Midline shift refers to when a person’s brain actually shifts beyond the center line of the brain. The shift is normally caused by a traumatic event involving the brain or head, and can indicate further problems with the brain, such as intracranial pressure or tumor growths. The brain normally shifts away from a traumatized section, causing neurological abnormalities that affect the behavior of the patient.
Causes of midline shift normally involve a violent event that impacted a person’s brain negatively. A severe head injury, such as a car accident or serious collision in a contact sport, can cause the brain to shift. Other traumatic events that can affect the positioning of the brain include strokes, brain swelling or the development of a brain tumor.
People who have suffered a midline shift show some specific signs of the condition. A person might lean to the side of the body that matches the direction the brain has shifted, and experience problems with walking straight or running into obstacles. The patient’s vision might also be affected, causing problems with perceiving spatial relationships and performing simple motor skills activities such as using playing cards. If a person is suffering from a shift, shining a light in his eyes does not cause the pupils to shrink as they normally would.
Treatment of midline shift might involve the patient using specialized prescription glasses. These glasses contain yoked prisms that affect the patient’s visual perception, compensating for the shift’s changes to the person’s vision. Wearing the glasses, a person who suffers from this condition can once again balance and otherwise function normally. An optometrist might need to alter the glasses later as the person’s condition changes, allowing them to continue operating without problems.
A neurosurgeon might decide to operate on a patient if the midline shift constitutes movement of about a fifth of an inch (five millimeters) or more. Such a dramatic shift of the brain constitutes a medical emergency since it threatens the patient’s life. The surgeon might remove any growth, whether it is benign or malignant, that is causing the shift, or even remove part of the patient’s skull if the brain is swelling, preventing permanent damage to the brain.
Intracranial Pressure (ICP) often goes hand-in-hand with midline shift. The causes of ICP include brain tumors, brain swelling or heart failure. Signs that a person is suffering from ICP might include unexplained vomiting, blurring at the edges of a person’s field of vision and persistent back pain.