EEG predictors of neuropathic pain

Spinal Cord Injury (SCI) affects a person's ability to move and feel sensation in the body. SCI is also an indirect cause of a persistent pain, called Central Neuropathic Pain (CNP). This pain typically develops several months after the injury. In 30-40% of SCI patients. Severe CNP affects their everyday living including sleep and mood. Many patients give up work, not because of the injury, but because of pain. Medical treatment of CNP is moderately effective and costly, both to the patient and to the health care system.

It is widely believed that cortical changes are a consequence of long standing neuropathic pain

Recent research at the Scottish Spinal Injuries Unit and the Universities of Glasgow and Strathclyde demonstrates that CNP in people with subacute spinal cord injury (SCI) has characteristic electroencephalographic (EEG) markers which precede the onset of pain. The primary aim of this study was to apply neurofeedback therapy which is hypothesised to be more effective in people who have suffered from CNP for a shorter period of time.

EEG was recorded in a relaxed state and during motor imagination tasks in 10 able bodied participants and 31 subacute SCI participants (11 with CNP, 10 without CNP and 10 who developed pain within 6 months of EEG recording).

All 20 SCI participants initially without CNP were tested for mechanically induced allodynia but only one person, who later developed pain, reported an unpleasant sensation. The EEG reactivity to opening eyes was reduced in the alpha band and absent in the theta and beta bands in participants who later developed pain, and it was reduced in participants who already had pain.

Alpha band power was reduced at BA7 in both the relaxed state and during motor imagination in participants who either had or later developed pain compared to participants without pain. All SCI groups had reduced dominant alpha frequency and beta band power at BA7.

Electroencephalographic reactivity to eyes opening, and reduced spontaneous and induced alpha activity over the parietal cortex were predictors of future NP as well as markers of existing NP.

Clinical Trial Registration Number: NCT02178917

https://clinicaltrials.gov/ct2/show/NCT02178917

Vuckovic, A., Jajrees, M., Purcell, M., Berry, H., & Fraser, M. (2018). Electroencephalographic predictors of neuropathic pain in subacute spinal cord injury. Journal of Pain, 1-35. DOI: 10.1016/j.jpain.2018.04.011

EEG, PainDerek Jones