Alterations in states of consciousness are one of the most dramatic and difficult clinical problems to face. The ancient Greeks already knew that normal consciousness required an intact brain and that an alteration of consciousness meant a neurological failure.
The brain is only able to withstand a limited degree of physical or metabolic damage and for a short time, which means that in the face of a sensorial disorder we find an imminent situation of irreversible brain damage. Consciousness is understood as the state in which the person knows himself and his environment, and has the capacity to respond appropriately to environmental stimuli. Two fundamental components of consciousness emerge from this definition:
- The, which is the sum of the higher mental, cognitive and affective functions. These are the language, reading, writing, memory, calculation, temporal and spatial orientation, gnosias, etc. Also called cognition.
- The level of consciousness, which is the degree of alertness or awakening of an individual, and the ability to react or be stimulated. Also called waking state.
As we will see later, there may be wakefulness without cognition, but there will be no cognition without wakefulness. Anatomically, the content will be found in different areas of the cerebral, frontal, parietal and temporal cortex mainly, and the level of consciousness is maintained thanks to the action of deeper neuronal groups located from the thalamus to the brainstem, known as the Ascending Reticular Activating System (ARAS). By means of intricate nets, the neurons located in the ARAS receive the stimuli from the sensory organs and send excitatory impulses to the cerebral cortex. When a person falls asleep, the information that travels from the deep structures to the cortical is different and there is a change in the functional conformation of the central nervous system (CNS). The ARAS is inactivated, but other areas increase its activity.
The causes that can produce a disruption in consciousness are diverse. Systemic disorders that affect the entire organism such as metabolic disorders such as hypoglycemia or hyponatremia, or direct lesions to the CNS. such as subarachnoid hemorrhages, thalamic hematomas, infections, tumors, etc. When we have a patient and we suspect that there is an alteration of his state of consciousness, there are certain crucial aspects that we must assess to determine the degree of commitment that this individual suffers.
It is important to assess the degree of response to verbal and motor commands and this is achieved by asking simple questions (such as asking if it is day or night) and asking to obey certain simple commands such as making a fist or showing three fingers, for example.
We have to establish if the patient is oriented in time, space and in person. First the temporal orientation is affected, then the spatial and later the personal orientation. We will also observe if the patient makes movements spontaneously, that is to say, without our orders, paying attention if he mobilizes the four limbs or if he presents some focal weakness in any part of the body. If necessary, we will have to perform stimuli to assess mobility, first verbal (asking him to move an arm or a leg), then sensitive or painful (performing some maneuver that produces pain or discomfort without producing injuries in the body of the patient, as compression in the temporomandibular joints or vigorous stimulation on the sternum). We also have to pay attention to whether the patient is with his eyes open and if he opens them when we ask. Once open eyes, you have to see the pupils, if they are both of the same size, if the size is normal (2-4 mm) and if they react to light stimuli.
Finally, we will assess the type of breathing that the patient has, whether normal, tachypneic, or arrhythmic. This systematic when evaluating a patient of these characteristics will guide us not only on the severity of the situation and the imminence of an irreversible neurological damage, but also can provide us with crucial data to make a precise etiological diagnosis, and with it an appropriate treatment.
The Glasgow Coma Scale, GCS, was originally used to monitor patients with head injury and gives us an objective assessment of the degree of sensory alteration. It is easy to perform by all health personnel. Three main aspects are evaluated: the ocular, verbal and motor response, giving a numerical score to each answer. The maximum score is 15 points (M6 V5 O4), and the minimum is 3 points.
The state of consciousness can be affected partially or globally if only one of its components is compromised, or both. We can divide the partial alterations in:
- Obnubilation, where attention and sensory perception are altered. Difficulty to follow simple orders and accomplish simple tasks By attracting his attention, he responds appropriately but is easily distracted. You can alternate periods of hyperexcitability (during the night) with periods of drowsiness (during the day). It is a transient state, which differentiates it from insane states.
- Stupor or drowsiness, where both content and level of consciousness are altered, but not completely. Patients have unintelligible language, poor response to verbal or motor commands and then return to deep sleep quickly.
- Delirium, which is a mental state with temporary and spatial disorientation but rarely in person. Difficulty maintaining attention, tends to present hallucinations and altered perceptions of reality. It is usually a fluctuating and short-lived state.
The global alterations usually appear later to the partial ones. We can catalog them according to their evolution time and certain distinctive clinical characteristics in:
- Coma (koma = deep sleep), is a state of unconsciousness, the patient remains with the eyes closed and has no response to external stimuli. There is a variable alteration of vegetative and reflex functions (heart rate, respiratory rate, body temperature, blood pressure, digestive movements, etc). Transient state that evolves to improvement or persistent vegetative state. It has a mortality higher than 50%.
- Persistent Vegetative State, usually occurs after a coma of 10-30 days. There is no evidence of personal or spatial awareness. They have an eye opening following wakefulness sleep cycles and preserve autonomic / involuntary functions (heart rate, respiration), but there is no awareness.
- Akinetic mutism is a post comatose state where there is a warning appearance, and silent immobility. The sleep-wake cycle is recovered but there is no external evidence of mental activity. There is an absence of purposive voluntary motor activity (with sense). There may be eye tracking movements.
- State of minimum consciousness: it presents a disorder of consciousness that resembles a state of hypervigilance. They have behaviors that show their own knowledge and the environment that surrounds them (they direct their gaze when they are called by their name, crying or motivated laughter …). In this state the waking sleep cycle and some motor automatisms remain, and patients can even vocalize some words. They can stay for years in this state.
- Locked In or “Enclaustramiento” is produced by specific injuries that cause a disconnection between the structures that control the whole body and the rest of the brain. Patients are aware but can not respond to external stimuli because they have paralysis of all four limbs (tetraparesis) and part of the cranial nerves. The eye movements are maintained for the vertical gaze and for the blinking, through which they can communicate, giving evidence that the consciousness remains intact.
- Cerebral Death is an irreversible state of loss of all brain functions with the inability to maintain respiratory and cardiovascular homeostasis by its own means. Its diagnosis is difficult because of the serious implications it has, it is based on the clinical picture and complementary methods.
In conclusion, the study and assessment of the state of consciousness begins with a clinical suspicion and in the first instance must be performed by all those health agents who have contact with patients.
It is important to be thorough when collecting data about how the person was before the event, and when the person does not respond, we will look for objective data that does not require the patient’s collaboration, since these data will be crucial when establishing an etiological diagnosis and a probable prognosis of the situation.
Finally, we will be very cautious when transmitting our findings to our colleagues and relatives of patients, trying to be precise and objective since they are usually confusing situations and the accompanying emotional charge is usually very important.
Neurology Service / Dr. Mandra