EEG Theta Band Rhythm in SCS

The aim of the study is to see if reversal in EEG theta power during trial period can predict a sustained response (At 6 months post implantation) and thus serve as an objective measure for SCS efficacy in a given patient, thus objectively identifying true responders.

Additionally, this study aims to see if spinal profile of baseline EEG abnormality as well as EEG response to a given SCS modality during trial period, alongside clinical correlation, can help in selection of SCS modality best suited to a given patient.

• Reversal in EEG Theta Power (Device): 32 lead EEG at baseline on day of surgery prior to trial lead implementation. Stimulation shall be started with high frequency and burst modes in alternate patients. First follow up EEG shall be performed with stimulation on day 3. Stimulation will then be switched over to the low frequency mode and a further EEG on this mode will be obtained on day 7. After this the third mode shall be tried and further EEG obtained on day 11. At this point, trial shall be concluded as per normal practice.

Primary outcomes

• The reduction in theta (4-7 Hz) power [Up to day 11 following trial lead implementation]: Used to differentiate responders from non-responders

Secondary outcomes

• Spatial profile of EEG changes [Up to day 11 following trial lead implementation]: Used to predict patient suitability to an SCS modality
• reduction in short and mid latency amplitude on SSEP [Up to day 11 following trial lead implementation]: Used to predict patient suitability to an SCS modality

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adults (Aged 18 years or above and able to consent) with failed back surgery syndrome leading to neuropathic leg/back pain deemed suitable for spinal cord stimulation trial

Exclusion Criteria:

* Patients with history of epilepsy or epileptiform disorders

• Deepti Bhargava, Principal investigator, Walton Centre NHS Foundation Trust