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Biomedical subjects

A Vighetto

Publications and source records attributed to A Vighetto.

At least 37 records · Page 2Linked to original sources
PubMed2000

An 'automatic pilot' for the hand in human posterior parietal cortex: toward reinterpreting optic ataxia.

We designed a protocol distinguishing between automatic and intentional motor reactions to changes in target location triggered at movement onset. In response to target jumps, but not to a similar change cued by a color switch, normal subjects often could not avoid automatically correcting fast aiming movements. This suggests that an 'automatic pilot' relying on spatial vision drives fast corrective arm movements that can escape intentional control. In a patient with a bilateral posterior parietal cortex (PPC) lesion, motor corrections could only be slow and deliberate. We propose that 'on-line' control is the most specific function of the PPC and that optic ataxia could result from a disruption of automatic hand guidance.

Adult↗
PubMed2000

Anatomy of optic nerve radiations as assessed by static perimetry and MRI after tailored temporal lobectomy.

AIMS: To determine the course of optic nerve radiations in the temporal lobe, especially their retinotopic organisation and the anterior limit of the Meyer's loop. METHODS: 18 adult patients who had undergone a tailored temporal lobectomy for epilepsy were included in this study between 1994 and 1998. The rostrocaudal extent of the lateral temporal lobe resection assessed intraoperatively by the surgeon and by postoperative MRI was compared with the postoperative visual fields determined by automated static perimetry (ASP). RESULTS: 15 patients (83%) presented a postoperative visual field deficit (VFD) confined to the superior homonymous field contralateral to the side of the resection. All degrees from a minimal upper field loss to a complete quadrantanopia were observed. The VFDs were somewhat stereotyped, predominating along the vertical meridian. The smallest anteroposterior resection resulting in a VFD was limited to 20 mm from the tip of the temporal lobe. A relation was observed between the extent of the lateral resection in front of the second and third convolutions and the occurrence and extent of postoperative VFDs. No patient reported persisting subjective visual impairment. CONCLUSION: The high frequency of postoperative VFDs appears to be due to the greater sensitivity of ASP. The characteristics of the stereotyped VFDs allow new conclusions about the course and retinotopy of optic nerve radiations. The anterior limit of Meyer's loop is likely to be located more rostrally than previously believed.

Adult↗
PubMed2000

Idiopathic ocular neuromyotonia: a neurovascular compression syndrome?

Ocular neuromyotonia in the muscles innervated by the right oculomotor nerve was diagnosed in a patient without a history of radiation therapy. Electromyography of the levator palpebrae showed continuous motor unit activity. Brain MRI disclosed a close contact between the right third cranial nerve and a basilar artery dolichoectasia. The patient partly benefited from carbamazepine therapy. This unique finding suggests that neurovascular compression syndrome could be an hitherto unrecognised cause of ocular neuromyotonia.

Aged↗
PubMed2000

Total recovery after bilateral paramedian thalamic infarct.

Bilateral paramedian thalamic infarcts are characterised initially by the association of acute vigilance disorders and vertical gaze palsy, followed by persisting dementia with severe mnemic disturbance, global aspontaneity and apathy. We describe a patient with a dramatic neuropsychological recovery, confirmed by testing examination and completed by a cerebral metabolism study. The pathophysiology of this type of cognitive deficit is discussed.

Akinetic Mutism↗
PubMed2000

[18F]fluorodeoxyglucose positron emission tomography in the diagnosis of cancer in patients with paraneoplastic neurological syndrome and anti-Hu antibodies.

The diagnosis of cancer is often difficult in patients with paraneoplastic neurological syndrome and anti-Hu antibodies. Fluorodeoxyglucose 18 positron emission tomography scanning is a highly sensitive and specific method to detect lung tumors. We investigated 15 patients with paraneoplastic neurological syndrome and anti-Hu antibodies. Radiological methods led to the diagnosis of cancer in 12 patients, and test results were negative in 3. Whole-body [18F]fluorodeoxyglucose positron emission tomography showed abnormal uptake in the mediastinum in these 3 patients in accordance with the expected location of the malignancy.

Aged↗
PubMed2000

Otolith dysfunction in skew deviation after brain stem lesions. Abnormalities of eye movements induced by off-vertical-axis rotation (OVAR).

We investigated the horizontal and the vertical otolith-ocular reflex induced by off-vertical-axis rotation and subjective visual vertical in 14 patients with skew deviation due to brain stem lesion. Patients were divided into two groups: the group C (N = 7) with caudal brain stem lesions and the group R (N = 7) with rostral brain stem lesions as defined by the midpons level. The patient group was compared to a control group of 20 healthy subjects. The otolith-ocular reflex was evoked by constant velocity rotation in yaw plane around an axis tilted at 15 deg with respect to gravity. In group C, the horizontal off-vertical-axis nystagmus bias was negative i.e. anticompensatory to chair rotation, when directed toward the lesioned side. Furthermore, patients of group C were presenting with a significant tilt of subjective visual vertical. In group R, a vertical downward offset was induced predominantly in the hypotropic eye and in the direction of rotation away from the lesion. Finally, in patients of group R, horizontal and vertical modulation was increased for rotation away from the lesion. These results are discussed in terms of 1) asymmetrical horizontal and vertical dynamic otolith signals feeding the velocity storage network after brain stem lesion, 2) possible involvement of cerebellar function in OVAN modulation.

