This is a basic article for medical students and other non-radiologists
Midline shift is a finding described on transverse (axial) slices from CT and MRI studies. It describes the situation where the midline of the intracranial anatomy is no longer in the midline and is the result of pushing or pulling forces within either side of the intracranial compartment.
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Reference article
This is a summary article; read more in our article on midline shift.
Summary
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anatomy
- midline structures
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pathophysiology
- the midline is either pushed or pulled out of place
- extra-axial collection causing mass effect
- parenchymal tumor causing mass effect
- stroke with associated edema causing mass effect
- the midline is either pushed or pulled out of place
Imaging
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role of imaging
- is there midline shift?
- if it was present previously, is it worse?
- what is the likely cause?
- is there an acute cause that needs an immediate intervention?
- who needs to know now?
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radiographic features
- midline structures should be in the midline
- if they are not, pathology may be causing displacement
- extra-axial collection
- parenchymal mass lesion
- parenchymal edema (secondary to underlying lesion)
- if they are not, pathology may be causing displacement
- parenchymal shift under the fibrous falx can cause injury
- midline shift may obstruct the lateral ventricular outflow and result in secondary hydrocephalus
- midline structures should be in the midline