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Minimally conscious state

The criteria for the minimally conscious state were recently proposed by the Aspen group to subcategorize patients above the vegetative state but unable to communicate consistently.

To be considered as minimally conscious, patients have to show limited but clearly discernible evidence of consciousness of self or environment, on a reproducible or sustained basis, by at least one of the following behaviors: (1) following simple commands, (2) gestural or verbal yes/no response (regardless of accuracy), (3) intelligible verbalization, (4) purposeful behavior (including movements or affective behavior that occur in contingent relation to relevant environment stimuli and are not due to reflexive activity).

The emergence from the minimally conscious state is defined by the ability to use functional interactive communication or functional use of objects [1]. Further improvement is more likely than in vegetative state patients [2]. However, some remain permanently in a minimally conscious state.

“Akinetic mutism” is an outdated term that should better be avoided [3] and is now considered to be a subcategory of the minimally conscious syndrome [1, 4]. It was first introduced by Cairns in 1941 to describe a condition characterised by severe poverty of movement, speech and thought without associated arousal disorder or descending motor tract impairment[5]. Typical for akinetic mutism is the complete or near-complete loss of spontaneity and initiation so that action, ideation, speech and emotion are uniformly reduced. The absence of internally guided behavior allows attention to be passively drawn to any environmental stimulus that the patient is exposed to [2]. The preservation of spontaneous visual tracking and occasional, albeit infrequent, speech and movement to command, help differentiate akinetic mutsim from the vegetative state. It is classically caused by bilateral lesions in orbito-mesial frontal cortex, limbic system encompassing anterior cingulate cortex and paramedian meso-diencephalic reticular formation [6].

 

References

1.         Giacino, J.T., et al. (2002). The minimally conscious state: Definition and diagnostic criteria. Neurology  58, 349-353.
2.         Giacino, J.T. (1997). Disorders of consciousness: differential diagnosis and neuropathologic features. Semin. Neurol.  17, 105-111.
3.         ANA Committee on Ethical Affairs (1993). Persistent vegetative state: report of the American Neurological Association Committee on Ethical Affairs. Ann. Neurol.  33, 386-390.
4.         American Congress of Rehabilitation Medicine (1995). Recommendations for use of uniform nomenclature pertinent to patients with severe alterations of consciousness. Arch. Phys. Med. Rehabil.  76, 205-209.
5.         Cairns, H., Oldfield, R.C., Pennybacker, J.B., and Whitteridge, D. (1941). Akinetic mutism with an epidermoid cyst of the third ventricle. Brain  64, 273-290.
6.         Nemeth, G., Hegedus, K., and Molnar, L. (1986). Akinetic mutism and locked-in syndrome: the functional-anatomical basis for their differentiation. Funct Neurol  1, 128-139.