Bilateral near infrared spectroscopy in space-occupying middle cerebral artery stroke

The crucial importance of monitoring both the infarcted and non-infarcted hemispheres in management of space occupying middle cerebral artery (MCA) infarction is increasingly recognized, but optimal technique is debated. We investigated the potential for bilateral Near Infrared Spectroscopy (NIRS) to non-invasively provide relevant information on intracranial oxygenation.

In patients with complete MCA stroke and brain swelling NIRS optodes were placed over both frontal lobes and regional cerebral oxygen saturation (rSO(2)) was measured at 30 s intervals for at least 12 h. The bilateral pattern of changes in rSO(2) was analysed with respect to clinical course and development of brain swelling, and patients compared according to outcome.

A total of 24 patients were analysed, of whom 13 underwent decompressive hemicraniectomy; outcome was good (GOS > or = 3) in 11 cases, and poor (GOS < 3) in 13. Absolute rSO(2) values varied widely and did not correlate with clinical data. The average difference in rSO(2) (rSO(2)-diff) between infarcted and contralateral hemisphere was 10.7% and higher on the infarct side in 22/24 cases. The rSO(2)-diff typically decreased with brain swelling, disappeared in patients who developed herniation, but increased markedly after successful craniectomy and management of brain swelling. The rSO(2)-diff at the end of monitoring was significantly higher in good outcome survivors. The time pattern of rSO(2)-diff can be explained by alterations of perfusion and O(2)-consumption depending on hemispheric swelling.

Bilateral NIRS may provide more useful information on cerebral oxygenation than unilateral measurements and its clinical validity to help predict worsening of brain swelling should be investigated further.