Nevzat Uzuner

Differentiation of Vascular Dementia and Alzheimer Disease A Functional Transcranial Doppler Ultrasonographic Study

In brain perfusion studies, perfusion defects have been reported mainly in the temporal and parietal regions in patients with Alzheimer disease (AD), but it is known that the occipital cortex is partially preserved from metabolic defects in patients with AD, at least in the early stage of the disease. We therefore evaluated the reactivity of the posterior cerebral arteries during visual stimulation with transcranial Doppler ultrasonography (TDU).

Right-to-Left Shunt Assessed by Contrast Transcranial Doppler Sonography New Insights

Objective. Simple diagnostic techniques such as contrast transcranial Doppler sonography (cTCDS) are popular for assessing a right‐to‐left shunt (RLS) because of their high sensitivity. In this study, we applied cTCDS to a large patient group with a patent foramen ovale, proved by contrast transesophageal echocardiography (TEE). Methods. One hundred one patients with stroke, in whom a patent RLS had been shown on contrast TEE, were investigated by TCDS of both middle cerebral arteries. Injection of 10 mL of agitated saline was applied without and subsequently with the Valsalva maneuver (VM) at the beginning of the contrast agent injection, and then 10 mL of a galactose‐based contrast agent was applied in the same protocol. Results. In all patients, cTCDS with the galactose contrast agent showed an RLS when performed with VM, but it showed an RLS in only 59 patients without VM. In contrast, saline showed an RLS in 54 patients with VM and in 20 patients without VM. The differences in diagnostic sensitivity were statistically significant (P < .001). Eighteen patients had only 1 microembolic signal (MES) after galactose injection, whereas others had more. The mean (SD) arrival times of the MES were 9 (6) seconds (range, 1–51 seconds) after galactose injection with VM and 9 (3) seconds (range, 2–20 seconds) after agitated saline with VM. The differences were not significant. Conclusions. Contrast TCDS with VM shows a TEE‐proven RLS with 100% sensitivity, but this was not true with galactose application without VM or agitated saline with or without VM. Therefore, use of the galactose contrast agent with VM is strongly recommended for detecting an RLS on TCDS. However, the arrival time and number of MESs detected need to be tested further.

Cerebral vasomotor reactivity of patients with acute ischemic stroke: Cortical versus subcortical infarcts: An Israeli–Turkish collaborative study

BACKGROUND Cerebral hemodynamic features of patients with different types of acute ischemic stroke are still obscure. We compared cerebral vasomotor reactivity (VMR) in acute cortical (CI) and subcortical (SI) brain infarcts. METHODS Acute stroke patients (within 72 h of stroke onset) underwent transcranial Doppler and the Diamox test (1 g acetazolamide IV). The percent difference between blood flow velocities in the middle cerebral arteries before and after acetazolamide was defined as VMR%. CI and SI infarcts were confirmed by computerized tomography and/or magnetic resonance imaging. Clinical status and disability were assessed by means of the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) respectively.VMR% values and stroke severity and disability parameters were compared between CI and SI groups using ANOVA and Pearsons correlation (r) coefficients. RESULTS VMR% values of the ipsilateral side to the brain infarct in the CI group were significantly lower as compared with SI group (12.2+/-15.9% and 25.6+/-24.4% respectively, P=0.03). VMR% values in both groups were not correlated with stroke severity and disability (P<0.2). CONCLUSIONS Our results suggest greater vulnerability of resistance arterioles in the setting of cortical gray matter infarcts. Although gray matter VMR is physiologically higher than white matter VMR, patients with acute CI have impaired cerebral vascular reserve.

The effect of methylprednisolone treatment on cerebral reactivity in patients with multiple sclerosis.

