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  • 1
    ISSN: 1432-1106
    Keywords: Key words Parkinson’s disease ; Postural set ; Stance ; Background activity ; EMG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Abnormal automatic postural responses are thought to contribute to balance impairment in Parkinson’s disease. However, because postural responses are modifiable by stance, we have speculated that some postural abnormalities in patients with Parkinson’s disease are secondary to their stooped stance. We have studied this assumption by assessing automatic postural responses in 30 healthy subjects who were instructed either to stand upright or to assume a typical parkinsonian posture. During both conditions, subjects received 20 serial 4°’toe-up’ rotational perturbations from a supporting forceplate. We recorded short-latency (SL) and medium-latency (ML) responses from stretched gastrocnemius muscles and long-latency (LL) responses from shortened tibialis anterior muscles. We also assessed changes in the center of foot pressure (CFP) and the center of gravity (COG). The results were qualitatively compared to a previously described group of patients with Parkinson’s disease who, under these circumstances, typically have large ML responses, small LL responses and insufficient voluntary postural corrections, accompanied by a slow rate of backward CFP displacement and an increased posterior COG displacement. The stooped posture resulted in unloading of medial gastrocnemius muscles and loading of tibialis anterior muscles. Onset latencies of stretch responses in gastrocnemius muscles were delayed in stooped subjects, but the onset of LL responses was markedly reduced. Amplitudes of both ML and LL responses were reduced in stooped subjects. Prestimulus COG and, to a lesser extent, CFP were shifted forwards in stooped subjects. Posterior COG displacement and the rate of backward CFP displacement were diminished in stooped subjects. Voluntary postural corrections were unchanged while standing stooped. These results indicate that some postural abnormalities of patients with Parkinson’s disease (most notably the reduced LL responses) can be reproduced in healthy subjects mimicking a stooped parkinsonian posture. Other postural abnormalities (most notably the increased ML responses and insufficient voluntary responses) did not appear in stooped controls and may contribute to balance impairment in Parkinson’s disease.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Herpes simplex virus ; Encephalitis ; Experimental design ; Cerebrospinal fluid ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of the inflammatory response within the brain, meninges and cerebrospinal fluid (CSF) compartment has been studied for the first time simultaneously in experimental herpes simplex virus (HSV) encephalitis after inoculation via the cornea. Two major viral pathways were found from the eye to the brain: one through the trigeminal nerve to the brain stem and one through the nasolacrimal duct to the olfactory system. Viral antigen was found to be present in the CNS before there were clinical signs or cellular infiltration of brain tissue. Subsequently, the virus spread to all parts of the trigeminal brain stem complex. This phenomenon was accompanied by severe inflammation of the meninges covering the trigeminal root near its entry into the brain stem. The meninges near the entry of the olfactory fila also contained antigen. However, HSV-1 did not spread along meningeal rami of the trigeminal nerve and, consequently, is — at least in this experimental model — not a route to reach the inferior frontal and temporal lobes. The development of CSF changes followed the histopathological development of meningitis and encephalitis closely. HSV-DNA could be detected in the CSF from day 4 post inoculation (p.i.) and HSV-1-specific immunofluorescence in CSF cells was convincingly present on day 5 p.i.; on the same days (4 and 5 p.i.) inflammatory cells were found in apposition to infected cells in the brain. We postulate that HSV is carried to the CSF by infected leukocytes rather than a direct spread to the CSF by simple extension of the encephalitic process to the meningeal surface. Consequently, the chances of detection of viral antigen in CSF cells or HSV-DNA by polymerase chain reaction in CSF at an early, pre-encephalitic stage of disease are slight. The relevance of the findings to the pathogenesis and diagnosis of human herpes simplex encephalitis is discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Indirect evidence suggests that patients with Parkinson's disease (PD) have deficits not only in motor performance, but also in the processing of sensory information. We investigated the role of sensory information processing in PD patients with a broad range of disease severities and in a group of age-matched controls. Subjects were tested in two conditions: pointing to a remembered visual target in complete darkness (DARK) and in the presence of an illuminated frame with a light attached to the index finger (FRAME). Differences in pointing errors in these two conditions reflect the effect of visual feedback on pointing. PD patients showed significantly larger constant and variable errors than controls in the DARK and FRAME condition. The difference of the variable error in the FRAME and DARK condition decreased as a function of the severity of PD. This indicates that any deficits in the processing of proprioceptive information occur already at very mild symptoms of PD, and that deficits in the use of visual feedback develop progressively in later stages of the disease. These results provide a tool for early diagnosis of PD and shed new light on the functional role of the brain structures that are affected in PD.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1920
    Keywords: SPECT ; Tc-99m HM-PAO ; Hereditary cerebral hemorrhage with amyloidosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We performed single photon emission computed tomography (SPECT) and cerebral CT-scans in nine patients with hereditary cerebral amyloid angiopathy. CT-scans showed 23 focal hypodense lesions, 13 of which were visible on SPECT as a CBF-defect. One patient showed a CBF-defect on SPECT without CT-scan lesion and had a cerebral hemorrhage three months later in that particular region. In two additional patients, who were 50% at risk for this autosomal dominant disease, CBF-defects on SPECT, but no cortical lesions on CT-scan were found. CT-scans may be more sensitive than SPECT to detect chronic lesions caused by cerebral hemorrhages, but another possibility is that hemorrhages do not always lead to persistent CBF-defects. SPECT can show the effect of amyloid deposits on CBF before the angiopathy causes clinical symptoms.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1459
    Keywords: Key words Parkinson’s disease ; Posture ; Dynamic posturography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Judgement of the ability to recover balance after a sudden shoulder pull is used as a clinical measure of postural instability in Parkinson’s disease. To further evaluate its merits, we compared this ‘retropulsion test’ with dynamic posturography in 23 Parkinson patients. Dynamic posturography involved 20 serial ‘toe-up’ support surface rotations, which induced backward body sway. We found a moderate correlation (Spearman’s ρ = 0.54; P 〈 0.05) between the retropulsion test and body sway after platform rotations during the ‘off’ phase, but no correlation during the ‘on’ phase (Spearman’s ρ = 0.43; P = 0.11). These results cast doubt on the use of the retropulsion test as a measure of postural instability in Parkinson’s disease.
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