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Abusive head trauma (AHT) is a potentially fatal result of child abuse, but the mechanisms by which injury occur are often unclear. To investigate the contention that shaking alone can elicit the injuries observed, effective computational models are necessary. The aim of this study was to develop a probabilistic model describing infant head kinematics in AHT. A deterministic model incorporating an infant's mechanical properties, subjected to different shaking motions, was developed in OpenSim. A Monte Carlo analysis was used to simulate the range of infant kinematics produced as a result of varying both the mechanical properties and the type of shaking motions. By excluding physically unrealistic shaking motions, worst-case shaking scenarios were simulated and compared to existing injury criteria for a newborn, a 4.5 month-old, and a 12 month-old infant. In none of the three cases were head kinematics observed to exceed previously-estimated subdural haemorrhage injury thresholds. The results of this study provide no biomechanical evidence to demonstrate how shaking by a human alone can cause the injuries observed in AHT, suggesting either that additional factors, such as impact, are required, or that the current estimates of injury thresholds are incorrect.

Existing tests of auditory comprehension are frequently unsuitable for patients with physically disabling conditions as tests require skills such as physical manipulation of materials. A suitable test is required to assess the reliability and validity of responses in patients who can only indicate 'yes' and 'no'. This has implications for enabling patients to participate, for example, in decision making over their care. In the construction of the Putney Auditory Comprehension Screening Test (PACST) 200 normal participants were tested with 258 yes/no questions. From their results a test consisting of 60 unambiguous questions, varying in difficulty, type, syntactic complexity and length were selected. A clinical trial was completed with 112 patients from the Royal Hospital for Neuro-disability. The 60 item test was found to be reliable and valid. Results were also compared with independent ratings by ward managers and speech and language therapists. Effects of demographic variables were as expected. A 60 question test was developed which was shown by the clinical trial to be a useful tool. Questions vary in difficulty, but not enough to establish a difficulty gradient. On the basis of performance on the test, patients can be allocated to three groups: normal, impaired, and chance performance.