Journal Club: Improved diagnosis of spinal cord disorders with contact heat evoked potentials

Abstract Study design An experimental study. Objectives To 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). Setting Centre for Pain Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland. Methods Individuals 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. Results QST, 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. Conclusions Combination 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.

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Increased baseline temperature improves the acquisition of contact heat evoked potentials after spinal cord injury

Clinical Neurophysiology ◽

10.1016/j.clinph.2011.08.013 ◽

2012 ◽

Vol 123 (3) ◽

pp. 582-589 ◽

Cited By ~ 30

Author(s):

J.L.K. Kramer ◽

J. Haefeli ◽

A. Curt ◽

J.D. Steeves

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Evoked Potentials ◽

Contact Heat ◽

Contact Heat Evoked Potentials ◽

Cord Injury ◽

Baseline Temperature

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Skin denervation does not alter cortical potentials to surface concentric electrode stimulation: A comparison with laser evoked potentials and contact heat evoked potentials

European Journal of Pain ◽

10.1002/ejp.1112 ◽

2017 ◽

Vol 22 (1) ◽

pp. 161-169 ◽

Cited By ~ 13

Author(s):

S. La Cesa ◽

G. Di Stefano ◽

C. Leone ◽

A. Pepe ◽

E. Galosi ◽

...

Keyword(s):

Evoked Potentials ◽

Contact Heat ◽

Laser Evoked Potentials ◽

Contact Heat Evoked Potentials ◽

Concentric Electrode ◽

Electrode Stimulation ◽

Cortical Potentials

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Application of Referencing Techniques in EEG-Based Recordings of Contact Heat Evoked Potentials (CHEPS)

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2020.559969 ◽

2020 ◽

Vol 14 ◽

Author(s):

Malte Anders ◽

Björn Anders ◽

Matthias Kreuzer ◽

Sebastian Zinn ◽

Carmen Walter

Keyword(s):

Evoked Potentials ◽

Reference Electrode ◽

Objective Measure ◽

Time Spectrum ◽

Electrode Site ◽

Contact Heat ◽

Theoretical Terms ◽

Average Reference ◽

Brain Responses ◽

Contact Heat Evoked Potentials

Evoked potentials in the amplitude-time spectrum of the electroencephalogram are commonly used to assess the extent of brain responses to stimulation with noxious contact heat. The magnitude of the N- and P-waves are used as a semi-objective measure of the response to the painful stimulus: the higher the magnitude, the more painful the stimulus has been perceived. The strength of the N-P-wave response is also largely dependent on the chosen reference electrode site. The goal of this study was to examine which reference technique excels both in practical and theoretical terms when analyzing noxious contact heat evoked potentials (CHEPS) in the amplitude-time spectrum. We recruited 21 subjects (10 male, 11 female, mean age of 55.79 years). We applied seven noxious contact heat stimuli using two temperatures, 51°C, and 54°C, to each subject. During EEG analysis, we aimed to identify the referencing technique which produces the highest N-wave and P-wave amplitudes with as little artifactual influence as possible. For this purpose, we applied the following six referencing techniques: mathematically linked A1/A2 (earlobes), average reference, REST, AFz, Pz, and mathematically linked PO7/PO8. We evaluated how these techniques impact the N-P amplitudes of CHEPS based on our data from healthy subjects. Considering all factors, we found that mathematically linked earlobes to be the ideal referencing site to use when displaying and evaluating CHEPS in the amplitude-time spectrum.

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The effect of nerve compression and capsaicin on contact heat evoked potentials (CHEPs) related to Aδ and C fibers

Scandinavian Journal of Pain ◽

10.1016/j.sjpain.2012.05.038 ◽

2012 ◽

Vol 3 (3) ◽

pp. 187-187

Author(s):

C.S. Madsen ◽

B. Johnsen ◽

A. Fuglsang-Frederiksen ◽

T.S. Jensen ◽

N.B. Finnerup

Keyword(s):

Evoked Potentials ◽

Pain Intensity ◽

Radial Nerve ◽

Nerve Compression ◽

Contact Heat ◽

Noxious Heat ◽

Superficial Radial Nerve ◽

C Fibers ◽

Contact Heat Evoked Potentials ◽

C Fiber

Abstract Background/aims Brief noxious heat stimuli activate Aδ and C fibers, and contact heat evoked potentials (CHEPs) can be recorded from the scalp. Under standard conditions, late responses related to AS fibers can be recorded. This study examines C-fiber responses to contact heat stimuli. Methods A preferential A-fiber blockade by compression to the superficial radial nerve was applied in 22 healthy subjects. Quality and intensity of heat evoked pain (NRS, 0–10), and CHEPs were examined at baseline, during nerve compression, and during further nerve compression with topical capsaicin (5%). Results During the A-fiber blockade, 3 subjects had CHEPs with latencies below 400 ms, 8 subjects within 400–800 ms and 6 subjects later than 800 ms. Pain intensity to contact heat stimuli was reduced and fewer subjects reported the heat stimuli as stinging. Following acute capsaicin application, ultralate CHEPs with latencies >800 ms could be recorded in 13 subjects, pain intensity to the contact heat stimuli was increased (p <0.01) and more subjects reported the heat stimuli as being more warm/hot-burning. Conclusion The results indicate that following a compression to the superficial radial nerve, CHEPs compatible within complete A fibers or C fibers were recorded. Following sensitization with capsaicin, C-fiber responses were recorded in 62% of subjects.

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