Pain quality of thermal grill illusion is similar to that of central neuropathic pain rather than peripheral neuropathic pain

Abstract Objectives Application of spatially interlaced innocuous warm and cool stimuli to the skin elicits illusory pain, known as the thermal grill illusion (TGI). This study aimed to discriminate the underlying mechanisms of central and peripheral neuropathic pain focusing on pain quality, which is considered to indicate the underlying mechanism(s) of pain. We compared pain qualities in central and peripheral neuropathic pain with reference to pain qualities of TGI-induced pain. Methods Experiment 1:137 healthy participants placed their hand on eight custom-built copper bars for 60 s and their pain quality was assessed by the McGill Pain Questionnaire. Experiment 2: Pain quality was evaluated in patients suffering from central and peripheral neuropathic pain (42 patients with spinal cord injury, 31 patients with stroke, 83 patients with trigeminal neuralgia and 131 patients with postherpetic neuralgia). Results Experiment 1: Two components of TGI-induced pain were found using principal component analysis: component 1 included aching, throbbing, heavy and burning pain, component 2 included itching, electrical-shock, numbness, and cold-freezing. Experiment 2: Multiple correspondence analysis (MCA) and cross tabulation analysis revealed specific pain qualities including aching, hot-burning, heavy, cold-freezing, numbness, and electrical-shock pain were associated with central neuropathic pain rather than peripheral neuropathic pain. Conclusions We found similar qualities between TGI-induced pain in healthy participants and central neuropathic pain rather than peripheral neuropathic pain. The mechanism of TGI is more similar to the mechanism of central neuropathic pain than that of neuropathic pain.

Download Full-text

A.02 Long-term outcomes in the management of central neuropathic pain syndromes

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/cjn.2018.83 ◽

2018 ◽

Vol 45 (s2) ◽

pp. S9-S9

Author(s):

MD Staudt ◽

AJ Clark ◽

AS Gordon ◽

ME Lynch ◽

PK Morley-Forster ◽

...

Keyword(s):

Neuropathic Pain ◽

Primary Outcome ◽

Pain Interference ◽

Peripheral Neuropathic Pain ◽

Central Neuropathic Pain ◽

Pain Syndromes ◽

Cord Injury ◽

Patient Reported

Background: Central neuropathic pain syndromes are a result of central nervous system injury, most commonly related to stroke, spinal cord injury, or multiple sclerosis. These syndromes are much less common than peripheral etiologies, with less known regarding optimal treatment. The objective of this study was to determine the long-term clinical effectiveness of the management of central relative to peripheral neuropathic pain at tertiary pain centers. Methods: Patients diagnosed with central (n=79) and peripheral (n=710) neuropathic pain were identified from a prospective observational cohort from seven Canadian tertiary centers. Data regarding patient -characteristics, analgesic use, and patient-reported outcomes were collected at baseline and 12-month follow-up. The primary outcome was the composite of reduced average pain intensity and pain interference. Secondary outcomes included assessments of function, mood, and quality-of-life. Results: At 12-month follow-up, 13.5% (95%CI,5.6-25.8) of patients achieved ≥30% reduction in pain, whereas 38.5% (95%CI,25.3-53.0) achieved a ≥1 point reduction in pain interference; 9.6% (95%CI,3.2-21.0) of patients achieving both these measures. Patients with peripheral neuropathic pain were more likely to achieve this primary outcome at 12-months (25.3% of patients; 95%CI,21.4-29.5) (p=.012). Conclusions: Patients with central neuropathic pain were less likely to achieve a meaningful improvement in pain and function compared to patients with peripheral neuropathic pain at 12-month follow-up.

Download Full-text

Central neuropathic pain in multiple sclerosis is associated with impaired innocuous thermal pathways and neuronal hyperexcitability

Pain Medicine ◽

10.1093/pm/pnab103 ◽

2021 ◽

Author(s):

Michal Rivel ◽

Anat Achiron ◽

Mark Dolev ◽

Yael Stern ◽

Gaby Zeilig ◽

...

Keyword(s):

Multiple Sclerosis ◽

Neuropathic Pain ◽

Cross Sectional Study ◽

Healthy Controls ◽

Sectional Study ◽

Sensory Testing ◽

Cross Sectional ◽

Central Neuropathic Pain ◽

Body Regions ◽

Thermal Grill Illusion

Abstract Objective About a third of patients with multiple sclerosis (MS) suffer from chronic and excruciating central neuropathic pain (CNP). The mechanism underlying CNP in MS is not clear, since previous studies are scarce and their results are inconsistent. Our aim was to determine whether CNP in MS is associated with impairment of the spinothalamic-thalamocortical pathways (STTCs) and/or increased excitability of the pain system. Design Cross sectional study Setting General hospital Subjects 47 MS patients with CNP, 42 MS patients without CNP, and 32 healthy controls. Methods Sensory testing included the measurement of temperature, pain, and touch thresholds and the thermal grill illusion (TGI) for evaluating STTCs function, and hyperpathia and allodynia as indicators of hyperexcitability. CNP was characterized using interviews and questionnaires. Results The CNP group had higher cold and warm thresholds (p < 0.01), as well as higher TGI perception thresholds (p < 0.05), especially in painful body regions compared to controls, whereas touch and pain thresholds values were normal. The CNP group also had a significantly greater prevalence of hyperpathia and allodynia. Regression analysis revealed that whereas presence of CNP was associated with a higher cold threshold, CNP intensity, and the number of painful body regions were associated with allodynia and hyperpathia, respectively. Conclusions CNP in MS is characterized by a specific impairment of STTC function; the innocuous thermal pathways, and by pain hyperexcitability. Whereas CNP presence is associated with STTC impairment, its severity and extent are associated with pain hyperexcitability. Interventions that reduce excitability level may therefore mitigate CNP severity.

Download Full-text