Can transcranial Doppler discriminate between solid and gaseous microemboli? Assessment of a dual-frequency transducer system.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasound can reliably detect both gaseous and solid cerebral emboli. However, conventional equipment is unable to discriminate between gaseous and solid emboli. This is a major limitation in situations in which the 2 coexist, because they may have very different clinical relevance. Recently, a novel Embo-Dop system, using insonation at 2 ultrasound transducer frequencies, has been developed. An initial study with a small sample size suggested it provided excellent discrimination. We performed a validation study in subjects with embolic signals of known nature. METHODS: Gaseous embolic signals were obtained in 7 patients with known patient foramen ovale by intravenous injection of agitated saline injections. Solid embolic signals were obtained in patients with symptomatic carotid stenosis (N=23). Discrimination of the 2 using the Embo-Dop system dual-frequency system was assessed. It was compared with discrimination using embolic signal maximum intensity with an intensity threshold. RESULTS: One hundred forty-five solid embolic signals were recorded from carotid stenosis patients. Seventy-three were classified as solid and 72 as gaseous by the Embo-Dop system. Six hundred forty-eight gaseous embolic signals were recorded from 7 patients with patent foramen ovale. Six hundred twenty-five were classified as gaseous and 23 as solid. This gave a sensitivity of 50.3% and specificity of 96.5% for detecting solid embolic signals. Discrimination was better than using a simple intensity threshold. CONCLUSIONS: The Embo-Dop dual-frequency system allows better discrimination than a simple intensity threshold but it is not accurate enough for use in clinical or research studies. Further work is needed to develop reliable clinical systems for discrimination of emboli.

"Pure word deafness": implications for assessment and management in communication disorder--a report of two cases.

In "pure word deafness" after acquired brain injury, the auditory comprehension of words is much more impaired than other aspects of communication or cognition. Two cases are presented, one early and one late presentation. The key to diagnosis of communication disorders is to remember to assess all six basic aspects of language function and to be vigilant for coexisting diagnoses that can complicate such assessment (especially psychiatric diagnoses). Rehabilitation management of impaired communication should emphasize the teaching of specific coping mechanisms to the patient and to all others who are involved.

Preliminary clinical-radiological assessment of a MR tissue signature model in human stroke.

We evaluated the ability of an MR signature model (SM) of cerebral ischemic injury to stage the evolution of cellular damage in human stroke. In 19 patients with ischemic stroke of presumed embolic or non-embolic cause we carried out diffusion-weighted and T2-weighted MR imaging within 48 h of onset, and obtained apparent diffusion coefficient of water (ADCw), and T2 weighted images. We used the signatures obtained from these ADCw/T2 maps to formulate two patterns of damage signifying accelerated or non-accelerated progression of cellular death after stroke onset. Those patients with the accelerated pattern corresponded to those with the neuroradiological (NRC) and clinical diagnosis (TOAST.1 and TOAST.2) of presumed embolic stroke, with clinical diagnosis performed blinded both to NRC and to SM. Agreement between the SM and NRC was substantial (kappa=0.62), moderate (0.60

[Rational cardiologic diagnosis after cerebral ischemic event]. / Rationelle kardiologische Diagnostik nach zerebralem ischämischen Ereignis.

Stroke continues to be a serious socioeconomic problem in the industrialized countries. The three disease processes responsible for most ischemic cerebrovascular events (CVE) are large-vessel and small-vessel atherothrombotic disease and, in up to 20-30% of cases, cardiac embolism. Data from the literature show that life expectancy after CVE is mainly dependent on the coexistence of cardiac disease. It is the responsibility of the cardiologist to exclude or identify the source of cardiac embolism and to initiate adequate treatment for the prevention of recurrences, as well as to diagnose, and treat any concomitant cardiac disease which may be present. We propose a cost-effective algorithmic approach to help the cardiologist in the diagnosis and treatment of patients with transient ischemic attacks and ischemic stroke.

