Objective:To analyze the electroencephalogram (EEG) features of patients with Alzheimer’s disease (AD) and mild cognitive impairment (MCI), and to combine the characteristics for classification and prediction.Methods:One hundred and thirty-five patients attending the Department of Neurology at the General Hospital of Tianjin Medical University were enrolled, including 34 patients with AD, 67 patients with MCI, and 34 healthy control (HC). The electroencephalogram signals of these patients in the resting state were collected and preprocessed. Relative power spectral density features and sample entropy features on a multi-band scale were extracted to compare the whole-brain differences in electroencephalogram features among the 3 groups of subjects, and then subdivided into brain regions and individual leads for in-depth analysis. The above two features were fused to classify and predict AD, MCI, and HC by support vector machine (SVM).Results:The frontal regions had higher δ relative power spectral densities than the other regions, and the occipital and temporal regions showed relatively lower distributions. θ-Band relative power spectral densities had a more even distribution of sizes across brain regions. α-Band relative power spectral densities were concentrated in the occipital lobe, while β-band relative power spectral densities were mainly concentrated in the parietal and temporal lobes. Except for the central lobe, the δ-band relative power spectral densities of the AD group were higher than those of the MCI group ( P < 0.05) and HC group ( P < 0.01) in all brain regions and the whole brain. θ-band relative power spectral densities of the AD group were higher than those of the MCI gourp ( P < 0.001) and HC group ( P < 0.001) in the whole brain and in all brain regions. α-Band relative power spectral densities of the AD group were lower than those of the other groups only in the temporal lobe (all P < 0.05). The relative power spectral density of the β-band in the AD group was higher than that of the other groups in the whole brain and in all brain regions ( P < 0.05, 0.01, 0.001). The difference in the relative power spectral density of the δ-band in the C3 lead in the central lobe of the AD and HC groups was statistically significant ( P < 0.05). The relative power spectral density of the γ-band in the temporal lobe was higher than that in the other regions of the AD group, the MCI group, and the HC group. The relative power spectral density of the γ-band in the T3 lead in the AD group was significantly lower than that in the T4 lead. The average entropy of samples in the whole brain and in each brain region was lower than that in the HC group in the AD and MCI groups (all P < 0.05). The entropy of the samples at lead C3 in the AD group was lower than that in the MCI group ( P < 0.05). The differences between the relative power spectral density, sample entropy, and the actual data classification evaluation indexes (accuracy rate, precision rate, recall rate, and F1 score) that fused the two features, and the rearranged data were all statistically significant (all P < 0.001). When the relative power spectral density feature and the sample entropy feature were fused in the classification features, the best classification prediction was achieved, with an accuracy rate of 80%, a precision rate of 78%, a recall rate of 78%, and the F1 score of 79%. Conclusions:Relative power spectral density and sample entropy analysis can reveal the abnormalities of electroencephalogram activities of AD and MCI patients from different perspectives (linear and nonlinear), and the combination of these two features in classification prediction can improve the classification effect.

The patient, an 84-year-old man, was admitted to the hospital with "low back pain with limitation of movement for more than half a year". Admission examination: mild kyphotic deformity of the spine, significant tenderness and percussion pain in the lower back, bilateral lower limb muscle strength graded 5, normal skin sensation. Lumbar MRI and CT revealed a compressive fracture of the L 4 vertebra. Dual-energy X-ray absorptiometry (DEXA) indicated a bone mineral density T-score of -2.6, suggesting osteoporosis. Admission diagnosis: osteoporotic compressive fracture of the L 4 vertebra. The patient underwent thorough examinations to exclude surgical contraindications. On the fourth day of admission, the patient underwent percutaneous vertebroplasty of the L 4 vertebra. At the end of the operation, the patient became unresponsive, with a blood pressure drop to 94/63 mmHg and oxygen saturation falling to 80%. Cranial CT showed multiple punctate gas density shadows within the brain. Lumbar CT revealed gas accumulation in the soft tissue adjacent to the lumbar spinous processes, localized intraductal gas, and punctate gas density shadows within the vessels in both groin areas. The diagnosis was intracranial arterial gas embolism. The patient's condition deteriorated further, with loss of consciousness, neck stiffness, increased muscle tone of both lower limbs, and positive Babinski's sign on both sides. Symptomatic treatments included brain protection, maintaining cerebral perfusion, and improving collateral cerebral circulation, but the patient did not regain consciousness. The patient developed a pulmonary infection one month postoperatively and died three months postoperatively due to respiratory failure. This case highlights the potential risk of gas embolism during vertebroplasty. Measures to reduce such complications should be implemented, such as minimizing the duration of venous blood-air contact, pre-filling the cannula with saline to reduce the venous blood-air interface, and appropriately increasing venous pressure to reduce the risk of gas entry. It is recommended to use smaller diameter catheters. For patients with pre-existing cardiac conditions or elderly patients, preoperative cardiac Doppler ultrasound should be performed to exclude anatomical abnormalities such as patent foramen ovale.