Reliability of Cutaneous Electrical Perceptual Threshold in the Assessment of Sensory Perception in Patients with Spinal Cord Injury

Psychometric properties of light touch-pressure somatosensory measures in adults with neurological disorders: A systematic review

OBJECTIVES

To critically appraise the psychometric properties of light touch-pressure somatosensory assessments to provide guidance for tool selection for research or clinical purposes.

DATA SOURCES

MEDLINE, CINAHL, and PsycInfo were searched for research indexed from January 1990-November 2022. English language and human subject filters were applied. "Somatosensation", "psychometric property", and "nervous system-based health condition" search terms were combined. Grey literature and manual searches were conducted to ensure thoroughness.

REVIEW METHODS

The reliability, construct validity, and/or measurement error of light touch-pressure assessments was reviewed in adult populations with neurological disorders. Reviewers individually extracted and managed data including patient demographics, assessment characteristics, statistical methods, and psychometric properties. Methodological quality of results was evaluated using an adapted version of the COnsensus-based Standards for the selection of health Measurement INstruments checklist.

RESULTS

Thirty-three of 1938 articles were included for review. Fifteen light touch-pressure assessments demonstrated good or excellent reliability. Further, five of those 15 assessments achieved adequate validity and one of the 15 assessments achieved adequate measurement error. Over 80% of the summarized study ratings were determined to be of low or very low quality.

CONCLUSION

We recommend using electrical perceptual tests, the Semmes-Weinstein Monofilaments, the Graded and Redefined Assessment of Strength, Sensibility, and Prehension, and the Moving Touch Pressure Test given that they demonstrated good to excellent results in three psychometric properties. No other assessment achieved adequate ratings in more than two psychometric properties. This review highlights a fundamental need to develop sensory assessments that are reliable, valid, and sensitive to change.

Quantitative electrophysiological assessments as predictive markers of lower limb motor recovery after spinal cord injury: a pilot study with an adaptive trial design

Study design

Observational, cohort study.

Objectives

(1) Determine the feasibility and relevance of assessing corticospinal, sensory, and spinal pathways early after traumatic spinal cord injury (SCI) in a rehabilitation setting. (2) Validate whether electrophysiological and magnetic resonance imaging (MRI) measures taken early after SCI could identify preserved neural pathways, which could then guide therapy.

Setting

Intensive functional rehabilitation hospital (IFR).

Methods

Five individuals with traumatic SCI and eight controls were recruited. The lower extremity motor score (LEMS), electrical perceptual threshold (EPT) at the S2 dermatome, soleus (SOL) H-reflex, and motor evoked potentials (MEPs) in the tibialis anterior (TA) muscle were assessed during the stay in IFR and in the chronic stage (>6 months post-SCI). Control participants were only assessed once. Feasibility criteria included the absence of adverse events, adequate experimental session duration, and complete dataset gathering. The relationship between electrophysiological data collected in IFR and LEMS in the chronic phase was studied. The admission MRI was used to calculate the maximal spinal cord compression (MSCC).

Results

No adverse events occurred, but a complete dataset could not be collected for all subjects due to set-up configuration limitations and time constraints. EPT measured at IFR correlated with LEMS in the chronic phases (r = −0.67), whereas SOL H/M ratio, H latency, MEPs and MSCC did not.

Conclusions

Adjustments are necessary to implement electrophysiological assessments in an IFR setting. Combining MRI and electrophysiological measures may lead to better assessment of neuronal deficits early after SCI.

