RESUMO
Objective:To investigate the characteristics of magnetic resonance myelography (MRM) and its application in the treatment of spontaneous intracranial hypotension (SIH).Methods:The clinical data, MRM characteristics, and treatment of 15 patients with SIH who underwent MRM examination in the First Affiliated Hospital of Zhengzhou University from August 2014 to August 2019 were retrospectively analyzed. According to treatment methods, nine patients were divided into conservative treatment group and six patients were divided into combined epidural blood patch treatment group. The gender, age, time interval from onset to MRM examination, cerebrospinal fluid pressure and MRM characteristics between the two groups were compared. SPSS 20.0 software was used for statistical description, and independent sample t-test was applied to compare the differences between groups. Results:All of the 15 cases reported orthostatic headache. Their cerebrospinal fluid pressure was (29.67±19.77, range 0-55) mmH 2O (1 mmH 2O=0.009 8 kPa), and onset-MRM interval was (33.07±24.22, range 7-90) days. The MRM characteristics were observed, including all 15 cases with periradicular leaks, four cases with anterior epidural fluid collections, six cases with posterior epidural fluid collections, and eight cases with high cervical (C 1-2 to C 2-3) retrospinal cerebrospinal fluid collections. There were 2 to 32 leak sites with an average of (10.20±7.87) sites. Among the 153 leak sites, 58(37.9%) sites were located at cervical vertebra, 77(50.3%) sites at thoracic vertebra, 18(11.8%) sites at lumbar vertebra, and 61(39.9%) sites at either the cervicothoracic junction (C 7-T 1 to T 1-2) or the upper thoracic region (T 2-3to T 6-7). Five patients responded well to one-time targeted autologous epidural blood patch on the basis of the location of the cerebrospinal fluid leakage. Besides, one patient improved with targeted epidural blood patch twice. There were no statistically significant differences in gender, age, onset-MRM interval, cerebrospinal fluid pressure, number and location of leak sites between the conservative treatment group and combined treatment group. Conclusions:The periradicular leaks of cerebrospinal fluid at cervical vertebra and thoracic vertebra are the most common feature of MRM in patients with SIH. MRM can identify the existence and location of cerebrospinal fluid leakage, assist in the diagnosis of SIH, and guide targeted epidural blood patch.
RESUMO
The recent SARS outbreak has spawned a major controversy concerning the protective performance of facemasks. The objective of this paper is to establish a mathematical model for describing the mechanism of viruses diffusion in a facemask during breathing cycles. In this model the mechanisms of the water vapor molecular diffusion, evaporation/condensation, sorption/desorption of moisture by fibers, Brownian diffusion of the virus, filtration of virus, capillary penetration of the viruses with the liquid water and latent heat generation due to phase change are considered. Meanwhile, the theoretical predictions are compared with experimental data, and good agreement is observed between the two, indicating that the model is satisfactory. Also, the effects of structural and materials properties on virus transfer are investigated.
