Brain lesions detected by magnetic resonance imaging in mild and severe head injuries

50 patients were studied by magnetic resonance imaging (MRI) within one week of a head injury. Abnormalities indicating primary brain damage were found in 46 patients, almost twice as many as with computed tomography. Cortical contusions were the most common finding, irrespective of the effect of injury on the level of consciousness. Intracerebral lesions were seen only in patients who had lost consciousness and were present in 29 of 42 patients whose consciousness was still impaired on arrival at hospital. Lesions in the deep white-matter of the cerebral hemispheres were seen in 15 patients; they were significantly more frequent in patients in coma but were also seen in patients who had lost consciousness for no more than 5 min. The findings indicate that lesions in the cerebral hemispheres may be the primary factor in traumatic unconsciousness. MRI studies may also clarify the sequelae of head injuries.