Postoperative hyperperfusion syndrome in elderly patients with chronic subdural hematoma

Temporary acute agitated delirium is a frequent complication after surgery for chronic subdural hematoma (CSH) in elderly patients. To clarify the pathogenic mechanism underlying this complication, we measured cerebral blood flow before and after surgery in elderly patients with CSHs.

Twenty-seven patients aged 75 years or older with unilateral CSH underwent treatment involving a single burr hole craniostomy with continuous catheter drainage. Cerebral blood flow was measured using single photon emission computed tomography 1 day before surgery, and at 1 hour and 24 hours after surgery. Acute agitated delirium was diagnosed by the characteristic behavioral abnormality.

SPECT imaging 1 hour after surgery demonstrated hyperperfusion in the cerebral cortex beneath the CSH in 14 patients (51.9%). Of these 14 patients, five showed acute agitated delirium a few hours after surgery that persisted for 10 to 12 hours. A hematoma was detected in the right hemisphere in all five patients. Hyperperfusion was significantly more intense in patients with acute agitated delirium both 1 hour and 24 hours after surgery than in patients (n = 9) without acute agitated delirium. Moreover, mean arterial blood pressure during the first postoperative hour was significantly higher in patients with acute agitated delirium.

In elderly patients with CSH, intense and prolonged hyperperfusion after surgery induces temporary acute agitated delirium. This postoperative hyperperfusion syndrome is exacerbated by hypertension.