Carol Derksen

Real-Time Hemodynamic Assessment of Downstream Effects of Intracranial Stenoses in Patients with Orthostatic Hypoperfusion Syndrome

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 ≧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 (ĸ = 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.

Derivation of transcranial Doppler criteria for angiographically proven middle cerebral artery vasospasm after aneurysmal subarachnoid hemorrhage.

Transcranial Doppler (TCD) has been subjected to criticism for detecting vasospasm (VSP). Our studys aim is to derive criteria for middle cerebral artery (MCA) vasospasm (MCA‐VSP) based on cerebral angiography (CA).

The role of transcranial Doppler embolic monitoring in the management of intracranial arterial stenosis.

Intracranial arterial stenosis (IAS) is thought to be responsible for 8% of all ischemic stroke subtypes. The best medical treatment for this condition is still controversial. Transcranial Doppler (TCD) emboli monitoring may help to guide the treatment by measuring the frequency of microembolic signals (MES). We report a case of IAS where TCD emboli monitoring proved useful in establishing the mechanism of stroke by being artery‐to‐artery emboli and guiding therapy based on the frequent symptoms and number of MES.

Transcranial Doppler and Cerebral Augmentation in Acute Ischemic Stroke

Collateral flow augmentation using partial aortic occlusion may improve cerebral perfusion in acute stroke. We assessed the effect of partial aortic occlusion on arterial flow velocities of acute stroke patients.

Cerebral blood flow dynamics of orthostatic transient ischemic attacks in a patient with carotid dissection and fibromuscular dysplasia.

In patients with critical carotid stenosis and ischemic stroke, it is crucial to determine whether distal hypoperfusion or artery‐to‐artery embolism is the predominant mechanism. The role of transcranial doppler (TCD) in this setting is vital. We report a patient with fibromuscular dysplasia and recurrent orthostatic transient ischemic attacks where fall in cerebral perfusion was clearly demonstrated by TCD.

Hemodynamic assessment of cervical internal carotid artery stenosis during head manipulation: case report.

Positional intermittent carotid ischemia has rarely been reported in the literature. We report a case of fluctuating hemiparesis in a 88-year-old woman in whom transcranial Doppler ultrasonography at various head positions proved useful in establishing the mechanism of the hypoperfusion transient ischemic attack. Head rotation to the side of the stenotic internal carotid artery resulted in significant drop in ipsilateral middle cerebral artery mean flow velocity.

Comparison of Carotid Doppler Ultrasound to Other Angiographic Modalities in the Measurement of Carotid Artery Stenosis: Carotid Doppler Ultrasound versus Other Angiographic Modalities

The purpose of this study was to compare Doppler ultrasound (DUS) to other angiographic modalities: computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA).

Transcranial Doppler and Transcranial Color Duplex in Defining Collateral Cerebral Blood Flow: TCD and TCCD in Defining Collateral Blood Flow

In an acute stroke setting, transcranial Doppler (TCD) and transcranial color‐coded duplex (TCCD) have an important diagnostic utility in the monitoring of an arterial occlusion and microemboli detection. In addition, TCD has proven to be a very useful tool in the detection and progression of cerebral vasospasm in patients with subarachnoid hemorrhage.

Ultrasound for the evaluation of stenosis after flow diversion

Background and purpose Flow diversion is a relatively new strategy used to treat complex cerebral aneurysms. The optimal method for radiographic follow-up of patients treated with flow diverters has not been established. The rate and clinical implications of in-stent stenosis for these devices is unclear. We evaluate the use of transcranial Doppler ultrasound (TCD) for follow-up of in-stent stenosis. Materials and methods We analyzed 28 patients treated with the Pipeline embolization device (PED) over the course of 42 months from January 2009 to June 2012. Standard conventional cerebral angiograms were performed in all patients. TCD studies were available in 23 patients. Results Angiographic and TCD results were compared and found to correlate well. Conclusions TCD is a potentially useful adjunct for evaluating in-stent stenosis after flow diversion.

Isolated intermittent vertigo: A presenting feature of persistent trigeminal artery

Embryonic carotid – basilar anastomosis when persistent in adult life can present with a variety of neurological symptoms. We present a patient with isolated intermittent vertigo attributable to the embryonic anastomosis and describe the different types of persistent trigeminal artery. A 76-year-old Caucasian man presented with isolated intermittent vertigo and symptoms suggestive of anterior and posterior circulation strokes. Impaired vasomotor reactivity was demonstrated on insonation of the anterior and posterior cerebral arteries in this patient with a persistent left trigeminal artery and 75% stenosis of the left internal carotid artery (ICA). The symptom of intermittent vertigo resolved with carotid endarterectomy. Decreased flow across the stenotic segment of the ICA which subserved the posterior circulation resulted in basilar insufficiency. Hypoperfusion to the flocculonodular lobe supplied by the anterior inferior cerebellar artery is a likely cause for the intermittent vertigo.