Akinetic Mutism

Definition and Clinical Features
Pathophysiology and Anatomical Correlates
Causes and Treatment
References

Definition and Clinical Features

Akinetic mutism is a profound neurological state often described as a "syndrome of negatives." It is characterized by a lack of voluntary movement (akinesia) and the absence of speech (mutism). Patients do not respond to questions or commands, yet they maintain normal alertness and sleep-wake cycles, distinguishing the condition from a coma.

Despite the profound inactivity, eye-opening and spontaneous blinking are preserved. Primitive reflexes, such as grasping and sucking (Frontal Release Signs), may be present. There is a notable lack of upper motor neuron signs, suggesting that descending motor pathways are relatively intact. Abulia, a state of severe apathy and lack of initiative, is considered a lesser form of akinetic mutism.

Akinetic mutism is a state of "wakeful unresponsiveness," where the patient appears alert with open eyes but does not move or speak.

Pathophysiology and Anatomical Correlates

Pathologically, akinetic mutism is associated with bilateral lesions affecting the "centromedial core" of the brain. These lesions interrupt crucial reticular-cortical or limbic-cortical pathways responsible for motivation and initiation, while sparing the primary corticospinal motor pathways. This damage can occur at any point from the frontal lobes to the brainstem, with key areas being:

The anterior cingulate cortex (medial frontal region)
The paramedian reticular formation, posterior diencephalon, and hypothalamus

Causes and Treatment

Akinetic mutism can arise from various pathologies, including vascular events, tumors, or structural issues like subacute communicating hydrocephalus. It may also represent the final common pathway for a number of end-stage neurodegenerative diseases.

Occasionally, treatment of the underlying cause can lead to improvement (e.g., shunting for hydrocephalus). Pharmacological agents that modulate dopamine, such as dopamine agonists (e.g., bromocriptine) and stimulants like ephedrine, have also been tried with some anecdotal success.