Detecting brainstem injury with acute MRI following severe head trauma

Abstract

Traumatic brain injury (TBI) is the most common cause of death and major disability in young people. Outcome is often difficult to predict from factors such as mechanism of injury, initial Glasgow Coma Score and imaging. Currently, CT is the imaging modality of choice and has led to the introduction of complex CT-based classification systems of head injury. CT is satisfactory for the detection of haematomas and contusions in the cerebral hemispheres but is much less effective at documenting diffuse injury and posterior fossa lesions. There are, therefore, a significant number of patients in whom outcome is much worse than would be predicted from their presenting CT scan. This aim of this study is to look at the role of acute MRI (T2, FLAIR, gradient echo) in detecting the presence of brainstem injury in patients following TBI and to correlate the findings with outcome at 6 months (Glasgow Outcome Score). Twenty-nine patients (mean age 37 years, range 18-70, 79% male) admitted to the neuro-critical care unit with TBI requiring ventilation underwent CT and MRI within 3 days of injury. Brainstem lesions were detected in 7 patients on MRI scan but none were diagnosed by CT. The types of brainstem injury varied widely and an assessment was made as to whether injury type had any relationship with the nature of supratentorial injury. All 7 patients with brainstem injury had an unfavorable outcome (death, vegetative state or severe disability). Of the 22 patients without brainstem lesions, 10 had a poor outcome. The relationship between brainstem lesions and outcome was highly significant. (p<0.005, Chi Squared Test). This study suggests that early MRI detects a significant number of brainstem lesions that are not seen on CT and offers the potential to increase our understanding of the nature of supratentorial injury following head trauma.