We assessed the effect of intravenous high-dose methylprednisolone (IVMP) on cerebral reactivity in multiple sclerosis (MS) patients during exacerbations by means of functional transcranial Doppler imaging. Forty-eight clinically defined MS patients were evaluated with visual evoked potentials (VEP) and functional transcranial Doppler sonography (TCD) of both posterior cerebral arteries before and after 5 days of 1000 mg IVMP. After treatment, mean Expanded Disability Status Scale score, mean blood flow velocities and mean blood flow velocities at rest and at stimulation, significantly decreased (p < 0.0001, for each). The change in cerebral blood flow velocity ratio (CBFv) with visual stimulation after treatment increased slightly (p = 0.20). All TCD parameters were not significantly correlated with VEP changes. In conclusion, we observed significant changes in CBFv with a non-significant increase in vascular reactivity after treatment with IVMP in exacerbations of MS. Case-control studies are necessary to draw conclusions regarding the beneficial effects of IVMP treatment.

Cerebral Hemodynamic Patterns With Technetium Tc 99m Exametazime Single Photon Emission Computed Tomography and Transcranial Doppler Sonography A Validation Study Using Visual Stimulation

Objective. To assess whether a correlation between perfusion changes to visual stimulus on the bilateral occipital areas and blood flow velocity changes to visual stimulus in both posterior cerebral arteries is present. Methods. Nine right‐handed healthy subjects (4 women and 5 men; mean ± SD age, 58.0 ± 5.6 years) were included in the study. Visual stimulation was performed in room light with the subjects eyes open and looking around versus eyes closed as the stimulus‐off condition. The blood flow velocities were recorded using transcranial Doppler sonography, and the regional cerebral blood flow measurements were recorded with the use of technetium Tc 99m exametazime and a single photon emission computed tomographic gamma camera system. Individual reactivity was defined as a relative increase of blood flow velocity and perfusion, which were calculated as percentage changes of baseline values. Results. Visual stimuli produced a marked increase of blood flow velocity in both posterior cerebral arteries (35.2 ± 2.3 cm/s; P < .001) without a significant side‐to‐side difference in all subjects as well as a marked increase of perfusion on both occipital areas (24.9 ± 4.8 cm/s; P < .01). Moreover, there was a positive correlation between blood flow velocity changes and perfusion changes on both sides (r = 0.833; P < .01). Conclusions. The use of bilateral simultaneous Doppler recordings by means of a flow velocity averaging algorithm to a specific stimulus allows quantitative assessment of blood flow responses, and simple visual stimuli can be applied for different disorders to assess the vasomotor regulation that may result in measurable abnormal cerebral flow regulation even when clinically stabilized.

An analysis of changes in cerebral blood flood velocities in depressive pseudo-dementia and Alzheimer disease patients.

Background Patients with pseudo-dementia are at particular risk of being labeled as Alzheimer dementia. We thus need better diagnostic methods. In this study, we evaluated the cerebral reactivity of the posterior cerebral arteries (PCAs) during visual stimulation by transcranial Doppler ultrasonography. Methods The study group consisted of 13 and 11 patients suffering from pseudo-dementia and Alzheimer disease (AD), respectively, and 10 healthy controls. Visual reactivity was defined as the differences of cerebral blood flow velocity (CBFv) against the visual stimulus. Mini Mental State Examination and Montgomery-Asberg Depression Rating Scales were used as psychometric tests. The transcranial Doppler ultrasonography device was applied for simultaneous recording of both PCAs. Obtained data were evaluated by Student t test, and 1-way analysis of variance tests, with a priori as P<0.05. Results Subjects with AD had a lower CBFv following visual stimuli (P<0.001). Mean CBFv throughout the procedure [P<0.001; right and left sides, in AD and depressive pseudo-dementia (DPD), respectively], velocity at rest (P<0.001 in each side for both groups), and velocity at stimulation (P<0.001; each side for both groups) on both PCAs were significantly lower in patients with AD and DPD than those of the controls. Compared with the controls, the relative (r) CBFvs (%) were found to be significantly lower in AD (P<0.05, P<0.01, for the right and left side, respectively). Conclusions We have shown that CBFv decreased in patients with AD and DPD, but vasoneuronal activity was only impaired in patients with AD. On the other hand, although the results do not show significant differences between depressive and demented groups by TCD, further studies will be needed for differentiating these diseases.

