1,720,982 research outputs found
Rapidly progressive cognitive impairment in a patient with high flow dural arteriovenous fistulas, cerebral sinus thrombosis and protein S deficiency
No full textDural arteriovenous fistula (DAVF) may present with a variety of neurological symptoms, ranging from tinnitus to fatal hemorrhage. We report a case of rapidly progressive cognitive impairment due to cerebral venous engorgement that reversed after endovascular treatment in a patient with DAVF, cerebral sinus thrombosis and protein S deficiency. DAVF may be a cause of vascular cognitive impairment and should be considered particularly in cases with a rapidly progressive course because they are potentially treatable
Pediatric inflammatory diseases. Part I: multiple sclerosis
No full textMultiple sclerosis (MS) is an inflammatory CNS disease characterized by multifocal areas of demyelination; usually it arises in young adults, but can also occur in children (under the age of 10) and adolescents (under the age of 18). As in adult, pediatric MS (PMS) diagnosis is based on the demonstration of multiple demyelination episodes separated in time and spaces. Diagnostic criteria realized for childhood are similar to those employed for adults. Although clinical and imaging features of PMS can be similar to those of adults, the disease is often characterized by a more aggressive course and atypical imaging findings, with giant and pseudotumoral plaques. Differential diagnosis between PMS and ADEM could be difficult: clinical findings and MRI are necessary; sometimes MRI follow-up is required for definitive diagnosis
Pediatric inflammatory diseases: Part II: Acute post-infectious immune disorders
No full textAcute post-infectious immune disorders include Acute Disseminated Encephalomyelitis (ADEM) and its variants such as Acute Hemorrhagic Encephalomyelitis (AHEM), acute necrotizing hemorrhagic leukoencephalitis (ANHLE) of Weston Hurst, multiphasic and recurrent ADEM. Acute Necrotizing Encephalopathy of Childhood (ANE or ANEC) represents a dramatic event, consequent to viral infections, especially Influenza-A, and is now considered different from ADEM. ADEM and variants are classically described as uniphasic syndrome occurring in association with an immunization or vaccination (postvaccine encephalomyelitis) or systemic viral infection (parainfectious encephalomyelitis). However, multiphasic forms are not rare. Pathologically, there is perivascular inflammation, edema, and demyelination within the CNS. Clinical features are focal or multifocal neurologic disorder following exposure to virus or receipt of vaccine. The onset of the CNS disorder is usually rapid and include encephalopathy ranging from lethargy to coma, seizures, and focal and multifocal signs reflecting cerebral and spinal cord involvement. The mortality rate is estimated at 10 to 30 percent, with complete recovery rates of 50 percent cited. Poor prognosis is correlated with severity and abruptness of onset of the clinical syndrome. Multifocal CNS lesions are generally evident on MRI that can be similar from those observed in MS
Hemodialysis access fistulas: MR angiography evaluation
No full textLearning Objectives: 1) To provide MRA technique for evaluating permanent hemodialysis access fistulas of the forearm. 2) To explore the possibilities of MRA in the diagnosis and grading of hemodialysis fistula stenosis.
Background: The patency of permanent hemodialysis access fistulas of the forearm is limited; with time, stenotic complications often compromise access function. Recognizing these complications is important to preserve the access. Evaluation of the vascular anatomy is fundamental for surgical or interventional treatment planning. Color Doppler ultrasound is usually the first step for diagnosis and treatment planning. It provides both morphological and functional information but DSA is still the gold standard. MRA has been proposed as a non-invasive alternative to DSA to evaluate the arterial and venous structures. We performed MRA in 23 patients with suspected haemodialysis forearm access dysfunction. The degree of stenosis was evaluated with a 3 point scale (1=mild; 3=severe); we compared MRA and ultrasound results.
Procedure Details: We used a 1.5T unit (Philips Intera) and performed the examinations with the knee coil. We propose a protocol based on both 3D-PC technique (VENC 30 cm/sec) before and after iv GD injection, and 3D-FFE-T1 sequence during iv GD injection (CE-MRA). MIP reconstructions were always obtained. We observed a good correlation between MRA and ultrasound findings. MRA always showed the entire fistula with an excellent evaluation of the stenosis. In 2 cases MRA showed stenoses missed by ultrasound. CE-MRA proved more useful than PC-MRA.
Conclusion: MRA is an effective tool to evaluate hemodialysis fistula complications, being a valid alternative to diagnostic DSA
Reversible focal splenial lesions
No full textReversible focal lesions in the splenium of the
corpus callosum (SCC) have recently been reported.They
are circumscribed and located in the median aspect of the
SCC. On MRI, they are hyperintense on T2-W and isohypointense
on T1-W sequences, with no contrast enhancement.
On DWI, SCC lesions are hyperintense with low
ADC values, reflecting restricted diffusion due to cytotoxic
edema. The common element is the disappearance of
imaging abnormalities with time, including normalization
of DWI. Clinical improvement is often reported. The most
established and frequent causes of reversible focal lesions
of the SCC are viral encephalitis, antiepileptic drug
toxicity/withdrawal and hypoglycemic encephalopathy.
Many other causes have been reported, including traumatic
axonal injury. The similar clinical and imaging features
suggest a common mechanism induced by different
pathological events leading to the same results. Edema
and diffusion restriction in focal reversible lesions of the
SCC have been attributed to excitotoxic mechanisms that
can result from different mechanisms; no unifying relationship
has been found to explain all the pathologies
associated with SCC lesions. In our opinion, the similar
imaging, clinical and prognostic aspects of these lesions
depend on a high vulnerability of the SCC to excitotoxic
edema and are less dependent on the underling pathology.
In this review, the relevant literature concerning reversible
focal lesions in the SCC is analyzed and hypotheses about
their pathogenesis are proposed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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