Head injury

Post-traumatic apallic syndrome following head injury. Part 1: clinical characteristics

Epidemiological studies made within the western countries indicate an incidence of 200-300 traumatic head injuries per 100 000 residents each year. Severe head injuries account for 5-25% of all head injuries; 10-14% of all severe head-injured patients develop into a vegetative state, in which a sleep-wake rhythm is apparent, but however in which there is no evidence of awakeness or reactivity to the environment. The most commonly used labels, in the German and international literature, for these patients are 'vegetative state', 'apallic syndrome' and 'coma vigile'. This clinical characterization is not sufficient. It is necessary to employ additional criteria to distinguish subsets of vegetative patients e.g. computerized tomography, magnetic resonance imaging, single photon emission tomography, electroencephalography, brainstem reflexes, evoked potentials, assessment scales, age, premorbid brain disorders. Diagnostic and prognostic parameters must form the basis for various decisions relating to patients' care and intervention.

Event-related potentials--neurophysiological tools for predicting emergence and early outcome from traumatic coma

OBJECTIVE

To determine the prognostic value of multimodal evoked potentials (EPs) and event-related (ERPs) potentials in coma (Glasgow Coma Score <8), after severe traumatic brain injury (TBI).

DESIGN

Prospective, longitudinal study of neurophysiological responses recorded during traumatic coma.

SETTING

Intensive Care Unit, Frenchay Hospital, Bristol, UK.

PARTICIPANTS

Fifty-four comatose TBI patients (age range 1-80 years, mean 36.4).

METHODS

Neurophysiological responses were recorded from 11 scalp electrodes with earlobe reference. Conduction times were measured for brainstem auditory, flash visual and somatosensory, short-latency EPs. Peak latencies and amplitudes were determined for long-latency components of visual and auditory ERPs, generated by passive "oddball" paradigms. These neurophysiological and various clinical parameters were correlated with patient outcome using Pearson's coefficient.

MAIN OUTCOME MEASURE

Three month Glasgow Outcome Scale (GOS).

RESULTS AND CONCLUSION

Highly significant (P <0.001) correlations exist between long-latency ERP components and 3-month outcome. Short-latency EPs, brainstem (wave I-V) and somatosensory conduction times also correlate significantly with the GOS (P <0.01). Of the clinical measurements, pupillary response patterns, APACHE II and Glasgow Coma Scores (GCS) correlate significantly with outcome, as do the retrospective measures of duration of coma and post-traumatic amnesia (PTA) in survivors. Unfortunately, due to variance of long-latency responses, even in controls, absolute values cannot be relied upon as prognosticators. The presence of "mismatch negativity" predicted the return of consciousness (89.7% sensitivity and 100% specificity) and preceded changes in GCS. Its latency was the single best indicator of 90-day outcome from coma (r = -0.641).

The use of CT scanning by accident and emergency departments in the UK: past, present and future

To determine the access to and use of computed tomography (CT) scanning by Accident and Emergency (A&E) departments a questionnaire was sent to all major A&E departments in the UK. Although CT scanners were present in over 80 per cent of the 225 responding hospitals, many centres (including 15.8 per cent of those with a CT scanner on site) did not have 24 h scanning facilities for emergency cases. Few departments (26 per cent) have agreed protocols with their radiology departments with regard to CT scanning and some departments transferred cases for emergency CT scans at another hospital. There are deficiencies in access to CT scanning in a significant number of hospitals. This results in some patients undergoing hazardous and in our view unnecessary transfer for scanning. Little use is made of agreed protocols between A&E and Radiology departments to simplify and speed up the process of arranging CT scans. We feel that the deficiencies identified need to be addressed particularly in the assessment of head injury.

The nature, distribution and causes of traumatic brain injury

The identification and interpretation of brain damage resulting from a non-missile head injury is often not easy with the result that the most obvious structural damage identified postmortem may not be the most important in trying to establish clinicopathological correlations. For example patients with a fracture of the skull, quite severe cerebral contusions or a large intracranial haematoma that is successfully treated can make an uneventful and complete recovery if no other types of brain damage are present. However, not infrequently more subtle forms of pathology are present and ones that can only be identified microscopically. A systematic and pragmatic approach through the autopsy is therefore required and one that recognises the need for tissue to be retained in ways that are appropriate for cellular and molecular studies.

Head injury

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Blood-brain barrier breakdown and edema formation following frontal cortical contusion: does hormonal status play a role?

The present experiment was designed to evaluate and correlate the time course of blood-brain barrier (BBB) integrity and cerebral edema in adult male rats given medial frontal cortex contusions. The effect of sex hormones on BBB integrity in the same injury model was also examined, because previous work has shown that progesterone can reduce cerebral edema (Roof et al., 1993). BBB breakdown was assessed by Evans blue extravasation and albumin immunostaining while edema formation was measured by the wet weight dry weight technique. These processes were examined beginning 2 h and continuing up to 10 days after injury. Our findings show that medial frontal contusion in rats produces changes in cerebral water content and opening of the BBB that endures at least 7 days postinjury. Although pseudopregnancy has been shown to reduce cerebral edema at day 1 postinjury, we did not find any evidence that this hormonal state is associated with BBB repair.