The effects of hematocrit and age on transcranial Doppler measurements in patients with recent ischemic stroke

BACKGROUND The effects of age and hematocrit on transcranial Doppler (TCD) velocities have not been evaluated in a large patient group with recent ischemic stroke. AIM This study assessed the effects of age and hematocrit on TCD measurements in patients with recent ischemic stroke compared to patients with non-vascular diseases. SETTINGS AND DESIGN University Hospital, retrospective study. MATERIALS AND METHODS TCD records and data files of 862 consecutive patients (mean age, 57+/-16 years) with various neurological diagnoses were reviewed retrospectively. The peak systolic, end diastolic and mean flow velocities (FV), systolic/diastolic ratios and pulsatility indices (PI) in the middle cerebral arteries were averaged and the effect of age and hematocrit values on these TCD values was studied. Independent samples t test, Pearsons coefficients of correlation, and linear regression test were used for statistical analysis. RESULTS Among 862 patients, 413 were women (mean age, 53+/-17 years) and 449 were men (mean age, 60+/-13 years). Peak systolic and mean FV were higher and hematocrit concentration was lower in women compared to men (P< 0.001). The relation of TCD velocities with age and hematocrit was more remarkable in the group of patients with non-vascular neurological disorders. PI values demonstrated a significant correlation to age (r=+0.47) (P< 0.001), but did not change significantly with hematocrit level. CONCLUSIONS It should be remembered that blood FV measured by TCD may be significantly affected by age and hematocrit level. However, there seems to be no significant association between TCD velocities and hematocrit in patients with a recent ischemic stroke.

Cerebrovascular manifestations of Behçet's disease

Behçets disease (BD) is a systemic inflammatory disease commonly characterized by oral and genital ulcerations, with skin and eye involvement. Its cause is still unknown, but vasculitis is the major pathologic feature. BD is a rare condition, seen more commonly in Turkey, as well as in Middle Eastern, Mediterranean and Far Eastern countries. Neurological involvement is reported to manifest as brainstem or corticospinal tract syndromes, increased intracranial pressure mostly related to venous sinus thrombosis or aseptic meningitis, isolated behavioral symptoms or isolated headache. This report presents a 34-year-old BD patient with secondary cerebral infarction due to head trauma. The clinical and central nervous system findings of BD are discussed.

Relationship between pulsatility index and clinical course of acute ischemic stroke after thrombolytic treatment.

Background. The relationship between the arterial recanalization after intravenous recombinant tissue plasminogen activator (rtPA) and outcomes is still uncertain. The aim of our study was to evaluate whether there is an association between the pulsatility indexes (PI) of the middle cerebral artery (MCA) measured by transcranial Doppler (TCD) after iv rtPA treatment and short- and long-term outcomes in ischemic stroke patients. Methods. Forty-eight patients with acute ischemia in the MCA territory who achieved complete recanalization after the administration of intravenous thrombolytic treatment were included in the study. The TCD was applied to patients after the iv rtPA treatment. Clinical and functional outcomes were assessed by National Institutes of Health Stroke Scale (NIHSS) scores and modified Rankin Scores (mRS), respectively. Results. Significant positive correlations were found between the PI value and NIHSS score at 24 hours, NIHSS score at 3 months, and mRS at 3 months (P < 0.005 for all). The cut-off value for PI in predicting a favorable prognosis and a good prognosis might be less than or equal to 1.1 and less than or equal to 1.4, respectively. Conclusions. PI may play a role in predicting the functional and clinical outcome after thrombolytic therapy in acute ischemic stroke patients.

Cerebral vasomotor reactivity and dementia after ischemic stroke

Gur AY, Gücüyener D, Korczyn AD, Üzüner N, Gilutz Y, Özdemir G, Bornstein NM. Cerebral vasomotor reactivity and dementia after ischemic stroke. 
Acta Neurol Scand: 2010: 122: 383–388.
© 2010 The Authors Journal compilation