Owing to the development of intensive health care, since the mid-20th century it has been possible to administer life support procedures to patients with serious brain or body injuries. Circulatory or respiratory support increased survival rate in serious accidents. Unfortunately, in the case of some survivors, no return to consciousness was observed in successive stages of treatment and care [1].
Technological advancement in medicine particularly associated with the use of new diagnostic techniques made it possible to identify various states of impaired consciousness. Neuroimaging examinations allowed us to reveal that not always is brain irreparably damaged and even in extremely serious cases there are still areas that function properly and may also be used to communicate with the surroundings. In both quantitative and qualitative terms, a variety of states of consciousness disorders created a need for clarifying and elaborating assessment methods and developing a standard classification system. It was acknowledged that previous ambiguous terms like ‘brain death’ or ‘vegetative state’ turned out to be too simplified. Therefore, a painstaking and ongoing process of redefining and reclassifying them was embarked on. This situation has become an impulse to seek and select the most accurate diagnostic tools and methods possible that would enable us to carry out precise and reliable assessment of a patient’s clinical state [1–3].
This study sought to review the classification of patients with disorders of consciousness according to the Royal College of Physicians and to present the scale of sensory and motor response known as SMART (Sensory Modality Assessment and Rehabilitation Technique) as a tool of behavioural bedside assessment of patients with disorders of consciousness.
As of today, the term Disorders of Consciousness includes impaired consciousness and awareness caused by profound brain damage resulting from an acute injury or with non-injury origin. It is estimated that in Poland, 25-30% of individuals after cerebral stroke suffer from impaired consciousness [4,5]. Unfortunately, there are no accurate epidemiological data on the percentage of qualitative impaired consciousness [4]. Problems with appropriate assessment and, consequently, a misdiagnosis pose a serious challenge to medical workers responsible for diagnosing, qualifying and selecting adequate rehabilitation methods for patients in the vegetative or minimally conscious state [6,7].
Wakefulness and awareness are axial terms associated with impaired consciousness. According to the Royal College of Physicians, wakefulness is a state when eyes are open and a certain degree of motor arousal can be observed. Awareness is an ability to experience anything of any kind. Further definitions are developed on the basis of these terms [8].
When the brain is damaged, its state of delicate balance is disturbed. Some minor brain injuries include concussion and cerebral contusion [9]. If there is no subsequent injury in a period when the nervous system is healing after the primary injury, usually full recovery is observed [10]. In the case of more serious injuries, greater areas of the brain can be damaged, including cortex and subcortex structures as well as diencephalon or mesencephalon [9]. The consequences of such injuries are pre-somnolence, somnolence, clouded consciousness or sopor [9]. When a period of unconsciousness lasts longer than 6 hours, the state of a patient is defined as coma.
Coma – clinical examinations did not reveal any signs of awareness and consciousness; eyes are closed and there is no response to any type of stimuli [8,11]. However, it should be remembered that the fact of having one’s eyes closed does not mean a person is in coma or any other state of disorders of consciousness. The study which focused on assessing states of consciousness in patients in the vegetative state proved that the majority of them were blind or had serious visual impairments [12].
Vegetative state (VS) – during an observation, a patient does not show any signs of intentional behaviour nor is there any motor or spontaneous response to visual, auditory, tactile or pain-inducing stimuli. There are no signs of speech or understanding. Spontaneous breathing and circulation can be noted. Moreover, sleep-wake cycles may be found. Behaviour perceived as conscious (crying, making sounds, smiling or grimacing) can also be highly confusing. In addition, it is noteworthy that the patient’s eyes may follow a moving object or sound and focus on the target and react to visual threat. It is significant that such patients do not usually follow a moving object for more than a split second. In the vegetative state, such reactions are unintentional [8].
Minimally conscious state (MCS) – in a minimally conscious state, the patient demonstrates minimal but discernible behavioural evidence of self- and environmental awareness. Responses may be inconsistent but reproducible. Patients are capable of following simple instructions. Through gestures or utterances, they answer ‘Yes/No’ questions (regardless of answer accuracy). Their speech becomes understandable; they take up intentional activities that will enable them to make choices. Occasional crying, smiling or laughing are linked with particular situations. Patients begin to demonstrate intentional motor behaviour patterns such as reaching for objects, touching or holding them. It is possible they will intentionally follow or focus on immobile or mobile objects. Depending on the complexity of responses, this state can be seen as ‘plus/positive’ or ‘minus/negative’ (MCS+, MCS-) [8].
When a patient remains in the state of wakefulness for more than 4 weeks but there are no signs of consciousness or it is limited, it may be classified as ‘a prolonged disorder of consciousness’. The Royal College of Physicians has introduced the following assessment criteria for this group of disorders [8]:
continuing VS – when a patient continues to show no signs of self- or environmental awareness for more than 4 weeks,
continuing MCS – when a patient continues to demonstrate inconsistent yet reproducible interaction with the surroundings (above the level of spontaneous or reflexive reactions) for more than 4 weeks,
permanent VS – a vegetative state which has persisted for more than 6 months following anoxic or metabolic brain injury. In the case of traumatic brain injury, the vegetative state is defined as permanent if it lasts for at least 1 year. In practice, however, it is necessary to give a diagnosis that awareness will never return or the current state will never change [8].
