The treatment of PVS is a great puzzle in clinical neuroscience. At present, there is no absolutely effective measure. Generally, comprehensive treatment methods including nursing, nutritional security, drug treatment, traditional Chinese medicine, hyperbaric oxygen treatment, nerve electrical stimulation, neural stem cell transplantation, rehabilitation measures and family care are adopted. Neural stem cell transplantation and nerve electrical stimulation are the research hotspots at present. Neural stem cell transplantation is to induce embryonic stem cells or bone marrow mesenchymal stem cells to differentiate into neural stem cells we need, and then transplant them into brain tissue to play a certain function. It has broad application prospects. However, according to the current research progress, its practicability and reliability need to be further confirmed. Xie Qiuyou, Department of neurorehabilitation, Guangzhou General Hospital of Guangzhou Military Region
At present, nerve electrical stimulation technology has attracted more attention. In 1973, cook and others first applied nerve electrical stimulation technology to the treatment of multiple sclerosis. Since then, this technology has been widely used in chronic pain, spasm, tremor, hemichorea, spastic torticollis, etc. for more than 20 years, it has been used by foreign scholars to wake up coma and PVS patients. Nerve electrical stimulation wake-up technology releases pulse stimulation to the brain through peripheral or implanted artificial electrical stimulator to improve the excitability of cortex and improve the state of PVS. After years of basic and clinical research, it has initially shown reliable curative effect, which brings hope to the treatment of PVS.
Nerve electrical stimulation technology mainly includes spinal cord electrical stimulation (CSCs), deep brain electrical stimulation (DBS, also known as “brain pacemaker”), peripheral nerve stimulation (including median nerve stimulation and vagus nerve stimulation).
For spinal cord electrical stimulation, high cervical spinal cord posterior cord electrical stimulation therapy is widely used at present, that is, under general anesthesia, the disc or needle electrode is placed in the middle of the epidural at the C2 ~ C4 level, and the stimulation device is implanted subcutaneously in the front chest or back. Electrical stimulation reaches the brain stem through the high cervical spinal cord and is transmitted to the cerebral cortex through the ascending reticular structure and the hypothalamic activation system. In 1982, komai first reported the application of this technology in the treatment of PVS. In 1988, Kanno et al.  reported that the clinical, EEG and CBF of patients were improved after cervical spinal cord electrical stimulation. In 1989, Momose et al.  first used SPECT and pet to evaluate the changes of cerebral glucose metabolism and cerebral blood flow in patients with CSCs. It was confirmed that the local cerebral glucose metabolic rate and cerebral blood flow increased significantly before and after stimulation. In 1993, Kuwata et al.  studied EEG and cortical acetylcholine, 5-hydroxyindoleacetic acid, aspartic acid, glutamate γ- Aminobutyric acid was detected, which confirmed that the content of acetylcholine increased by 320% after stimulation. In 1998, Fuji et al.  pointed out that CSCs were given in the early stage of hypoxic encephalopathy, i.e. within one month. 58% of patients showed significant improvement after 2 weeks of stimulation. They can communicate with the outside language and express their emotions, and the effect is significantly better than those given CSCs in the chronic stage. Those with no obvious infarction of basal ganglia, average CBF more than 25ml / 100g.min and somatosensory evoked potential N20 had a better prognosis. In 1998, Kanno et al. Summarized that among 130 cases of PVS treated, 56 cases (43%) recovered consciousness, and the GCS score of 23 cases increased by 5 points. In 2007, Morita and Kanno analyzed the operation, mechanism and clinical effect of CSCs in 32 patients (21 cases of brain trauma, 8 cases of hypoxic encephalopathy and 3 cases of cerebrovascular disease), and pointed out that the effective rate reached 80% . At present, it is considered that SCS has definite curative effect, and the total effective rate is 20% ~ 40%. For PVS after brain injury, the wake-up promotion rate and effective rate are higher.
Deep brain stimulation stimulates the reticular ascending activation system to awaken cortical function, including thalamic stimulation, brainstem midbrain stimulation and cerebellar stimulation. The specific method is to implant the deep brain stimulation electrode into the wedge-shaped nucleus of the midbrain reticular structure or the nonspecific nucleus of the thalamus through stereotactic surgery, and stimulate it according to certain stimulation parameters, usually for 3 ~ 24 months. In 1990, tsubokawa et al.  reported that 4 of 8 patients had obvious effects after DBS treatment, of which 3 were out of vegetative state. It was pointed out that if DBS was performed within 2 months after brain injury and lasted for 6 ~ 8 months, the effect was better. In 1993, cohadon et al.  reported that 25 patients with PVS after traumatic brain injury were given DBS at 3 months. After 1 ~ 12 years of follow-up, it was found that 12 cases had no significant change and 13 cases had positive improvement, but the long-term effect was not ideal. Moreover, due to the lack of ideal control, the exact effect of DBS is still difficult to be confirmed. In 2005, Yamamoto et al.  observed 21 patients after DBS for more than 10 years and found that 8 patients were separated from PVS, but most of them still need to stay in bed. They pointed out that DBS is an effective wake-up method with better effect on MCS if it is selected properly, but stressed the need to cooperate with complete neurorehabilitation treatment. Compared with CSCs, DBS can show stronger arousal response, significant and lasting increase in total cortical hemoglobin and oxygenated hemoglobin. In 2007, Schiff et al.  reported that a patient who had been in MCS for 6 years after traumatic brain injury was given DBS, and his cognitive, limb movement, eating and other functions were still significantly improved. They believed that DBS could significantly promote the functional recovery in the later stage of severe brain injury. Statistics show that the total effective rate of deep electrical stimulation therapy is 44.3%, and the effective rates of head trauma, hypoxic encephalopathy and cerebrovascular disease are 57.1%, 31.2% and 29.4% respectively. The therapeutic effect was closely related to the etiology, age and course of disease. 80.6% were effective under the age of 30, and 67.7% were effective within 12 months.