Assessment of Brain Midline Shift Using Sonography in Traumatic Brain Injury (TBI) in Critically Ill Patients: A Comparative Study with CT

Brain midline shift (MLS) is a life-threatening condition that requires urgent diagnosis and treatment.

The aim of this study was to assess brain midline shift using transcranial sonography in comparison to plain CT.

The study was carried out on 45 neurocritical patients of both sex admitted to the critical care department in Ain shams University Hospital. The ultrasound MLS was assessed through the temporal bone window by measuring the distance from skull to the third ventricle on both sides prior to plain CT. CT MLS was determined either by the distance from the external bone table to the center of the third ventricle bilaterally (method 1) or the distance between the ideal midline and the septum pellucidum (method 2).

60% of patients were males, the mean GCS on admission was 7.12±1.66.All the patients were mechanically ventilated.

Measurement of MLS by transcranial sonography was possible in all 45 patients. MLS of 4.29 ± 2.17 mm. A MLS >6 mm was observed in 24% (11/45) of the patients. CT MLS was 5.18 ± 2.49 mm (using method 1) and 5.35 ± 2.64 mm (using method 2). A MLS >8 mm with CT was observed in 29% (13/45) of the patients. The sensitivity and the specificity of US to detect a significant MLS (that is, MLS >5 mm) was 100, 91.3% respectively when using CT method (2) to measure MLS. The sensitivity and the specificity of US to detect a significant MLS (that is, MLS >5 mm) was 95.2, 95.8% respectively when using CT method (1) to measure MLS. The correlation coefficient between (the difference between US MLS and CTMLS) and CTMLS was 0.619 (p < 0.001).The smaller the MLS the narrower the difference between the measurement of USMLS and CTMLS. The narrowest difference between US MLS and CT MLS 0.5 (0.5 -0.7) was at MLS <2 mm. At this reading was the most accurate point of comparison between US MLS and CTMLS. The relation between US MLS and GCS was statistically significant, the greater the US MLS the lower the GCS. The relation between US MLS and length of ICU stay and ventilation days was tested and it was statistically significant. The greater the US MLS the longer the length of ICU stay and ventilation days. There was significant relation between US MLS and mortality, 100 % of the cases survived with US MLS less than 4 mm. 100 % of the cases with US MLS greater than 6 mm died. The greater the US MLS the higher the mortality.

This study suggests that TCS can be used as an easy bedside tool to detect MLS in neurocritical patients.