Deep Brain Stimulation for Patients With Dementia With Lewy Bodies

We will perform a pilot study to evaluate the effectiveness of human NBM DBS at improving cognitive deficits in DLB patients. Six patients with DLB with moderate cognitive impairments (including but not restricted to deficits in attention and working memory) will have bilateral DBS electrodes implanted to ensure that superficial contacts lie in the motor Globus Pallidum interna (GPi) target, while the deepest electrical contacts lie in the NBM. We will place electrodes using our conventional image-guided, stereotactic frame-based procedure. Once the surgical wounds have healed, patients will be randomised into 2 groups in a crossover trial design to have 6 week periods of NBM stimulation switched on or switched off separated by a 2 week washout period, following which the patient will cross over to have the opposite condition for a further 6 weeks. Outcome measures collected at the 6 weeks and 14 weeks timepoints will be compared according to whether each patient was ON or OFF stimulation at that timepoint.

At the end of the crossover period, all patients will be invited for continued follow up with stimulation switched on and will have neuropsychological evaluations at 6 monthly intervals. Patients will be given the option of receiving additional conventional stimulation to the motor GPi, through the higher contacts of each electrode, at the end of the crossover period if required for any coexisting Parkinsonian motor complications of DLB.

Inclusion criteria

• DLB Consortium Criteria for diagnosis
• Score between 2 & 12 on Clinician Assessment of Fluctuations scale
• MMSE score between 21 and 27
• Appropriate Surgical candidates in terms of general health
• Aged between 50 & 80
• Able to give Informed consent
• Living at home with Carer
• Able to comply with protocol
• On stable dosage of cholinesterase inhibitor

Exclusion criteria

• Diagnosis of other cause for dementia
• Abnormality on brain imaging considered likely to compromise compliance with trial protocol.
• Prior intracerebral surgical intervention