Carotid stenosis. A neurologist's perspective.

The initial step performed by neurologists in the evaluation of patients with potential carotid disease is to establish whether patients have had carotid territory symptoms. Symptoms are most often believed to be caused by emboli passing onto the cerebral circulation. Despite some limitations, conventional angiography remains the gold standard test to evaluate the carotid bifurcation. Because of the costs and risks of angiography, some combination of carotid duplex ultrasonography and MR angiography is chosen to select patients for angiography. Future research will focus on markers other than percent stenosis to assess stroke risk and treatments, such as angioplasty and stenting, for carotid lesions.

Assessment of cerebral fat embolism by magnetic resonance imaging in the acute stage.

The authors assessed the characteristic appearance of magnetic resonance imaging (MRI) of cerebral fat embolism in three patients. The MRI features in the acute stage were characterized by widespread, spotty lesions in the white matter, which appeared hyperintense on T2-weighted images and iso- or hypointense on T1-weighted images. The relation between clinical features and MRI findings are discussed.

Serial assessment of acute stroke using the NIH Stroke Scale.

BACKGROUND AND PURPOSE: The National Institutes of Health (NIH) Stroke Scale has been used in clinical trials to assess neurological outcome after investigational therapy for acute stroke. We used the NIH Stroke Scale to study the degree and time course of recovery in patients with acute stroke who were treated with conventional therapy. METHODS: We serially assessed 50 patients with ischemic stroke who presented within 24 hours of onset of symptoms. Patients were grouped by stroke subtype. Major neurological improvement was defined as a decrease in the stroke score by 4 points or more. RESULTS: The mean NIH stroke score for all patients improved significantly by 7 to 10 days and at last follow-up (average, 44 days). Major neurological improvement was seen in 5 of 41 patients (12%; 95% confidence interval [CI], 2% to 22%) by 24 hours, 11 of 40 patients (28%; 95% CI, 14% to 41%) by 48 hours, and 19 of 37 patients (51%; 95% CI, 35% to 67%) by follow-up. The subgroup of patients with middle cerebral artery territory embolism showed a similar pattern of improvement; in contrast, patients with lacunar infarcts did not show significant change in scores during the study period. The score on admission did not correlate with the degree of subsequent improvement or deterioration. CONCLUSIONS: A significant percentage of patients with acute ischemic stroke treated with conventional therapy show early improvement as assessed by the NIH Stroke Scale. The degree and time course of recovery may be influenced by stroke type.

Potential flaws in the assessment of minor cerebrovascular events after heart valve replacement.

The specificity and sensitivity of the questionnaire method, whether through direct contact or via mail, in collecting information on thrombosis, embolism and bleeding after heart valve replacement were assessed by a critical analysis of methods currently in clinical use. The 16 questions contained in the standard questionnaire of the Albert Einstein College of Medicine searching for transient events were put to 1000 apparently healthy individuals. Additional questions related to risk factors such as previous heart valve replacement, any existing heart disease, hypertension, diabetes or current anticoagulant treatment for any reason were also asked. The male/female ratio was 54.9/45.1, and the mean age was 36.3 years with a range of 14-97 years. Eighty-five persons had one or more risk factors, 915 had none. A positive answer to at least one of the questions searching for TIA (transient ischemic attack) was given by 69.4% (n = 59) of those with, and by 54.8% (n = 501) without any risk factors. The total number of reported 'events' was 164 (1.93/person) for those with, and 1331 (1.45/person) for those without any risk factors. Four different follow up methods were applied to each of 123 patients after heart valve replacement: (a) regular follow up at an out-patient clinic, questionnaires sent at (b) six, (c) 18 and (d) 36 months after the start of the study. 57% of the transient and reversible events reported at the out-patient clinic were forgotten and not mentioned by the same patients in the 36 month questionnaire. One of the three permanent disabilities was also 'forgotten'.(ABSTRACT TRUNCATED AT 250 WORDS)