Sensorimotor Cortical Activity in Acute Low Back Pain: A Cross-Sectional Study

Area of Science:

• Neuroscience
• Pain Research
• Motor Control

Background:

• Sensorimotor cortical activity shifts in musculoskeletal pain, decreasing in acute experimental pain and increasing in chronic clinical pain.
• The neurophysiological changes in acute clinical musculoskeletal pain, specifically low back pain (LBP), remain largely unexplored.
• Understanding these changes is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate sensorimotor cortical activity in individuals experiencing acute clinical low back pain (LBP).
• To compare the processing of non-noxious sensory inputs and corticomotor excitability between acute LBP patients and healthy controls.
• To explore the relationship between acute LBP and alterations in primary motor cortex organization.

Main Methods:

• Utilized sensory evoked potentials (SEPs) to assess the processing of non-noxious afferent inputs.
• Employed transcranial magnetic stimulation (TMS) to examine corticomotor excitability and primary motor cortex organization.
• Compared findings in 36 individuals with acute LBP (<4 weeks) against 36 age- and sex-matched pain-free controls.

Main Results:

• Acute LBP was associated with significantly lower processing of non-noxious sensory inputs, indicated by a smaller N80-N150-P260 SEP complex area.
• Specific SEP components (N150, P260) were smaller in acute LBP, though with high interindividual variability.
• Motor cortical map volume was reduced in individuals with acute LBP compared to controls.

Conclusions:

• Acute clinical low back pain is characterized by reduced sensorimotor cortical activity at a group level.
• High individual variability in findings suggests adaptive cortical plasticity mechanisms in acute pain.
• This study provides novel insights into the neurophysiology of acute LBP, differentiating it from experimental acute pain and chronic pain states.