1,721,157 research outputs found
Balance control in Sensory Neuron Disease
No full textOBJECTIVE: Balance control under static and dynamic conditions was assessed in
patients with Sensory Neuron Disease (SND) in order to shed further light on the
pathophysiology of ataxia.
METHODS: Fourteen patients with diabetic polyneuropathy and 11 with SND underwent
clinical and neurophysiological evaluation, stabilometric recording of body sway
during quiet stance with and without vision, stereometric analysis of body
segment displacement while riding a platform translating in anterior-posterior
direction with and without vision (dynamic condition), and EMG recording of leg
muscle responses to abrupt stance perturbation produced by rotation of a
supporting platform. The findings were compared to those of age matched normal
subjects.
RESULTS: Clinical and neurophysiological evaluation revealed a more severe motor
impairment in patients with diabetes than SND, while sensory impairment was
superimposable. Some patients with SND had vestibular dysfunction of diverse
severity. Body sway during stance was larger in patients with SND than diabetes
with and without vision. In the stance perturbation condition, the latency of the
long-loop EMG response to platform rotation was disproportionately increased with
respect to the spinal response in the SND but not in diabetic patients. Under
dynamic condition, patients with SND oscillated more than diabetic patients and
several of them easily lost balance with eyes closed.
CONCLUSIONS: Patients with SND show severe unsteadiness under both static and
dynamic conditions, particularly with eyes closed. The patchy sensory loss of
SND, disrupting sensation from territories other than the lower limbs and
possibly including the vestibular nerve, could be responsible for this
instability. Ataxia is correlated to the abnormal latency of the muscle responses
to stance perturbation. Since increased response latencies cannot be attributed
to a vestibular deficit, the deterioration of equilibrium control would be
ascribed mainly to the degeneration of the central branch of the afferent fibres.
SIGNIFICANCE: Measures of body balance under quiet stance and dynamic conditions
can provide relevant diagnostic information as to the pathophysiology and
severity of ataxia and viability of the central branch of the sensory fibres, and
help in separating patients with peripheral neuropathy from patients with loss of
sensory neurones
Peripheral neuropathy in mitochondrial disorders
No full textWhy is peripheral neuropathy common but mild in many mitochondrial disorders, and why is it, in some cases, the predominant or only manifestation? Although this question remains largely unanswered, recent advances in cellular and molecular biology have begun to clarify the importance of mitochondrial functioning and distribution in the peripheral nerve. Mutations in proteins involved in mitochondrial dynamics (ie, fusion and fission) frequently result in a Charcot-Marie-Tooth phenotype. Peripheral neuropathies with different phenotypic presentations occur in mitochondrial diseases associated with abnormalities in mitochondrial DNA replication and maintenance, or associated with defects in mitochondrial respiratory chain complex V. Our knowledge of mitochondrial disorders is rapidly growing as new nuclear genes are identified and new phenotypes described. Early diagnosis of mitochondrial disorders, essential to provide appropriate genetic counselling, has become crucial in a few treatable conditions. Recognising and diagnosing an underlying mitochondrial defect in patients presenting with peripheral neuropathy is therefore of paramount importance. © 2013 Elsevier Ltd
Vertical supranuclear gaze palsy in Niemann-Pick type C disease
No full textVertical supranuclear gaze palsy (VSGP) is a key clinical feature in patients with Niemann-Pick type C disease (NP-C), a rare, autosomal recessive, neuro-visceral disorder caused by mutations in either the NPC1 or NPC2 gene. VSGP is present in approximately 65 % of the cases and is, with gelastic cataplexy, an important risk indicator for NP-C. VSGP in NP-C is characterized by a paralysis of vertical saccades, especially downward, with the slow vertical eye movement systems (smooth pursuit and the vestibulo-ocular reflex) spared in the early phase of the disease. This dissociation is caused by a selective vulnerability of the neurons in the rostral interstitial nuclei of the medial longitudinal fasciculus (riMLF) in NP-C. Here we discuss VSGP in NP-C and how clinicians can best elicit this sign
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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