Applicability and tolerability of electrical stimulation applied to the upper and lower leg skin surface for cueing applications in Parkinson's disease

Due to possible sensory impairments in people with Parkinson's disease, several methodological aspects of electrical stimulation as a potential cueing method remain to be explored. This study aimed to investigate the applicability and tolerability of sensory and motor electrical stimulation in 10 people with Parkinson's disease. The study focused on assessing the electrical stimulation voltages and visual analogue scale discomfort scores at the electrical sensory, motor, discomfort, and pain thresholds. Results show that sensory electrical stimulation at the tibialis anterior, soleus, hamstrings, and quadriceps stimulation sites was applicable and tolerable for 6/10, 10/10, 9/10, and 10/10 participants, respectively. Furthermore, motor electrical stimulation at the tibialis anterior, soleus, hamstrings, and quadriceps stimulation sites were applicable and tolerable for 7/10, 7/10, 7/10, and 8/10 participants, respectively. Interestingly, the thresholds for the lower leg were higher than those of the upper leg. The data presented in this paper indicate that sensory and motor electrical stimulation is applicable and tolerable for cueing applications in people with Parkinson's disease. Sensory electrical stimulation was applicable and tolerable at the soleus and quadriceps sites. Motor electrical stimulation was not tolerable for two participants at any of the proposed stimulation sites. Therefore, future studies investigating motor electrical stimulation cueing, should apply it with caution in people with Parkinson's disease.

Time-Dependent Discrepancies between Assessments of Sensory Function after Incomplete Cervical Spinal Cord Injury

We recently demonstrated that the electrical perceptual threshold (EPT) examination reveals spared sensory function at lower spinal segments compared with the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) examination in humans with chronic incomplete cervical spinal cord injury (SCI). Here, we investigated whether discrepancies in sensory function detected by both sensory examinations change over time after SCI. Forty-five participants with acute (<1 year), chronic (≥1-10 years), and extended-chronic (>10 years) incomplete cervical SCI and 30 control subjects were tested on dermatomes C2-T4 bilaterally. EPT values were higher in subjects with acute (2.5 ± 0.8 mA), chronic (2.2 ± 0.7 mA), or extended-chronic (2.8 ± 1.1 mA) SCI compared with controls (1.0 ± 0.1 mA). The EPT examination detected sensory impairments in spinal segments above (2.3 ± 0.9) and below (4.2 ± 2.6) the level detected by the ISNCSCI sensory examination in participants with acute and chronic SCI, respectively. Notably, both examinations detected similar levels of spared sensory function in the extended-chronic phase of SCI (0.8 ± 0.5). A negative correlation was found between differences in EPT and ISNCSCI sensory levels and time post-injury. These observations indicate that discrepancies between EPT and ISNCSCI sensory scores are time-dependent, with the EPT revealing impaired sensory function above, below, or at the same spinal segment as the ISNCSCI examination. We propose that the EPT is a sensitive tool to assess changes in sensory function over time after incomplete cervical SCI.

Discrepancies between clinical assessments of sensory function and electrical perceptual thresholds after incomplete chronic cervical spinal cord injury

Study Design

Prospective experimental.

Objectives

To compare sensory function as revealed by light touch and pin prick tests of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) and the electrical perceptual threshold (EPT) exams in individuals with chronic incomplete cervical spinal cord injury (SCI).

Setting

Pittsburgh, United States.

Methods

EPT was tested using cutaneous electrical stimulation (0.5 ms pulse width, 3 Hz) in 32 healthy controls and in 17 participants with SCI over key points on dermatomes C2 to T4 on each side of the body. Light touch and pin prick ISNCSCI scores were tested at the same key dermatomes in SCI participants.

Results

In controls, EPT values were higher in older males (1.26±0.2 mA, mean±s.d.) compared with younger males (1.0±0.2 mA) and older females (0.9±0.2 mA), regardless of the dermatome and side tested. Fifteen out of seventeen SCI participants showed that the level of sensory impairment detected by the EPT was below the level detected by the ISNCSCI (mean=4.5±2.4, range 1–9). The frequency distribution of EPTs was similar to older male controls in dermatomes above but not below the ISNCSCI sensory level. The difference between EPT and ISNCSCI sensory level was negatively correlated with the time post injury.

Conclusions

The results show that, in the chronic stage of cervical SCI, the EPT reveals spared sensory function at lower (~5) spinal segments than the ISNCSCI sensory exam. It is hence found that the EPT is a sensitive tool to assess recovery of sensory function after chronic SCI.

