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Biomedical subjects

N Accornero

Publications and source records attributed to N Accornero.

At least 19 recordsLinked to original sources
PubMed2006

Effects of repetitive transcranial magnetic stimulation in a patient with fixation-off sensitivity.

Aim of the present study was to evaluate the acute and long-term effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) on focal epileptiform interictal EEG activity in a patient with fixation-off sensitivity and partial epilepsy. Real and sham rTMS were delivered over the vertex. Two trains of 500 stimuli per day were delivered at 0.33 Hz frequency and threshold intensity for five consecutive days. The number of posterior EEG spikes and spike-and-wave complexes/min before and after the application of rTMS were compared in a blinded manner. In our patient, real-rTMS induced a long-lasting decrease in the number of posterior EEG spikes and spike-and-wave complexes/min. Despite the limitations of a single case report, our study confirms that low-frequency rTMS significantly reduces interictal focal epileptic activity over time.

Adult↗
PubMed2006

Luminance and chromatic visual evoked potentials in type I and type II diabetes: relationships with peripheral neuropathy.

The objective of the study was to investigate the subclinical visual deficit in type I and II diabetes, and its relationship with peripheral neuropathy. Thirty-two healthy volunteers, 20 patients with type I diabetes and 30 patients with type II diabetes were studied in a clinical neurophysiology setting. Luminance (VEPs) and chromatic visual evoked potentials (CVEPs) were recorded, with white-black, grey-black, red-green and blue-yellow sinusoidal gratings. The peak latencies of the VEP positive wave and CVEP negative wave were recorded. Ten patients with type I and 8 with type II diabetes had peripheral neuropathy. VEPs were slower in patients with type II diabetes and CVEPs were slower in patients with type I and type II diabetes than in controls. Blue-yellow CVEPs were slower in type II than in type I diabetes. VEPs and red-green CVEPs were slower in patients with diabetes with neuropathy than in those without. In conclusion, we found that visual system impairment differs in diabetes with and without peripheral neuropathy.

Adult↗
PubMed2004

Observations on EEG patterns in neurally-mediated syncope: an inspective and quantitative study.

We performed an observational EEG study in 43 patients with neurally-mediated syncope in basal condition and during hyperventilation (HV), and compared it with 32 healthy controls. On blind analysis at rest, EEG was classified as normal in 47% of patients (vs. 94% of controls, P < 0.001). More abundant and pronounced delta-theta activities and alpha slowing were found in patients than in control subjects on both visual inspection and quantitative spectral analysis. During prolonged HV, the EEG remained normal in 21% of patients only. Slow activities became more evident in patients than in control subjects, and intermittent rhythmic delta activity appeared in 40% of syncopal patients. These "pseudoparoxysmal" EEG changes differed from the common slowings induced by HV in adult subjects and were not observed in our control subjects. Moreover, these distinctive EEG changes, a common finding in syncopal patients, could not be confused with epileptiform activity of any kind. Further studies will clarify the pathophysiology of these EEG modifications.

Adult↗
PubMed2003

Surface electromyography and mechanomyography recording: a new differential composite probe.

The objective of the study was to develop a new surface probe for differential mechanomyographic (MMG) and electromyographic (EMG) recording. Differential amplification is commonly used in electromyography to improve the signal-to-noise ratio. A new composite probe was developed with two electrodes (EMG) and two identical piezo-electric membranes (MMG) to be positioned on muscle. The probe had two built-in fixed-gain differential amplifiers: one to amplify the electric signal and the other to amplify the vibration signal. A similar non-differential MMG probe was used for comparisons. Burst muscular activity was recorded using the non-differential and differential probes and was used to test the performance of the two probes in suppressing artifacts of non-muscular origin. Power spectrum analysis of signals from the two probes showed that differential amplification significantly improved the signal-to-noise ratio in MMG recordings and significantly suppressed artifacts (power difference > 90%). The composite probe allowed simultaneous differential recording of MMG and EMG signals from the same muscular site. It recorded muscular activity more efficiently than the non-differential probe and could therefore be useful in studying fatigue and neuromuscular diseases.

