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Haemodynamic classification of symptomatic obstructive carotid artery disease
A Sorteberg1, W Sorteberg, K F Lindegaard
1Department of Neurosurgery, Rikshospitalet, National Hospital, University of Oslo, Norway.
Insights
The Uhem index effectively differentiates stroke types in obstructive carotid artery disease. This transcranial Doppler ultrasonography method aids in identifying stroke subtypes and potential differing causes of transient ischemic attacks.
Area of Science:
- Neurology
- Vascular Neurology
- Neurosonology
Background:
- Obstructive carotid artery disease poses a significant risk for stroke.
- Accurate differentiation of stroke types is crucial for appropriate management and understanding pathogenesis.
- Transcranial Doppler ultrasonography (TCD) offers non-invasive insights into cerebral hemodynamics.
Purpose of the Study:
- To evaluate the utility of the Uhem index derived from TCD in classifying stroke subtypes in patients with symptomatic obstructive carotid artery disease.
- To compare hemodynamic parameters and vasomotor reactivity across different stroke groups.
Main Methods:
- Sixty-three subjects with obstructive carotid artery disease underwent TCD to measure blood velocities and pulsatility index (PI) in cerebral arteries.
- The Uhem index (VMCA.PIMCA/VPCA.PIPCA) and total vasomotor reactivity were calculated.
- Subjects were categorized into lacunar/territorial infarction, watershed infarction, and transient ischemic attack (TIA) groups based on clinical and CT findings.
Main Results:
- The Uhem index successfully differentiated between lacunar/territorial infarction, watershed infarction, and TIA groups.
- Watershed infarction and stroke patients with negative CT findings showed subnormal Uhem index and vasomotor reactivity.
- TIA patients exhibited distinct hemodynamic patterns, suggesting potential subgroups with different underlying pathogenetic mechanisms.
Conclusions:
- The Uhem index is a valuable tool for classifying stroke subtypes in obstructive carotid artery disease.
- TCD-derived hemodynamic parameters, particularly the Uhem index, offer diagnostic potential in neurovascular assessment.
- Further investigation into TIA subgroups using the Uhem index may elucidate distinct etiologies.
Abstract:
63 subjects with symptomatic obstructive carotid artery disease were investigated with transcranial Doppler ultrasonography. Their blood velocities at rest (V) in the middle and posterior cerebral artery (MCA and PCA) and in the extracranial internal carotid artery were measured and the pulsatility index (PI) and Uhem index (VMCA.PIMCA/VPCA.PIPCA) calculated. The vasomotor responses in both MCAs were also tested. The subjects were divided into groups based on the findings on physical examination and cerebral computed tomography. In the patient group with lacunar/territorial infarction we found in the stroke hemisphere: VMCA > VPCA, PIMCA = PIPCA and normal values for the Uhem index and total vasomotor reactivity. In the patient group with watershed infarction this hemisphere was characterized by: VMCA < VPCA, PIMCA < PIPCA and subnormal scores for the Uhem index and total vasomotor reactivity. Displaying features from both stroke groups, we obtained in the hemisphere of interest in patients with transient ischaemic attacks: VMCA = VPCA, PIMCA < PIPCA and normal values for the Uhem index and total vasomotor reactivity. Five patients with clinical evidence of stroke but with negative cerebral computed tomography findings had scores similar to those of the watershed group of patients. For the stroke patients, individual measurements of V, PI and total vasomotor reactivity failed to clearly identify to which stroke group a subject might belong. However, such an identification was achieved in all subjects when using the Uhem index. The Uhem index data in patients with transient ischaemic attacks suggest two subgroups with different pathogenesis underlying, the ischaemic events.