Bryan Jennett

ASSESSMENT OF COMA AND IMPAIRED CONSCIOUSNESS: A Practical Scale

Abstract A clinical scale has been evolved for assessing the depth and duration of impaired consciousness and coma. Three aspects of behaviour are independently measured—motor responsiveness, verbal performance, and eye opening. These can be evaluated consistently by doctors and nurses and recorded on a simple chart which has proved practical both in a neurosurgical unit and in a general hospital. The scale facilitates consultations between general and special units in cases of recent brain damage, and is useful also in defining the duration of prolonged coma.

ASSESSMENT OF OUTCOME AFTER SEVERE BRAIN DAMAGE: A Practical Scale

Abstract Persisting disability after brain damage usually comprises both mental and physical handicap. The mental component is often the more important in contributing to overall social disability. Lack of an objective scale leads to vague and over-optimistic estimates of outcome, which obscure the ultimate results of early management. A five-point scale is described—death, persistent vegetative state, severe disability, moderate disability, and good recovery. Duration as well as intensity of disability should be included in an index of ill-health; this applies particularly after head injury, because many disabled survivors are young.

PREDICTING OUTCOME IN INDIVIDUAL PATIENTS AFTER SEVERE HEAD-INJURY

Clinical data available in the first few days after severe head injury have been collected prospectively on 600 patients from Glasgow and the Netherlands and stored on computer; the patients in the two countries were similar in initial severity and in their outcome on a defined scale at 6 months. Calculated predictions of outcome were made in 200 randomly selected cases, using Bayesian statistics to compare the data from each patient with those from the 400 remaining cases whose outcome was known. Confident predictions (greater than 0-97 probability) were made in 44% of cases within the first 24 hours of coma, and in 52-61% when data up to 3 days were available. The higher confidence-rate occurred when prediction was limited to two outcomes (death or survival). Comparison of predicted with actual outcomes showed that 96-98% of confident predictions were correct. More logical clinical decisions should be possible when these predictions are available.

PERSISTENT VEGETATIVE STATE AFTER BRAIN DAMAGE: A Syndrome in Search of a Name

Abstract Patients with severe brain damage due to trauma or ischaemia may now survive indefinitely. Some never regain recognisable mental function, but recover from sleep-like coma in that they have periods of wakefulness when their eyes are open and move; their responsiveness is limited to primitive postural and reflex movements of the limbs, and they never speak. Such patients are best described as in a persistent vegetative state, which should be clearly distinguished from other conditions associated with prolonged unresponsiveness. What is common to these patients is the absence of function in the cerebral cortex as judged behaviourally; the lesion may be in the cortex itself, in subcortical structures of the hemisphere, or in the brain-stem, or in all of these sites. But the exact site and nature of the lesion is unknown to the bedside clinician, and the name for the syndrome should not imply more than is known.

Disability after severe head injury: observations on the use of the Glasgow Outcome Scale.

The nature of the neurological and mental disabilities resulting from severe head injuries are analysed in 150 patients. Mental handicap contributed more significantly to overall social disability than did neurological deficits. This social handicap is readily described by the Glasgow Outcome Scale, an extended version of which is described and compared with alternatives. Comments are made about the quality of life in disabled survivors.

Severe head injuries in three countries.

Methods for assessing early characteristics and late outcome after severe head injury have been devised and applied to 700 cases in three countries (Scotland, Netherlands, and USA). There was a close similarity between the initial features of patients in the three series; in spite of differences on organisation of care and in details of management , the mortality was exactly the same in each country. This data bank of cases (which is still being enlarged) can be used for predicting outcome in new cases, and for setting up trials of management.

Prognosis of Patients with Severe Head Injury

The relationship between clinical features of brain dysfunction in the first week after severe head injury and outcome 6 months later has been analyzed for 1000 patients. Depth of coma, pupil reaction, eye movements, and motor response pattern, and patient age prove to be the most reliable predictors. The degree of brain dysfunction changes markedly soon after injury, and more reliable predictions of outcome result when assessment is based on the best level of functioning recorded in each early epoch. Predictions based on very early assessment are, therefore, often unduly pessimistic. Individual predictions of outcome, based on a large data bank, provide a powerful tool for assessing the relative efficacy of alternative treatments.

ASPECTS OF COMA AFTER SEVERE HEAD INJURY

Features of coma during the first week after sever head injury were analysed in 700 patients. Coma is best defined as inability to obey commands, to speak, or to open the eyes. If eye opening is omitted from the definition then some less severly affected patients will be included in the early stages, the duration of coma will be overestimated, and in the later stages the distiction between coma and other unresponsive states may be blurred. Other features which correlate with responsiveness (as judged by motor response, speech, and eye opening) are pupil reactions and eye movements; respiratory abnormalities are less common and less closely related to other aspects of severity. A rigorous fefinition of coma is necessary for valid commparisons between individual patients and between different series of patients with head injury. This is essential for the assessment of alternative management regimens and for establishing predictive criteria.

Epidemiology of head injury.

To find the incidence of the various types of head injury that occur in the community separate yearly rates (per 10(5) population in Scotland) for deaths, admissions to hospital, and attendance at accident and emergency departments were estimated and compared (when possible) with rates in England and Wales and the United States. Hospital admissions provide the best data for comparing incidences in different geographical areas and rates of attendance at accident and emergency departments the most reliable guide to incidences in the community. Admission rates, however, vary with local facilities and policies, and these also determine the proportion of patients referred to regional neurosurgical units. Such epidemiological data must be sought both for planning health care for head injury and for monitoring the effectiveness of services.

Avoidable factors contributing to death after head injury

We reviewed 116 patients, known to have talked before dying after head injury, to discover factors which had contributed to death but which might have been avoided. All the patients were admitted to a neurosurgical unit and had a neuropathological post-mortem examination. One or more avoidable factors were identified in 86 patients (74%); an avoidable factor was judged certainly to have contributed to death in 63 patients (54%). The most common avoidable factor was delay in the treatment of an intracranial haematoma; others included poorly controlled epilepsy, meningitis, hypoxia, and hypotension. Changes in the management of patients with head injuries which reduce the incidence of avoidable factors should decrease mortality from this condition.