Reliability of the electrical perceptual threshold and Semmes-Weinstein monofilament tests of cutaneous sensibility

STUDY DESIGN

Prospective experimental.

OBJECTIVES

To compare the reliability and repeatability of the electrical perceptual threshold (EPT) and Semmes-Weinstein monofilament (SWM) tests for cutaneous sensibility. EPT and SWM tests have potential as quantitative and sensitive adjuncts to the American Spinal Injuries Association (ASIA) Impairment Scale (AIS) assessment of spinal cord injury (SCI).

SETTING

London, UK.

METHODS

EPT and SWM tests were carried out on 40 neurologically healthy individuals (20 male). One examiner carried out all the tests. Each individual was examined for EPT and SWM sensitivity at ASIA key points on four dermatomes (C4, T1, T6, L4) on both sides of the body. The tests were repeated after an interval of approximately 1 week. Intra-rater reliability was determined using intra-class correlation coefficients (ICC). Repeatability was determined using the method of Bland and Altman.

RESULTS

There were no significant differences in the mean values of EPT or SWM between assessments for any dermatome. Significant difference in mean values for both EPT and SWM were observed between some dermatomes. ICC ranged from 0.67 to 0.81 for the EPT and from 0.46 to 0.61 for the SWM. Higher ICC for the EPT compared with the SWM was again revealed when male and female subjects were assessed separately. Correlation between EPT and SWM was weak or (largely) absent.

CONCLUSION

EPT has better reliability than SWM in healthy subjects. However, as both tests have the potential to add sensitivity and resolution to the AIS assessment, a further comparison of their repeatability in SCI is warranted.

Quantitative testing in spinal cord injury: overview of reliability and predictive validity

Object

The objective of this study was to identify commonly used physiological outcome measures and summarize evidence on the reliability and predictive validity of quantitative measures used in monitoring persons with spinal cord injury (SCI).

Methods

A systematic search of PubMed through January 5, 2012, was conducted to identify publications using common outcome measures in persons with SCI and for studies that were specifically designed to evaluate the reliability and predictive validity of selected quantitative measures. Quantitative measures were defined as tests that quantify sensory and motor function, such as amount of force or torque, as well as thresholds, amplitudes, and latencies of evoked potentials that might be useful in studies and monitoring of patients with SCI. Reliability studies reporting interclass correlation coefficients (ICCs) or weighted κ coefficients were considered for inclusion. Studies explicitly evaluating correlation between measures and specific functional outcomes were considered for predictive validity.

Results

From a total of 121 potentially relevant citations, 6 studies of reliability and 4 studies of predictive validity for quantitative tests met the inclusion criteria. In persons with incomplete SCI, ICCs for both interrater and intrarater reliability of electrical perceptual threshold (EPT) were ≥ 0.7 above the sensory level of SCI but were less reliable below the sensory level. Interclass correlation coefficients for interrater and intrarater reliability of the Graded Redefined Assessment of Strength, Sensibility, and Prehension (GRASSP) components ranged from 0.84 to 0.98. For electromyography, the ICC was consistently high for within-day tests. The overall quality of reliability of the majority of studies was poor, due to the potential for selection bias and small sample sizes. No classic validation studies were found for the selected measures, and evidence regarding the predictive validity of the measures was limited. Somatosensory evoked potentials (SSEPs) may be correlated with ambulatory capacity, as well as the Barthel Index and motor index scores, but this correlation was limited for evaluation of bladder function recovery in 3 studies that assessed the correlation between baseline or initial SSEPs and a specific clinical outcome at a later follow-up time. All studies used convenience samples and the overall sample quality was low.

Conclusions

Evidence on the reliability and validity of the quantitative measures selected for this review is limited, and the overall quality of existing studies is poor. There is some evidence for the reliability of the EPT, dermatomal SSEPs, and the GRASSP to suggest that they may be useful in longitudinal studies of patients with SCI. There is a need for high quality studies of reliability, responsiveness, and validity for quantitative measures to monitor the level and degree of SCI.

