Disorders of Consciousness

Original Editor - Anna Ziemer

Top Contributors - Naomi O'Reilly  

Introduction

There is a group of patients following moderate to severe traumatic brain injury who would present with profound and prolonged consciousness impairment. Their rehabilitation needs might differ from other patients’ group and usually require treatment enhancing the consciousness along with other forms of treatment and therapy used in traumatic brain injury neurorehabilitation. Prevention of medical and neurological complications is agreed as main focus and currently there is no pharmacological treatment proven to speed up or improve the recovery from disorders of consciousness. 

There is no formal register of patients with disorders of consciousness mainly due to the difficulties with diagnostic code and transient nature of some of the consciousness disease. Although patients with disorders of consciousness demonstrate damage in various areas of the brain the corticothalamic networks activation deficits are common to these patients. 

The patients with disorders of consciousness can be treated in various environment from acute through in-patient rehabilitation to community/ nursing care facilities. The facilities and treating team should be experienced in looking after patients with disorders of consciousness and have multidisciplinary approach with family and relatives engaged. It is recommended that multisensory stimulation is provided with auditory (normal talking), visual (pictures), tactile-kinaesthetic (movement and touch) and olfactory (familiar scents like perfumes, food) are used along nursing care and therapy. Altered consciousness results from moderate to severe traumatic brain injury, relates to changes in person’s state of consciousness, awareness or responsiveness. Consciousness requires simultaneous wakefulness and awareness and the relationship between them both is different for different types of consciousness disorder:

Wakefulness Awareness
Coma - -
Vegetative State + to ++ -
Minimally Conscious State + to ++ +
Emerged from Minimally Conscious State ++ ++

Unconsciousness Conditions

Unconsciousness conditions include:

Coma

A person in a coma is not aroused, unaware of self and environment and unable to respond to any stimulus. This results from widespread damage to all parts of the brain. The person with TBI may emerge from a coma or enter a vegetative state at various time after the trauma.

Vegetative State

Basic wakefulness is demonstrated and some degree of sleep-wake cycle restored, but there is no awareness. The person is unaware of surroundings, but might open eyes, make sounds, respond to reflexes or move. Some facial expression can be observed without apparent cause. Demonstrated behaviour might include: posturing in response to pain, vocalisation, reflexive movement patterns, startle to visual stimuli. The person can remain in vegetative state permanently, but some patients can make a transition to a minimally conscious state. The speed of transition and degree of emerging from coma or vegetative state depends on extend of the brain damage. About 50% of people with TBI in vegetative state one months since the trauma would recover the consciousness, however various degree of residual physical and cognitive deficits are often present. 

Person in coma require complex care and some of the needs might include:

  • Postural management programme preventing deformities, contractures and pressure sores including muscle tone management through positioning, splinting, mobilising, sitting in alternative seating systems
  • Bladder and bowel management
  • Respiratory care including secretion management, like suctioning, tracheostomy management
  • PEG Feeding
  • Management of infections like urine tract infection, chest infection
  • Management or prevention of medical and neurological complications like seizures.

Conscious Conditions

Conscious conditions include:

Minimally Conscious State

A condition of severely altered consciousness but with some signs of self-awareness or awareness of an environment. The awareness can be fluctuating in the degree and consistency but is reproducible. Different forms of minimally conscious state have been defined:

1.    Minimally conscious state minus characterised by no linguistically mediated behaviour presence, i.e.: visual pursuit.

2.    Minimally conscious state plus characterised by linguistically mediated behaviour like command following, verbalisation. 

3.    Emerged from minimally conscious state return to functional object use and functional communication. (Eapen at al 2018)

Behaviours specific to minimally conscious state include: localization to pain stimuli, non-reflexive movement patterns, fixation and pursuit for visual stimuli, intelligible verbalisation, some, however, inconsistent following commands, unreliable yes/no responses and some inconsistent object manipulation. Minimally conscious state is sometimes an intermittent state between coma or VS and full consciousness.

