Long-term Effects of Subthalamic Nucleus Deep Brain Stimulation in Tardive Dystonia.

To the Editor: Tardive dystonia (TD) is a specific type of secondary dystonia caused primarily by the chronic application of dopamine receptors antagonists.[1] Deep brain stimulation (DBS) has been becoming a promising therapy to treat dystonia. Here, we report the long-term effect of subthalamic nucleus (STN) stimulation for a TD patient after a 12-year follow-up.

A 28-year-old woman was diagnosed with TD in May 2000. The history of illness, physical examination, and auxiliary examination were precisely described in our previous report.[2] The Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS) total score was 98.5 (motor score: 70.5, disability score: 28.0) in May 2003 [Figure 1a and 1b]. In July 2003, she underwent bilateral STN electrodes implantation. After stimulation, the patient showed distinct improvement of the motor symptoms without any side effects. Three months after the operation, BFMDRS total score was 8.0 (motor score: 6.0, disability score: 2.0) [Figure 1c]. The involuntary movement disappeared. There was only slight elevation of right shoulder and slightly tremor of hands. Six years after the operation, BFMDRS total score decreased to 0 [Figure 1d]. She could walk for 1–2 h with the IPG turned off in the morning. Nine years after the operation, her right leg had slight stiffness. BFMDRS total score was 3.0 (motor score: 2.0, disability score: 1.0) [Figure 1e]. She could also turn off the stimulation for several hours every day without any serious symptoms. Twelve years after operation, the gait disturbance disappeared. BFMDRS total score was 0 [Figure 1f]. The off time of stimulation markedly increased from several hours to several days. She could live with DBS off when sitting, eating, and even doing physical exercises. She turned on the stimulation only when she felt tired. Except the psychiatric episodes that the patient experienced before surgery, she did not have any extra psychiatric complications in the 12 years follow-up.

Figure 1

Clinical pictures of the patient before surgery and in the long-term follow-up. (a and b) Prior to operation, the patient cannot sit and walk steadily. (c) Three months after the operation, the patient can walk and run in a natural manner. (d) Six years after the operation, the efficacy sustained. (e) Nine years after the operation, although the patient experienced slight stiffness of the right leg, she could still climb stairs steadily. (f) Twelve years after the operation, the patient completely recovered without any motor symoptoms.

In the treatment of dystonia, globus pallidus internus (GPi) is the preferred target. However, STN-DBS also could produce 77% of improvement of BFMDRS scores and remarkable improvement in the quality of life in primary dystonia without any psychiatric complications.[3] Here, we demonstrated that STN-DBS also worked perfectly in TD patients. The promising results in our patient were that the time of DBS interruption gradually increased, and the patient could perform daily activities independent of stimulation. Although Gruber et al.[4] reported that sudden cessation of stimulation after long-term stimulation of GPi would result in a severe relapse of the symptoms within minutes to hours in TD patients, we did not observe this phenomenon in our patient after 12 years of STN-DBS treatment. The sustained effect of DBS in our patient may be maintained by converting the maladaptive plasticity to normal plasticity in the pathological brain. It is promising that our patient could stop the stimulation completely in the future. Therefore, STN is promising to become an optimal target for TD patients. However, large cohorts studies are needed to fully evaluate the efficacy of STN-DBS for TD in future.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This study was supported by a grant from the Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding (No. ZYLX201305).

Conflicts of interest

There are no conflicts of interest.