A 69-year-old man presented with a sudden headache followed by unconsciousness. There was no head injury. The Glasgow Coma Scale (GCS) score was 3/15 and there was a left mydriasis, unreactive to light. The CT-scan showed a left acute subdural haematoma causing a remarkable mass effect. A supratentorial hemispheric craniotomy was performed. Nevertheless, after several weeks at the intensive care unit (ICU), the patient was still unresponsive to external stimuli and did not show any motor activity. A comfort care attitude was decided on with the family and the patient was extubated. However, a few days later, the patient subsequently showed a surprisingly favourable course, with improved wakefulness. Indeed, the GCS score improved, and the treatment plan was modified so that the patient benefited from rehabilitation. The MRI showed a right cerebral peduncle lesion, consistent with a Kernohan-Woltman notch phenomenon (KWNP). Six months later, the patient was able to walk and live quite normally.