Whilst emerging from minimally conscious state people experience confusions which will present as disorientation, attention and memory deficits, restlessness, fluctuating responsiveness, drowsiness, possible delusions.  Usually the shorter the confusion state the better the recovery. (Sherer at al.2007)

Cognitive and motor impairment correspondence pattern following severe traumatic brain injury. The grey box shows the large region of diagnostic uncertainty in establishing the true cognitive level of patients who behaviourally cannot reliably signal through controlled goal-directed movements. (Schiff 2010)

Different States of Consciousness also include:

Locked In Syndrome

Locked In Syndrome usually results from brainstem pathology which disrupts the voluntary control of movement without abolishing either wakefulness or awareness ([null RCP Guideline 2013]). Patients who are ‘locked-in’ are profoundly paralysed but conscious. They can use various forms of communication like simple facial expression, eyes or eyelids movements, computerized eye gaze systems after their clinical status has been established. However, the diagnosis can be prolonged thus very frustrating for the patient. With medical advances person living with locked-in syndrome have extensive life expectancy and are able to control their environment and access the technology for word processing, voice synthesis and internet access. 

The personal experience of locked in syndrome was described by Journalist, Jean-Dominique Bauby, in his book “The Diving Bell and the Butterfly”, which was also successfully filmed.

Brainstem Death

Brainstem death is declared when there is no measurable activity in the brain and the brainstem.  During strict testing routine following findings will confirm brain death: coma, lack of brain stem reflexes, apnoea. In a person who has been declared brain dead, removal of breathing devices will result in cessation of breathing and eventual heart failure. Brain death is considered irreversible and can be declared by 2 senior doctors completing the test twice. Only is all the tests at both times provide negative outcome the brain death can be certified. The process is followed by certain steps allowing the liaison with relatives and further steps of removing the mechanical ventilation or engaging transplant teams clearly described in national clinical guidelines.

Assessment of Consciousness

Assessment of consciousness have an important role in rehabilitation of people with DoC following brain injury. According to Schnakers and colleagues (2009) approximately 40% of people certified as persistent VS demonstrated some degree of consciousness and 10% patients certified as MCS has actually emerged from it. The misdiagnosis relates to:

  • Lack of knowledge and understanding the distinctive features of VS and minimally conscious state
  • Relaying on neurological bedside assessment and underestimation of the importance of neurobehavioural outcome measures
  • Lack of serial evaluation over time
  • Coexisting complex impairment masking certain behaviour like vision or hearing impairment
  • Pharmacological agents supressing consciousness like sedating medication.
  • Misdiagnosis has wide consequences for long term recovery as might restrict access to neurorehabilitation and limit access to communication strategy development, treatment access and impact on withdrawal of care. 

The golden standard of consciousness assessment are behavioural assessment tools. The VS spectrum patients might benefit from functional neuroimagining testing based on yes/no responses using different brain centres activation pattern (Monti at al 2010). It must be noted that in both circumstances negative findings has been noted, which means some patients were diagnose with MCS but actually demonstrated no consciousness.  

Coma Recovery Scale Revised

Tool to differentiate between VS and MCS to assess the emerging from MCS developed by Gacino and his colleagues available in many languages including JFK English, JFK Chinese, JFK French. Constructed within subscales similar to GSC but with much more thorough and detailed itemisation. The score ranges from 0 to 23 allowing greater attention to detail however making the scale much more complicated and assessment time extended which could be a disadvantage in ICU.

 SMART

The Sensory Modality Assessment and Rehabilitation Technique (SMART) originated from Royal Hospital for Neuro-disability London. It is a tool recommended by Royal College of Physicians National Guideline and is used to assess and rehabilitate of people with Prolonged Disorders of Consciousness (PDoC) due to severe brain injury.

The SMART assessment and treatment can be used by accredited therapists, doctors or nurses who undergo structured training as well as relatives. The format of the assessment is systemised and includes ten observational sessions over 3 week period and followed by 8 week treatment. 

