Parkinsonism Treatment with Chronic Bilateral Electrostimulation of a Subthalamic Nucleus: Preliminary Results

A.A. Tomsky, V.A. Shabalov

(Burdenko Research Institute of Neurosurgery, Moscow)

Parkinson’s disease with predominant hypokinesia and rigidity was traditionally subject to conservative treatment in the Russian Federation. It was conditioned by no effect of destruction of a ventrolateral complex of thalamic nuclei on hypokinesia and complications of dopamine-replacement therapy (DRT).

The study goal was to estimate an effect of chronic bilateral electrostimulation of a subthalamic nucleus (ES-STN) in Parkinson’s syndrome and DRT.

Materials and Methods. ES-STN was used in 11 cases. A catamnestic period was more than 3 months (9 months as a maximum). Catamnestic data were estimated in 9 patients. Parkinson’s disease was diagnosed in 7 cases. Secondary parkinsonism was watched in 2 cases. There were 2 patients, who had undergone ventrolateral thalamotomy before. Treatment results were assessed on the basis of the Unified Parkinson’s Disease Rating Scale (UPDRS). General motor activity was estimated according to Sections II and III of the UPDRS and Schwab & England Scale, complications of drug therapy – according to Section IV of the UPDRS, a treatment stage – according to Hoehn & Yahr Scale, life quality - according the questionnaire, known as PDQ-39. Preoperative examination was carried out under two conditions: without use of L-dopa preparations (an OFF-state) and at the level of the most marked effect of DRT (an ON- state). Postoperative examinations were carried out each three months in OFF- and ON-states against a background of electrostimulation. Dynamics of daily motor activity was assessed on the basis of a journal of hour-by-hour observation. Shaltenbrand-Waren Atlas (1977) was used for CT-stereotaxic planning. Macrostimulation was carried out for intraoperative verification of a target-point. A position of electrodes was controlled by postoperative MRI and/or CT.

Results. ES-STN resulted in less marked main symptoms of the disease in 6 cases both in their OFF- and ON-states; it was confirmed by quantitative changes of data, obtained on the basis of the above scales. Besides, ES-STN improved life quality, estimated according to PDQ-39. A daily dose of DRT was reduced in 4 cases. L-dopa preparations were given up in 2 cases. A number of complications of drug therapy decreased in all the patients. There was one female of 70 years old with marked vegetative and psychoemotional disorders. One could watch improved UPDRS II and III in her OFF-period and marked improvement of UPDRS IV against a background of poorer motor indices, estimated on the basis of the same scale, in her ON-period. Reduced tremor and rigidity were watched in 2 cases with secondary parkinsonism in the absence of a positive effect on hypokinesia. Speech impairment developed in 4 cases; it regressed in a smaller amplitude of stimulation. There were no persistent neurological complications. Seroma suppuration in the area of a pulse generator demanded temporary removal of a subcutaneous part of a neurostimulator in one female patient. Her state returned to its preoperative level after 3 days of “stimulation abolition”. Then a neurostimulator was reimplanted with a good clinical effect. One of the electrodes was moved into the thalamus VIM with the purpose of better tremor correction in 1 case. It was accompanied by a smaller effect of ES on hypokinesia.

Conclusion. ES-STN is a little-invasive method of surgical treatment. It allows to reduce a state severity in the OFF-period, to increase duration of the ON-period, to reduce a dose of DRT (up to refusal of L-dopa therapy), to decrease severity of complications, watched in DRT. Treatment results are dependent on a response of cases to L-dopa preparations. As for secondary parkinsonism, ES-STN is capable of improving only some symptoms. An effect of electrostimulation is reversible.