There is no set time framework according to which a minimally conscious state could be regarded as permanent. It is reported that the prognosis is less favourable for non-traumatic injuries and that cases of improvement after a period of 5 years are very rare. Factors influencing the fact that any improvement is highly unlikely include the patient’s general condition and other comorbidities, the cause and severity of the injury, responsiveness level and the improvement trajectory observed post injury. If a patient remains in MCS for 5 years without any improvement, emergence to full consciousness is highly improbable, thus warranting a diagnosis of permanent MCS. In certain cases, this period may be reduced to 3-4 years (Tab.1). The moment of transition from one state to another is usually difficult to observe, so it requires extremely accurate neuropsychological assessment [8].
Determination of the patient’s state on the basis of injury type and time from injury onset [after 8]
| Stan wegetatywny/Vegetative state | Stan minimalnej świadomości/Minimally conscious state | |||
|---|---|---|---|---|
| Uraz/Traumatic injury | Nieurazowy/Non-traumatic injury | Uraz/Traumatic injury | Nieurazowy/Non-traumatic injury | |
| Kontynuujący/ | >4 tygodnie | >4 tygodnie | >4 tygodnie | >4 tygodnie |
| Permanentny/ | >1 rok | 6 miesięcy | - | - |
According to the research results, the state of consciousness was wrongly diagnosed in approx. 41% of patients [13]. Studies carried out in a number of countries have revealed disturbing data. Out of 44 patients diagnosed as vegetative, 18 met the criteria of minimally conscious state, while 16 out of 18 patients who were difficult to diagnose demonstrated signs of consciousness [14]. Another research on 40 patients referred as being in the vegetative state revealed that 17 individuals (43%) were misdiagnosed. As many as 70% of the patients were able to make short utterances, 90% were capable of making decisions, while 60% were oriented in time, place and person [12]. In turn, the research on 49 individuals in the persistent vegetative state revealed that 18 study participants (37%) were misdiagnosed. Those individuals were able to interact with the surroundings. The lack of uniform terminology, too short observation period and a shortage of well-qualified staff were the causes of wrong diagnosis [15].
As for difficulties in making an accurate diagnosis, it is worth analysing the work of Gill-Thwaites, who distinguishes five elements that help to give a correct diagnosis. One of them is to develop an appropriate system that clearly defines the patient’s patterns of behaviour and classifies them in the right manner [11]. It is also connected with clear terminology that will facilitate work in an interdisciplinary team. It highlights the need to exercise caution when using precise vocabulary and not to mix terms and elements of particular states. Unfortunately, there occur problems already at this stage. In some countries (including Poland), the problems are language-related. The lack of Polish equivalents and vocabulary items that explicitly reflect the meaning of particular words or phrases defining states of consciousness makes it considerably more difficult to translate them from the English language and to classify them in Polish. Another element is to develop precise research tools and to have a patient assessed by two independent experts. The availability of the patient to be evaluated is significant as being able to undergo frequent examinations improves the chance of being diagnosed accurately. The author also identifies other crucial factors affecting assessment such as taking care of the patient at an interdisciplinary level as well as involvement of the patient’s family and carers [11].
Due to a limited content of this article, not all recommendations concerning the states under discussion have been included. However, it is worth paying attention to some of them, e.g. Misdiagnosis of the vegetative state: retrospective study in a rehabilitation unit [12].
Behaviour of a patient is the sum of many complicated reactions that occur at a motor and cognitive level. In order to ensure complex evaluation, it is necessary to find a tool that would help to assess communication and the functioning of as many sensory modalities as possible. Aiming to find more and more precise definitions and clear criteria of states translates into the types of measurement tools which include behavioural scales based on observational criteria. In the process of creating and developing research tools, it is essential that they should be easy to use and that assessment could be carried out quickly and precisely [16,17].
An example of a scale that can meet all the requirements and which is currently most accurate is SMART. It is a research tool used to assess the state of consciousness of patients after brain injuries. It makes it possible to establish the level of consistency of patients’ responses in already defined states and to determine how they should communicate properly with the surroundings [18].
