Approximately one third of stroke patients experience another stroke while they're still in the hospital. Nurses therefore keep a close eye on them, and arrange for them to be taken for tests if a subsequent stroke is suspected. Unfortunately these tests can be invasive, and in some cases are even potentially harmful to the patient. A new device being developed at the Mayo Clinic in Florida, however, could watch for strokes simply by shining light onto a patient's forehead.
The device, known as near-infrared spectroscopy (NIRS), attaches to the brow skin like a sticker. It then measures blood oxygen levels in the brain, by emitting near-infrared light that penetrates the scalp, and proceeds about 2.5 centimeters (0.98 inches) into the underlying brain tissue. It functions like the presently-used pulse oximeter, which clamps onto the finger.
Ordinarily, in order to test for a stroke, a CT perfusion scan is performed. This measures blood flow and oxygenation through the use of an introduced contrast medium, which can in some cases cause airway or kidney damage. If multiple scans are required, the process can also expose the patient to excessive radiation.
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In extreme cases, an oxygen probe may instead be inserted into the brain. Needless to say, the procedure is invasive, plus it only covers a limited area of the brain.
When compared to CT perfusion scans performed on eight patients, NIRS was shown to produce statistically similar results. It did offer a more limited field of measurement, however, so the scientists believe it may not be ideal for all cases.
Further studies on the device are now planned. If miniaturized, it is hoped that it could be used in the battlefield on soldiers, to assess the extent of brain injuries.
More details on NIRS are available in the video below.
Source: Mayo Clinic