Intermediate
Technical
In the Industry Vocabulary Test
mass effect
Displacement or compression of brain structures caused by an expanding lesion or collection.
Full Definition
Mass effect refers to the displacement, distortion, or compression of normal brain structures caused by an expanding intracranial lesion, hematoma, or other space-occupying process. This phenomenon occurs because the skull provides a fixed volume, and any additional mass must displace normal tissue. Mass effect can manifest as midline shift, ventricular compression, herniation syndromes, or compression of vital structures. The degree of mass effect often correlates with clinical symptoms and may require urgent intervention to prevent life-threatening complications.
Usage
Usage note: Hyphenate when used as an adjective (mass-effect phenomenon).
In Context
- "The large frontal hematoma demonstrates significant mass effect with 8mm of midline shift." — Emergency CT report
- "No appreciable mass effect is seen despite the size of the lesion." — Follow-up imaging report
Also known as
space-occupying effect
mass effect phenomenon
Contrasted with
no mass effect
negative mass effect
Don't confuse with
midline shift
herniation