for those interested, here's the currently accepted definition
http://pmj.bmjjournals.com/cgi/content/full/75/884/321
The generally accepted features of the vegetative state based on these
various reports are:
* After a period of coma the patient opens his/her eyes, at first
to pain and then to less arousing stimuli. This is then followed by
periods with the eyes open. This intermittent wakefulness, manifest by
sleep-wake cycles, is the point of evolution from coma. Some
authorities do not like to talk in terms of `sleep-awake' since this
implies a higher cortical function. They prefer to use the simple
terms of eye opening and closing. It is very difficult, however, to
persuade caring staff and relatives not to talk in terms of asleep and
awake.
* The patient may blink to menace but appear not to be attentive.
It is of note that other authorities14 have regarded a blink to threat
as evidence of cortical connection and therefore indicating that the
patient is not vegetative. This is a very questionable approach since
the concept of the vegetative state is the demonstration of awareness,
not whether there are some cortical connections. The Multi-Society
Task Force11 urges caution in making the diagnosis of the vegetative
state if there is blinking to threat but does not go as far as to
claim that, if present, it indicates that the patient is no longer
vegetative.
* There may be roving eye movements and the patient's eyes may
seem to briefly follow moving objects. The movement is usually
inconsistent and never sustained. The main early sign that the patient
is emerging from the vegetative state is that he begins to focus on
and/or tracks a moving object or person. The difficulty here is that
Andrews et al found that 60% of patients who were misdiagnosed as
being vegetative were blind or had severe visual impairments which
would make focussing an impossibility.
* The predominant feature is that all responses are reflex in
nature. In the vegetative state these present as:
(a) No evidence of sustained, reproducible, purposeful, or
voluntary behavioural responses to visual, auditory, tactile, or
noxious stimuli. The Aspen Consensus Group have emphasised that if any
of these parameters (sustained, reproducible, purposeful or voluntary
responses) are present then the diagnosis of the vegetative state
should be made with caution. If any of these responses occur but are
not consistent then a safer diagnosis is that of the minimal conscious
state.
(b) Reflex posturing. This is common with any severe brain
damage, even when there is awareness.
(c) Flexor withdrawal occurs but usually after a delay and
never takes the form of a brisk response. The response is slow and
dystonic
(d) A non-volitional grasp reflex may be present. This can
cause considerable concern to relatives who feel that the patient
recognises them when they hold his hand.
(e) Fragments of co-ordinated movement, such as scratching or
even moving hands towards a noxious stimulus may occur.
(f) Reflex postural alterations of the limbs may be provoked by
neck movements.
(g) Chewing movements or grinding of teeth, sometimes
accompanied by constant movement of the tongue. These again cause
concern to relatives who may feel that the patient is indicating that
he is thirsty or hungry.
(h) Liquid and food placed in the mouth may be swallowed. A few
vegetative patients can take all their nourishment orally. In the vast
majority of patients, however, there is gross disturbance of the
swallowing mechanism.
(i) Grunting and groaning may be provoked by noxious stimuli
but no speech occurs. These sounds are often interpreted by relatives
as indicating an attempt to communicate. This can cause disagreement
between family and clinicians when some relatives claim to be able to
`understand' the words spoken when others only hear sounds.
(j) Sufficiently preserved hypothalamic and brainstem automatic
functions to permit survival with medical and nursing care. Basically
this means that the patient does not require ventilation and breathes
spontaneously.
* No evidence of awareness of self or environment and an inability
to react with others or have any meaningful response to the spoken
word. This begs the question "meaningful to whom?". Giacino and
Zasler1 have pointed out that there is no method yet available to
clinically assess `internal awareness' in a patient who is otherwise
unable to express awareness relative to external environmental
stimuli. The concept that we are only able to infer the presence or
absence of conscious experience has also been pointed out by Bernat16
and the Multi-Society Task Force. The International Working Party on
the Vegetative State discussed this point in detail and criticised the
use of the term `meaningful response' on the grounds that it requires
a considerable amount of subjective interpretation on the part of the
observer and that what was meaningful for the patient may not be
considered meaningful by those treating the patient. Similarly the
term `purposeful response' was criticised because of the subjective
interpretation and that a withdrawal reflex could be considered as
purposeful in that it removes the limb, for instance, from danger.
The Royal College of Physicians has more recently defined a code of
practice following the recommendations of the House of Lords Select
Committee on Medical Ethics. Their criteria for the vegetative state
were very similar to the above definitions except that they added
"There will not be nystagmus in response to ice water caloric testing,
the patient will not have visual fixation, be able to track moving
objects with the eyes or show a `menace' response". Whilst tracking
moving objects is generally regarded as evidence of some form of
awareness, the other tests indicate a neuronal connection to the
cortex but, as far as I am concerned, do not imply that the patient is
aware.
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