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Biomedical subjects

A Vighetto

Publications and source records attributed to A Vighetto.

At least 19 recordsLinked to original sources
PubMed2006

[HIV infection presenting with bilateral optic neuropathy].

We report the case of a 57-year-old man who presented bilateral subacute and painless optic neuropathy after meningopolyradiculitis revealing a primary human immunodeficiency virus infection. Both antiretroviral and steroid treatments were ineffective. Clinical symptoms and evolutive pattern were consistent with a mechanism of microvascular ischaemia of the optic nerve head. Optic neuropathies related to HIV infection are rare compared to those resulting from opportunistic infections. There are several pathophysiological mechanisms involved.

AIDS Serodiagnosis↗
PubMed2006

[Part I: Face recognition].

Faces represent a crucial vector of interhuman communication. The message transmitted by the face has multiple features. Recognition of each feature can be impaired independently or in combination with others. In order to understand the behavioral consequences of such impairments, which can be a major social handicap, we first must specify the neural networks involved in face recognition. We propose in this first part to present the systems involved in face recognition, in particular the question of identity and prosopagnosia. Different neural networks are indeed implicated in the recognition of invariant facial features such as identity, gender, ethnicity, and recognition of variant features like facial expression and eye gaze. This paper is illustrated by some of our scalp and intracranial electrophysiological studies performed in humans allowing us to describe some aspects of face recognition dynamics combining an excellent spatial and temporal resolution. Intracranial recordings were performed in drug refractory epileptical patients implanted with depth electrodes. These studies demonstrate that numerous deep brain and cortical structures participate early and sometimes in a sustained manner in face recognition.

Face↗
PubMed2006

[Part II: Recognising facial expressions].

In this second part, we address particularly the question of the neural mechanisms and structures involved in the recognition of facial emotional expressions that are crucial in social cognition. Emotion recognition in others can be critically impaired in some neurodegenerative and neurovascular diseases. That dysfunction sometimes correlated to disabling behavioural disorders and interpersonal communication impairment must be further understood. The results of a series of scalp and intracranial event related potential recordings, as well as recent advances in the literature, are reported. ERPs to facial emotional expressions were thus recorded in multiple subcortical and cortical areas in drug refractory epileptical patients implanted with depth electrodes. The roles of amygdala, insula and prefrontal cortex located at crossroads between perceptive analysis and emotional conceptual knowledge are particularly underlined. Altogether, these studies demonstrate that facial expressions are widely processed in space and time, some structures reacting very early and automatically, others providing a sustained reaction depending on the attention.

Amygdala↗
PubMed2005

Optic ataxia errors depend on remapped, not viewed, target location.

Optic ataxia is a disorder associated with posterior parietal lobe lesions, in which visually guided reaching errors typically occur for peripheral targets. It has been assumed that these errors are related to a faulty sensorimotor transformation of inputs from the 'ataxic visual field'. However, we show here that the errors observed in the contralesional field in optic ataxia depend on a dynamic gaze-centered internal representation of reach space.

Adult↗
PubMed2005

Visually guided reaching: bilateral posterior parietal lesions cause a switch from fast visuomotor to slow cognitive control.

The visually guided reaching of two patients with bilateral optic ataxia was explored in two experiments. In Experiment 1 simple delayed pointing was compared with immediate pointing. In the immediate pointing task both variable and constant errors increased with target eccentricity. In contrast to the performance of control subjects and contrary to their own beliefs, the patients both showed improved accuracy in the delay condition. This improvement was manifest as a reduction in both pointing variability and in the constant angular error towards the point of fixation. Both angular errors and their improvement with the delay were proportional to target eccentricity. Experiment 2 used a task in which the target was pre-viewed 5s prior to its re-exposure for pointing ('delayed real pointing'). On some trials a conflict was introduced between the present and previous visual information by changing the target's location during the delay. In contrast to control subjects, who ignored the pre-viewed location and aimed directly at the current target, both patients with optic ataxia initiated their movements towards the previously viewed target location. Evidently they relied on off-line information in preference to on-line visual information. In addition, the patients often failed to detect the changes in target location. One of the patients sometimes even guessed incorrectly that the target had changed its location, and her movement trajectory was then more affected by her false belief than by the target's actual location. These findings confirm that posterior parietal lesions severely disrupt direct visuomotor transformations, and suggest that the residual performance is mediated indirectly by expectations or beliefs about target position.

