Dystonia is a complex dyskinesia in clinic. Many patients still have poor results in drug treatment and surgery. As a kind of functional surgery, deep brain stimulation is increasingly used in the treatment of drug-resistant dyskinesia.
Dystonia is a neurological disease that causes abnormal movement or posture by continuous or intermittent muscle contraction. At present, therapeutic drugs include anticholinergic drugs, dopamine, benzodiazepines, tetraphenylquinazine, baclofen, etc. Botulinum toxin injection into target muscles can also alleviate symptoms. Surgical interventions include rhizotomy for severe cervical dystonia and ablation of thalamus and basal ganglia for more extensive dystonia.
Deep brain electrical stimulation (DBS) has become one of the surgical intervention methods for drug refractory torsion dystonia (torsion spasm). Its advantages include reversible stimulation effect, adjustable according to needs, and relatively good safety.
Considering the heterogeneity of diseases and the different responses of different types of dystonia to stimuli, the selection of patients for DBS treatment is very complex. At present, DBS is only approved for primary systemic, segmental or cervical dystonia. Other types of dystonia treated with DBS are used outside the indications.
Patients considering DBS treatment should be evaluated in the following aspects:
Patients with good effect of noninvasive treatment were excluded;
Identify the related factors that predict the positive and negative reactions of stimulation therapy. Levodopa test is needed to eliminate levodopa reactive dystonia. For patients with poor therapeutic effect of botulinum toxin, it is necessary to reconfirm whether the therapeutic target and dose are appropriate. Patients with psychogenic dystonia usually have poor drug response and should be referred for DBS treatment.
It is important to assess the patient’s skeletal deformity, spasm and the presence of myelopathy, which can reduce their response to DBS. Preoperative examination also includes MRI to exclude structural abnormalities that may lead to secondary dystonia. Finally, screening for psychiatric symptoms or cognitive impairment is also needed.
The appropriate time for DBS surgery is still a controversial issue. In general, once it is determined that the patient is ineffective for medical treatment, DBS surgery can be considered, and the surgery needs to be performed before the occurrence of complex bone deformity or cervical myelopathy.