Near infrared spectroscopy in detecting delayed cerebral ischemia in subarachnoid hemorrhage patients

Abstract

Background: Aneurysmal subarachnoid hemorrhage (aSAH) affects 30,000 Americans each year. Delayed cerebral ischemia caused by cerebral vasospasm is a complication that occurs in approximately 30% of aSAH patients and is a major cause of morbidity and mortality (Hijdra et al., 1986; Roos et al., 2000). The only two established screening methods for vasospasm, transcranial doppler (TCD) and CT angiography (CTA), have their own shortcomings (Jan van Gijn, Kerr, & Rinkel). Studies have shown that TCD has a 63% sensitivity and 52% specificity in detecting vasospasm (Carrera et al., 2009). Furthermore, TCDs require skilled technicians to insonate the cerebral blood vessels thereby explaining why TCDs can only be performed once per day. While CTA is highly specific and sensitive in detecting vasospasm, it requires the use of contrast dye which and carries the risk of contrast nephropathy. Near Infrared Spectroscopy (NIRS), however, is an FDA approved imaging technique that has been used in carotid endarterectomy surgeries to monitor for cerebral ischemia. It is a non-invasive technique and can take continuous, 24-hour measurements of cortical oxygenation. Additionally, NIRS does not require a trained technician to operate, nor does it confer any risk of nephropathy. Also, it is markedly cheaper than the other methods of detection mentioned here because there is no other cost other than the purchase of the machine and the disposable sensors. [TRUNCATED]