Clinical neurophysiology in the prognosis and monitoring of traumatic spinal cord injury

Preclinical studies for the repair of spinal cord injury (SCI) and potential therapies for accessing the inherent plasticity of the central nervous system (CNS) to promote recovery of function are currently moving into the translational stage. These emerging clinical trials of therapeutic interventions for the repair of SCI require improved assessment techniques and quantitative outcome measures to supplement the American Spinal Injuries Association (ASIA) Impairment Scales. This chapter attempts to identify those electrophysiological techniques that show the most promise for provision of objective and quantitative measures of sensory, motor, and autonomic function in SCI. Reviewed are: (1) somatosensory evoked potentials, including dermatomal somatosensory evoked potentials, and the electrical perceptual threshold as tests of the dorsal (posterior) column pathway; (2) laser evoked potentials and contact heat evoked potentials as tests of the anterior spinothalamic tract; (3) motor evoked potentials in limb muscles, in response to transcranial magnetic stimulation of the motor cortex as tests of the corticospinal tract, and the application of the technique to assessment of trunk and sphincter muscles; and (4) the sympathetic skin response as a test of spinal cord access to the sympathetic chain.

Changes in Electrical Perception Threshold Within the First 6 Months After Traumatic Spinal Cord Injury

Objective. To assess the reliability of the electrical perception threshold (EPT) in healthy participants and its responsiveness in patients for 6 months after traumatic spinal cord injury (SCI). Methods. The reliability of EPT measures was assessed in 15 healthy volunteers (from C3 to S2). EPT measures were assessed in 37 patients at 1, 3, and 6 months after SCI. EPT was determined in dermatomes at, above, and below the neurological level of lesion. Reliability was quantified with an intraclass correlation coefficient (ICC) and responsiveness with the standardized response mean (SRM). Dermatomes were classified as having normal or pathological sensory perception, based on both light touch (LT) and EPT testing. The percentage of agreement between LT and EPT classifications was determined. Results. The ICCs varied considerably between dermatomes (0.00 ≤ ICC ≤ 0.86). Overall, EPTs changed little within the first 6 months after SCI, resulting in small SRM values. Agreement between classifications according to EPT or LT testing varied from 30% to 100%. The least agreement was observed in the first segment below the lesion. Conclusion. Future studies must note that the reliability of EPT differs between dermatomes in healthy participants. Furthermore, at and below the level of the lesion, spontaneous recovery of sensory perception is poor within the first 6 months after SCI. Based on subgroup analyses, if a translational trial aims to improve sensory perception around the level of the lesion, sensory-incomplete tetraplegic patients could be included. These patients show poor spontaneous recovery, and the EPT may detect subtle changes in perception.

Action of 5 Hz repetitive transcranial magnetic stimulation on sensory, motor and autonomic function in human spinal cord injury

OBJECTIVE

To assess the effectiveness of physiological outcome measures in detecting functional change in the degree of impairment of spinal cord injury (SCI) following repetitive transcranial magnetic stimulation (rTMS) of the sensorimotor cortex.

METHODS

Subjects with complete or incomplete cervical (or T1) SCI received real and sham rTMS in a randomised placebo-controlled single-blinded cross-over trial. rTMS at sub-threshold intensity for upper-limb muscles was applied (5 Hz, 900 stimuli) on 5 consecutive days. Assessments made before and for 2 weeks after treatment comprised the ASIA (American Spinal Injuries Association) impairment scale (AIS), the Action Research Arm Test (ARAT), a peg-board test, electrical perceptual test (EPT), motor evoked potentials, cortical silent period, cardiovascular and sympathetic skin responses.

RESULTS

There were no significant differences in AIS outcomes between real and sham rTMS. The ARAT was increased at 1h after real rTMS compared to baseline. Active motor threshold for the most caudally innervated hand muscle was increased at 72 and 120 h compared to baseline. Persistent reductions in EPT to rTMS occurred in two individuals.

CONCLUSIONS

Changes in cortical motor threshold measures may accompany functional gains to rTMS in SCI subjects.

SIGNIFICANCE

Electrophysiological measures may provide a useful adjunct to ASIA impairment scales.