Objective:  To report a case.

Background: Loss of psychic self-activation or even akinetic mutism has rarely been described in patients who suffered bilateral thalamic insults. Its pathophysiology is not completely understood but it is thought to be related to the disturbance of the striatal-ventral pallidal-thalamic-frontomesial limbic loop.

Methods: Case report

Results: 61-year-old female diagnosed with late-onset essential tremor at the age of 55. The postural and action tremor first affected both hands, with a slight left predominance, and then the head and legs. No known family history. The different therapeutic strategies failed due to side effects. The tremor became increasingly disturbing for daily activities. The patient was thoroughly studied due to the detection of a right mesencephalic lesion on MRI that was concluded to be an ischemic scar. Her neuropsychological profile was judged fit, and the patient underwent awake bilateral deep brain stimulation of the thalamic ventral intermediate nuclei without intra-operative complications. Post-operatively, the patient showed significant psycho-motor slowness, progressing to a state of apathy and akinesia mimicking a language disturbance. Although awake and capable of walking, the patient showed scarce eye contact and did not respond to questions or commands. Her head CT and blood workup were unremarkable. The electrodes were correctly positioned and there was no sign of surgical complications. This state did not differ according to the stimulation parameters. The patient was managed by the team psychiatrist and progressively medicated with sertraline 100mg daily. The neuropsychiatric symptoms gradually and completely subsided during the following 10 days at which point the patient performed an MRI. A small area of cytotoxic edema was found on the left corona radiata, posterior to the electrode. The patient was discharged home with an excellent motor benefit from the stimulation.

Conclusions: To our knowledge this is the first description of transient loss of self-activation following deep brain stimulation. We hypothesize it might be due to a transient disturbance of the deep circuitry involved in purposeful behavior, temporally and anatomically related to the electrode implantation in the thalamus. It is important to keep this diagnosis in mind when managing post-operative complications of these procedures.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/transient-loss-of-psychic-self-activation-following-bilateral-thalamic-ventral-intermediate-nucleus-stimulation-for-essential-tremor/