Craniocerebral Trauma

As there was no similar previous study conducted using the time to an event data model, the sample size was determined by using single population proportion formula with the following assumptions; 52.8% proportion of death among head injury patients in the ICU [17 ], 95% confidence level and 5% margin of error. Based on this, the actual sample size for the study was computed by using the following formula: $$\mathbf{n}=\frac{\left(Z\right)2\text{P}\left(1-\text{p}\right)}{{\text{d}}^2}=\frac{\left(1.96\right)2\left(0.528\right)\left(1-0.528\right)}{\left(0.05\right)2}=\mathbf{383},$$ where n = sample size, Z = critical value of 95% CI = 1.96, P = Proportion mortality among trauma patients in the ICU (52.8%) = 0.528, D = precision (marginal error) = 0.05.
Thus, by adding 10% for possible incomplete charts and lost medical records, the total sample size was 421.

The study design and protocol have been approved by the ethics committees for human research at our institute (IRB number: R2019-227). This study followed a prospective and observational design. The study was performed in accordance with the approved guidelines of the Declaration of Helsinki. From November 2020 to February 2022, 133 healthy volunteers aged ≥ 20 years underwent MRI after providing written informed consent explaining the potential for detection of brain disease. Volunteers were recruited from medical staff and students, and their families by open recruitment. Inclusion criteria for this study were those who had no history of brain injury, brain tumor or cerebrovascular disease on previous brain MRI, or those who had never undergone brain MRI and no neurological symptoms including cognitive function. One volunteer aged 84 years old was excluded from this study because of a history of head surgery due to a head injury over 30 years ago. In addition, three volunteers were incidentally found small unruptured intracranial aneurysms with a maximum diameter of < 2 mm on this MRI. They were included in this study, because small unruptured aneurysms might not affect CSF motion.
Patients’ MRI data was used in an opt-out method, after their personal information was anonymized in a linkable manner. Among 44 patients suspected with NPH, 5 patients diagnosed with secondary NPH [29 (link)] that developed after subarachnoid hemorrhage [3 (link)], intracerebral hemorrhage [1 (link)], and severe meningitis [1 (link)], and 3 patients diagnosed with congenital/developmental etiology NPH [30 (link)] were excluded from this study. Finally, 36 patients diagnosed with iNPH who had radiological findings of disproportionately enlarged subarachnoid space hydrocephalus (DESH) [31 (link)], specifically ventricular dilatation, enlarged Sylvian fissure, and narrow sulci at the high convexity, and triad symptoms of gait disturbance, cognitive impairment, and/or urinary incontinence were included in this study, according to the Japanese guidelines for management of iNPH [32 (link)]. Of them, 18 patients (50%) underwent CSF removal in 30–35 ml via a lumbar tap and were evaluated for changes in their symptoms before, one day and two days after the CSF tap test. In addition, 21 patients (86%) underwent CSF shunt surgery and their symptoms improved by ≥ 1 point on the modified Rankin Scale and/or the Japanese iNPH grading scale [32 (link)].