From the Guidelines
Midline shift greater than 5mm on brain imaging is strongly associated with poor outcomes in patients with traumatic brain injury, and urgent neurosurgical consultation is recommended to reduce intracranial pressure and prevent further brain damage. This correlation is supported by the management guidelines for severe traumatic brain injury, which suggest monitoring intracranial pressure (ICP) after post-traumatic intracranial haematoma evacuation in cases with preoperative severity signs on cerebral imaging, including brain midline shift over 5 mm 1. The guidelines also indicate that neurosurgical indications at the early phase of severe TBI include removal of a significant acute subdural haematoma with displacement of the median line greater than 5 mm 1.
The poor outcomes associated with significant midline shift include increased mortality, severe disability, prolonged hospital stays, and cognitive impairments. This correlation exists because midline shift indicates mass effect with compression of vital brain structures and potential herniation syndromes, which disrupt normal brain function and blood flow. The degree of shift correlates with outcome severity - shifts exceeding 5mm represent significant brain displacement that often compromises cerebral perfusion and neurological function.
Key considerations in managing patients with midline shift greater than 5mm include:
- Urgent neurosurgical consultation to determine the need for intervention to reduce intracranial pressure
- Treatment options such as osmotic therapy with mannitol or hypertonic saline, hyperventilation, elevation of the head of bed, and possibly surgical decompression depending on the underlying cause
- Continuous intracranial pressure monitoring if the Glasgow Coma Scale score is less than 9
- Attention to the control of systemic haemodynamics in the choice of drugs and their modalities of administration 1.
Overall, the correlation between midline shift greater than 5mm and poor outcomes in patients with traumatic brain injury emphasizes the importance of prompt recognition and management of this condition to improve patient outcomes.
From the Research
Correlation between Midline Shift and Poor Outcomes in TBI
- The correlation between midline shift of more than 5 millimeters and poor outcomes in patients with traumatic brain injury (TBI) is supported by several studies 2, 3.
- A study published in 2015 found that a lateral ventricular volume ratio (LVR) of >1.67 was associated with a sensitivity of 73.3% and a specificity of 73.3% for predicting midline shift development of >5 mm 2.
- Another study published in 2010 found that the degree of midline shift on CT scans was related to the severity of head injury and was significantly associated with poor clinical outcomes, with 81% of patients with midline shifting greater than 10 mm having severe head injury 3.
- However, the exact mechanism driving midline shift is still debated, with some studies suggesting that cerebral perfusion pressure rather than intracranial pressure may be the driving force behind midline shift 4.
- The use of computer tomography (CT) imaging and measurements of midline shift can assist physicians in diagnosing injury and guiding treatment, and may allow for earlier interventions to attenuate midline shift and improve outcomes 5, 2.
Predictive Value of Midline Shift
- Midline shift has been established as a predictor of poor outcome in TBI patients, with studies showing a correlation between the degree of midline shift and clinical outcomes 2, 3.
- The predictive value of midline shift is supported by studies that have found associations between midline shift and other clinical parameters, such as Glasgow Coma Score (GCS) and lateral ventricular volume ratio (LVR) 2, 3.
- However, the predictive value of midline shift may be influenced by other factors, such as the presence of interhemispheric pressure gradients and cerebral perfusion pressure 4.