878

ASPECTS OF COMA AFTER SEVERE HEAD

INJURY GRAHAM TEASDALE JENNETT University Department of Neurosurgery, Institute of Neurological Sciences, Southern General Hospital, Glasgow G51 4TF

BRYAN

Features of coma during the first week after severe 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 severely affected patients will be included in the early stages, the duration of coma will be overestimated, and in the later stages the distinction between coma and other unresponsive states may be blurred. Other features which cor-

Summary

relate 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 definition of coma is necessary for valid comparisons 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.

Introduction THE degree of coma after severe head injury is the reliable clinical indication of the severity of brain damage, whether from impact injury or subsequent events. There are several good reasons for assessing severity: to decide whether or not severity is sufficient to require or justify certain types of treatment; to compare different series of injuries, particularly if alternative methods of management are on trial; and as a guide to the degree of ultimate recovery to be expected. Moreover, repeated assessment of responsiveness is essential in the monitoring of the patient with a head injury, on which depends the recognition of early complications which may require urgent treatment. Emphasis has been placed on the need to establish, in the patient with coma of undetermined origin, the pathological cause and the anatomical site of the dysfunction. Plum and Posner’ proposed that the diagnosis of cause and site should be based on the pattern of change in five physiological functions: state of consciousness, breathing, pupillary size and reaction, eye movements, ocular reflexes, and motor responses. Lack of eye opening is also important, particularly in distinguishing coma from other unresponsive states.23 In head-injured patients however, the cause is already declared, and the lesions are usually widespread in the brain. What is important to record is the degree and duration of the coma; and to recognise changes by repeated observation of a few aspects of brain function. Many neurosurgeons have developed their own system, but most published systems seem to have disadvantages. Many depend on a series of levels which assume that certain degrees of dysfunction in different aspects of behaviour always occur together; most depend on signs which have not been tested for reliability in the hands of different observers; and some rely on specific anatomico-pathological correlations which can seldom be verified. The use of the term most

can be confusing; it usually refers to the degree depth of coma, but it can also mean the anatomical level (in the rostrocaudal axis) at which function is thought to be affected.

"level"

or

We have tried to describe the abnormalities in various functions in coma due to head injury, and in such a way that correlations between them can be calculated and comparisons made between different series of patients. We have also sought to discover how often different disorders of function occur together. We analysed the relationship between motor activity, verbal response, eye opening, pupil reaction, eye movements, and respiration in 700 patients with severe head injuries.

Methods Patients The patients all had non-missile head injuries and were collected prospectively in three countries (Scotland, Netherlands, and U.S.A.) as part of a multicentre study into prediction of outcome after severe head injury. Details of the patients and the outcome have been published.* The mean age was 33 years; children were rather fewer than in many head injury reports, 11% of the series being under 10 years and 20% aged 10-19 years. The sole criterion for inclusion was that they had been in coma for at least 6 hours, either immediately after injury or after a lucid interval. The period of 6 hours was chosen in order to exclude patients who might temporarily be in coma because of factors other than the head injury e.g., hypoxia,

hypotension, or alcohol.

Definition of Coma A patient giving no verbal response, not obeying commands, and not opening the eyes either spontaneously or to any stimulus was judged to be in coma. This definition has been used for several years by the collaborative study’ 11 and it corresponds to that recommended by the Head Injury Committee of the ,

W.F.N.S.3

Aspects of Coma Recorded To assess the changing clinical state in the early stages after injury the "best" and the "worst" state of the patient, judged by several measures of activity, was recorded in each of three periods after onset of coma-the first 24 hours, 2-3 days, and 4-7 days. There are therefore many observations for each patient-more for those who survived longer-in fact, more

than 3000

tients. The

"Coma"

sets

analysis

or

of concurrent observations on the 700 pahas been made on the whole pool of data.

Responsiveness Scale

A scale for the assessment of brain TABLE I—GLASGOW

EMV

score or

"COMA"

responsiveness

sum

damage due to various

OR RESPONSIVENESS SCALE

3-15

879

adopted by the collaborative study, which includes not only head injuries’ but also patients with coma due to nontraumatic conditions.6 The scale is suitable for use by junior medical and nursing staff, who are the commonest clinical assessors of responsiveness. When used by them and by more experienced clinicians, the scale is reliable.’ Plum8 commented on the practical usefulness of this system, and it has been widely adopted. Eye opening in response to various stimuli, the nature of verbal behaviour, and the motor response to pain are each described, using terms evolved by trial and error (table i). Some observations may be missing because one component could not be tested (e.g., speech in patients with tracheostomy, or eye opening when this is mechanically impossible). Analysis here has been limited to observations when all three components of the scale were tested. One of the advantages of the scale is, however, that it provides information even when part of it is missing; the value of such incomplete data depends on knowing how the separate responses are linked to each other, which we now report. Not all observations were of patients in coma by our definition, because as time passed some patients emerged from coma, even by the end of the first 24 hours.

causes was

Results Motor and Verbal Responses

Definitions of coma are usually based on inability to obey commands or to utter recognisable words; often only one of these is specified as defining coma. However, TABLE II—INTERACTION OF MOTOR AND VERBAL RESPONSE

Ot 2657 not speaking 97 (3.7%) obeyed. Of 2663 not obeying 102 (3.8%) spoke. Of 365 speaking 102 (28%) did not obey. Of 360 obeying 97 (27%) did not speak. (Pooled data for all epochs in first week).

of these had been used in the present series, patients would have been misclassified by a definition which required inability both to speak and to obey commands. Thus, of 2657 observations on patients who could not speak 97 (3.7%) were recorded as obeying commands; and speech was recorded in the absence of ability to obey commands in 102 (38%) out of 2663 (table u). When patients were emerging from coma much greater discrepancies were found; 27% of patients who could obey were unable to speak, and 28% of those who spoke were unable to obey commands. if only

one

some

TABLE III-EYE OPENING IN THOSE NOT OBEYING OR SPEAKING

A:

Proportion

with eyes open

(of those

not

obeying

or

speaking)

9’.’c. of 1107 observations at 24 hours 20% of 908 observations at 2-3 days 33% of 440 observations at 4-7 days 16% of 2555 observations in first week B:

Of all observations, proportion who with eyes closed

Effect of eye opening on

outcome

Outcome Dead or n

Eyes closed Eyes open

obeying or speaking

with eyes open 90% of 1262 observations at 24 hours 90% of 1072 observations at 2-3 days 67% of 663 observations at 4-7 days

88% 68% 44% C:

were not

327 105

vegetative 208 (64%) 32 (30‘%)

6 months Moderate or

disability good recovery 87 (26%) S6 (54%) P

Aspects of coma after severe head injury.

878 ASPECTS OF COMA AFTER SEVERE HEAD INJURY GRAHAM TEASDALE JENNETT University Department of Neurosurgery, Institute of Neurological Sciences, Sout...
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