Eye Examination Could Obviate The Need For MRI In Stroke Diagnosis

A new study suggests that gadolinium used during MRI imaging in stroke patients leaks into the eyes and can provide clues about the stroke. The study was published in Neurology. The study evaluated the MRI (magnetic resonance imaging) reports of 167 stroke patients. Some patients did not receive treatment before the test while others were treated with the clot-dissolving drug called tissue plasminogen activator. The MRI was first done without and then with a contrast dye called gadolinium which was injected into the blood. The use of a contrast allows the easy detection of the damaged area of the brain. The test was repeated 2 and 24 hours after the initial MRI. The scientists found that:

• Leakage of gadolinium occurred into the eyes of 76% individuals.
• There also appeared to be a specific pattern for the leakage. The MRI done after 2 hours showed leakage in the aqueous chamber, the part of the eye in front of the iris in 67% individuals, in the vitreous chamber, the part of the eye behind the iris in 6% patients, and in both the aqueous and the vitreous chamber in 27% of patients. Patients with gadolinium in both the chambers had a larger part of the brain affected by the stroke.
• The MRI performed at 24 hours detected the leakage in the vitreous chamber of the eyes in 75% patients, and in both the chambers in 6% patients. In older patients, patients with greater affliction of the white matter of the brain due to aging, and patients with hypertension, gadolinium was detected more commonly in the vitreous chamber at 24 hours.

The leakage of gadolinium, however, could not be associated with the extent of the disability caused by the stroke.

Gadolinium does not leak into the eyes of individuals without brain damage. The scientists therefore suggest that the stroke could make the blood vessels of the eyes leakier and therefore allows the leakage of gadolinium into the eyes.

Further studies on the phenomenon could reveal ways in which, using a special dye that accumulates in the eye in stroke patients similar to gadolinium, an eye examination will be able to provide clues into the severity of brain damage caused by the stroke.

About MRI

Magnetic resonance imaging (MRI) is an imaging test during which images of the brain or other parts of the body are obtained using a magnetic field. A contrast is sometimes injected to highlight the damaged part. In a normal brain, leakage of the dye through the blood vessels into the brain does not occur. Damage to the brain on the other hand, allows the contrast to enter the brain and settle down in damaged areas, thus enabling easy detection of the damaged parts.

References:

1. Hitomi et al. Blood-ocular barrier disruption in acute stroke patients. Neurology. February 7, 2018. doi: 10.1212/WNL.0000000000005123.

Source-Medindia