Background: We examined the cerebral blood flow (CBF) and intracranial pressure (ICP) in 15 patients with chronic subdural hematomas to clarify the clinical pathophysiology of this disorder.
Methods: All patients had hemiparesis and/or mental disturbance, including confusion or lethargy, and demonstrated either midline shift or herniation on computed tomography (CT) scans. CBF was measured using xenon-enhanced CT preoperatively, 1 day postoperatively, and 3-4 weeks later. ICP was monitored continuously for 24 hours both before and after surgery.
Results: The CBF was severely reduced on both sides. It stayed at the preoperative level 1 day after surgery, when all patients improved clinically, but returned to subnormal levels in 3-4 weeks. Acetazolamide-enhanced CBF values that were abnormally elevated in each region preoperatively stayed the same during each stage in the hemisphere and cortex despite the different baseline values. However, these measurements increased gradually after surgery in the thalamus and putamen. The ICP was moderately high preoperatively (14.2-25.3 mmHg; mean: 19.4 +/- 3.7 mmHg) and remained high (13.4-31.7 mmHg; mean: 21.4 +/- 6.0 mmHg) 1 day postoperatively. There was no correlation between the CBF values and ICP values in any region either before surgery or 1 day after surgery.
Conclusions: We conclude that chronic subdural hematomas may induce neurologic dysfunction primarily through a mechanical distortion of central brain regions such as the thalamus with a secondary influence on remote regions due to transneural depression. The effect of a subdural hematoma on CBF and ICP is not a major cause of neurologic dysfunction. The thalamus seems to be at the core of the pathophysiology of chronic subdural hematomas.