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This study discusses a head injury mechanism in case of a human head subjected to impact, from results of impact experiments by using a physical model of a human head with high-shape fidelity. The physical model was constructed by using rapid prototyping technology from the three-dimensional CAD data, which obtained from CT/MRI images of a subject's head. As results of the experiments, positive pressure responses occurred at the impacted site, whereas negative pressure responses occurred at opposite the impacted site. Moreover, the absolute maximum value of pressure occurring at the frontal region of the intracranial space of the head model resulted in same or higher than that at the occipital site in each case that the impact force was imposed on frontal or occipital region. This result has not been showed in other study using simple shape physical models. And, the result corresponds with clinical evidences that brain contusion mainly occurs at the frontal part in each impact direction. Thus, physical model with accurate skull shape is needed to clarify the mechanism of brain contusion.

The aim of this prospective controlled study is to compare healing rate and amount of union callus formed in patients with long bone fractures and concomitant head or spinal cord injuries to patients with long bone fractures only. The healing markers of fractures were compared in three groups of patients: (A) patients with head injuries and long bone fractures, (B) patients with acute traumatic spinal cord injuries and long bone fractures, and (C) patients with long bone fractures only. The mean (range) time to union of long bone fractures in groups (A), (B), and (C) patients was 6.9 (3–20), 6.2 (3–7.7), and 22.4 (13–41) weeks. The mean (range) healing rate of long bone fractures in groups (A), (B), and (C) patients was 4.5(0.2–10.6), 4.7 (2.6–7.5), and 0.38(0.11–1) mm/week. The mean (range) thickness of callus formed at fracture sites in groups (A), (B), and (C) patients was 26(4–48), 29(10–48), and 1(2–20)mm. There were no cases of delayed or nonunion in groups (A) and (B) patients while 5 of 69 fractures (7.3%) had delayed union in group (C) and 9/69 (13%) fractures had nonunion. These results suggest acceleration of long bone fractures in patients with head or spinal cord injuries.

The Role of Biomarker in Personalized Medicine: Concept, Technology and Challenges.

Personalized Medicine in Cancer.

Trends, Challenges and Opportunities of Biomarkers in Translational Medicine.

Brain Injury Biomarkers and their Utilities in Personalized Medicine.

In this paper, a transparent physical head model with air bubbles to simulate the brain cavitation phenomena in head decelerating impact is presented. The transparent skull model was generated based on a real human skull through the turnover formwork technique, and a transparent gel was used to substitute the brain tissue. Air bubbles were created in the gel at the representative sites such as coup site and contrecoup site. After this, the head model was made to free fall from a position and impact on a fixed platform. The decelerating impacting process was recorded by a high-speed video camera and an accelerometer system. Through analyzing the video, the volume change of the air bubbles, namely, the mean pressure change of the air bubbles were calculated and compared. This new method has an advantage in investigating the brain cavitation phenomena using a direct and visual technique. The results showed explicitly and effectively that during the decelerating impact the contrecoup site air bubble was exposed mainly to a negative pressure which value became smaller and smaller in the first half of the impacting cycle and then came near to the normal level in the second half of the cycle; contrarily, the coup site air bubble was exposed mainly to a positive pressure which value became greater and greater in the first half of the impacting cycle and then came near to the normal level in the second half cycle. The probable biomechanics of the cavitation phenomenon is also given in this paper.

In vehicle side collisions, traumatic brain injury caused by the impact between occupant’s head and the interior parts of A or B pillar is a major reason of death and disability. In order to analyze the biomechanical response and injury mechanism of occupant’s brain in side collisions, a refined finite element head model representing the 50th percentile Chinese male was developed. Its improvements of biofidelity comparing to the original head model were illustrated through model simulation against the same post mortem human subjects test. Based on the refined head model, the brain biomechanical responses and injuries in the side impact with interior parts of A pillar and B pillar were analyzed according to FMVSS 201U, and the influences of different impact locations and directions were investigated. The results showed that the brain tissues on impact side sustained positive pressure and those on the opposite side experienced negative pressure. The transmission of pressure wave was easy to cause brain concussion and other diffuse brain injuries. The intracranial pressure distribution exhibited a typical pattern of contrecoup injury. The extreme stress concentration in the junction area of the cerebrum, cerebellum and brain stem could lead to focal injury such as brain contusion and laceration. Moreover, the impact injury of A pillar was more serious than that of B pillar, which was consistent with the traffic injury statistics that the head injury in oblique side collisions was more serious than that of vertical side collisions. Therefore, the interior parts of A pillar should be designed to absorb more energy than those of B pillar under the same conditions. In addition, the severity of brain injury is more sensitive to the variation of the horizontal angle than that of the vertical angle. Both the peak values of the occipital fossa pressure in effect simulations of the horizontal and vertical angles were three to four times of the peak values of the forehead pressure. When the impact horizontal angle was up to 255${}^{\circ }$, or the vertical angle was up to 45${}^{\circ }$, the head HIC(d) values would be up to 1320.45 and 1101.06, respectively, which indicated a AIS 3$+$ injury risk of the head.

In this paper, wave propagation in head generated by a local axisymmetric impact on its outer surface is studied. The skull material is treated as isotropic and homogeneous, but presence of the cerebrospinal fluid (considered as a compressible but inviscid irrotational fluid) inside the cranium has been accounted for in the analysis. Some numerical results obtained on the basis of the analytical study, are also presented.

Functional near-infrared spectroscopy (fNIRS), a growing neuroimaging modality, has been utilized over the past few decades to understand the neuronal behavior in the brain. The technique has been used to assess the brain hemodynamics of impaired cohorts as well as able-bodied. Neuroimaging is a critical technique for patients with impaired cognitive or motor behaviors. The portable nature of the fNIRS system is suitable for frequent monitoring of the patients who exhibit impaired brain activity. This study comprehensively reviews brain-impaired patients: The studies involving patient populations and the diseases discussed in more than 10 works are included. Eleven diseases examined in this paper include autism spectrum disorder, attention-deficit hyperactivity disorder, epilepsy, depressive disorders, anxiety and panic disorder, schizophrenia, mild cognitive impairment, Alzheimer’s disease, Parkinson’s disease, stroke, and traumatic brain injury. For each disease, the tasks used for examination, fNIRS variables, and significant findings on the impairment are discussed. The channel configurations and the regions of interest are also outlined. Detecting the occurrence of symptoms at an earlier stage is vital for better rehabilitation and faster recovery. This paper illustrates the usability of fNIRS for early detection of impairment and the usefulness in monitoring the rehabilitation process. Finally, the limitations of the current fNIRS systems (i.e., nonexistence of a standard method and the lack of well-established features for classification) and future research directions are discussed. The authors hope that the findings in this paper would lead to advanced breakthrough discoveries in the fNIRS field in the future.