Consciousness and its disorders

From WikiLectures

Quantity, somnolence, stupor, coma, brain stem, ARAS, awake:

Quality, awareness, hallucinations, illusions, delirium, NPH:

Apallic & locked-out syndrome, vegetative state, coma vigil, DAI:

Locked-in syndrome, awareness & vertical eye movement, ALS, ODS:

Syncope: cardiac, vasovagal, micturition, orthostatic, CSS, tLOC:

GCS, brainstem reflexes, brain death, hypercapnia test, CTA, MRA:

The human dimension of consciousness is conditioned by vigilance (vigilance).

Vigilance is the optimal state of the CNS, when a person is able to adequately respond to changes in the external environment.

From a neurophysiological point of view, the basic mechanism is reticular formation. It includes the ARAS (ascending reticular activating system) = non-specific afferent pathways leading impulses from the periphery to the stem, diencephala and to the cortex; this is a very old integration system.

Psychiatric definition of consciousness: It is the ability to be aware of oneself as an individuality in relation to the surrounding world; the ability to correctly interpret ones own experiences.

  • If vigilance is alteredquantitative disorder.
  • If the ability to self-identify or experience experiences is "altered" → "qualitative disorder".

Quantitative Disorders

They arise in ARAS lesions[1].

From a time point of view, we divide them into long-term and short-term.

Short term


Short-term unconsciousness immediately threatening a persons life (e.g. when driving a car, falling from a height, etc.).

Searchtool right.svg For more information see Syncope.

Epileptic seizure

Irritating lesions. They have a longer development. Unconsciousness - confusion - urinary/faecal incontinence - gradual awakening.

Searchtool right.svg For more information see Epileptic seizure.

Metabolic diseases

Conditions that do not end on their own. Hypoxia, hypoxemia, hypoglycemia.

Long term


A state of increased sleepiness. The patient has little spontaneous activity, controls the sphincters. Responds to words.


Deep sleep from which the patient can be awakened by painful stimuli. It does not control the sphincters.


The most severe state of impaired consciousness. They extinguish basic reflexes, e.g. the pupils stop responding to light. It does not control the sphincters. Respiratory and circulatory disorders occur.

  • Mild coma - mydriasis, mild photoreaction.
  • Deeper Coma - miosis.
  • Deepest coma - paralytic mydriasis without response.
Searchtool right.svg For more information see Coma.

Brain Death[2]

It occurs when there is a complete irreversible loss of all brain functions. Spontaneous breathing stops, the photoreaction is extinguished

and response to nociceptive stimuli. Trunk reflexes are also extinguished. During angiography, cerebral circulation arrest is demonstrated. Brain death is considered the death of an individual. Authorizes the physician to terminate resuscitation and use appropriate organs for transplantation. However, this is governed by strict criteria (formation of an expert committee, determination of the cause of the coma, angiographic findings, etc.).

Causes of quantitative disorders of consciousness

  • Cerebral hypoxia.
  • It is also possible to reflexively evoke emotions (sight of blood).
  • Internal causes: cardiological, circulatory, hypoglycemia, uremia, etc.
  • Intoxication.
  • Surgical causes: head injuries, concussions, contusions, etc.
  • Neurological causes: cerebral embolism, hemorrhage, malacia, inflammation, epilepsy, etc.

Differential diagnosis of quantitative disorders of consciousness

A simple device for use on a patient - A Dozen Causes of Unconsciousness

Structural lesions

Often accompanied by focal neurological findings with a picture of rostrocaudal deterioration. When the central structures or both hemispheres are affected, the image can be symmetrical, imitating metabolic/toxic involvement.

Metabolic and toxic lesions

Symmetrical dispersion neurological symptomatology. There is no rostrocaudal deterioration. Pupils mostly symmetrical, miotic with a positive photoreaction. Often stray movements of the bulbs and involuntary movements of other parts of the body. Mental disorders.

Apalic Syndrome (Persistent Vegetative State)

Severe corticosubcortical lesion with preserved brainstem function. Trunk reflexes are preserved, including breathing, the eyes involuntarily follow the surroundings, but the patient does not perceive the surroundings. No cognitive functions are present. The most common cause is global hypoxia of the brain and diffuse axonal damage. The condition is usually irreversible. In some cases, the condition may improve. First come primitive food (putting things in the mouth) and sexual (touching staff, masturbation) reactions, later confusion, slowed mental functions, sometimes complete recovery.

Locked-in syndrome

This is a loss of momentum due to interruption of the corticospinal and corticobulbar pathways. Consciousness is preserved and the patient can be fully lucid! With the classic form, the patient is able to blink and move vertically bulbs.

Psychiatric Affection

For example abuli or catatonia. However, vigilance is maintained in both cases.

Qualitative disorders

Vigilance is more or less preserved.

