Wide perivascular gap on magnetic resonance plain scanning of the head refers to a potential widening of the lumen between the soft meninges and the blood vessels in the brain, and is often associated with a number of neurologic disorders. The perivascular gap refers to the fact that when a cerebral blood vessel enters the brain parenchyma from the subarachnoid space, the adjacent soft meninges are invaginated around the small blood vessel, creating a gap between the blood vessel and the surrounding soft meninges. A wide perivascular gap on MRI scanning of the head is often caused by cerebrovascular diseases such as multiple sclerosis of the cerebral vessels; it can also cause poor cerebrospinal fluid reflux, resulting in hydrocephalus. When the patient’s head MRI scan shows wide perivascular gaps, he should go to the hospital for further examination and be treated under the guidance of a specialized doctor.