Deep brain stimulation for chronic post-stroke pain

INTERVENTION: The design is a pragmatic assessor‐blinded, randomised controlled trial. The design seeks to exploit the feature of deep brain stimulation technique that the surgery to implant the DBS device is not the treatment effect, rather the electrical stimulation of the targeted region is. The trial team will be divided into clinical members and research members. The participant themselves and the nurse specialist will not be blinded, but surgical members of the clinical team and the researcher (assessor) who performs participant assessments will be blinded as to whether the stimulation is on or off in the participant at all point postoperatively. Participants will be counselled as to avoid giving clues to the researcher as to whether stimulation is on or off through an augmented consent process. To identify a placebo effect of the surgery itself before the randomisation phase, participants will undergo a 2‐month period off stimulation after surgical implant of the DBS device. Researcher (assessor) will be blinded as to whether the individual participant is on or off stimulation at all phases post‐surgery. Trial design The DBS for CPSP trial is an assessor‐blinded single centre randomised controlled trial comparing DBS stimulation with absence of stimulation in individual participants. The trial has two prospective cohort arms, pre‐randomisation to assess for placebo effects from the surgery itself and post‐randomisation to assess the effect of any changes in stimulation parameters. The elements of the trial are: Clear distinction between research and clinical roles Screening Recruitment Surgery Cohor CONDITION: Chronic post‐stroke pain ; Signs and Symptoms PRIMARY OUTCOME: ; Pain experience of participants assessed by the following tools by a member of the research team pre operatively and post operatively, blinded as to whether stimulation is on or off in the first 6 months post‐operatively, then unblinded after 6 months:; 1. Pain severity assessed using the Visual analogue scale (VAS), McGill Pain Questionnaire (MPQ), brief pain inventory (BPI)); 2. Affective component of pain assessed using the Montgomery Asberg Depression Rating Scale (MADRS), McGill Affective Pain index; 3. Quality of life assessed using EuroQol‐5D (EQ‐5D), Medical Outcomes Study 36‐Item Short‐Form General Health Survey (SF‐36), Hospital Anxiety and Depression Scale (HADS) and the Functional Limitation Profile (FLP); 4. Neuropsychological test battery (Wisconsin Card Sorting Test, Weschler Memory Scale III, Intra‐/Extra‐Dimensional Set‐Shifting, Spatial Span, Spatial Working Memory, Verbal Fluency, Recall Test (from the adult memory and information processing battery) and Raven’s Standard Progressive Matrices); INCLUSION CRITERIA: 1. Participant is willing and able to give informed consent for participation in the study 2. Patient is willing and able to follow pre and post‐operative follow up in Oxford 3. Male or female, aged 18 years or above 4. Participants are diagnosed as having probable chronic post‐stroke pain of 2 years’ minimum duration refractory to at least 1 opiate medication, 1 anti‐epileptic and 1 anti‐depressant, AND mean usual VAS pain score > 7/10 despite input from a multidisciplinary pain team SECONDARY OUTCOME: ; 1. Pre‐operative neuroimaging and pain assessments to develop algorithms which help predict response to test stimulation and thus improve patient selection. Specific measures are resting‐state functional connectivity, task‐related functional network connectivity and diffusion‐weighted tensor imaging of connectivity of targeted regions i.e. the sensory thalamus or periaqueductal grey.; 2. Economic impact of the surgical intervention, assessed using patient‐level resource use data including health and social care costs relating to the intervention (e.g. surgical costs, drug costs, hospital stay, GP costs, referrals etc). In line with recent recommendations from the National Institute for Health and Clinical Excellence (NICE) the economic evaluation will also include the generic quality of life instrument, the EuroQol EQ‐5D‐5L (EuroQol 1990).;