Observation of activity demonstrated to no stimuli for 10 minutes prior the assessment session  and eight modalities stimuli in couple of carefully organised environment setups including therapy session and leisure activities like watching TV aims to establish any residual awareness in people with vegetative state or to establish residual communication, sensorimotor responses and function potential of patient with minimally conscious state. Careful observation of meaningful responses allows to establish any degree awareness. There are several potential level of responses to stimuli:

  • No response at all
  • Responses occurring at reflex level (non-purposeful, spontaneous response over which the patient has no control)
  • Withdrawal (turning or pulling away from a stimulus)
  • Localising (finding the stimuli and focusing on it)
  • Ability to differentiate between two different stimuli.

A consistent response on 5 consecutive assessment at level 5 following any type of stimuli demonstrates a meaningful response pointing to minimally conscious state or higher level of function. If the minimally conscious state is certified the person assessed using SMART can undergo SMART rehabilitation enhancing communication effectiveness and reproducibility of the responses.

Wessex Head Injury Matrix

The Wessex Head Injury Matrix (WHIM) is an observational assessment which was developed by Shiel and colleagues to observe patients emerging from coma through post-traumatic amnesia, monitoring subtle MCS responses and reflect the performance in everyday life.  Initially observed 145 behaviours following the recording of basic responses during longitudinal studies of large cohort were systemised into 6 subscales and contain 62 items. The subscales are as follows:

  • Communication
  • Attention
  • Social behaviour
  • Concentration
  • Visual awareness
  • Cognition

The items are systemised in hierarchical order of statistically appearing behaviour. The WHIM score represents the rank of the most advanced item observed. The WHIM demonstrated good to very good reliability and superiority to the GCS and GLS in recording subtle changes between VS and MCS with particularly high sensitiveness of change in patients in minimally conscious state. The pattern of recovery proposed by WHIM lacks precision and further studies are required to strengthen the sequence of recovery validity.       

Glasgow Coma Scale (GCS)

The Glasgow Coma Scale (GCS) is a point scale used to assess a patient's level of consciousness and neurological functioning after brain injury. The scoring is based on best eye-opening response (1-4 points), best motor response (1-6points) and best verbal response (1-5 points) with cut off point for coma at 8 points. For more in depth information see GCS Student’s Guide.    

Disorder of Consciousness Scale

The Disorder of Consciousness Scale (DoCS-25) is a structured evaluation tool assessing subtle changes in neurobehavioural functioning during consciousness recovery after TBI. 25 items describe the behaviour in response to auditory, somatosensory, visual and olfactory stimuli. Raw scores from 0 to 50 are assigned to logits and rescaled on 0 to 100-point scale.

Rehabilitation of Individuals with Disorders of Consciousness 

The unique components of rehabilitation of patients with Disorders of Consciousness are:

  1. Assessment of level of consciousness and residual voluntary mobility
  2. Providing treatment enhancing the level of consciousness

The interventions should address reversible causes of impaired consciousness. Eapen and colleagues (2018) points to areas to explored before specialist management of Disorders of Consciousness to be addressed:

  • Undermobilisation/understimulation
  • Disrupted sleep-wake cycle
  • Pharmacological sedation
  • Co-existing medical conditions like infection, metabolic abnormalities
  • Neuroendocrine abnormalities
  • Intracranial abnormalities
  • Seizures

Another group of intervention include treatment directly modulating and enhancing awareness. Those treatments include: 

  • General neurorehabilitation containing multimodal interventions(sensory stimulation, mobilisation like handling, FES cycling, postural management with positions changes and sitting out of bed, verticalization through tilt table or body weight support, interpersonal interaction especially relatives). 

There is a strong evidence that verticalisation increases the brain activation (Krewer 2015) as well as environmental enrichment (Abbasi at al 2009).

  • Pharmacological agents use(some promising effect has been demonstrated in use of neurostimulants engaging catecholaminergic pathways like amantadine, levodopa, amphetamine and GABA agonist like zolpidem)
  • Energy modalities(deep brain stimulation, transcranial magnetic stimulation, vagus nerve stimulation, low intensity focused ultrasound)
  • Biological therapies like stem cell therapy

All of those interventions aim to activate undamaged but suppressed networks responsible for consciousness and allow the clinicians to believe that in case of network intact and optimal stimulation provided in some cases patients can be moved from VS to MCS or emerge from MCS.

