RAMB - Julho 2016

morim

RLO

378

ssoc

ras

2016; 62(4):377-384

tory of recent trauma, personal history, life habits and

medications in use are valuable for clinical management.

Among the states that are characterized by altered

content of consciousness are delirium and dementia. De-

lirium is characterized by disorientation, attention defi-

cit, a feeling of fear, irritability and changes in the per-

ception of sensory stimuli, such as visual hallucinations.

In dementia, there is the progressive and permanent loss

of cognitive function over months or years, without chang-

es in alertness or level of consciousness.

The following behavioral states can be commonly

confused with coma: persistent vegetative state, minimal-

ly conscious state, abulia, catatonia, locked-in syndrome,

akinetic mutism and psychogenic passivity (Table 1). The

first two can be states subsequent to coma.

TABLE 1

Types of consciousness disorder; -(absent),

+(present); UWS: unresponsive wakefulness syndrome.

State

Alert

Consciousness

Coma

Persistent vegetative state/UWS

+++ -

Minimally conscious state

+++

Delirium

Abulia

Catatonia

Akinetic mutism

+++

Locked in syndrome

+++

Psychogenic passivity

+++

The clinical definition of the vegetative state, most recent-

ly described as unresponsive wakefulness syndrome

(UWS)

5,8,10

the clinical condition of complete unconscious-

ness of self and the environment. However, the sleep-wake

cycle is maintained and the autonomic functions of the

hypothalamus and brainstem are completely or partially

preserved.

6,8

The patient usually presents reflexes, eye

opening and spontaneous breathing and may perform

spontaneous movements like chewing and swallowing,

emitting unintelligible sounds, and demonstrating cer-

tain spontaneous reactions such as smiling and crying.

The main causes are TBI and cardiorespiratory arrest.

These symptoms must be present for more than 4 weeks

after the event that led to brain injury.

In a minimally conscious state, the patient may pos-

sess some degree of consciousness, obey verbal commands

sporadically, and try to communicate; however, this is

most often unintelligible, and they may cry or smile in

response to affective stimuli, as well as track moving ob-

jects, voices or people.

Abulia is a behavior in which there is serious indiffer-

ence with a reduction or absence of emotional or mental

behavior, in which the patient does not speak or move

spontaneously, although alert and recognizing stimuli

from the environment.

This usually occurs in patients

with bilateral frontal lesions. Akinetic mutism presents

symptoms similar to those of abulia but less severe; the pa-

tient shows an unwillingness/extreme difficulty to move

or speak, with the level and content of consciousness pre-

served, and eyes following the observer or sound although

the patient does not obey commands. Muscle tone and re-

flexes are usually intact. In the case of locked-in syndrome,

the patient also has the level and content of consciousness

preserved; however, the patient presents complete paraly-

sis, preventing any type of movement or verbal communi-

cation. In some cases, eye movement may be present. This

syndrome usually occurs in patients with basilar artery

thrombosis and ischemic infarction of the base of the pons

and must be differentiated from coma and persistent veg-

etative state. This condition may show symptoms similar

to those of acute polyneuropathies, myasthenia gravis and

acute use of neuromuscular blockers. Advances in the field

of neuroimaging suggest a new diagnosis: Functional

locked-in syndrome. In this condition, patients do not

show any behavioral signs of consciousness and differ from

patients who are in a vegetative state as only examinations

such as functional magnetic resonance imaging, positron

emission tomography or evoked potential tests are able to

identify responses that suggest some degree of conscious-

ness.

Catatonia is a state in which the individual may re-

main mute and with a marked decrease of motor activity,

usually associated with psychiatric symptoms, but it can

also occur due to metabolic disorders or induced by drugs.

The patient exhibits bizarre and repetitive behavior, pos-

ture disturbances and rigidity.

Psychogenic passivity is also associated with psychi-

atric conditions and includes preserved muscular tone,

resistance to passive movement of the limbs, resistance

to opening of the eyelids or forcibly closed eye, eyes fo-

cused on the ground regardless of the side on which they

are lying, or the presence of non-epileptic seizures.

So, how can we differentiate a patient in a coma from

a brain dead patient? In brain death, brain damage is so

extensive that there is no potential for structural and

functional recovery of the brain and internal homeosta-

sis cannot be maintained. What separates the state of

coma from a diagnosis of brain death is the irreversible

nature of the latter, with systemic repercussions on the

homeostasis of vital organs, based on permanent focal or

diffuse structural damage to the brain.