Artifacts↗
PubMed2003

Autoantibodies to glutamic acid decarboxylase in downbeat nystagmus.

The cause of downbeat nystagmus (DBN) remains undiagnosed in about 40% of patients. This paper reports the presence of antiglutamic acid decarboxylase antibodies (GAD-Ab) in a patient with DBN. Antibodies against GABAergic neurons located in the vestibular complex may induce chemical denervation of the floccular neurons, which normally suppress the peripheral imbalance between vertical semicircular canal systems, thereby causing DBN. Testing for GAD-Ab may be indicated in DBN patients without an identifiable anatomical brain lesion.

Aged↗
PubMed2001

Video color perimetry: impairment in glaucoma suspects.

PURPOSE: To detect mild visual field impairment in asymptomatic glaucoma suspect patients. METHODS: Color perception within the visual field was tested with customized color video perimetry. The key features of the system were stimuli color desaturation, low-level luminance and equiluminant gray background. Twenty patients with asymptomatic glaucoma were tested and compared with a group of age-matched control subjects. RESULTS: Automated perimetry test findings differed significantly in the two groups, particularly for short-wavelength sensitivity (blue). The severity of color impairment correlated directly with intraocular pressure. CONCLUSION: Desaturated low-luminance video perimetry will reliably detect and quantify asymptomatic visual field defects. A previous work on multiple sclerosis has detected a mild long-wavelength (red) impairment in asymptomatic patients after an episode of optic neuritis, even in clinically unaffected fellow eyes. Our findings in glaucoma suspect patients indicate that a mild blue impairment could be the initial sign of this disease.

Adult↗
PubMed2000

Sympathetic skin response and cardiovascular autonomic function tests in Parkinson's disease and multiple system atrophy with autonomic failure.

The relationship between sympathetic skin response (SSR) and cardiovascular autonomic function tests (CVTs) was investigated in 15 patients with idiopathic Parkinson's disease (PD), 15 patients with clinical evidence of multiple system atrophy (MSA) with autonomic failure, and in 15 healthy control subjects. SSR was elicited by electrical stimulation of the right and left median nerves and simultaneously recorded on the palms of both hands. CVTs included the following sympathetic and parasympathetic tests: orthostatism, head-up tilt, cold pressor test, deep breathing, Valsalva maneuver, and hyperventilation. The SSR was normal in all patients with PD and control subjects but was abnormal or absent in all patients with MSA. For patients with MSA, SSR latency was significantly longer and amplitude was significantly smaller than that of patients with PD and control subjects. For patients with PD, SSR did not differ from that of control subjects. In these patients, SSR latency was significantly longer and SSR amplitude was smaller when the side with more marked motor symptoms was stimulated, both ipsilaterally and contralaterally to the side of stimulation. A statistically significant difference in SSR latencies and amplitudes was found between patients with PD and control subjects only when motor asymmetries were considered. CVTs showed severe sympathetic and parasympathetic hypofunction in patients with MSA, but not in patients with PD or control subjects. No correlation was found between SSR and CVTs that assess sympathetic function in patients and control subjects. SSR is indicated as an additional test for the evaluation of sympathetic degeneration in patients with MSA.

Aged↗
PubMed2000

Three-dimensional mapping of brainstem functional lesions.

The human brainstem is a highly complex structure where even small lesions can give rise to a variety of symptoms and outward signs. Localising the area of dysfunction within the brainstem is often a difficult task. To make localisation easier, a neural net system has been developed which uses 72 clinical and neurophysiological data inputs to provide a display (using 5268 voxels) on a three-dimensional model of the human brainstem. The net was trained by means of a back-propagation algorithm, over a pool of 580 example cases. Assessed on 200 test cases, the net correctly localised 83.6% of the target voxels; furthermore the net correctly localised the lesions in 31 out of 37 patients. Because this computer-assisted method provides reliable and quantitative localisation of brainstem areas of dysfunction and can be used as a 3D interactive functional atlas, it is expected to prove useful as a diagnostic tool for assessing focal brainstem lesions.

