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[Cerebral blood flow distribution and reactivity during the symptom-free stages of transient ischemic attacks--a
1Department of Diagnostic Radiology, Osaka National Hospital.
Insights
Transient ischemic attack (TIA) patients often have cerebral blood flow (CBF) issues even without symptoms. CBF-SPECT imaging detected lesions better than CT, revealing hypoperfusion linked to arterial problems.
Area of Science:
- Neurology
- Radiology
- Vascular Medicine
Background:
- Transient ischemic attacks (TIAs) can present with subtle or absent symptoms.
- Cerebral blood flow (CBF) disturbances may occur even in asymptomatic TIA phases.
- Understanding the causes of these CBF abnormalities is crucial for TIA management.
Purpose of the Study:
- To evaluate factors causing CBF abnormalities in TIA patients.
- To assess CBF and its reactivity to acetazolamide (Diamox) in TIA.
- To compare CBF-SPECT findings with other diagnostic methods.
Main Methods:
- Utilized 99mTc-hexamethylpropyleneamine oxime (HMPAO) SPECT for CBF and acetazolamide reactivity assessment.
- Compared CBF-SPECT results with X-ray CT and cerebral arteriography.
- Correlated findings with TIA clinical characteristics and cerebrovascular risk factors.
Main Results:
- CBF-SPECT showed a 68% sensitivity in lesion detection, significantly higher than CT (9%).
- Wider hypoperfusion areas correlated with intracranial, severe stenotic, or multiple ipsilateral arterial lesions.
- Cortical hypoperfusion was associated with arteriographic abnormalities and higher stenosis severity compared to subcortical hypoperfusion.
Conclusions:
- CBF-SPECT is a sensitive tool for detecting hypoperfusion in TIA patients, even in asymptomatic stages.
- Hypoperfusion patterns can indicate underlying cerebrovascular pathology, including arterial stenosis and intracranial lesions.
- CBF reactivity to acetazolamide provides additional insights into cerebrovascular reserve in TIA.
Abstract:
Even during the symptom-free stages, patients with transient ischemic attacks (TIA) often show cerebral blood flow (CBF) disturbances. For evaluating the factors which cause these abnormalities, we studied CBF and CBF reactivity to acetazolamide (Diamox) using a 99mTc-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT). The results from CBF-SPECT were compared with X-ray computed tomography (CT), cerebral arteriogram, clinical characteristics of TIA and cerebrovascular risk factors. The overall sensitivity rates in detecting the lesion were 68% in CBF-SPECT and 9% in CT. The size of the hypoperfused area tended to be wide in patients who had intracranial, severe stenotic or multiple arterial lesions on the ipsilateral side. No such relations were found between CBF and other examinations. Brain hypoperfusion was located in the subcortical region in eight patients; two patients showed a small hypodense lesion on CT which corresponded to the hypoperfusion on SPECT, and three patients showed no arteriographic abnormality. Hypoperfusion in the cortex was seen in seven patients; all patients showed arteriographic abnormality, but no CT abnormality. The severity rating of the vascular stenosis and hypoperfusion, and the incidence of the intracranial lesions were higher in this group than the group with subcotical hypoperfusion. Seven patients showed fixed normoperfusion before and after diamox injection. Two patients with a subcortical small infarction showed fixed hypoperfusion even after diamox injection. Twelve patients showed focal hypoperfusion before diamox with a new filling-in after diamox. Only one patient showed resting hypoperfusion and decreased CBF reactivity to diamox.(ABSTRACT TRUNCATED AT 250 WORDS)