Adult↗
PubMed1999

High prevalence of CACNA1A truncations and broader clinical spectrum in episodic ataxia type 2.

OBJECTIVE: To characterize the nature of CACNA1A mutations in episodic ataxia type 2 (EA2), to search for mutations in sporadic cases, and to delineate better the clinical spectrum. BACKGROUND: EA2 is an autosomal dominant disorder characterized by recurrent acetazolamide-responsive attacks of cerebellar ataxia. The mutated gene, CACNA1A, located on chromosome 19, encodes the alpha1A subunit of a voltage-dependent calcium channel. So far, only three CACNA1A mutations have been identified-in two EA2 families and in one sporadic case. These three mutations disrupted the reading frame and led to truncated proteins. Interestingly, distinct types of CACNA1A mutations have been identified in familial hemiplegic migraine (missense mutations) and spinocerebellar ataxia type 6 (SCA-6) progressive cerebellar ataxia (expanded CAG repeats). However, except for SCA-6, these genotype-phenotype correlations relied on the analysis of very few families. METHODS: To characterize CACNA1A mutations, eight familial and seven sporadic EA2 patients were selected. All 47 exons of CACNA1A were screened by a combination of single-strand conformer polymorphism and sequencing analysis. In addition, the length of the CAG repeat has been determined in all patients. RESULTS: Seven new mutations were detected in four multiple case families and three sporadic cases. Six of them lead most likely to truncated or aberrant proteins. CAG repeat sizes were in the normal range. CONCLUSION: These data clearly establish the specificity of EA2 mutations compared with SCA-6 and familial hemiplegic migraine. Detailed clinical analysis of the mutation carriers showed the highly variable penetrance and expression of this disorder: Several of the carriers did not show any clinical symptom; others displayed atypical or permanent neurologic symptoms (such as recurrent, transient diplopia or severe, permanent, and isolated cerebellar ataxia).

Adolescent↗
PubMed1999

A selective imaging of tinnitus.

We selectively imaged the neural correlates of tinnitus, by contrasting a condition with no phantom auditory sensation with a condition during which tinnitus is present, using a rare form of tinnitus elicited by eye movements. Using positron emission tomography (PET), we demonstrate that phantom auditory sensation increases regional cerebral blood flow bilaterally in temporo-parietal association auditory areas but not in the primary auditory cortex. These results confirm that conscious perception does not necessarily require activation in primary areas and suggest that the perceptual qualities of tinnitus, e.g. intensity, frequency and spatial localization, are represented in temporo-parietal regions. Activation in these regions is compatible with cortical processing of ascending auditory messages generated at subcortical levels.

Adult↗
PubMed1999

Phosphorus and proton magnetic resonance spectroscopy in episodic ataxia type 2.

Localized phosphorus (31P) and proton (1H) magnetic resonance spectroscopy was performed in the cerebellum and the occipital lobe of 6 patients with episodic ataxia type 2. From use of 31P magnetic resonance spectroscopy, untreated patients showed decreased high-energy phosphate ratios in the cerebrum, and increased pH in the cerebellum and cerebrum, which normalized under acetazolamide. 1H magnetic resonance spectra demonstrated high lactate peaks in 3 of the 6 patients. These metabolic alterations, probably induced by the calcium channelopathy, may characterize episodic ataxia type 2.

Acetazolamide↗
PubMed1999

Vestibulo-ocular dysfunction induced by cortical damage in man: a case report.

We studied the rare case of a patient presenting with vestibulo-ocular dysfunction and clinical vestibular symptoms after right temporo-parietal cortex infarction. The vestibulo-ocular reflex (VOR) was elicited in the dark, by sinusoidal (0.02; 0.05 and 0.1 Hz) and by step velocity rotation (100 degrees/s2) in clockwise and counterclockwise directions. Horizontal and vertical eye movements were recorded by DC electro-oculography (EOG). When compared to a control group of 8 healthy subjects, this patient presented VOR asymmetry with (1) a significant VOR velocity bias toward the lesioned side revealed as a vestibulo-ocular offset that occurred only under dynamic conditions (2) a significant reduction of the VOR time constant when rotation was directed to the lesioned side. VOR gain was normal. We suggest that the parieto-temporal cortex is implicated in the regulation of vestibulo-ocular symmetry in man. This cortical processing of vestibular integration might involve a multidimensional velocity storage integrator that subserves the maintenance of spatial coordinates along the spatial vertical axis.

Case-Control Studies↗
PubMed1999

MRI assessment of the anatomy of optic radiations after temporal lobe epilepsy surgery.

