Abstract
Cerebral hemodynamics and metabolism of six men (mean age: 51 years) with arteriovenous malformation (AVM) of the brain were studied using the 150-labelled gas steady state method and positron emission tomography (PET). The AVMs were identified by X-ray CT and angiography as five non-hemorrhagic (retrosylvian-Rolandic, frontal, cerebellar regions on the right, and occipital dural, frontal ones on the left) and one hemorrhagic (right occipital). The duration from the onset or the last episode to the study was 22 days to three years. Neurologic abnormalities at the time of the study were found in two of patients; one with horizontal nystagmus and the other with light sensory aphasia (dysphasia).
The affected hemisphere was covered with tortuous enraged vessels in one patient with a large frontal AVM and could hardly be evaluated quantitatively due to the partial volume effect. Expect for this case, values were acceptable when the regions of interest (ROIs) were placed properly so as not to cover the component of the AVM.
The CBF and cerebral oxygen metabolism (CMRO2) of the whole brain was decreased in the patient with a hematoma in spite of having no neurologic deterioration. The patient with dysphasia presented low CBF and CMRO2 with increased cerebral blood volume (CBV) on the affected side.
In every case, the flow and oxygen metabolism was decreased in various degrees in the distant area with the same arterial supply and/or venous drainages as the AVM (“non-Nidus”), and the surrounding part of the nidus (“peri-Nidus”).
While cerebral blood volume (CBV) increased significantly, uncoupling between flow and metabolism could not be observed in those parts.
Vasoactivities to changes of PaCO2 and blood pressure were further studied in one case using the H215O bolus injection method. In regions adjacent to the nidus (peri-Nidus), CO2-reactivities were good to the hypercapnia, while less to hypocapnia. On the other hand, opposite corelations were documented at the distant area (non-Nidus). Autoregulation indices were all below 0.3%, which are considered to be well reserved autoregulatory changes.
Our results suggest that AVMs can bring hemodynamic and metabolic chages not only to the neighboring structures, but also their distant areas with the same vascular supply and/or drainage.