SMART was developed due to shortcomings of previous methods regarding accurate assessment of patients in the vegetative or minimally conscious state. The authors were trying to create a tool that would encompass a wider variety of options of assessing responses to sensory stimuli and that would specify types of consciousness precisely at the same time involving family and therapists. As a diagnostic and therapeutic tool, SMART enables examiners to assess sensory modalities (visual, auditory, tactile, olfactory and gustatory), functional motor abilities and communication. Owing to a thorough analysis, an examiner can build an accurate image of responses that are rated according to a 5-level hierarchical scale [19]:
level 1 – no response,
level 2 – reflex response (e.g. blinking or facial reflexes),
level 3 – withdrawal response (e.g. turning the head from a stimulus),
level 4 – localizing response (e.g. turn the head or eyes towards a stimulus),
level 5 – differentiating response (a patient follows simple commands such as ‘close your eyes’/‘press the button’ or is able to distinguish a colour, a shape, a letter and a word or can choose between ‘yes’ and ‘no’).
An informal examination seeks to gather information regarding the patient’s lifestyle prior to the accident/morbidity. Collecting information about their likes and dislikes as well as about their relationships with particular people helps with a better plan of the therapy. It is also a way of involving family members, who fill in forms and provide information on the patient’s behaviour outside working hours of a therapeutic team. Thus, it is possible to juxtapose the findings of the informal examination (family observation) with the formal one (observations of an examiner) [7,20].
The formal examination includes 10 sessions conducted by the same examiner within a period of 3 weeks. Five sessions ought to be performed in the morning, while the other 5 should be realised in the afternoon. It is recommended that each examination session should be preceded by a 30-minute rest period. Each session consists of two parts:
SMART (Behavioural Observation Assessment) – its main purpose is to assess the patient’s behaviour at rest without interference of the third party and in a non-stimulating environment. It allows an examiner to observe intentional movements of the patient, their reflexive and spontaneous behaviour without external stimuli as well as establish the level of wakefulness. The examiner alternately spends 10 seconds observing the patient and 10 seconds filling in a special form. Each response is defined as:
reflexive – automatic reaction not controlled by the patient,
spontaneous – unintentional and aimless movement that occurs without any stimuli,
purposeful – intentional and deliberate movement.
SMART Sensory Assessment – the first aim of sensory assessment using classified stimuli is to establish the quality and types of responses. The second goal is to assess the patient’s state of consciousness. Sensory assessment follows behavioural assessment of the patient. Five sensory modalities (visual, auditory, tactile, olfactory and gustatory), motor abilities, communication and the level of wakefulness are evaluated. During each session, sensory modalities are assessed in a different order so that the next evaluation does not begin with the same element. Twenty-nine standardised techniques and stimuli are employed in the assessment. Responses are described on the aforementioned 5-point hierarchical scale [20,21].
The works of Aspen Workgroup realised between 1995 and 2000 played a key role in developing the criteria for defining the minimally conscious state [22]. The group consists of specialists in the field of bioethics, neurology, neuropsychology, neurosurgery, psychiatry, nursing and in other areas of public health.
The SMART scale is in line with the recommendations of Aspen Workgroup related to giving an accurate diagnosis. Owing to a detailed interview and close cooperation of team members, it is possible to rule out aphasia, agnosia, apraxia, or other motor-related limitations that could lead to a misdiagnosis of the actual cognitive state of the patient. Also, the effects of medications could be ruled out. Thanks to the forms, an adequate stimulation protocol can be implemented to ensure maximum wakefulness levels. The examination includes a wide range of stimuli (assessment of 8 categories). Additionally, tasks that patients have to perform match their capacities. What is significant is the fact that the examination is performed 10 times in order to confirm (or not) the diagnosis. Apart from the staff working with patients, their families are involved in the assessment process [22]. The most important elements of the tool are as follows:
the patient’s preparation – special training is necessary,
duration of the examination – it may be fairly long, i.e. it may exceed 60 minutes,
a specified number of sessions – it includes 10 sessions,
assessment of natural behaviour – at first, the patient’s behaviour at rest (without any external stimuli) is assessed,
sensory assessment – visual, auditory, tactile, olfactory and gustatory modalities, arousal level as well as functional motor and communication abilities are evaluated,
response hierarchy – each response is rated according to a 5-point hierarchical scale,
family involvement – the patient’s family are engaged in the assessment process as they have to fill in special forms,
selection of stimuli – the selection with regard to the patient’s interests/preferences,
functional communication – the examination seeks to answer the question whether the patient is capable of communicating with the surroundings and, if so, to what extent,
the role of the tool in a social/public context – owing to its diagnostic accuracy, SMART is also recognised in non-medical environments. Examination results are respected by insurance companies or courts and they are crucial when discussing a possible termination of the therapy,
standardisation – all the tools used in the assessment as well as assessment techniques and data analysis protocols are standardised and ought to be applied in compliance with specific procedures.
The recovery process of a patient with impaired consciousness may be long-lasting and slight changes may be hard to discern. There is a high percentage of misdiagnosed patients. Working in an interdisciplinary team is a key to an accurate diagnosis and rehabilitation planning. Despite being time-consuming and difficult to use, some scales may guarantee the most precise diagnosis of the patient’s state. SMART scale may constitute a proper standard tool for assessing patients with disorders of consciousness.