Abstract: Objective:To investigate the clinical efficacy and action mechanism of hyperbaric oxygen (HBO) combined with microsurgical lysis in the treatment of lipoma-type tethered cord syndrome (TCS).Methods:The clinical data of 59 patients with lipoma-type TCS treated in the Department of Orthopedics of Yantai Mountain Hospital and the Department of Orthopedics of Yantai Yuhuangding Hospital from January 2015 to January 2020 were retrospectively analyzed. According to the treatment, they were divided into observation group ( n=33) and control group ( n=26). The control group was treated with conventional microsurgical lysis, while the observation group was treated with HBO on the basis of the treatment in the control group. The clinical efficacy was evaluated according to the Kirollos grading system of postoperative TCS lysis. The optical densities ( D) of malondialdehyde (MDA) and superoxide dismutase (SOD) in cerebrospinal fluid were measured by spectrophotometer before microsurgical lysis and after 3 courses of treatment. Somatosensory evoked potential (SEP) was used to monitor and judge the efficacy of operation and the recovery of neurological function after treatment, including the amplitude, latency, and conduction velocity of posterior tibial nerve sensory evoked potential (PTNSEP). The reflexes, motor function, and the bladder and bowel function were evaluated according to the spina bifida neurological scale (SBNS). The bladder compliance, detrusor reflex, and detrusor strength after operation were measured by multifunctional urodynamic manometry. Postoperative complications, such as headache, nerve damage, cerebrospinal fluid leakage pseudocyst, and re-tethering were evaluated. Results:The total effective rate of the observation group (87.88%) was significantly higher than that of the control group (73.08%) ( χ2=4.991, P<0.05). There were significant differences in detrusor hyperreflexia, decreased bladder compliance, and detrusor weakness between the two groups after treatment ( F=6.534, P<0.05). After three weeks of treatment, compared with those before treatment, the levels of MDA in cerebrospinal fluid of the two groups were significantly decreased, and the levels of SOD of the two groups were significantly increased than those before treatment; the level of MDA in cerebrospinal fluid in the observation group was significantly lower than that of the control group, and the level of SOD in the observation group was significantly higher than that in the control group ( P<0.05). After 3 courses of treatment, compared with those before treatment, the conduction velocity and evoked potential amplitude of the two groups were significantly increased, and the latency was significantly shortened in the two groups; and the conduction velocity and evoked potential amplitude of the observation group were significantly increased than those in the control group, and the latency of the observation group was significantly lower than that of the control group ( P<0.05). In the six-month follow-up after operation, the total SBNS score of the observation group [(14.49±1.76) points] was significantly higher than that of the control group [(10.86±1.44) points], with a statistically significant difference ( χ2=5.782, P<0.05). The incidences of headache, cerebrospinal fluid leakage pseudocyst, nerve damage, and re-tethering in the observation groups were significantly lower than those in the control group ( F=6.395, P<0.05). Conclusion:HBO combined with microsurgical lysis is effective in the treatment of lipoma-type TCS, which can improve the anoxic-ischemic state of spinal cord neurons, accelerate the tibial nerve conduction velocity, significantly improve the comprehensive score of SBNS, and significantly reduce the incidence of postoperative complications. Thus, it is worthy of clinical application.