PET Imaging May Aid Alzheimer's Diagnosis
There were significant differences in brain amyloid content exhibited on positron emission tomography of patients with normal and impaired cognition, suggesting PET might have a role in differential diagnosis of dementia, investigators in a multicenter study concluded.
The standard uptake value ratios (SUVRs) for the tracer florbetapir F 18 declined in linear fashion from patients with probable Alzheimer's disease to those with mild cognitive impairment to a group of older normal controls.
The pattern of differences in SUVR persisted in analyses of mean cortical florbetapir, proportion of patients with amyloid levels associated with Alzheimer's disease, and the proportion with any identifiable fibrillar beta-amyloid ( P .
"The findings of our analysis confirm the ability of florbetapir-PET SUVRs to characterize amyloid levels in clinically probable Alzheimer's disease, mild cognitive impairment, and older healthy control groups using continuous and binary measures of fibrillar beta-amyloid burden," Adam Fleisher, MD, of the Banner Alzheimer's Institute in Phoenix, and co-authors wrote in conclusion.
"It introduces criteria to determine whether an image is associated with an intermediate-to-high likelihood of pathologic Alzheimer's disease or with having any identifiable cortical amyloid level above that seen in low-risk young controls."
In another article published online ahead of print, investigators reported a significant association between PET tracer uptake and amount of beta-amyloid in patients with normal-pressure hydrocephalus.
Amyloid imaging has shown promise as a means of evaluating patients with Alzheimer's disease and other forms of dementia and cognitive impairment. In particular, florbetapir has demonstrated potential for measuring cortical fibrillar beta-amyloid in preclinical and clinical studies.
Continuing the investigation of florbetapir-PET imaging, Fleisher and colleagues analyzed pooled data from four phase I-II trials of the imaging modality. They sought to determine whether measures of florbetapir-PET activity would allow them to assess global differences between diagnostic groups, confirm expected regional distribution patterns of beta-amyloid, and calculate the proportion of positive scans by various cutoffs for tracer activity.
The investigators considered an SUVR ≥1.17 as reflecting amyloid levels associated with Alzheimer's disease, a threshold based on antemortem PET and postmortem neuropathologic data from 19 patients.
Low Pressure Hydrocephalus - News
above that seen in low-risk young controls." In another article published online ahead of print, investigators reported a significant association between PET tracer uptake and amount of beta-amyloid in patients with normal-pressure hydrocephalus.
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Negative-pressure and low-pressure hydrocephalus: the role of ...
Journal of Neurosurgery, Volume 0, Issue 0, Page 1-7, Ahead of Print.
Aristotelis S. Filippidis, M.D., Ph.D., M. Yashar S. Kalani, M.D., Ph.D., Peter Nakaji, M.D., and Harold L. Rekate, M.D.
Object
Negative-pressure and low-pressure hydrocephalus are rare clinical entities that are frequently misdiagnosed. They are characterized by recurrent episodes of shunt failure because the intracranial pressure is lower than the opening pressure of the valve. In this report the authors discuss iatrogenic CSF leaks as a cause of low- or negative-pressure hydrocephalus after approaches to the cranial base.
Methods
The authors retrospectively reviewed cases of low-pressure or negative-pressure hydrocephalus presenting after cranial approaches complicated with a CSF leak at their institution.
Results
Three patients were identified. Symptoms of high intracranial pressure and ventriculomegaly were present, although the measured pressures were low or negative. A blocked communication between the ventricles and the subarachnoid space was documented in 2 of the cases and presumed in the third. Shunt revisions failed repeatedly. In all cases, temporary clinical and radiographic improvement resulted from external ventricular drainage at subatmospheric pressures. The CSF leaks were sealed and CSF communication was reestablished operatively. In 1 case, neck wrapping was used with temporary success.
Conclusions
Negative-pressure or low-pressure hydrocephalus associated with CSF leaks, especially after cranial base approaches, is difficult to treat. The solution often requires the utilization of subatmospheric external ventricular drains to establish a lower ventricular drainage pressure than the drainage pressure created in the subarachnoid space, where the pressure is artificially lowered by the CSF leak. Treatment involves correction of the CSF leak, neck wrapping to increase brain turgor and allow the pressure in the ventricles to rise to the level of the opening pressure of the valve, and reestablishing the CSF route.
http://thejns.org/doi/abs/10.3171/2011.6.JNS101504?
Low Pressure Hydrocephalus - Bookshelf
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The ICP dynamics may reveal a relatively low-pressure range as the ... Great confusion in the term "normal-pressure hydrocephalus" begins from this point. ...Abstracts of papers presented, 18th World Congress [of] International College of Surgeons, Rome, Italy, 28-31 May 1972
The cortical capillaries in our patients with low pressure hydrocephalus ... Angiographic diagnosis of low pressure hydrocephalus in infancy and childhood. ...Handbook of Neurosurgery
Rosen H, Swigar ME: Depression and normal pressure hydrocephalus. ... Dorsch NW C. Stephens RJ: Pressure waves in so-called low-pressure hydrocephalus. ...Intracranial pressure II
THE CEREBRAL BLOOD FLOW IN LOW PRESSURE HYDROCEPHALUS David H. Ingvar, Martin S. Schwartz Introduction In organic dementia of the Alzheimer type (presenile ...Brain edema XIII
The mechanics of hydrocephalus and normal pressure hydrocephalus. ... Meier U ( 2002) The grading of normal pressure hydrocephalus. ...Day-by-day Knowledge Directory
Low pressure hydrocephalus - Wikipedia, the free encyclopedia
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Provides information about the condition, treatment, complications, outcomes and research. ... Symptoms of normal pressure hydrocephalus include, problems with walking, impaired ...
The Genesis of Low Pressure Hydrocephalus.
BACKGROUND: Low pressure hydrocephalus (LPH) is an uncommon entity. Recognition of this treatable condition is important when clinicians are faced with the para...
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