Acoustic Stimulation↗
PubMed2005

[Rhinocerebral mucormycosis].

INTRODUCTION: Mucormycosis is a rare and acute fungal infection which is frequently lethal. The rhinocerebral form is usually seen in diabetics, but other localizations may occur in severely immunocompromised subjects. OBSERVATION: We report the case of a sphenoidal sinusitis associated with a probable cavernous sinus thrombosis and carotid artery thrombosis with middle cerebral artery territory infarction. Diagnosis was made on histological examination following sphenoidotomy. Early medical and surgical treatment led to a good outcome. CONCLUSION: The diagnosis of rhinocerebral mucormycosis should be considered in the clinical setting of necrotic sinusitis and acute neurologic deficit in diabetic patients. Early diagnosis and treatment are crucial factors leading to a good outcome.

Aged↗
PubMed2005

[Painful oculomotor palsy: a diagnostic approach].

We review the question of diagnosis of painful and relatively isolated ophthalmoplegia due to diseases affecting the ocular motor nerves. For each clinical setting, we provide an overview of the main causes and a practical way to approach the diagnosis. As vascular malformations should always be kept in mind in patients with painful ophthalmoplegia, emergency neuroradiological investigations may be needed. However, the etiological scope is wide and the rationale for choosing the more appropriate examination and its optimal timing depends exclusively on the clinical evaluation. Despite advances in investigation techniques, diagnosis may remain difficult or even unresolved in a certain number of patients. We discuss successively paralysis of the third, sixth and fourth nerve, paralysis of several ocular motor nerves, recurrent ophthalmoplegia and ischaemic ocular motor palsies, which are the most frequent cause.

Abducens Nerve Diseases↗
PubMed2005

[Heidenhain's variant of Creutzfeldt-Jakob's disease].

INTRODUCTION: Creutzfeldt-Jakob's disease has various anatomoclinical presentations including a rare form with preponderant visual signs described by Heidenhain. In this form, the visual symptoms may be isolated for a few weeks, leading to multiple ophthalmological examinations. OBSERVATION: We report the case of a 75-year-old woman who developed isolated visual disorders which rapidly increased over a period of two months. Addition of neurological symptoms, abnormalities of EEG and positivity of 14-3-3 protein led to the diagnosis of Creutzfeldt-Jakob's disease. The patient died 14 months after the first neuroophthalmologic signs. The diagnosis was established by post-mortem examination and immuno-electrophoretic demonstration of type 1 prion protein. CONCLUSION: Heidenhain's form of Creutzfeldt-Jakob's disease highlights the importance of general rules for prevention of iatrogenic hazard during ophthalmological examinations.

14-3-3 Proteins↗
PubMed2004

Preserved prism adaptation in bilateral optic ataxia: strategic versus adaptive reaction to prisms.

To date the anatomical substrate(s) of prism adaptation remain(s) particularly debated, with two main candidates emerging from the literature: the posterior parietal cortex (PPC) and the cerebellum. The functional processes involved in the acquisition of the adaptive aftereffects also remain largely unknown. The main result shown here is that a patient with a bilateral optic ataxia can adapt to an optical deviation, which allows us to make a step forward on these two issues. First, it demonstrates that the corresponding part of the PPC is not a necessary substrate for prism adaptation. Second, since this patient exhibits deficit for fast visuo-motor guidance, it provides direct evidence for a dissociation between on-line visuo-motor control and visuo-motor plasticity. Since the intermanual transfer rate of adaptation is larger in this patient than in control subjects, the PPC may still have an influence on adaptation under normal conditions. We propose a model of the relative contribution of the PPC and the cerebellum during prism exposure, associating these two structures with the two interacting behavioural components of prism adaptation described by previous psychophysical experiments: the strategic component would be linked to the PPC and the adaptive component to the cerebellum. In this model, the strategic component enters in conflict with the development and the generalisation of the adaptive aftereffects. This idea is compatible with the fact that a lesion of the PPC increases the transfer rate and the generalisation of the adaptation, as is also observed in unilateral neglect.