Addressing the request limiting the medical treatment, relatives education and support, long-term placement planning. Consideration must be given to neurorehabilitation programmes versus end of life/ palliative care. The quality of life issue relates to timely and precise diagnosis of VS or MNS and availability of specialist rehabilitation and care facilities. The patients placed in generic placements demonstrate higher rate of complications and poorer consciousness recover. It must be recognised that medical stability is a prerequisite for full access to neurotherapeutic treatment, therefore the placement needs to be timed accordingly to ensure full use of offered neurorehabilitation. 

The families of patients with DoC require special attention due to their needs related to difficulty of decisions they are exposed to immediately after their relatives TBI. They might be exposed to issues about termination of treatment or organs donation. They also often struggled when they relatives experience prolonged DoC and show lack of improvement. The difficult nature of consciousness and complicated procedures accompanied the care and rehabilitation of people with DoC are another stressful factor. For non-medically trained person it might be difficult to understand that person who can open eyes, supposedly look at, make noises or reflexive movements might be unconscious. Therefore, support and education are crucial for positive inclusion of relatives and friends in multidisciplinary team. 

Families provide invaluable information and extend “the observation time” often spending time with the person with DoC when clinical staff is not present, i.e.: in the evenings (Eapen 2018). They also might recognise subtle changes and provide more powerful stimuli than medical staff enhancing the behavioural response of person with DoC. 

Special consideration of training must be given to families which do wish their relatives to be discharged home.  The rehabilitation of patients with DoC also shares general features of rehabilitation of patient with sever TBI:

4.    Bodily functions management: skin integrity, respiratory, nutrition, bladder and bowel care

5.    Managing medical and neurological complications which usually are consistent with general TBI complications however often more severe [cross reference with Medical Complications and Neurological Complications sections]

6.    Managing Neuromusculoskeletal Problems.  

Patients with DoC often present with: weakness, spasticity, contractures, heterotopic ossification, peripheral nerve damage, critical illness polyneuropathy. This area of intervention has got enormous impact on general neurorehabilitation as often motor response is assessed during consciousness examinations, which then impact the pathway of care. The musculoskeletal health allows more efficient pain management, positioning and mobilisation and determine degree of voluntary movement in the future. 

7.    Establishing communication when appropriate

8.    Providing optimal level of nursing care to prevent complication of immobilisation like pressure sores or provide treatment for existing medical problems like neuroinfection.

9.    Pain Management. Patients in MCS are capable of feeling pain and with multiple sources of pain like muscle tone changes, infections, cannulation, etc the analgesic treatment is appropriate, however consideration must be given to sedative nature of those pharmacological agents during consciousness assessment.

Clinical Outcomes in Disorders of Consciousness

The outcome can be measured by mortality, consciousness recovery or functional recovery and is directly related to diagnosis and with better prognosis of patients in Minimally Conscious State than Vegetative State.  Patients with traumatic brain injury have better prognosis than those with nontraumatic. The time of Disorders of Consciousness also is a prognostic factor with patients being longer in VS having worse chances to recover the consciousness. According to Eapen and colleagues 52% patients certified with VS at 1 month can recover consciousness, 35% of patients with VS at 3 months, 16% of patients with VS at 6 months and nearly no chance when VS still certified at 12 months. 

The functional recovery is also determined by time of Disorders of Consciousness and often this group of patient demonstrates moderate to severe impairment in different proportions. However, due medical, care and therapeutic advances the functional recovery chance is now much greater than even 20 years ago therefore this group of patients should receive structured neurorehabilitation programmes to higher their chances of recovery including inpatient and community-based rehabilitation. There is no prognostication tool of clear reliability when quantifying the potential of recovering from Disorders of Consciousness, however some techniques becoming more useful like functional imaging or cognitive testing.

The Ethical Issues

There are many factors to be considered when looking after patients with Disorders of Consciousness:

  • Diagnostic and prognostic uncertainty related to decision making should treatment withdrawal considered
  • Use of new assessment and treatments methods
  • Research participation
  • Limitation / withdrawal of medical treatment in patient with persistent VS.

At this point in time there is ethical and legal consensus that patients with chronic VS can have the treatment withdrawn and no agreement for those in MCS.

References