Brain Diseases↗
PubMed2000

A new color vep procedure discloses asymptomatic visual impairments in optic neuritis and glaucoma suspects.

OBJECTIVE: To evaluate the reliability of visual evoked potentials obtained with a set of multiple chromatic and achromatic patterns (C-VEPs) in differentiating asymptomatic perifoveal retinal impairment from central conduction impairment. METHODS: We propose a set of colored pattern stimuli that allows relatively differential activation of the magnocellular and parvocellular pathways. The system runs on a standard Pentium PC with peripherals that present stimuli and collect, analyze and print data. P1 latencies of C-VEPs obtained with achromatic (black/white) and chromatic (blue/black and red/black isocontrast) checkerboards were evaluated in normal subjects and patients with subclinical retinal impairment (glaucoma suspects) or mild neural conduction impairment (optic neuritis), none of whom had subjective visual defects. RESULTS: The procedure evoked robust cortical signals and statistically distinguished the 3 groups of subjects. The achromatic and chromatic stimuli used distinguished controls from glaucoma suspects and patients with optic neuritis. Glaucoma suspects had greater impairment of C-VEPs to blue/black checkerboards whereas patients with optic neuritis had greater impairment of responses to red/black stimuli. CONCLUSIONS: Our data suggest that chromatic patterns (color/ black, red and blue), that may activate the parvocellular and magnocellular systems differentially but not selectively, can distinguish between mild perifoveal or foveal conduction impairment. They have the additional advantage of evoking large, stable responses across all the subjects.

Adult↗
PubMed1999

Localisation of a reporter transcript by the c-myc 3'-UTR is linked to translation.

The 3'-untranslated region of c-myc mRNA contains a perinuclear localisation signal which is sufficient to target beta-globin coding sequences. The link between perinuclear mRNA localisation and translation has been investigated using cells transfected with chimeric gene constructs in which globin reporter sequences were linked to the c-myc 3'-untranslated region and the iron-responsive element from ferritin mRNA. Iron supplementation of the medium promoted translation of the chimeric mRNA as assessed by its presence in polysomes; in situ hybridisation showed that the mRNA was localised around the nucleus. Treatment with the iron chelator desferrioxamine for 16 h prevented both translation and mRNA localisation. In controls where the expressed mRNA lacked the iron-responsive element desferrioxamine had no effect upon localisation. In contrast, arrest of on-going global translation by puromycin treatment had no effect on mRNA localisation. The data suggest that if initiation of translation of a mRNA containing the c-myc localisation signal is prevented in some way then localisation does not occur, whereas once the mRNA has been localised further translation is not required to maintain mRNA localisation.

3' Untranslated Regions↗
PubMed1999

Systemic lupus erythematosus and myoclonic epileptic manifestations.

Systemic lupus erythematosus (SLE) frequently involves the central nervous system (CNS) and, in fact, epileptic manifestations may be one of the earliest symptoms of SLE. These early occurrences of epilepsy, however, can easily be misdiagnosed as indication of pure epileptic syndrome when the SLE diagnosis is still largely incomplete. We present a young girl who developed myoclonic photosensitive seizures at the onset of the illness, erroneously diagnosed as manifestation of a "pure" epileptic syndrome. Shortly after the onset of an anticonvulsant therapy (lamotrigine), there was a remarkable impairment of the general clinical condition: at that time a diagnosis of SLE was made and a specific treatment began. However, the seizures persisted and evolved toward status epilepticus which needed pentobarbitone therapy in an intensive care unit (ICU). After recovery, the girl gradually got better and during the 23 months of follow-up she received only corticosteroid therapy and did not experience seizures nor SLE relapses.

Anti-Inflammatory Agents↗
PubMed1999

Migraine and ocular pain in "glaucoma suspect".