OBJECTIVE: The aim of this study was to determine the course of the temporal optic radiations. MATERIAL AND METHODS: Eighteen patients were included in this prospective study. All of them underwent a temporal lobectomy for epilepsy, including the mesial temporal structures and a variable extent of lateral neocortex (from 2 to 7 cm behind the temporal tip). An MRI was performed 2 months postoperatively, allowing assessment of the extent of lateral resection. Postoperative visual fields were determined by automatic static perimetry (ASP). RESULTS: (1) No patient complained of a disabling visual field deficit. (2) ASP, a highly sensitive technique, however, detected postoperative visual field deficits in 83% of patients, confined to the superior homonymous field contralateral to the resection. (3) A strong correlation was found between the presence of a visual field deficit and the extent of laterotemporal resection. (4) The smallest anteroposterior resection resulting in a field defect was limited to 20 mm from the temporal tip. CONCLUSION: (1) This study confirms a strong correlation between postoperative visual field deficits and the extent of lateral neocortical temporal resection. (2) The anterior limit of Meyer's loop is likely to be located more rostrally than previously believed. (3) Despite this, lateral resection remains useful in some cases for seizure control.

Adult↗
PubMed1998

Saccadic eye movements in schizophrenic patients.

The nature of saccadic abnormalities in schizophrenia was investigated in three different paradigms: (1) the visually guided saccade; (2) the antisaccade; and (3) the remembered saccade paradigm. Subjects comprised 14 schizophrenic patients and 14 normal volunteers. Deficits in the schizophrenic group were observed in the antisaccade and remembered saccade tasks, both of which were characterized by increased latency and reduced gain. Moreover, in the antisaccade task, schizophrenic patients showed an increased number of errors compared with control subjects. Saccadic abnormalities in the patients were correlated with impaired performance on the Wisconsin Card Sorting Test. These data suggest that schizophrenic patients have difficulty in inhibiting reflexive saccades and in producing voluntary saccades. The implications of these findings for a prefrontal cortex dysfunction involved in oculomotor control in schizophrenia are discussed.

Adult↗
PubMed1998

Course of valvular strands in patients with stroke: cooperative study with transesophageal echocardiography.

BACKGROUND: Native valve strands might be related to the acute stage of thrombosis or might suggest a long-term valvular change. We aimed to estimate changes in the strands in patients with stroke through a serial transesophageal echocardiographic (TEE) study. METHODS AND RESULTS: A study was conducted among patients who were referred for TEE for stroke or cardiac pathology. Patients had TEE examinations with a 5-MHz multiplane TEE probe. Echocardiography was repeated 3 months later in patients with stroke. TEE was performed in 180 patients admitted to cardiology units and in 160 patients referred to neurology units. Among 34 patients with valvular strands, 30 were referred to neurology for stroke, whereas 4 patients were admitted to cardiology (18.8% versus 2.2%, difference 16.5%, 95% confidence interval 10% to 22.9%, P =.001). Strands were located on the mitral valve in 16 patients, the aortic valve in 6 patients, and both left heart valves in 8 patients. Among the 38 valves with strands, 17 (44. 7%) were morphologically normal, 4 (10.5%) were thickened, 7 (18.4%) were redundant, and 10 (26.3%) had both abnormalities. TEE showed other abnormalities in 16 (53.3%) patients, whereas 14 patients had only strands. Twenty-six (86.6%) patients had a second TEE study 3 months later. Strands were not found in 4 (15.4%) patients (95% confidence interval 4.3% to 34.9%). CONCLUSIONS: Valvular thickening or redundancy may predispose valves to strand formation. Native valve strands usually persist and thus reflect a chronic valvular change.

Adolescent↗
PubMed1998

[Intramedullary tuberculoma: a case report].

A fifty-year-old Portuguese man presented with a six-month history of low back pain, which initially was mechanical and slowly became inflammatory. Secondarily, he complained of right atypical sciatalgia. He did not report any fever, loss of weight, cough nor personal or familial history of tuberculosis. General examination was normal. Neurologic examination showed weakness of the extensors of the right leg, with a symmetric increased reflexes of the lower extremities suggesting a pyramidal syndrome without Babinski's sign. Laboratory data were normal as well as chest radiographs. Dorsolumbar gadolinium enhanced MRI revealed an intramedullary ringlike enhancing mass at T12 level. Lumbar puncture showed 11 WBC/mm3 (95 p. 100 lymphocytes), a normal protein and glucose content. PCR and culture for Mycobacterium tuberculosis were negative. Within a few days, he developed meningoencephalitis with fever, CSF examination revealed then 360 WBC/mm3 (65 p. 100 lymphocytes and 17 p. 100 neutrophils), a protein content of 7 g/l and a glucose level of 1.7 mmol/l. The clinical picture was then suggestive of tuberculosis and a specific therapy with rifampin, izoniazid, pyrazinamid, ethambutol and steroids was started. Clinical improvement and a second CSF culture that revealed one month later Mycobacterium tuberculosis complex confirmed this diagnosis. Ten months later, the patient was asymptomatic with a normal MRI. To our knowledge, this is the first total recovery of an intramedullary tuberculoma on medical therapy alone, confirmed by MRI normalization. We reviewed also 19 recent cases of tuberculomas in the literature, intending a therapeutic attitude when discovering an intramedullary ringlike enhancing mass on MRI.

Antitubercular Agents↗