Akinetic mutism: types, symptoms and causes
Akinetic mutism is a syndrome that is characterized by a reduction in the frequency of movements, including verbal behaviors, associated with motivational deficits that occur as a result of brain damage.
In this article we will describe What is akinetic mutism? and what are its symptoms, causes and main types.
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What is akinetic mutism?
In the year 1941 Cairns, Oldfield, Pennybacker and Whitteridge described the case of Elsie Nicks, a 14-year-old girl with a cyst in the right lateral ventricle. As it grew, the malformation caused Elsie increasingly intense headaches that led doctors to apply a treatment with morphine.
The patient began to show signs of apathy along with significant impairments in her ability to speak and to control movements. The symptoms progressed to a state that Cairns and his collaborators baptized with the name "akinetic mutism".
These authors described the disorder as a state in which the person remains immobile , although it can fix the look in objects and follow movements. Statism also affects the movements necessary for speech and other vocalizations. Although sometimes actions are carried out and sounds are issued, these are usually not voluntary.
As we will see below, the Cairns team's proposal has been updated over the years and the consequent scientific progress. Nowadays the term "akinetic mutism" is often used to describe any case that shows the absence of motor and verbal behavior which give it a name, and which may also consist of less serious deficits.
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Symptoms and main signs
Cairns et al. (1941) pointed out five key signs for the diagnosis of akinetic mutism: the presence of alertness, the ability to fix the gaze on other people, the execution of eye movements as a reaction to auditory stimuli, actions in response to orders that are they repeat and the difficulties to talk and communicate in general.
However, at present we have more specific knowledge about akinetic mutism. In his review of the relevant scientific literature, Rodríguez-Bailón et al. (2012) conclude that significant reduction in the number of verbal behaviors and the ability to follow objects with the gaze they are the two basic diagnostic criteria.
The authors of this work highlight the variability of emotional disturbances in these cases. Thus, patients with obvious impairments in the expression of emotions have been identified, but also others with signs of disinhibition. This clinical diversity has to do with the specific location of the brain lesions that cause akinetic mutism.
The immobility characteristic of this alteration is manifested in all facets of motor skills, so that those who have akinetic mutism can not talk, make gestures or form facial expressions , or they suffer serious difficulties to do it. When they do, movements tend to be slow and scanty, and monosyllabic responses.
People with akinetic mutism are not paralyzed at motor level, but the alterations that cause it seem to affect the will and motivation to perform behaviors, including verbal ones. Many patients with this disorder have reported that they notice a resistance that prevents them from moving when they try to do so.
Types of akinetic mutism and its causes
The symptoms and signs of each case of akinetic mutism depend on the brain regions damaged by the causative factor of the disorder. Broadly speaking, we can distinguish two variants of akinetic mutism: the frontal and the mesencephalic mutism, which are associated with lesions in the frontal lobe of the brain and in the mesencephalon, respectively.
Frontal akinetic mutism is frequently due to alterations in the blood supply, specifically in the anterior cerebral artery. Disorders and strokes are the most frequent causes of akinetic mutism, although it can also appear as a consequence of infections, contact with toxic substances and neurodegenerative diseases.
When akinetic mutism arises as a result of frontal lesions, it often appears together with signs of disinhibition typical of the frontal syndrome. Thus, in these cases impulsive emotional responses are frequently related, especially with passivity.
The mesencephalon is a subcortical structure that contains brain nuclei as relevant as the colliculi, involved in visual and auditory perception, and the substantia nigra, fundamental in the production of dopamine and therefore in the reinforcement. This kind of akinetic mutism it is associated with hypersomnolence and motivational deficits .
Akinetic mutism can also be caused by respiratory arrest (which can lead to cerebral hypoxia), head trauma, tumors, meningitis, hydrocephalus, damage to the thalamus, destruction of the cingulate gyrus, and Creuztfeldt-Jakob disease, a neurodegenerative disorder caused by prion infections.
Bibliographic references:
- Cairns, H .; Oldfield, R. C .; Pennybacker, J. B. & Whitteridge, D. (1941). Akinetic mutism with an epidermoid cyst of the 3rd ventricle. Brain, 64 (4): 273-90.
- Rodríguez-Bailón, M .; Triviño-Mosquera, M .; Ruiz-Pérez, R. & Arnedo-Montoro, M. (2012). Akinetic mutism: review, proposal of neuropsychological protocol and application to a case. Annals of Psychology, 28 (3): 834-41.
