Symptomatological classification of coma
Advances in rescuscitation methods (and especially the prevention of anoxia by tracheotomy) have made it possible for the majority of comatose patients to survive the acute stage during which autonomic disturbances often conceal some of the deficiency aspects of the loss of consciousness. For this reason, it is more interesting to study the chronic and prolonged cases of coma which are now more frequently encountered. Many attempts have been made at classifying the various "depths" of coma - namely, the classical one which distinguishes between obnubilation, torpor, light coma and coma carus. Most authors distinguish three or four stages or "depths" (Mansuy et al. 1955; Fischgold and Mathis 1959; Loeb 1958).
These classifications have the distinct advantage of simplicity, but they fail to distinguish between the signs of cortical damage and those of brain stem damage. Besides, the evolution of states of unconsciousness is often variable, and the fluctuations must be followed fairly closely as they are of great prognostic value and may influence the line of treatment. For this reason it is desirable to have a less rigid classification which would recognize a wider range of objective signs easy to elicit on simple physical examination. The following classification is based on the criteria of per ceptivity and of reactivity described earlier (Jouvet and Dechaume 1960).
The basis of this classification is the study of 40 unconscious patients (the duration of un consciousness ranging from 40 to 3700 days). The majority of these (17) were posttraumatic, the others resulted from encephalitis, vascular accident, and the outcome of neurosurgery.
In addition to these 40 cases of prolonged un consciousness, we have studied 14 cases of brain death, kept alive by artificial methods from 24 hours to 6 days (10 posttraumatic, 2 post operative, 2 vascular accident).
The following are the tests we selected :
In the first place, test the response to a written order: "close your eyes", "put out your tongue".
The second question is designed to test the pa tient's orientation in time and space: "do you know where you are ?", "do you know which day it is ? which month? which year?"
The third test consists of a simple mental calculation: "what is 8 x 7 -- 6 x 6 ?" Usually, the answer to 8 x 7 disappears long before that to 6 x 6. The fourth test consists in asking the patient to name ten flowers. Usually, during progressive "dissolution of consciousness", the patients can only name one flower, most often the rose.
The fifth test consists in studying the patient's ability to obey a spoken command: ask him to shut his eyes or to put his tongue out. (Asking him to open his eyes is pointless, as some patients will open their eyes in response to any auditory stimulus; this is the nonspecific reaction.)
In the sixth test, one watches for the presence of the blink reflex: this is carefully tested by suddenly moving a reflex hammer towards the root of the nose (the palm of the hand must not be used as air displacement may well trigger of the corneal reflex).
Thus (Table 2), depending on the responses to these different tests, it will be possible to place the patient in one of five categories, according to the disturbances of perception:
Nonspecific reactions (R)
These are easily tested. It is essential to start by testing the audition to make certain that one is not dealing with a deaf patient: this is done by testing the cochleopalpebral reflex, where a loud noise causes blinking of the eyelid.
if the patient has his eyes open, one stands by the side of the bed and makes a loud noise or calls his name: the orientation reaction, if present, will cause the patient to rotate first his eyes, and then his head towards the source of the noise.
if the patient keeps his eyes shut and appears to be "asleep", the same ma noeuvre is performed, and one watches for the opening of the eyes. If the eyes stay open, it is then possible to place the patient in one of three groups:
Reaction to pain (D)
This is the next stage of the examination - it is judged according to three criteria (Fig. 6):
Facial expression must be observed carefully. It is usually a combination of upper facial move ment with wrinkling of the lids, sometimes with opening of the eyes, wrinkling of the forehead and especially a mimic of the lower part of the face with the grimace characteristic of pain: it is usually accompanied by a vocal reaction, a grunt, sometimes heard with difficulty in tracheotomized patients. It is also important to note if in certain patients a painful stimulus only elicits a waking reaction
Finally, the terminal stage of the reaction to pain is the withdrawal of the stimulated limb: pinching of a limb usually causes a reaction which may be obvious, or which is only perceptible in one muscle group.
On the basis of the reaction to pain, patients can again be divided into four groups
Autonomic reaction (V)
These are assessed by watching the reactions of respiration, of the
ECG, and of the alteration in pupil size following painful stimulation.
In the majority of cases, a painful stimulus causes a period of apnoea
followed by a longer lasting tachypnoea. The heart rhythm may either ac
celerate or slow down. Quite often vasomotor changes are observed - rubor,
sweating. Mydriasis is also quite common.
The end of the examination consists in testing the classical reflexes: the swallowing reflex, tendon reflexes, and cutaneous reflexes.
We would like to stress the importance of ob serving from day to day the changes in muscle tone. For this, it seemed to us that photographs or whole body diagrams could be of great use. We shall mention the three main groups most com monly encountered (Fig.7): the rigidity of de cortication with the upper limbs in triple flexion, the lower limbs in extension and a bilateral posi tive Babinski sign. This form of rigidity in man is sometimes accompanied by a positive Magnus De Klein reflex. In contradistinction to this, there is the very rare rigidity of decerebration (some times seen in children but hardly ever observed in adults for any length of time) with hypertonicity of the limbs and flexed wrists. And finally, there is the important group of those with no changes in muscle tone.
Clinical form used for the assessment of nervous function in prolonged coma.