After severe traumatic brain injury a small number of patients fail to wake up despite withdrawal of sedation. Rarely, they may be in a persistent coma, or be locked in. Others (6% of those admitted with severe TBI in one study from 1970s) develop a prolonged disorder of consciousness where there is wakefulness without awareness. This has been described as a vegetative state (Jennet and Plum, 1972); this term has replaced ‘apallic syndrome, total dementia, akinetic mutism’. To make this diagnosis, any persisting effects of medication, metabolic disturbance, or other complications such as hydrocephalus have to be excluded and the patient should be assessed repeatedly by clinicians experienced in managing patients with this condition.

Patients in a vegetative state (VS) demonstrate:

• sleep wake cycle
• ‘no evidence of awareness or self or environment at any time’
• no responses to visual, auditory, or noxious stimuli ‘of a kind suggesting volition or conscious purpose’
• no evidence of language comprehension or meaningful expression

The minimally conscious state (MCS)

Some patients will demonstrate severely altered consciousness but have some very limited awareness where there is minimal but definite behavioural evidence of self or environment. This condition was first described as the minimally conscious state by Giacino in 2002.
Before making any diagnosis of VS or MCS it is imperative to exclude reversible causes of the lack of behavioural response to environmental stimuli.
Assessment should be repeated on several occasions and include a thorough neurological as well as general examination looking for signs of raised intracranial pressure or infection, paying particular attention to eye movements, blink responses to visual threat, other cranial nerves and checking spinal reflexes to ensure there is no critical illness neuropathy or spinal cord injury preventing peripheral responses.

Investigations

These will be guided by the history and management to date but might include:

• repeat CT brain scan to exclude hydrocephalus or re-bleeding or rarer problems such as ‘syndrome of the trephined’
• MRI of the brain may show areas of diffuse axonal injury and brain stem damage more clearly
• EEG to exclude subclinical seizures
• bloods to exclude hypercapnia, hypoglycaemia, hyponatraemia, hypopituitarism

Management

The same management principles apply to this patient group as they do with any other unconscious patient. The key additional point to emphasise to staff is that the patient may be able to understand them. Optimal postural and pain management is also crucial (both in long term but also before confirming a diagnosis of VS). Patients are often more responsive when sat out but may need gradual adjustment to achieve this over many weeks.

Assessment of the disorder of consciousness

Before assessing a person’s level of awareness the following should be considered:

• effect of sedating drugs, eg. baclofen – this patient group is generally more sensitive to the sedative effects of drugs so any sedating agent should be slowly withdrawn if possible before diagnostically labelling the person as in a vegetative state.
• effect of fatigue – people with a DOC fatigue very rapidly during assessment so these need to be kept short, eg. limited to 10–15 minutes only to ensure potential responses are not affected by fatigue.

After specialist assessment and with specialist monitoring it may be helpful to consider a trial of alerting medication such as modafinil although there is limited evidence for long term benefit to date.

Measuring any change

Systematic assessment of the patient’s change in response to a range of stimuli is facilitated through the use of a range of formal measures which are designed to pick up small but meaningful differences that might denote an improvement in the patient’s level of consciousness over time.

1. Coma Recovery Score (CRS) (Giacino et al, 2002) most straight forward and useable by whole team
2. Wessex head injury matrix. (WHIM) (Shiel et al,2000)
• documents recovery from coma to end of PTA
• correlates with FIM/FAM
• observed or elicited behaviours
• training required
3. Sensory, modality assessment rehabilitation technique (SMART) assessment
(Gill-Thwaites et al, 1997)
• ten repeated detailed assessments of reactions to sensory stimuli in many domains over a period of three weeks
• training required

Research tools

Various research groups have designed Funchonal MRI (fMRI) and electrophysiological paradigms to explore whether this group of patients have any covert awareness but none of these is ready for widespread clinical use at present.

Prognosis

It is best to avoid being drawn in to making firm predictions about recovery in the first few months as there are few reliable predictors of outcome other than age. While the prognosis is grave with very few recovering to full independence it is worth considering that a number of European studies have documented up to 20% significant recovery including return to work in cohorts of patients described as in a vegetative state at one month post injury. A report by a multi society task force in the USA has indicated that if a person remains in a vegetative state after four years then the mean survival is 12.5 years.

Further discussions with the family including withdrawal of artificial nutrition and hydration are beyond the scope of this manual and should only be embarked upon if the family request it; once there is no further sign of change; once all the treatable causes have been actively excluded; and after a full assessment has been completed by experienced clinicians.

The timing of such discussion remains debateable but current RCP guidelines indicate that in England it is not appropriate to consider for at least 12 months after traumatic brain injury and that it is a matter for the High Court to advise on every such case where withdrawal of artificial nutrition and hydration is being considered. If an advance directive has been made this should be discussed with the family and the hospital legal team to ensure that it is valid in the circumstances before acting as it directs.