However, there is an "alteration" of some "psychic functions" - i.e.:


  1. dazzled consciousness:
    1. confusion,
    2. delirium,
  2. gloomy states.

Demented Consciousness

Confusion (amence)


Disintegrated Content of the Psyche,

Perception is broken,

Illusions and hallucinations,

Thinking disorder.

Facts can be misinterpreted,

autopsychic disorientation (he doesnt know who he is),
→ "allopsychic disorientation" (does not know where he is),
time disorientation (doesnt know when it is).

These are "short-term" and "long-term" conditions (up to weeks).

After the end of the ament state, the patient has amnesia for the duration of the ament.


Internal: atherosclerosis of cerebral arteries, diabetes mellitus etc.


It is an organic mental disorder.

Characterized by a group of psychological and behavioral symptoms caused by brain dysfunction.

Former names: acute organic cerebral syndrome, acute confusional state.

Incidence: in hospital 10-15% (elderly 30-50%).

Diagnostic criteria:

  • reduced long-term attention to external stimuli;
  • disorganization of thinking, leads to incoherence;
  • at least two of the following symptoms:
    1. reduced level of consciousness,
    2. disorders of perception,
    3. sleep-wake cycle disorders,
    4. "decrease or increase in psychomotor activity",
    5. disorientation by time, place, person,
    6. memory degradation.

Development over a short period of time (maximum days) and fluctuations.

Mortality is determined not only by the causative disease but also by causes given by the condition (rupture of infusion vessels, falls, etc.).


Clinical signs:

  • common prodromes: night terrors, anxiety, headaches;
  • in developed delirium - psychological symptoms: deterioration of short-term memory, attention difficulties, perception disorders, illusions, hallucinations, delusions, disorientation;
  • evidence of cortical dysfunction - alexia, apraxia, agnosia, dysgraphia and aphasia;
  • behavioral disorders;
  • somatic symptoms - symptoms of general brain dysfunction (tremor, ataxia, dysarthria, myoclonus);
  • symptoms of autonomic dysfunctions (increased temperature, tachycardia, increased blood pressure, incontinence, sweating, mydriasis).

Differential diagnosis:

  • rule out dementia, which is often complicated by delirium;
  • exclude depression, catatonia.


  • the patient must be protected from himself to avoid self-harm → hospitalization, courting, enclosures, etc.
  • pharmacotherapy:
    • "specific treatment" if we know the cause (hypotensive drugs, benzodiazepines for abstinence, etc.);
    • symptomatic treatment (haloperidol);
    • "internal" symptomatic treatment (infusion therapy, cardiotonics, antibiotics, etc.).

Dull states (obnubilation)

Similar symptoms to delirium, but differs in the sudden loss and sudden return of consciousness.

Amnesia for the duration of the disorder.


  • in epilepsy (psychomotor);
  • after head trauma;
  • after stroke;
  • starvation;
  • endogenous psychoses;
  • pathic drunkenness, pathic affect;
  • dissociative disorders.


Stuporous Form:

  • poorest for symptoms;
  • the patient does not move, the gaze is fixed indeterminately, there is no facial expression;
  • does not rage, does not eat, incontinence, catatonic stupor, melancholic stupor, dissociative.

Delirious Form:

  • opposite stuporous,
  • constant pomovement, noisy, increased facial expressions and motor skills;
  • severe anxiety, delusions, aggression;
  • appears in pathic drunkenness, amok (tropics).

Automatic (vigilambulatory) form:

  • the patient behaves inconspicuously;
  • at first glance, he is as if conscious, but he performs acts contrary to a healthy personality;
  • does not speak, but answers;
  • fugues present;
    • the sick person travels unexpectedly → takes care of himself on the way;
    • the target is familiar, emotionally significant places;
    • there is complete amnesia on the fugue;
    • tends to be of epileptic or dissociative etiology.

Ganser syndrome,

Searchtool right.svg For more information see Ganser Syndrome.
  • rarer, hysterical stupor;
  • often in custody = custody reaction (result of criminal activity);
  • appropriate but incorrect answers give the impression of approval (instead of greeting, he barks, gives a different date of birth - a different century, etc.);
  • is debatable.

Assessment of consciousness

We monitor the patients attention, ability to react, and his mental and motor activity. When assessing the state of consciousness, we assess whether the patient is oriented to place (does he know where he is?), time (does he know what year is it?) and person (does he know who he is?).

If these abilities are weakened, we refer to it as obscured consciousness. We distinguish between 3 basic options. Somnolence means the patient is sleepy but can be easily awakened. Sopor is a deeper disorder where the patient is in a deep sleep and can be awakened by a painful stimulus. Coma is the most serious disorder of consciousness, the patient cannot be awakened and his reactions die out.

We divide consciousness disorders into qualitative and quantitative. Among the qualitative disorders are amence (confusion), the patient is disoriented in time and place (disorders of perception and restlessness may appear), and delirium. Quantitative disorders include the already mentioned syncope, sopor and coma.

