Botulinum toxin (BTX) is a phagocytic protein produced by G+ anaerobic bacterium Clostridium botulinum, which is one of the most potent microbial toxins and can cause death by poisoning in humans and animals. Botulinum toxin was discovered as early as the end of the 19th century. In 1946, Schantz EJ purified botulinum toxin crystals, and in 1973, Dr. Scott confirmed for the first time in animal experiments that BTX-A has the effect of paralyzing the extraocular muscles, and in 1979, Scott injected botulinum toxin into the over-contracted eye muscles of volunteers for the first time under the monitoring of ocular electromyography, and successfully corrected strabismus. studies confirmed that botulinum toxin type A could be safely and effectively used to treat muscle disorders. In addition to strabismus, Scott et al. began research on the treatment of dystonia, such as blepharospasm, and later expanded to other facial dystonia, spastic squint, treatment of limb dystonia (e.g., spinal cord injury, post-stroke limb muscle spasm, spasticity in children with cerebral palsy), neurogenic bladder and rectal sphincter spasm due to spinal cord injury, and the treatment of axillary odor by inhibiting the secretion of sweat glands. It is also used to treat axillary odor by inhibiting the secretion of sweat glands. It is currently one of the preferred methods in the field of rehabilitation medicine to relieve muscle spasm caused by stroke, cerebral palsy, traumatic brain injury, spinal cord injury, and other upper motor neuron injuries, and can effectively improve patients’ motor function and self-care ability. Botulinum toxin principle BTX-A acts selectively on peripheral cholinergic nerve endings, with the strongest effect at the neuromuscular junction (i.e., synapse). Botulinum toxin acts on the presynaptic membrane of the motor nerve endplates, blocking the release of acetylcholine into the synaptic gap; the nerve endplates gradually degenerate and die, resulting in the inability of the affected nerve to stimulate the contraction of the innervated muscle, resulting in a temporary reduction in muscle strength or paralysis. The effective action of botulinum toxin usually arrives within 3-14 days, and the blocking effect can last for several 3-4 months. When the motor nerve endings produce new shoots, forming new motor end plates and replacing the dead end plates, the muscle regains innervation and gradually regains function or reappears in a state of muscle spasm. Is botulinum toxin safe? Botulinum toxin type A is a toxin that was first discovered when people accidentally ate spoiled sausage and died from ingesting large amounts of botulinum toxin. The current projected use limit for botulinum toxin type A is an LD50 of approximately 40 units/kg, or 2,400 units for a 60 kg person. However, the amount currently used in clinical applications is very small and therefore safe. Botulinum toxin type A treatment is safe and no teratogenicity has been reported, but after all, experience is limited and therefore BTX-A is not recommended for pregnant or breastfeeding women. botulinum toxin should not be used in patients with neuromuscular diseases, especially those affecting the neuromuscular junction, such as myasthenia gravis. In contrast, allergy and hypersensitivity to the drug, infections or skin breakdown at the injection site, patients with fever and acute infectious diseases, and patients with serious organ diseases should be contraindicated for Botox injections. Because aminoglycoside antibiotics (such as gentamicin) can enhance the effect of botulinum toxin, the use of these antibiotics should be prohibited during the use of botulinum toxin. In addition, cholinesterase antagonists, succinylcholine, arrow toxin-like depolarization antagonists, sulfatase, quinidine, calcium channel blockers, lincomycin, polymyxin, etc. are prohibited during botulinum toxin. Nevertheless, Botox treatment may have certain complications and side effects, often occurring 3 to 5 days after treatment, but of course these side effects will all lessen with time until they disappear, usually gradually fading in 2 to 4 weeks. The common ones are skin allergy and rash, numbness and pain at the injection site, bleeding and hematoma at the injection site, “flu-like” symptoms, weakness of adjacent muscles, high dose and repeated injections may cause immune complex disease, muscle paralysis resulting in inability to make various expressions and false mask-like sensation, and anaphylaxis may occur in very few patients. Shock. Botulinum toxin injections generally have no effect at the time of injection, and it takes 3 d to 2 weeks for the drug to take effect, so it is not possible to judge prematurely whether the treatment dose is insufficient. Since repeated injections can cause immune resistance, additional injections within 3 months after injection are not advisable to avoid the effect of repeated injections. It is generally believed that repeated injections can be given after 3 months when the therapeutic effect is weakened, at which time repeated injections of BTXA can generally still have a therapeutic effect, and repeated injections do not cause accumulation of toxicity. Use ice packs locally after injection; gently compress locally after injection instead of massaging, and do not massage locally within 2-3 hours after injection; active muscle contraction activity and electrical stimulation after injection are conducive to drug internalization and improve drug action. Therefore, patients should be encouraged to strengthen functional exercises after injection without resting and braking. Evidence from 20 RCTs and 2 meta-analyses illustrates that treatment with botulinum toxin results in a significant decrease in muscle tone and improvement in passive function (reduced impairment and increased ability to participate in activities). There is growing evidence that reducing spasticity improves active function, i.e., reduces activity limitation. To date, although there are no randomized clinical trials, functional improvement has been reported by reducing knee stiffness gait. Reducing muscle tone increases the likelihood of functional training. Therefore, the use of botulinum toxin is beneficial in improving function, and repeated use of botulinum toxin can significantly improve mobility, improve the ability to use the affected limb, reduce the burden on caregivers, and is an effective method of relieving muscle spasm.