DeepBrainStimulation (DBS) has been clinically used for nearly 30 years. It uses stereotactic technology to apply electrical stimulation directly to the disease-related brain area by embedding stimulation electrodes in the deep part of the brain, and the intensity, wave width, frequency and other parameters of the stimulation can be controlled and adjusted by the stimulator outside the brain. Compared with other methods of neurostimulation, DBS has the advantages of clear target, high selectivity, reversibility, tunability, and non-destructive. In recent years, with the development of increasingly advanced target stereotactic equipment such as MRI and CT, the emergence of more sophisticated stimulation electrodes and stimulators has made DBS a more precise and safe means of treatment. It is gradually becoming a very promising tool for the treatment of neuropsychiatric diseases, especially advanced Parkinson’s disease and refractory epilepsy. The mechanism of action and effects of stimulation The mechanism of action of deep brain electrical stimulation for PD is still difficult to determine, but it is generally believed that due to the implantation of electrodes, first of all, the direct interference of electrodes (probably the effect of temporary brain tissue edema causing slight destruction) inhibits the electrophysiological activity of the nucleus accumbens Caparros_lefebvre found that when electrodes were implanted early and not stimulated, tremor was also significantly This was tentatively confirmed by the fact that tremor was suppressed when electrodes were implanted early and not stimulated, but it reappeared after 3-5 days. Later, due to high-frequency electrical stimulation, local brain tissue excitability was altered and nerve conduction was inhibited, cutting off the nerve conduction loops that cause PD tremor, thus suppressing PD symptoms well. However, it is not clear whether the effect of stimulation is caused by direct stimulation of nerve cells by current diffusion or by coupling effects through other factors.Cooper suggested that the relief of dyskinesia is due to an increase in inhibitory mechanisms in the central nervous system caused by deep brain stimulation. Recent studies have also found a relationship between the improvement of PD symptoms after high-frequency stimulation of the STN and the interaction of neurotransmitters such as striatal Glu, DA, and SP. However, the exact mechanism needs to be further investigated. It is generally believed that deep brain electrical stimulation has the same therapeutic effect as thalamus or pallidotomy. However, it was found that the former is more preferable than the latter, especially pallidum or STN electrical stimulation is more suitable for elderly patients, patients with severe disease, patients with bilateral lesions and patients with dopaminergic drug-induced dyskinesia, etc., and does not bring serious complications. benebiol reported 46 cases of DBS, 62% of patients had disappearance of tremor and 88% had significant improvement. benabid et al. performed STN stimulation on 2 patients with severe PD Benabid et al. performed STN stimulation on two patients with severe PD and found that the symptoms of myotonia and dyskinesia improved significantly during the stimulation process in the two patients, and the limb movement increased significantly and flexibility improved. At 8 months postoperative follow-up, the PD-like symptoms disappeared and the dopamine-induced “on-off” phenomenon was completely improved. 1.The application of DBS in the treatment of advanced Parkinson’s disease (PD) The treatment of PD mainly relies on dopaminergic drugs, but the drugs themselves can cause adverse motor effects such as motor retardation, and the on-off effect can occur due to fluctuations in blood concentration. In 1993, the first patient with advanced PD received high-frequency electrical stimulation of the subthalamic nucleus (STN), and his symptoms of tremor, rigidity, and bradykinesia were relieved, and the dose of levodopa was reduced by 60%. The dose of levodopa was reduced by 60%. Since then, numerous clinical trials have confirmed that high-frequency electrical stimulation of the STN can effectively relieve the symptoms of advanced PD. Bilateral monopolar stimulation, which is most commonly used today, can start at a weak intensity and then slowly increase until the optimal intensity is reached, meaning that the intensity is not so strong as to cause bradykinesia and does not cause emotional apathy or hypoacusis. A 5-year clinical trial found that high-frequency electrical stimulation of the STN resulted in a 70-75% improvement in tremor and rigidity and a 50% improvement in motor inability. Similar results were obtained in a recent long-term clinical trial. Another randomized paired clinical trial including 156 patients reported a 41% and 23% improvement in motor function compared to the preoperative period without and with the drug, respectively. the long-term efficacy of high-frequency electrical stimulation of the STN is stable, with the motor improvement maintained at more than 40% after 2 to 4 years. Although electrical stimulation of STN can significantly improve motor function in patients with advanced PD and significantly reduce the dose of dopaminergic drugs (about 1/3 of patients remained on low-dose dopaminergic drugs after 5 years, requiring 54% less dose), it has become the gold standard for surgical treatment of PD, but high-frequency electrical stimulation of STN has more side effects. And it has no effect on atypical Parkinson’s disease. 2, DBS in the treatment of refractory epilepsy The incidence of epilepsy in the world population is about 0.5% to 1%, of which 30% of patients whose symptoms cannot be controlled by antiepileptic drugs develop refractory epilepsy, and the chance of refractory epilepsy in temporal lobe epilepsy is even higher than 60% to 70%. Currently, the main treatment for refractory epilepsy is the surgical removal of epileptic foci, but 40% of patients with refractory epilepsy are multifocal and not suitable for surgical treatment, and surgery often inevitably damages normal brain function. Some patients also have recurrent epilepsy after surgery. Therefore, refractory epilepsy has been a challenge for clinical treatment. Since DBS was used to treat epilepsy in 1978, it has been found that electrical stimulation of seizure foci and structures closely related to epilepsy, such as the thalamus, caudate nucleus, posterior hypothalamus, structures in the Papez loop, and cerebellum, can suppress seizures. the efficacy of DBS is closely related to the site of stimulation, the type of epilepsy, and the parameters of stimulation. Preliminary results show that DBS stimulation of the anterior thalamic nucleus resulted in a 38% reduction in seizure frequency in a short period of time to begin with, and after 1 year, a reduction of more than 60% in 50% of patients, with the best results especially in bilateral median temporal lobe epilepsy. A long-term (18 months to 7 years) clinical trial in Mexico that included 9 patients also found that in patients without hippocampal sclerosis with median temporal lobe epilepsy, high-frequency electrical stimulation of the hippocampus suppressed seizures by more than 95%; in patients with hippocampal sclerosis, the suppression rate was 50% to 70%, and no progression was observed in all patients, and no side effects were noted. However, some researchers have also found that electrical stimulation of the hippocampus has a limited ameliorative effect on median temporal lobe epilepsy. To more fully and scientifically evaluate the efficacy and safety of hippocampal DBS in median temporal lobe epilepsy and to compare it with hippocampal surgical resection, a number of large clinical trials are currently underway. In 1976, Cooper et al. first used cerebellar DBS for the treatment of epilepsy and found that seizures were reduced by more than 50% in 67% of patients and that electrical stimulation of the anterior cerebellar lobe was better than stimulation of the posterior lobe. Subsequent long-term (17 years) studies demonstrated that stimulation of the mid-upper cerebellar cortex with electrical pulses of 10 to 180 Hz resulted in symptomatic relief in 85% of patients. A recent long-term clinical trial including 5 patients found that a 6-month period of electrical stimulation of the superior middle cerebellar cortex resulted in an average 41% reduction in generalized tonic clonic seizures and a 43% reduction in tonic seizures. This suppressive effect on epilepsy persisted after stimulation was stopped, and at 2 years there was still a 24% reduction in generalized tonic clonic seizures compared to pre-stimulation seizures. No side effects or complications were found, except for one patient who developed an infection. However, there are also clinical trials that have found very limited efficacy of DBS in the cerebellum for epilepsy. Research on this continues.