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Biomedical subjects

N Accornero

Publications and source records attributed to N Accornero.

At least 19 recordsLinked to original sources
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↗
PubMed1997

Performance of sequential arm movements with and without advance knowledge of motor pathways in Parkinson's disease.

Patients with Parkinson's disease are slower than normal subjects in executing sequential arm movements, and their bradykinesia worsens as the execution of motor sequences progresses. In parkinsonian and normal subjects, we studied the execution of two types of fast sequential arm movements. The subjects had to perform a motor sequence following with their arm a path marked by six targets on a screen. In one experimental condition, they performed the motor sequence without advance knowledge of its path and executed each submovement in response to the consecutive appearance of the targets on the screen (unknown motor sequences). In the other condition, all the targets appeared simultaneously on the screen before the subject moved, and the subject internally determined when to execute each submovement (known motor sequences). Patients were slower than normal subjects in executing both sequences. Patients and normal subjects were faster in executing known than unknown sequences, but the patients' percentage of total movement time diminished less. During the unknown condition, both groups tended to lengthen submovement duration whereas, during the known condition, both groups tended to correct this trend. Patients performed submovements during both sequences with longer acceleration phases. The submovement symmetry ratio of the velocity profile changed according to the direction of movement (up or down). We conclude that these findings depend mainly on the model of movement execution. They also suggest that patients with Parkinson's disease have more difficulty in executing internally determined than externally triggered sequential movements.

Adult↗
PubMed1997

Clinical multisegmental posturography: age-related changes in stance control.

Unlike conventional platform posturography, which analyses the sway in the projection of the body baricentre on a supporting plane, multisegmental posturography provides information about body segmental movements during stance, including those that keep the baricentre still. This paper presents a new technical approach to multisegmental posturography using Virtual Reality electromagnetic tracking devices. This device was used to study age-related differences in normal subjects in the control of upright posture. Body sway was studied by recording the oscillations of two trackers placed on the head and the hip during the Romberg test. The tracking device allowed us to detect age-related differences in postural stance strategies. Although the amplitude and velocity of the oscillations measured at the head did not differ in the two groups, the flexibility of the ankle-hip head axis differed significantly: elderly subjects exhibited a more rigid stance. Closing the eyes increased rigidity in both age groups and this change appear more pronounced in the young.

Adolescent↗
PubMed1997

Recurrent neck pain as a variant of migraine: description of four cases.

Four patients who had recurrent attacks of idiopathic unilateral neck pain and tenderness of the ipsilateral carotid artery are described. Two patients had never had headache. The other two had migraine without aura. All patients had dilatation of extracranial arteries during the attacks (telethermographic examination), oculosympathetic hypofunction (pupillary tests), and positive responses to vasoactive drugs which are commonly used for migraine treatment. Recurrent neck pain involving the carotid artery seems to be a variant form of migraine that may occur alone or in association with headache in patients with involvement of extracranial arteries.

Adult↗
PubMed1997

Color perimetry with personal computer.

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in M. S., 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. 264 colored patches subtending 1 degree angle of 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 informations. Comparison between normals and a selected population of Patients with Multiple Sclerosis and with Glaucoma without luminance visual field defects, showed high statistical difference.

Adult↗
PubMed1994

Analysis of repetitive and nonrepetitive sequential arm movements in patients with Parkinson's disease.

We examined the motor performance of Parkinson's disease patients and normal subjects during nonrepetitive and repetitive sequential tasks. Parkinson's disease patients took longer than normal subjects to complete the nonrepetitive task, the sequential drawing of a pentagon. In patients, movement times lengthened as the sequence neared completion. The amount of lengthening was similar in nonrepetitive and repetitive tasks (sequential alternating drawing of each side of the pentagon). In parkinsonian patients the slowing at the end of the sequential tasks does not appear to be influenced by whether the sequential task involves nonrepetitive or repetitive movements.

Adult↗
PubMed1994

Color VEPs in Parkinson's disease.

Evoked potential studies have confirmed visual pathway impairment in Parkinson's disease. Dopamine is also known to be involved in retinal color vision mechanisms. In this study, pattern evoked potentials were recorded in 20 parkinsonian patients in "on" and "off" conditions to compare the sensitivity of black-and-white and color pattern stimuli. Evoked responses to colored patterns proved more sensitive to L-DOPA therapy. This finding supports the proposed dopamine modulation of the retinal color system and suggests that color pattern evoked potential studies might be used in monitoring dopamine therapy in parkinsonian patients.

