gms | German Medical Science

Objective: The aim of this prospective study was to determine the predictive value of brainstem tractography in patients with severe head injury.

Methods: 20 patients with severe head injury were included. 12 patients (60 per cent) were male. Median age at the time of injury was 36.5 years (mean: 40 years, range: 14 to 90 years). Diffusion tensor raw data was acquired at 1.5 Tesla within one week after the injury. Data conversion and tractography were performed using the Mricronmac and MedINRIA software packages. Tractography images were analysed for lesions of the pyramidal and somatosensory tracts in the brainstem. Outcome at 6 months after the injury was assessed with the Glasgow Outcome Score (GOS). Statistical analysis was conducted using Fisher's Exact test, whereas p less than 0.05 was supposed to be statistically significant.

Results: 6 months' mortality was 30 per cent. In patients with bilateral lesions of the pyramidal tract, 6 months' mortality was higher as compared to other patients (42.9 vs. 23.1 per cent, p=0.61). In patients with bilateral lesions of the somatosensory tracts, 6 months' mortality was slightly higher as compared to other patients (33.3 vs. 28.6 per cent, p=1). At 6 months after the injury, favourable outcomes (GOS 4 and 5) were absent in patients with bilateral lesions of the pyramidal or somatosensory tracts. Favourable outcomes at 6 months after the injury were found in 5 out of 13 patients with unilateral or no lesion of the pyramidal tract (38.5 per cent vs. 0 per cent, p=0.11) and in 5 out of 14 patients with unilateral or no lesion of the somatosensory tracts (35.7 per cent vs. 0 per cent, p=0.26). 3 out of 6 patients with bilateral lesions of the somatosensory tracts in or below the midbrain were in persistent vegetative state (PVS) at 6 months after the injury, whereas no other patient was in PVS at 6 months after the injury (50 per cent vs. 0 per cent, p=0.018).

Conclusions: In patients with severe head injury, bilateral lesions of the somatosensory tracts in or below the midbrain as visualized in brainstem tractography at 1.5 Tesla are significantly correlated with PVS at 6 months after the injury. Therefore, we consider brainstem tractography at 1.5 Tesla suitable to predict PVS in patients with severe head injury. The correlation of brainstem tractography with other outcomes should be studied in larger series of patients and/or at a higher magnetic field strength.