[Evaluation of comatose states]

The most informative neurological symptoms allowing the differentiation of 7 phases of consciousness disorders have been identified on the basis of clinico-physiological correlations and mathematical processing. In the first phase of coma the patient cannot be waken up. Addition of muscle atonia characterizes the transfer to the second phase of coma and of bilateral mydriasis indicates the transfer to the third phase. Eye opening in response to sound or pain points to awakening and transfer to the phase of apallitic syndrome. The performance of simple instructions is characteristic of the phase of deep stupor. Responses to questions characterize stupor, and recovery of orientation in the environment indicates clear consciousness.