Adult↗
PubMed1994

Motor cortical inhibition and the dopaminergic system. Pharmacological changes in the silent period after transcranial brain stimulation in normal subjects, patients with Parkinson's disease and drug-induced parkinsonism.

The silent period after contralateral and ipsilateral transcranial magnetic brain stimulation was studied in patients with Parkinson's disease before and after dopaminergic and anticholinergic therapy; in normal subjects before and after L-dopa administration and in patients with drug-induced parkinsonism. In patients and normal subjects the silent period was also studied after peripheral nerve stimulation. The silent period after transcranial cortical stimulation was shorter in Parkinson's disease patients than in normal subjects. In patients with Parkinson's disease L-dopa prolonged the silent period after transcranial brain stimulation and after ipsilateral cortical stimulation. Biperiden prolonged the silent period after transcranial brain stimulation. In normal subjects, L-dopa produced similar but smaller changes. In the patients with drug-induced parkinsonism the silent period after transcranial magnetic stimulation was shorter than normal subjects. The peripheral silent period was similar in normal subjects and in patients and did not change after drug administration. In conclusion cortical silent period is abnormal in patients with Parkinson's disease and drug-induced parkinsonism. Dopaminergic drugs modulate the duration of the cortical silent periods in patients and in normal subjects, through mechanisms acting mainly at basal ganglia and possibly also directly at cortical level.

Adult↗
PubMed1992

Automatic visual field: a software diagnostic procedure.

A recently developed technique for the automatic acquisition of data on visual field losses was tested, with reliable neuro-ophthalmological parameters, on 300 subjects with and without eye disorders. Algorithms for acquisition and processing of the central visual field were implemented on an IBM-AT personal computer with standard peripherals. The contours of scotomata (visual field losses) were best estimated by probabilistic adaptive enhancement of data sampling in those areas with greater visual variability. Image processing tools were specially designed to extract information concerning the size, shape, position and number of scotomata in the visual field. The diagnosis of wider campimetric lesions required parameters such as symmetry or specularity coefficients, obtainable by analysing the visual field of both eyes. Data obtained were correlated to the pathology involved by univariate statistical tools.

Algorithms↗
PubMed1992

Sequential arm movements in patients with Parkinson's disease, Huntington's disease and dystonia.

We studied the performance of sequential arm movements in 14 patients with Parkinson's disease, nine patients with Huntington's disease and seven patients with arm dystonia. The results were compared with those from normal subjects. Subjects had to perform each movement of the sequence as fast as possible, stopping as briefly as possible between two successive movements. In one set of experiments, patients with Parkinson's disease drew four different geometrical patterns in a counter-clockwise direction. The patterns consisted of two, three, four and five segments of identical length. In a second set, the subjects drew a pentagon in a counter-clockwise and a clockwise direction and each side of the pentagon singly in a counter-clockwise direction. All three groups of patients were slow in executing movements and in switching from one movement to the next. Only patients with Parkinson's disease took longer to perform the segments at the end of a sequence. In other words, their movement times lengthened progressively as the sequence progressed. This phenomenon could still be recognized when the direction and position of the segments were changed (pentagon drawn in the counter-clockwise and the clockwise direction) and when the extra-time needed, mainly due to the sequential nature of the task, was considered by computing the differences between movement times obtained during drawing of the pentagon and those obtained when each segment was traced singly. This study demonstrates that sequential movements are abnormal in Parkinson's disease, Huntington's disease and dystonia and that in the performance of long motor sequences, the deficit in sequencing movements is exacerbated only in patients with Parkinson's disease.

Adult↗
PubMed1989

Critical fusion frequency in MS during mild induced hyperthermia.

By raising the body temperature of 0.5 degrees C the critical fusion frequency of a flickering light increases in normal subjects but decreases in multiple sclerosis (MS) patients. The change was present in 14 patients with definite MS and in 5 of 10 patients with probable MS. No clinical worsening was observed during the procedure or in the following hours.

Adult↗
PubMed1988

The first agonist and antagonist burst in patients with an upper motor neuron syndrome.

Rapid elbow flexion movements were studied in patients with an upper motor neuron syndrome following a stroke. The velocity of movements was slower than normal. The initial bursts of electromyographic (EMG) activity in both the agonist and antagonist muscles were prolonged. As in normal subjects, the first agonist burst increased in duration with larger movements, but it generally remained about 40 ms longer than normal. The size of the first agonist burst also increased with larger movements. A fixed linkage between burst duration and level of motor unit recruitment, together with a deficient corticospinal command, could explain the prolonged burst duration with preserved ability to modulate the burst.

Aged↗