Adaptation, Physiological↗
PubMed2003

Pointing errors in immediate and delayed conditions in unilateral optic ataxia.

The present paper provides an analysis of the pointing errors of a patient with unilateral optic ataxia (O.K.) following right hemispheric damage, revealing the type of errors related tothe use of the contralesional hand and/or to the reaching of targets located in the contralesional visual field. In addition, comparison between immediate and delayed pantomime pointing allow testing of whether pointing deficits of this patient are specific to real-time visuo-motor control and, subsequently, whether delay could improve his pointing performance. The results show different patterns in the four hand-field combinations. The following conclusion can be drawn from the results of the delayed condition. In the case of patient O. K., the delay reduced the pointing variability for both hands in the left visual field but not in the right visual field. However, the pointing biases did not improve accordingly. As in healthy subjects, target locations tended to be coded in memory with a bias directed toward the fixation point. These results are discussed and contrasted with respect to those previously obtained in the literature in patients with bilateral optic ataxia.

Adult↗
PubMed2002

Thalamic venous infarction as a cause of subacute dementia.

The clinical picture of deep cerebral vein thromboses (DCVT) usually is acute, combining vigilance disorders, headaches, and focal neurologic deficit. The authors describe a patient who presented with isolated subacute dementia as the sole manifestation of DCVT. In the setting of subacute cognitive deficit, the diagnosis of DCVT must be considered when neuroimaging shows bilateral thalamic changes. Enhanced venous MR angiography is the noninvasive method of choice to ascertain the diagnosis.

Brain Infarction↗
PubMed2002

Bilateral vestibular stimulation does not improve visual hemineglect.

This work compared the effect of unilateral (right and left) and bilateral vestibular stimulation in a right-brain-damaged patient with neglect. Neglect was improved following left caloric vestibular stimulation, and worsened following right vestibular stimulation. On the other hand, no modification of neglect was observed after bilateral vestibular stimulation. These results support the idea that caloric vestibular stimulation may improve neglect through a specific effect; bilateral stimulation making the putative activation bilateral and symmetrical does not affect the lateral bias of neglect.

Aged↗
PubMed2001

[Inflammatory optic neuropathies].

Diagnosis of inflammatory optic neuropathy is very likely in a young adult presenting acute, unilateral and painful visual loss. Relative afferent pupillary defect is a very sensitive and specific sign of optic neuropathy. Ophthalmological exam is mandatory to estimate severity of visual loss, appearance of optic disks and check for another eye disease. Magnetic resonance imaging is indicated to rule out a compressive optic neuropathy and to quantify the inflammatory lesion index, which is the best prognostic indicator of multiple sclerosis development (MRI is abnormal at entry in about 50% of patients with isolated optic neuritis). Spontaneous outcome of optic neuropathies is favourable. Corticosteroids have demonstrated efficacy only in shortening length of evolution and by using parenteral high doses. Clinical benefit from introducing beta-interferons treatment after a first episode of isolated optic neuritis remains to be evaluated. Secondary inflammatory optic neuritis (infection, vasculitis, sarcoïdosis) are rare and usually present atypical evolution or other symptoms.

Adjuvants, Immunologic↗
PubMed2001

Grasping the past. delay can improve visuomotor performance.

"Optic ataxia" is caused by damage to the human posterior parietal cortex (PPC). It disrupts all components of a visually guided prehension movement, not only the transport of the hand toward an object's location, but also the in-flight finger movements pretailored to the metric properties of the object. Like previous cases, our patient (I.G.) was quite unable to open her handgrip appropriately when directly reaching out to pick up objects of different sizes. When first tested, she failed to do this even when she had previewed the target object 5 s earlier. Yet despite this deficit in "real" grasping, we found, counterintuitively, that I.G. showed good grip scaling when "pantomiming" a grasp for an object seen earlier but no longer present. We then found that, after practice, I.G. became able to scale her handgrip when grasping a real target object that she had previewed earlier. By interposing catch trials in which a different object was covertly substituted for the original object during the delay between preview and grasp, we found that I.G. was now using memorized visual information to calibrate her real grasping movements. These results provide new evidence that "off-line" visuomotor guidance can be provided by networks independent of the PPC.

