Motor corticospinal excitability abnormalities differ between distinct chronic low back pain syndromes

Marcelo Luiz da Silva; Ana Mércia Fernandes; Valquíria A Silva; Ricardo Galhardoni; Valter Felau; Joaci O de Araujo; Jefferson Rosi Jr; Roger S Brock; Gabriel T Kubota; Manoel J Teixeira; Lin T Yeng; Daniel Ciampi de Andrade

doi:10.1016/j.neucli.2023.102853

Motor corticospinal excitability abnormalities differ between distinct chronic low back pain syndromes

Neurophysiol Clin. 2023 Jun;53(3):102853. doi: 10.1016/j.neucli.2023.102853. Epub 2023 Apr 3.

Affiliations

¹ LIM-62, Pain Center, Department of Neurology, University of São Paulo, São Paulo, Brazil.
² School of Medicine, University of City of São Paulo (UNICID), São Paulo, Brazil.
³ Pain Center, Institute of Orthopedics and Traumatology, University of São Paulo, São Paulo, Brazil.
⁴ LIM-62, Pain Center, Department of Neurology, University of São Paulo, São Paulo, Brazil; Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark. Electronic address: dca@hst.aau.dk.

PMID: 37018953
DOI: 10.1016/j.neucli.2023.102853

Abstract

Objectives: It is not known whether cortical plastic changes reported in low-back pain (LBP) are present in all etiologies of LBP. Here we report on the assessment of patients with three LBP conditions: non-specific-LBP (ns-LBP), failed back surgery syndrome (FBSS), and sciatica (Sc).

Methods: Patients underwent a standardized assessment of clinical pain, conditioned pain modulation (CPM), and measures of motor evoked potential (MEPs)-based motor corticospinal excitability (CE) by transcranial magnetic stimulation, including short interval intracortical inhibition (SICI), and intracortical facilitation (ICF). Comparisons were also made with normative data from sex- and age-matched healthy volunteers.

Results: 60 patients (42 women, 55.1±9.1 years old) with LBP were included (20 in each group). Pain intensity was higher in patients with neuropathic pain [FBSS (6.8±1.3), and Sc (6.4±1.4)] than in those with ns-LBP (4.7±1.0, P<0.001). The same was shown for pain interference (5.9±2.0, 5.9±1.8, 3.2±1.9, P<0.001), disability (16.4±3.3, 16.3±4.3, 10.4±4.3, P<0.001), and catastrophism (31.1±12.3, 33.0±10.4, 17.4±10.7, P<0.001) scores for FBSS, Sc, and ns-LBP groups, respectively. Patients with neuropathic pain (FBSS, Sc) had lower CPM (-14.8±1.9, -14.1±16.7, respectively) compared to ns-LBP (-25.4±16.6; P<0.02). 80.0% of the FBSS group had defective ICF compared to the other two groups (52.5% for ns-LBP, P=0.025 and 52.5% for Sc, P=0.046). MEPs (140%-rest motor threshold) were low in 50.0% of patients in the FBSS group compared to 20.0% of ns-LBP (P=0.018) and 15.0% of Sc (P=0.001) groups. Higher MEPs were correlated with mood scores (r=0.489), and with lower neuropathic pain symptom scores(r=-0.415) in FBSS.

Conclusions: Different types of LBP were associated with different clinical, CPM and CE profiles, which were not uniquely related to the presence of neuropathic pain. These results highlight the need to further characterize patients with LBP in psychophysics and cortical neurophysiology studies.

Keywords: Chronic pain; Failed back syndrome surgery; Low back pain; Motor corticospinal excitability; Neuropathic pain; Nonspecific low back pain; Sciatica; Transcranial magnetic stimulation.

MeSH terms

Evoked Potentials, Motor / physiology
Female
Humans
Low Back Pain*
Middle Aged
Neuralgia* / diagnosis
Pain Measurement
Syndrome
Transcranial Magnetic Stimulation / methods