A relationship between glaucoma and migraine has been hypothesized by some authors, but not confirmed by others. We studied the prevalence and features of migraine and ocular pain in 460 "glaucoma suspect" patients (with ocular hypertension, but without optic disc and visual field abnormalities) and 460 controls. A higher prevalence of migraine was found in patients (13%), particularly in women (17%), than in controls (7%). At the time of the interview, migraine was still active in 68% of the patients and had decreased in the remaining 32% (prevalently those not being treated for ocular hypertension), whereas it had ceased in 52% of controls. Attacks of "ocular pain" of mild and moderate intensity were found to occur in 51% of the patients with both "glaucoma suspect" and migraine, in almost all who were not taking treatment for ocular hypertension. "Ocular pain" was time-related to the history of glaucoma. Changes in intraocular pressure may play a role in the interaction between "glaucoma suspect", migraine, and ocular pain.

Female↗
PubMed1998

Polarization of the human motor cortex through the scalp.

Direct currents (DC) applied directly to central nervous system structures produce substantial and long-lasting effects in animal experiments. We tested the functional effects of very weak scalp DC (< 0.5 mA, 7 s) on the human motor cortex by assessing the changes in motor potentials evoked by transcranial magnetic brain stimulation. We performed four different experiments in 15 healthy volunteers. Our findings led to the conclusion that such weak (< 0.5 mA) anodal scalp DC, alternated with a cathodal DC, significantly depresses the excitability of the human motor cortex, providing evidence that a small electric field crosses the skull and influences the brain. A possible mechanism of action of scalp DC is the hyperpolarization of the superficial excitatory interneurones in the human motor cortex.

Adult↗
PubMed1998

Clinical impairment of sequential finger movements in Parkinson's disease.

A retrospective analysis was performed on the records of 33 off-therapy parkinsonian patients. We analyzed the clinical score of three sequential upper limb movements: finger tapping, hand opening and closing, and forearm pronation and supination. The records showed that nearly all patients had difficulty in performing all three motor tasks, but movement scores showed that they found the sequential finger-tapping task significantly more difficult than the other two tasks. We suggest that parkinsonian patients find individual finger movements more difficult to execute than gross hand movements because--owing to their abnormal basal ganglia output--they lack the finer cortical control and greater facilitation that the finger task demands.

Aged↗
PubMed1998

Subclinical visual impairment in phenylketonuria. A neurophysiological study (VEP-P) with clinical, biochemical, and neuroradiological (MRI) correlations.

During detailed visual function testing, pattern-reversal visual evoked potentials (VEP), generated by different spatial frequencies (3 c/d, 1 c/d and 0.6 c/d) and visual contrasts (100% and 10%) were recorded in 21 adolescent and young adult phenylketonuric (PKU) patients (11 females and 10 males; mean age 14.8 years, range 9-22.8) on and off diet. In 14 of the 21 patients, disease had been detected at neonatal screening and in 7 later. Ten age-matched healthy subjects acted as controls. Recordings in more than 40% of eyes in the whole group and 30% of eyes in the screening subgroup showed a prolonged P100 latency. All visual pattern stimuli elicited a significantly longer P100 latency in PKU patients than in controls. VEP latencies to 3 c/d, 1 c/d and 1 c/d with 10% contrast--but not to 0.6 c/d--were longer in patients off diet than in patients on diet. No differences were found between VEP latencies in early- and later-detected subjects. To study the link between biochemical variables and VEP latencies, we envisaged either a linear relationship between recent exposure to phenylalanine (Phe) and VEP abnormalities or a threshold model considering phenylalanine (Phe) concentrations among the factors influencing VEP latencies. The correlation analysis detected an association between plasma Phe concentrations and abnormal VEP latencies, predicting that plasma Phe concentrations > 901 mumol/L would prolong VEP latencies to 1 c/d; concentrations > 879 mumol/L would prolong latencies to 3 c/d; and concentrations > 898 mumol/L would prolong latencies to 1 c/d with 10% contrast.

Adolescent↗
PubMed1998

Computerized color perimetry in multiple sclerosis.

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in MS, yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. Two hundred and sixty-four colored patches subtending 1 degree angle vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative information. Comparison between normals and a selected population of MS patients with no actual luminance visual field defects, showed high statistical difference.

Adolescent↗