Vegetative state is a separate type of disturbance of consciousness, characterized by the preservation of the functions of the hypothalamus and brain stem with gross dysfunction of the cerebral hemispheres. It is a way out of a deep coma. There are no signs of mindfulness, intervals of wakefulness, opening/closing of the eyes, preservation of unconditional reflexes are characteristic. Vegetative state is diagnosed clinically. Additionally, EEG, MRI, PET, VP examination, cerebral hemodynamics are carried out. Treatment consists in stimulating the resumption of work of the hemispheres, ensuring adequate nutrition and care, and preventing possible complications.
ICD 10
R40.2 Coma, unspecified
General information
The term “vegetative state” (VS) has been introduced since 1972. “Vegetate” means to live, exercising all the functions of a biological organism, except social and intellectual. At the heart of the VS is a violation of awareness of the environment and one’s personality, which is the result of the disintegration of the functions of the cerebral cortex and subcortical structures. The degree of the disorder is assessed by specialists from the field of neurology and intensive care by clinical signs using special standardized scales. Today, medicine does not possess accurate instrumental methods of assessing consciousness. The inability to respond to external stimuli definitely does not exclude the possibility of their conscious perception. Therefore, it is impossible to reliably determine whether a vegetative perceives the speech of others, whether he lives a separate “inner” life, etc.
Causes
The syndrome is based on cerebral dysfunction resulting from the effects of various brain-damaging factors. By the nature of the action , the following types of etiofactors are distinguished:
- Mechanical. Severe traumatic brain injuries: brain contusion, diffuse axonal injury. They cause a coma with a transition to a vegetative state in 50% of cases.
- Metabolic: hypoxia and acute intoxication. Hypoxic brain damage develops as a result of extensive ischemic stroke, cardiac arrest, asphyxia, significant arterial hypotension, carbon monoxide poisoning. Toxic damage to cerebral structures is observed in drug overdose, exposure to neurotropic poisons, acute dysmetabolic conditions (uremia, hepatic coma, hyper- or hypoglycemia in diabetes mellitus).
- Organic. Caused by structural changes in cerebral tissues. They include brain tumors, intracranial hemorrhages, infectious lesions (encephalitis, meningitis).
Pathogenesis
The influence of these etiological factors provokes the rupture of connections between the cortex, reticular formation and subcortical centers. A coma develops. Coming out of the coma is due to the resumption of the lost cerebral connections, the formation of new interneuronal contacts, enhanced functioning of the preserved synapses, reactivation of neurotransmitters. The result is an “awakening reaction” — the patient opens his eyes. Then there is a gradual restoration of consciousness. A vegetative state occurs if the recovery processes are delayed at the stage of “awakening”. Presumably, this is due to the pathological course of the reintegration processes.
Morphologically, VS is characterized by diffuse necrotic changes in the cortex and thalamus, widespread damage to the subcortical substance. Less often there is cerebral atrophy, demyelination of subcortical structures. Some authors suggest that the activation of apoptosis — the removal of defective cells by the body – plays a leading role in the pathogenesis of VS.
Symptoms
VS is characterized by the preservation of all vital functions: adequate cardiovascular activity, respiration, digestion. There is no contact with the environment and signs of awareness of what is happening around. Conscious reactions to stimuli, purposeful motor acts have been lost. The patient can make movements within the framework of unconditional reflexes: to show non-directional motor activity in response to a painful impulse, to grab an object touching the brush. Chewing and swallowing reflexes are preserved. The patient performs chewing movements, swallows food placed in his mouth, yawns, and gnashes his teeth. He is able to blink, involuntarily move his eyes. Tear production is preserved.
The vegetative state is characterized by the presence of periods of wakefulness when the patient opens his eyes. The opening of the eyes is noted with flashes of light, loud sounds. Speech is absent, vocalization is observed — the ability to produce individual sounds. Painful effects sometimes cause groans or sighs. Slow spontaneous movements of the eyeballs should be distinguished from conscious gaze tracking. Along with guttural sounds and sighs, they cause the relatives of the vegetative to have a false impression of restoring awareness.
The duration of the sun varies from several months to ten years. There are 2 stages. If the symptoms persist for more than 1 month, they talk about persistent VS. Duration of symptoms >3 months. with non-traumatic genesis and > 12 months. in case of traumatic refers to permanent sun. The exit of patients from the vegetative state occurs through a state of small consciousness. The first signs: fixation of the gaze, eye tracking, execution of simple requests (show tongue, squeeze fingers).
