"No-reflow" phenomenon as a cause of hypoperfusion after severe head injury?

Severe head injuries are known to cause secondary ischaemic brain damage. Ischaemia may develop due to transtentorial herniation or due to increased intracranial pressure leading to decreased perfusion. Compression of the brain due to extracerebral haematoma may cause hypoperfusion as well.

29 patients with postraumatic transtentorial herniation were studied. Haematoma was urgently removed in these patients and CT and SPECT was performed on the 1st and 5th postoperative day. 26 patients had hypoperfusion on SPECT in the vicinity of the previous haematoma. Only 9 of them, however, had ischaemia on CT. There were 11 patients in whom the previous ischaemia seen on SPECT improved on the follow up SPECT examination. 10 of them had a good treatment result.

A possible mechanism of hypoperfusion caused by compression of the brain may be a kind of "no-reflow" phenomenon which is known from pathophysiology of classical brain ischaemia. Patients in whom the collateral blood flow overcomes the decreased perfusion in the microcirculation should have a better outcome. (Tab. 1, Fig. 1, Ref. 13).