Real-time hemodynamic assessment of downstream effects of intracranial stenoses in patients with orthostatic hypoperfusion syndrome

Abstract

Background: Arterial flow velocity changes on transcranial Doppler can reflect changes in cerebral flow during position-induced ischemia if obtained during short-term monitoring of positional changes.

Subjects and methods: Our multicenter group monitored symptomatic and asymptomatic arteries in patients with recurrent neurological deficits during positional changes and documented intracranial arterial stenosis. Bilateral posterior cerebral and middle cerebral arteries were monitored dependent on clinical symptom localization. The symptomatic artery was monitored distal to the intracranial stenosis, and mean flow velocities (MFV) were recorded at different body positions. The symptomatic artery relative MFV ratio was defined as the ratio of symptomatic artery MFV in the asymptomatic position--MFV in the symptomatic position/MFV in the asymptomatic position.

Results: Sixteen patients underwent transcranial Doppler monitoring: mean age 62 +/- 19 years, 11 (69%) men, 6 (40%) with transient ischemic attacks. Ten patients (63%) had posterior and 6 anterior circulation symptoms. Patients developed neurological symptoms while standing up (63%) and/or sitting (44%), walking (13%) or during neck extension (6%). Symptomatic artery MFV dropped by > or =25% from the resting to the symptomatic position in all patients except for one. The mean symptomatic artery MFV relative ratio was higher compared with the mean asymptomatic artery MFV relative ratio: 0.5 +/- 0.28 versus -0.02 +/- 0.1 (p = 0.001, Wilcoxon test). The symptomatic artery relative ratio of >0.25 had a 94% sensitivity and 100% specificity for predicting neurological symptom development during testing (kappa = 0.9, p < 0.001).

Conclusions: A significant reduction in intracranial flow velocity distal to an intracranial stenosis can identify patients whose symptoms can worsen with positional changes. These patients may prove a target for interventional revascularization techniques.

Fig. 1

An example of 3 patients with anterior and posterior circulation hypoperfusion TIA syndrome. a Anterior circulation hypoperfusion TIA: a 55-year-old man with orthostatic episodes of expressive aphasia and right-arm weakness. Digital subtraction angiography showed critical left supraclinoid internal carotid artery (ICA) stenosis. The affected MCA MFV dropped from 110 cm/s in the lying down position to 78 cm/s in the standing position. The affected artery MCA MFV relative ratio was 0.29 (110–78/110) and the unaffected MCA relative MFV ratio was 0.13 (46–40/40). b Posterior circulation hypoperfusion TIA: a 64-year-old man with orthostatic episodes of dysarthria, dysphasia and ataxia. Cerebral angiography revealed left vertebral artery (VA) occlusion and right vertebral artery stenosis. The affected PCA MFV dropped from 17 cm/s in the lying flat position to 0 cm/s in the sitting-up position. The affected artery PCA relative MFV ratio was 1 (17–0/17), and the unaffected (control) right MCA MFV relative ratio was 0 (67–67/67). c Posterior circulation hypoperfusion TIA: a 50-year-old man with transient episodes of ataxia and vertigo induced by neck extension. The patient had large cervical anterior and posterior osteophytes that were causing mechanical compression of the left vertebral artery in the neck. In addition, his right vertebral artery was hypoplastic on CT angiography. His TCD monitoring of bilateral PCAs revealed a drop in the MFV from 19 to 0 cm/s with neck extension. The affected artery MFV relative ratio was 1 (19–0/19) and the unaffected (control) left MCA MFV relative ratio was 0 (48–48/48).

Fig. 1

An example of 3 patients with anterior and posterior circulation hypoperfusion TIA syndrome. a Anterior circulation hypoperfusion TIA: a 55-year-old man with orthostatic episodes of expressive aphasia and right-arm weakness. Digital subtraction angiography showed critical left supraclinoid internal carotid artery (ICA) stenosis. The affected MCA MFV dropped from 110 cm/s in the lying down position to 78 cm/s in the standing position. The affected artery MCA MFV relative ratio was 0.29 (110–78/110) and the unaffected MCA relative MFV ratio was 0.13 (46–40/40). b Posterior circulation hypoperfusion TIA: a 64-year-old man with orthostatic episodes of dysarthria, dysphasia and ataxia. Cerebral angiography revealed left vertebral artery (VA) occlusion and right vertebral artery stenosis. The affected PCA MFV dropped from 17 cm/s in the lying flat position to 0 cm/s in the sitting-up position. The affected artery PCA relative MFV ratio was 1 (17–0/17), and the unaffected (control) right MCA MFV relative ratio was 0 (67–67/67). c Posterior circulation hypoperfusion TIA: a 50-year-old man with transient episodes of ataxia and vertigo induced by neck extension. The patient had large cervical anterior and posterior osteophytes that were causing mechanical compression of the left vertebral artery in the neck. In addition, his right vertebral artery was hypoplastic on CT angiography. His TCD monitoring of bilateral PCAs revealed a drop in the MFV from 19 to 0 cm/s with neck extension. The affected artery MFV relative ratio was 1 (19–0/19) and the unaffected (control) left MCA MFV relative ratio was 0 (48–48/48).

Fig. 1

An example of 3 patients with anterior and posterior circulation hypoperfusion TIA syndrome. a Anterior circulation hypoperfusion TIA: a 55-year-old man with orthostatic episodes of expressive aphasia and right-arm weakness. Digital subtraction angiography showed critical left supraclinoid internal carotid artery (ICA) stenosis. The affected MCA MFV dropped from 110 cm/s in the lying down position to 78 cm/s in the standing position. The affected artery MCA MFV relative ratio was 0.29 (110–78/110) and the unaffected MCA relative MFV ratio was 0.13 (46–40/40). b Posterior circulation hypoperfusion TIA: a 64-year-old man with orthostatic episodes of dysarthria, dysphasia and ataxia. Cerebral angiography revealed left vertebral artery (VA) occlusion and right vertebral artery stenosis. The affected PCA MFV dropped from 17 cm/s in the lying flat position to 0 cm/s in the sitting-up position. The affected artery PCA relative MFV ratio was 1 (17–0/17), and the unaffected (control) right MCA MFV relative ratio was 0 (67–67/67). c Posterior circulation hypoperfusion TIA: a 50-year-old man with transient episodes of ataxia and vertigo induced by neck extension. The patient had large cervical anterior and posterior osteophytes that were causing mechanical compression of the left vertebral artery in the neck. In addition, his right vertebral artery was hypoplastic on CT angiography. His TCD monitoring of bilateral PCAs revealed a drop in the MFV from 19 to 0 cm/s with neck extension. The affected artery MFV relative ratio was 1 (19–0/19) and the unaffected (control) left MCA MFV relative ratio was 0 (48–48/48).