A 68-year-old woman with no history of headache, hypertension or medications consulted our hospital for general malaise. No abnormalities were detected in any examination. However, brain imaging using MRI showed abnormalities in the white matter of the occipital lobes (fig 1A). She was placed on a close follow-up without any treatment. Four months later, she suddenly became apneic followed by hyperventilation. No neurological deficits were seen at admission, apart …