Emergence from the minimally conscious state

The emergence from the minimally conscious state is defined by the ability to use functional interactive communication or functional use of objects [1].

 

recovery from coma

 

Figure. Different clinical entities encountered on the gradual recovery from coma, illustrated as a function of cognitive and motor capacities. From Laureys et al., Current Opinion in Neurology, 2005.


Restoration of spontaneous or elicited eye-opening (bilateral ptosis should be ruled out as a complicating factor), in the absence of voluntary motor activity, marks the transition from coma to vegetative state (VS).

The passage from the VS to the minimally conscious state (MCS) is marked by reproducible evidence of 'voluntary behavior' defined as (1) simple command following, (2) gestural or verbal yes/no responses (regardless of accuracy), (3) intelligible verbalization, or (4) motor activity occurring in contingent relation to relevant, often emotional, stimuli (also including pursuit eye movement or sustained fixation).

Emergence from MCS is signaled by the return of functional communication or object use.

The Glasgow Outcome Scale then terms patients as severely disabled until return of autonomy (coined moderate disability). Return to work or school determines the transition to 'good recovery'. Note that our clinical evaluation of cognition depends upon motor responsiveness.

The locked-in syndrome (LIS) is the extreme example of intact cognition with nearly complete motor deficit (only permitting eye-coded communication).

It remains controversial from what stage neurological recovery is 'meaningful' and when a palliative care approach is warranted.

 

 

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.