Circadian rhythms in the vegetative state.

OBJECTIVE

To evaluate whether vegetative state patients maintain circadian rhythms.

RESEARCH DESIGN

An observational study of five single cases.

METHODS AND PROCEDURES

Five chronic vegetative state patients underwent clinical and neurological evaluations and 2-week continuous temperature measurements.

MAIN OUTCOMES AND RESULTS

The two patients with traumatic brain injury showed well-formed circadian temperature rhythms and had more reflexive behaviours and relatively low cortical and sub-cortical atrophy, whereas the three patients from anoxic-hypoxic origin demonstrated no cycles or rhythmic behaviour.

CONCLUSIONS

The presence of periods of wakefulness does not imply preserved sleep-wake cycling capacity, nor preserved circadian rhythms and it should not be taken as a distinguishing feature for the definition of the vegetative state.