Animals↗
PubMed2001

Cerebellar ataxia with anti-glutamic acid decarboxylase antibodies: study of 14 patients.

BACKGROUND: Antibodies to glutamic acid decarboxylase (GAD-Ab) are described in patients with insulin-dependent (type 1) diabetes mellitus (IDDM), in stiff-man syndrome, and, recently, in a few patients with cerebellar ataxia. OBJECTIVES: To show a link between GAD-Ab and some patients with cerebellar ataxia and to clarify their clinical and immunologic profiles. METHODS: Serum samples were selected from 9000 samples of 4 laboratories. The selection criterion was an immunohistochemical pattern compatible with GAD-Ab that was confirmed by radioimmunoassay. We identified 22 patients with stiff-man syndrome and 14 with cerebellar ataxia and GAD-Ab. RESULTS: Thirteen of the 14 patients with cerebellar ataxia and GAD-Ab were women, and 11 had late-onset IDDM. Patients did not have clinical or radiologic evidence of brainstem involvement. Ten patients had oligoclonal IgG bands in the cerebrospinal fluid, and intrathecal GAD-Ab synthesis was observed in 5 of the 6 patients studied. The level of GAD-Ab of these patients was similar to those with stiff-man syndrome and significantly higher than those with IDDM or with polyendocrine autoimmunity (P<.001). However, the GAD-Ab levels of 6 of the 9 patients with polyendocrine autoimmunity overlapped with those of patients with cerebellar ataxia. CONCLUSIONS: These results suggest a link between high level of GAD-Ab and some cases of cerebellar ataxia, particularly women with IDDM. If high serum levels of GAD-Ab are detected, the cerebrospinal fluid should be evaluated for the presence of oligoclonal IgG bands and intrathecal synthesis of GAD-Ab to further prove an autoimmune origin of the syndrome.

Adult↗
PubMed2001

Processing of facial emotional expression: spatio-temporal data as assessed by scalp event-related potentials.

Event-related potentials (ERPs) were recorded in 10 adult volunteers, who were asked to view pictures of faces with different emotional expressions, i.e. fear, happiness, disgust, surprise and neutral expression [Ekman, P. & Friesen, W.V. (1975). Pictures of Facial Affect. Consulting Psychologist Press, Palo Alto, CA]. ERPs were recorded during two different tasks with the same stimuli. Firstly, subjects were instructed to pay attention to the gender of the faces by counting males or females. Secondly, they had to focus on facial expressions by counting faces who looked surprised. The classical scalp 'face-related potentials', i.e. a vertex-positive potential and a bilateral temporal negativity, were recorded 150 ms after the stimulus onset. Significant differences were found, firstly between late-latency ERPs to emotional faces and to neutral faces, between 250 and 550 ms of latency and, secondly, among the ERPs to the different facial expressions between 550 and 750 ms of latency. These differences appeared only during the expression discrimination task, not during the gender discrimination task. Topographic maps of these differences showed a specific right temporal activity related to each emotional expression, some particularities being observed for each expression. This study provides new data concerning the spatio-temporal features of facial expression processing, particularly a late-latency activity related to specific attention to facial expressions.

Adult↗
PubMed2001

[Otolith manifestations in Wallenberg syndrome].

Central vestibular pathways issuing from the otolith may be involved in Wallenberg syndrome, resulting in specific symptoms. These "otolith" symptoms are less well known than vestibular symptoms issuing from the canal. We report 15 patients with Wallenberg syndrome who had one or more clinical signs suggestive of otolith pathway involvement. Clinical examination looked for: Eleven patients presented ipsilesional skew deviation; ipsilesional tilt of subjective visual vertical was found in 8 patients; a room tilt illusion was described in 4 patients in either the frontal or the sagittal plane: 9 patients presented axial lateropulsion toward the lesioned side; 8 patients presented ipsilesional ocular lateropulsion, 6 of them in association with axial lateropulsion. Finally, 3 patients presented positional nystagmus evoked by head tilt in the roll or the pitch plane. Pathophysiology of these symptoms and evidence for an otolith pathway involvement are discussed.

Adult↗