Zuzana Hummelová

Dementia after DBS Surgery: A Case Report and Literature Review

We report the case history of a 75-year-old woman with Parkinsons disease who developed severe cognitive problems after deep brain stimulation (DBS) of the bilateral subthalamic nuclei (STN). After a brief cognitive improvement, the patient gradually deteriorated until she developed full-blown dementia. We discuss the case with respect to the cognitive effects of STN DBS and the possible risk factors of dementia after STN DBS surgery.

Factors responsible for early postoperative mental alterations after bilateral implantation of subthalamic electrodes.

Abstract Introduction: Early postoperative mental changes are the most frequent problem after bilateral subthalamic electrode implantation. The study aims to find an association between them and factors related to patient, disease and surgery, including the size of the third ventricle as brain atrophy marker. Material and methods: The study included 80 patients with bilateral subthalamic electrodes implanted for motor complications of Parkinson’s disease (PD). Patients’ age, disease and motor complications duration, medication, neuropsychological tests, surgical reports, third ventricle length (intercommissural distance) and width (intermammillary distance) were analysed. Results: Early mental alterations requiring treatment were observed in 25.0% of patients with higher age being significant predictor. The duration of PD motor complications, L DOPA equivalent dose, DSR Mattis, third ventricle length and width were not statistically significant predictors. The incidence of postoperative mental alteration with intermammillary distance > 8 mm was 60%. The percentage of left sided electrodes implanted in anterior trajectory is significantly higher in patients with early mental changes. Conclusions: Higher age is a risk factor for early postoperative mental changes, but not disease, late motor complications duration and parameters describing third ventricular size except the excessive intermammillary distance. Left sided electrode implanted in anterior position is a risk factor.

Preoperative Visual Memory Performance as a Predictive Factor of Cognitive Changes after Deep Brain Stimulation of Subthalamic Nucleus in Parkinson's Disease

Aim: Deep brain stimulation of subthalamic nucleus (DBS STN) is considered to be a clinically established treatment method to manage the symptoms of advanced stage Parkinson’s disease. Despite the strict inclusion criteria, it may have negative impact on the quality of cognitive functions. Our research aimed to identify predictive neuropsychological factors that signal risk of postoperative deterioration of cognitive functions before the DBS STN. Patients and methods: Forty-six patients with idiopathic Parkinson’s disease were included in the study (mean age at the time of operation 59.61 years; SD = 7.06). The patients were examined by a neuropsychologist before and after the DBS STN implantation. The neuropsychological test battery included Wechsler Adult Intelligence Scale short form, Mattis Dementia Rating Scale, Word list, Rey-Osterrieth Complex Figure Test, Stroop Colour Word Test and verbal fluency tests. Results: The quality of visual memory proved to be a sensitive predictive factor related to risk of cognitive changes after DBS STN implantation, as before the implantation the level of visual memory statistically negatively corresponded to impairment of cognitive performance in neuropsychological tests after the implantation. Conclusion: Low performance in the area of visual memory before the implantation may predict an increased risk of cognitive deterioration after the implantation of DBS STN in Parkinson’s disease. We assume that the changes in visual memory reflect progression of degenerative process in Parkinson’s disease into other brain areas away from the frontostriatal circuit, mainly to posterior temporoparietal areas.

ARE SUBTHALAMICUS NUCLEUS, INTERNAL GLOBUS PALLIDUS AND THALAMUS INVOLVED IN THINKING?

Introduction The aim was to compare evoked potentials (EP) from the P300 paradigm against mismatch negativity (MMN) paradigm, both recorded in the subthalamic nucleus (STN), internal globus pallidus (GPi) and thalamus (Th) and thus electrophysiologically isolate conscious cognition component in these structures. Methods We included 8 patients in Deep brain stimulation program and recorded EP (patients with Parkinsons disease, Generalized dystonia, Essential tremor, Epilepsy). The two four-contacts intracerebral electrodes were implanted into the left and right STN, GPi or Th bilaterally. We computed local potentials on the left and right electrode and we studied the latency of cognitive response (from 200 to 400 ms). Results In the comparison of infrequent stimuli related P300 and MMN a significant difference was found in 14 from 16 electrodes. Comparing frequent answers we found significant difference in 13 from 16 electrodes. Conclusion The difference between evoked potentials of MMN and P300 protocols in 200–400 ms latency suggests that STN, GPi and Th are involved in conscious cognitive processes at the time of stimuli application.