Thalamic stimulation in multiple sclerosis: evidence for a 'demyelinative thalamotomy'

Area of Science:

• Neurology
• Neuroscience
• Medical Imaging

Background:

• The mechanism of deep brain stimulation (DBS) for tremor in neurological disorders remains unclear.
• The potential for surgical trauma to induce new lesions in multiple sclerosis (MS) is debated.

Observation:

• This study presents post-mortem imaging and pathological findings of a multiple sclerosis patient who received thalamic DBS for tremor.
• High-field MRI (1.5, 3, 7 Tesla) of fixed brain slices was correlated with histopathology.
• Numerous demyelinative plaques were observed throughout the brain, but not along the DBS tract in the white matter.

Findings:

• Focal demyelination was observed deep within the thalamus, closely approximating the DBS tract, specifically within the estimated electrical field region.
• No demyelinative plaques were found along the DBS tract in the sampled deep hemispheric white matter.

Implications:

• The findings suggest that the electrical field of DBS, rather than surgical trauma, may induce focal demyelination.
• This localized demyelination could be responsible for the long-lasting tremor alleviation observed in some patients, even without continuous stimulation.
• This provides a potential mechanism for DBS efficacy in managing tremor in MS and other neurological conditions.