Magnetic resonance imaging in cases of persistent vegetative state

Magnetic resonance imaging (MRI) was used to investigate 6 cases of a persistent vegetative state and 3 cases who had regained consciousness from a coma prolonged for over one month. All nine states were caused by cerebrovascular diseases or by injuries to the central nervous system. The cases of persistent vegetative states were divided neurologically into two groups in terms of the cognitive responses. Group A (3 cases) had no cognitive responses, while Group B (3 cases) had some cognitive responses. The MRIs of Group A showed paramedian lesions in the tegmentum of the mesencephalon. In the MRIs of Group B, some localized lesions were detected in the brain stem, but they were not involved with the tegmentum. Conversely, all three cases with a good recovery of consciousness were almost free from injuries to the brain stem. Brain-stem auditory-evoked potentials (BAEP) were performed in 8 cases; the only exception had a good recovery of consciousness. Mild to moderate conduction delays of the V wave with an increase in the I - III or III - V interwave latencies were noted in half of the vegetative-state patients. MRI was thus found to be useful in predicting the prognosis of these vegetative-state patients. (author)