Why a standard contrast-enhanced MRI might be useful in intracranial internal carotid artery stenosis.

In patients with ischemic stroke of unknown cause cerebral vasculitis is a rare but relevant differential diagnosis, especially when signs of intracranial artery stenosis are found and laboratory findings show systemic inflammation. In such cases, high-resolution T1w vessel wall magnetic resonance imaging (MRI; 'black blood' technique) at 3 T is preferentially performed, but may not be available in every hospital. We report a case of an 84-year-old man with right hemispheric transient ischemic attack and signs of distal occlusion in the right internal carotid artery (ICA) in duplex sonography. Standard MRI with contrast agent pointed the way to the correct diagnosis since it showed an intramural contrast uptake in the right ICA and both vertebral arteries. Temporal artery biopsy confirmed the suspected diagnosis of a giant cell arteritis and dedicated vessel wall MRI performed later supported the suspected intracranial large artery inflammation. Our case also shows that early diagnosis and immunosuppressive therapy may not always prevent disease progression, as our patient suffered several infarcts in the left middle cerebral artery (MCA) territory with consecutive high-grade hemiparesis of the right side within the following four months.

Spatial mapping of dynamic cerebral autoregulation by multichannel near-infrared spectroscopy in high-grade carotid artery disease.

The exact spatial distribution of impaired cerebral autoregulation in carotid artery disease is unknown. In this pilot study, we present a new approach of multichannel near-infrared spectroscopy (mcNIRS) for non-invasive spatial mapping of dynamic autoregulation in carotid artery disease. In 15 patients with unilateral severe carotid artery stenosis or occlusion, cortical hemodynamics in the bilateral frontal cortex were assessed from changes in oxyhemoglobin concentration using 52-channel NIRS (spatial resolution ∼2 cm). Dynamic autoregulation was graded by the phase shift between respiratory-induced 0.1 Hz oscillations of blood pressure and oxyhemoglobin. Ten of 15 patients showed regular phase values in the expected (patho) physiological range.Five patients had clearly outlying irregular phase values mostly due to artifacts. In patients with a regular phase pattern, a significant side-to-side difference of dynamic autoregulation was observed for the cortical border zone area between the middle and anterior cerebral artery (p < 0.05). In conclusion, dynamic cerebral autoregulation can be spatially assessed from slow hemodynamic oscillations with mcNIRS. In high-grade carotid artery disease,cortical dynamic autoregulation is affected mostly in the vascular border zone. Spatial mapping of dynamic autoregulation may serve as a powerful tool for identifying brain regions at specific risks for hemodynamic infarction.

Dynamic cerebral autoregulation in acute intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Cerebral autoregulation (CA) is not universally impaired in acute intracerebral hemorrhage (ICH); however, the dynamic components of CA are probably more vulnerable. This study, therefore, evaluates the time course of dynamic CA in acute ICH and its relationship to clinical outcome. METHODS: Twenty-six patients with ICH were studied on days 1, 3, and 5 after ictus. Dynamic CA was measured from spontaneous fluctuations in blood pressure and middle cerebral artery flow velocity by transfer function phase (reflecting rapidity of CA) and gain (reflecting damping characteristics of CA) in the low frequency range. Results were compared with those from 55 controls and related with clinical factors and 90-day outcome (modified Rankin scale). RESULTS: Phase did not fluctuate significantly over time, nor did it differ between sides or differ from controls. Gain was always higher in patients than in controls but showed no significant association with outcome or other clinical factors. At day 1, poorer ipsilateral phase was associated with lower blood pressure and higher ICH volume. Poorer phase always coincided with lower Glasgow Coma Scale values. Poorer ipsilateral phase on day 5 was related with poorer clinical outcome according to multivariate analysis (P=0.013). CONCLUSIONS: Dynamic temporal characteristics of CA (phase) are not generally altered in acute ICH. Poorer individual phase values are, however, associated with larger ICH volume, lower blood pressure, and worsened outcome. Dampening characteristics of CA (gain) are generally impaired in acute ICH but not related to clinical factors or outcome.