Impairment of consciousness can accompany some disease states. Impairment of consciousness occurs, for example, when brain tissue is damaged (hemorrhage, tumor, inflammation, injury), when cerebral blood flow is impaired (thrombosis, embolism), during circulatory failure, in diabetes mellitus or intoxication.

Glasgow Coma Scale

The Glasgow Unconsciousness Scale, modified for children, is used to assess the state of consciousness . To assess the state of consciousness in children under 3 years of age , the Best Possible Coma Score scale is developed based on the assessment of maximum abilities with respect to maturation ( Reilly et al. ).

The scale helps to assess the patient's state of consciousness and the changes that occur during hospitalization.

The resulting score is created by the sum of three values, where each numerical value corresponds to the highest achieved degree of the patient's response to a given stimulus. (The score may be skewed by associated diseases or disorders of the patient, it does not evaluate the lateralization of symptoms.)


Glasgow Scale of Depth of Unconsciousness[3][4]
eye opening adults and older children little children
1 does not open does not open
2 open by pain open by pain
3 open by voice open by voice
4 open spontaneously open spontaneously
Verbal response
1 none none
2 incomprehensible sounds moans by painful stimuli
3 individual words shouts or cry by painful stimuli
4 inadequate speech screams spontaneously, cries, inappropriate reactions
5 adequate speech hums, yells, watches the surroundings, turns to the sound
Motor response
1 none none
2 non-specific extension at the site of painful stimuli non-specific extension at the site of painful stimuli
3 non-specific stimulation by painful stimuli non-specific stimulation by painful stimuli
4 escape reaction by a painful stimulus escape reaction by a painful stimulus
5 targeted defense response to a painful stimulus targeted defense response to a painful stimulus
6 adequate motor response normal spontaneous mobility
15–13 no or mild failure
9–12 moderate disorder
up to 8 serious disorder


  • GCS values ​​can only range from 15 to 3 . For a rough assessment of the patient's condition, the disorder of consciousness can be divided into three stages:
    • mild (GSC 15–13),
    • intermediate (GSC 12–9),
    • severe (GSC 8–3) impaired consciousness.
  • In order to correctly determine the score, it is necessary to reflect in the evaluation of other comorbidities that affect the result of the evaluation, but are not a manifestation of a disorder of consciousness. We do not evaluate localized pathologies, but the overall condition of the CNS. E.g. Of course, GCS 15 is also achieved by a quadruplegic patient with expressive aphasia, although this does not seem so at first glance. In contrast, muscle relaxation, intubation or analgesia make evaluation impossible.
  • GCS assessment should be performed at the first contact with the patient, especially in conditions related to CNS and conscious damage.


MediaWiki:Lékařská kalkulačka/GCS We are currently working on a medical calculation.

Assessment of Brainstem Function[2]

It is carried out through the equipment of trunk reflexes:

Oculocephalic Reflex

The unconscious patient lies on his back, the examiner holds the patients head with both hands. The eyes of the unconscious fixate on a point in front of them. The examiner quickly and gently turns the head from side to side, while the patients eyes always fixate on one point, i.e. they turn against the direction of movement. This finding indicates intact trunk functions and a lesion in the diencephalon or hemispheres. If the eyes do not fixate on one point and rotate with the head, this would indicate a trunk lesion. The test is not performed if a cervical spine injury is suspected.

Oculovestibular Reflex

The patient lies on his back, the examiner flexes his head by approx. 30°. 20 ml of cold water (0 °C) is slowly applied to the external ear canal. With intact trunk functions, after a while the eyes deviate to the side of irritation. This would not occur with a trunk lesion. If the patient was not unconscious, nystagmus against the side of irritation would also be provoked. If warm water were used and the patient was not unconscious, the nystagmus would be in the direction of irritation. The test is performed with an intact eardrum.

Investigations focused on the precipitating cause of the disturbance of consciousness


Related Articles

External links



  1. OBLIVIOUS, Sonia – RUŽIČKA, Eugene – QUIET, George. Neurology. 1. edition. Galen, 2002. 368 pp. ISBN 80-7262-160-2.
  2. a b AMBLER, Zdeněk. Fundamentals of Neurology. 6. edition. Galen, 2006. 0 pp. ISBN 80-7262-433-4.
  3. STAŇKOVÁ, M. České ošetřovatelství 6 – Hodnocení a měřící techniky v ošetřovatelské praxi. 1. edition. Brno : Institut pro další vzdělávání pracovníků ve zdravotnictví, 2000. ISBN 80-7013-323-6.
  4. ROWLETT, Russ. How Many? A Dictionary of Units of Measurement [online]. ©2001. The last revision 2001-07-30, [cit. 2009-10-28]. <>.