Complications
Due to the almost complete immobility of patients in the VS, joint contractures, bedsores, and congestive pneumonia develop. The need for constant catheterization of the bladder causes the risk of infection of the urinary tract with the development of pyelonephritis, urosepsis. These complications may cause the death of the patient. Sudden death is possible. Careful care, prevention of bedsores, necessary supportive therapy can prevent the development of complications and prolong the patient’s life.
Diagnostics
The vegetative state is diagnosed according to the following clinical criteria: the absence of signs of awareness, the presence of sleep-wake phases, the preservation of unconditioned reflexes and nervous regulation of vital functions. The diagnosis is carried out by a neurologist during the study of the neurological status. Instrumental methods of examination are used to assess cerebral hemodynamics, metabolism, bioelectric activity:
- Electroencephalography registers delta and tetarrhythm, sometimes – paroxysmal flashes. In exceptional cases, an alpha rhythm close to normal is observed.
- The study of evoked potentials gives a heterogeneous picture. Indicates anatomical interruption of the conducting cerebral tracts.
- MRI of the brain reveals nonspecific changes: signs of atrophy, an increase in the volume of the ventricles and subarachnoid spaces. Some clinicians trace the relationship of the degree of atrophic changes with the prognosis of the sun.
- Ultrasound of intracranial vessels allows us to judge the state of cerebral blood flow. It reveals a violation of venous outflow, difficulty in perfusion.
- PET of the brain diagnoses a 50 percent decrease in metabolic processes in the cortex. Permanent sun is accompanied by a drop in metabolism to the level of 40-30% of normal. The exit from the sun is accompanied by activation, first of all, of the multifunctional areas of the associative cortex.
It is necessary to differentiate the vegetative state from coma. Unlike patients with coma, vegetarians retain unconditional reflexes, there is an opening of the eyes to strong sound stimuli and pain effects, there is a change of sleep-wakefulness phases.
Treatment
Recent studies have refuted the claim that adult nerve cells do not regenerate. Cerebral progenitor cells and stem cells with the ability to transform into neurons have been found. Recovery is possible due to the proliferation of processes of preserved nerve cells, the use of reserve brain areas. SUN therapy is reduced to stimulation of the listed recovery processes. It is carried out against the background of adequate patient care and prevention of complications. Therapeutic tactics include:
- Stimulation of the restoration of consciousness. It implies pharmacotherapy and regular sensory effects. Visual, auditory, olfactory, painful, tactile stimuli are used with a gradual increase in stimulation time. The method is aimed at eliminating sensory hunger, which prevents the exit from vegetative consciousness. The search for effective methods of activating cerebral reintegration continues. Japanese and French doctors are conducting research in the direction of electrical stimulation of the brain stem. The positive effect of amphetamines was revealed.
- Prevention and treatment of complications. Proper use of catheters, timely change of diapers, changing the patient’s posture, dropping the patient off with the help of orthopedic systems help to avoid the addition of secondary infection. Massage, passive movements, medical correction of muscle tone are necessary to combat contractures. The development of the latter is eliminated by tendotomy.
- Artificial nutrition. It should ensure adequate intake of calories, proteins, trace elements, vitamins into the body. Preferably feeding by gastrostomy. Probe feeding can be complicated by aspiration, mucosal ulcers, gastroesophageal reflux.
- Optimal care. It includes brushing teeth, regular change of underwear, controlling the patient’s posture, maintaining adequate moisture of the skin.
Treatment is carried out with the involvement and training of the rules of care of the patient’s relatives. Persistent vegetative state is an indication for the use of methods of stimulation of the central nervous system. With a permanent course, the main task of therapeutic measures becomes the prevention of complications.
Prognosis and prevention
The outcome of VS depends on the cause of occurrence, the age of the patient, the duration of the previous coma and the period of vegetative consciousness. Recovery occurs during the first 3 months of non-traumatic sun, throughout the year from the moment of the post-traumatic SUN. The literature indicates cases of improvement in a later period. Motor activity is better restored in young patients. The resumption of the functioning of the cortex to the previous level does not occur, in most cases severe disability is observed. When the duration of the sun is > 6 months. five-year survival is observed in a quarter of vegetarians. As a rule, these are cases of well-placed care and supervision. Prevention of VS includes prevention of TBI, vascular catastrophes, exogenous intoxication, neuroinfections, timely correction of metabolic disorders.