Probabilistic description of infant head kinematics in abusive head trauma.

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.

Head kinematics during shaking associated with abusive head trauma.

Abusive head trauma (AHT) is a potentially fatal result of child abuse but the mechanisms of injury are controversial. To address the hypothesis that shaking alone is sufficient to elicit the injuries observed, effective computational and experimental models are necessary. This paper investigates the use of a coupled rigid-body computational modelling framework to reproduce in vivo shaking kinematics in AHT. A sagittal plane OpenSim computational model of a lamb was developed and used to interpret biomechanical data from in vivo shaking experiments. The acceleration of the head during shaking was used to provide in vivo validation of the associated computational model. Results of this study demonstrated that peak accelerations occurred when the head impacted the torso and produced acceleration magnitudes exceeding 200ms(-)(2). The computational model demonstrated good agreement with the experimental measurements and was shown to be able to reproduce the high accelerations that occur during impact. The biomechanical results obtained with the computational model demonstrate the utility of using a coupled rigid-body modelling framework to describe infant head kinematics in AHT.

Quality of Life (QoL) in severely disabled multiple sclerosis patients: comparison of three QoL measures using multidimensional scaling.

This study reports a comparison of three quality of life (QoL) measures completed by patients with advanced multiple sclerosis. Multidimensional scaling analysis explored the structure of relationships amongst a general health measure (the Short Form 36--SF 36) and two person-centred measures (the Patient Generated Index--PGI; and the Schedule for the Evaluation of Individual Quality of Life-Direct Weighting version--SEIQoL-DW). Results showed distinct differences both between the two person-centred measures, and when compared against the general health measure, reflecting the different conceptual bases of these measures. The findings suggest that PGI scores closely relate to measures of physical functioning, whereas SEIQoL-DW scores relate more closely to feelings of health and vitality. The implications of these results for selection and development of appropriate QoL scales for the target population are discussed.

Autobiographical memory, depression and quality of life in multiple sclerosis.

The relationship between autobiographical memory, depression and quality of life (QoL) was investigated in a study of 30 persons with severe neurodisability resulting from multiple sclerosis. Sixty percent (n = 18) of patients were found to have deficits in autobiographical memory (AMI) for incidents in their earlier life; these deficits were associated with significant impairments in personal semantic memory of facts from their past life. Patients with impaired autobiographical memory who had been diagnosed for longer than 21 years reported significantly better QoL (SF-36: Role Physical) than those diagnosed more recently, or those with normal autobiographical memory; patients who had been diagnosed for longer were also significantly less depressed than patients diagnosed more recently. Patients with normal autobiographical memory reported the highest levels of depression (HADS) and the lowest levels of QoL (Role Physical). It is concluded that impairment of autobiographical memory affects perception of QoL; patients with deficits in autobiographical memory had impaired knowledge about their past QoL and may therefore be unable to make valid comparative judgements about the quality of their present life.

A screening test of auditory comprehension for individuals with severe physical disability (PACST).

Tests of auditory comprehension are frequently unsuitable for patients with physically disabling conditions as they require abilities such as good vision or physical manipulation of test materials. A suitable test is required to assess patients who can only indicate 'yes' or 'no'. This has implications for enabling patients to make decisions about their care. A test consisting of 60 Yes-No questions was developed from a larger set tested on normals. A clinical trial was completed and the test found to be a useful tool. It allocates patients to three groups: normal, impaired and chance performance.

Assessing auditory comprehension in the context of severe physical disability: the PACST.

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.