditions with numerical rating scale (0-10), sensory mapping to a cool roller, and quantitative sensory testing (QST), in the groin regions, before and after each ultrasound-guided block. A needle approach of 1 to 2 cm superior and medial to the anterior superior iliac spine was used. Outcomes were changes in pain ratings, sensory mapping, and QST compared with preblock values. Lidocaine responders were a priori defined by a pain reduction of ≥80% after lidocaine block and ≤25% after placebo block, nonresponders by pain reduction of <80% after lidocaine block and ≤25% after placebo block, and placebo responders by pain reduction of >25% after placebo block. One of 12 pain patients was a lidocaine responder, 6 patients were nonresponders, and 5 patients were placebo responders. No consistent QST changes were observed in patients after the lidocaine block. In 10 of 12 healthy controls, a cool hypoesthesia area developed in the groin after the lidocaine block. Furthermore, QST assessments demonstrated significantly decreased suprathreshold heat pain perception in the groin after lidocaine versus placebo blocks (95% confidence interval = -3.5 to -0.5, P = 0.008). Ultrasound-guided lidocaine blocks of the ilioinguinal and iliohypogastric nerves, at the level of the anterior superior iliac spine, are not useful in diagnosis and management of persistent inguinal postherniorrhaphy pain.

Altered quantitative sensory testing outcome in subjects with opioid therapy

Preclinical studies have suggested that opioid exposure may induce a paradoxical decrease in the nociceptive threshold, commonly referred as opioid-induced hyperalgesia (OIH). While OIH may have implications in acute and chronic pain management, its clinical features remain unclear. Using an office-based quantitative sensory testing (QST) method, we compared pain threshold, pain tolerance, and the degree of temporal summation of the second pain in response to thermal stimulation among three groups of subjects: those with neither pain nor opioid therapy (group 1), with chronic pain but without opioid therapy (group 2), and with both chronic pain and opioid therapy (group 3). We also examined the possible correlation between QST responses to thermal stimulation and opioid dose, opioid treatment duration, opioid analgesic type, pain duration, or gender in group 3 subjects. As compared with both group 1 ( n = 41) and group 2 ( n = 41) subjects, group 3 subjects ( n = 58) displayed a decreased heat pain threshold and exacerbated temporal summation of the second pain to thermal stimulation. In contrast, there were no differences in cold or warm sensation among three groups. Among clinical factors, daily opioid dose consistently correlated with the decreased heat pain threshold and exacerbated temporal summation of the second pain in group 3 subjects. These results indicate that decreased heat pain threshold and exacerbated temporal summation of the second pain may be characteristic QST changes in subjects with opioid therapy. The data suggest that QST may be a useful tool in the clinical assessment of OIH.

Interaction of Hyperalgesia and Sensory Loss in Complex Regional Pain Syndrome Type I (CRPS I)

BackgroundSensory abnormalities are a key feature of Complex Regional Pain Syndrome (CRPS). In order to characterise these changes in patients suffering from acute or chronic CRPS I, we used Quantitative Sensory Testing (QST) in comparison to an age and gender matched control group.Methods61 patients presenting with CRPS I of the upper extremity and 56 healthy subjects were prospectively assessed using QST. The patients' warm and cold detection thresholds (WDT; CDT), the heat and cold pain thresholds (HPT; CPT) and the occurrence of paradoxical heat sensation (PHS) were observed.ResultsIn acute CRPS I, patients showed warm and cold hyperalgesia, indicated by significant changes in HPT and CPT. WDT and CDT were significantly increased as well, indicating warm and cold hypoaesthesia. In chronic CRPS, thermal hyperalgesia declined, but CDT as well as WDT further deteriorated. Solely patients with acute CRPS displayed PHS. To a minor degree, all QST changes were also present on the contralateral limb.ConclusionsWe propose three pathomechanisms of CRPS I, which follow a distinct time course: Thermal hyperalgesia, observed in acute CRPS, indicates an ongoing aseptic peripheral inflammation. Thermal hypoaesthesia, as detected in acute and chronic CRPS, signals a degeneration of A-delta and C-fibres, which further deteriorates in chronic CRPS. PHS in acute CRPS I indicates that both inflammation and degeneration are present, whilst in chronic CRPS I, the pathomechanism of degeneration dominates, signalled by the absence of PHS. The contralateral changes observed strongly suggest the involvement of the central nervous system.