Functional magnetic resonance imaging: cerebral function alterations in subthreshold and suprathreshold spinal cord...

Area of Science:

• Neuroscience
• Pain Management
• Medical Imaging

Background:

• Failed back surgery syndrome (FBSS) is a debilitating neuropathic pain condition.
• Conventional spinal cord stimulation (SCS) uses suprathreshold pulses (40-60 Hz) for pain relief.
• Newer SCS techniques involve subthreshold stimulation and higher frequencies, but mechanisms are unclear.

Purpose of the Study:

• Investigate brain alterations during subthreshold and suprathreshold SCS at various frequencies in FBSS patients.
• Clarify the neural mechanisms underlying different SCS parameters.

Main Methods:

• Functional MRI (fMRI) assessed cerebral activity in 10 FBSS subjects.
• Subjects received randomized SCS at 4 Hz, 60 Hz, 500 Hz, and 1 kHz over four days.
• Both subthreshold and suprathreshold stimulation were applied at each frequency.

Main Results:

• Suprathreshold SCS induced greater brain activity (activation and deactivation) than subthreshold SCS.
• Increased activation observed in frontal cortex, thalamus, sensory/motor areas, and basal ganglia.
• Deactivation noted in parahippocampus, amygdala, and posterior cingulate regions.

Conclusions:

• Suprathreshold SCS significantly impacts frontal brain regions, sensory, limbic, and motor cortices, and diencephalon compared to subthreshold SCS.
• Specific SCS frequencies at suprathreshold levels elicit distinct brain activation patterns.
• Findings provide insights into SCS mechanisms for FBSS pain management.