Biomedical subjects

P F Gangemi

Publications and source records attributed to P F Gangemi.

9 recordsLinked to original sources

PubMed1992

Smooth-pursuit eye movements: alterations in Alzheimer's disease.

Smooth-pursuit eye movements induced by targets moving at constant velocities (from 5 to 100 deg/sec) were recorded from 13 patients with Alzheimer's disease (AD) and from 11 healthy subjects. Four variables were evaluated to quantify the patients' response to the eye movement tests: (1) average peak velocity of smooth-pursuit; (2) percent target matching index after saccade removal (percent ratio between the area of the velocity curve of smooth-pursuit eye movement after saccade removal and the area of target velocity) which is related to the eye performance for each value of target velocity; (3) total amplitude of anticipatory saccades; (4) total number of anticipatory saccades. Compared to the controls, AD patients were found to have significantly lower values of average peak velocity of smooth pursuit and of percent target matching index and a significantly increased number and amplitude of anticipatory saccades. A discriminant stepwise analysis indicated that 5 oculographic variables were significantly associated with the patient's clinical condition (healthy volunteer or AD patient). These statistics yielded an equation for predicting the patient's status according to which the percentage of cases classified correctly was 82.6% in the overall group (n = 23). The predictive performance was similar between the healthy volunteers subgroup (81.8%, n = 11) and the AD subgroup (83.3%, n = 12). The discriminant score was significantly correlated with the score resulting from the MiniMental test (r = 0.67). A significant correlation was also found between the MiniMental score and the number of anticipatory saccades (r = -0.61). No significant correlation was present between the gain of smooth pursuit and the patients' cognitive decline.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Changes in bit-mapped contingent negative variation (CNV) activity due to initial normal involutional processes of the human brain.

Bit-color mapped multicomponent CNV complexes and RTs to S2 evoked with a simple warned CNV/RT paradigm were recorded and measured in 20 selected right-handed very healthy volunteers (10 young adults and 10 presenile subjects, mean age 28.3 and 59.6, respectively). EEG and CNV components (post S1, N1, P2, P3; early CNV; N1200; late CNV; CNV resolution) were recorded from Fz, C3, Cz, C4, P3, Pz, and P4 referenced to linked mastoid electrodes. EOG, RT and stimuli were also recorded. The presenile group differed significantly from the younger group in the auditory post-S1 N1 and early (O-wave) and late (P-wave) CNV complex components. A progressive amplitude reduction limited to frontal leads between O-wave and P-wave, the lowest point being reached in the P-wave, was characteristic in the presenile group. Moreover, presenile subjects showed relatively flat CNV waveshapes of low amplitude and, on the whole, performed a little less well than young ones. This finding suggests that the statistically significant changes in auditory post-S1 N1 and CNV activity recorded in our presenile subjects, without any appreciable deficits in behavioral or mental performance, could be alerting signs of early brain involutional processes related to minimal and subclinical decline in orienting, attentiveness and response preparation capabilities. If such is the case, and it could be confirmed in a larger sample of very healthy subjects, these age-related changes in the presenium might prove to be of considerable practical importance for clinical research.

Adult↗

PubMed1992

Effects of oxcarbazepine and carbamazepine on the central nervous system: computerised analysis of saccadic and smooth-pursuit eye movements.

Oxcarbazepine (OXC) is a new anti-epileptic agent structurally related to carbamazepine (CBZ). OXC seems to have a similar efficacy and a better tolerability profile than CBZ. In the present study we compared the subclinical side-effects on the CNS of OXC and CBZ using a computerised analysis of saccadic and smooth-pursuit eye movements. Six healthy male volunteers (mean age 29 yrs) participated in the study, which was conducted by a double-blind cross-over design. Each subject was given a single dose of either CBZ 400 mg or OXC 600 mg (according to the random assignment) after which the drug effects on eye movements were evaluated. One week later, the trial was repeated using the other drug. The parametrisation of both saccadic and smooth-pursuit eye movements was carried out by measuring a series of performance parameters [e.g. the maximum saccade peak velocity (MSPV) and the typical target velocity (TTV)]. OXC was found to induce a lesser degree of alteration on the values of both MSPV (p = 0.07) and TTV (p less than 0.03) than CBZ. In particular, the TTV values were virtually unaffected by OXC administration, while the effects of CBZ on both variables were particularly evident at 8 and 10 h after dosing which correspond to the time at which the plasma concentrations of CBZ and of its 10,11-epoxide reach the peak. In conclusion, our preliminary results indicate that OXC induces negligible alterations, if any, on the eye movement parameters evaluated in our study.

Adult↗

PubMed1991

A new method for analyzing smooth-pursuit eye movements. Description of a microcomputer program and evaluation in healthy volunteers.

The study of ocular movements has been increasingly used to detect subtle pathological modifications, caused by a wide variety of neurological diseases. We have developed a new microcomputer-based method for the analysis of smooth-pursuit ocular movements induced by constant velocity targets moving unpredictably at different velocities (including velocity values as high as 100 deg/s). The ocular movements are recorded by an electro-oculographic technique using silver-silver chloride electrodes fixed near the inner and outer canthi of both eyes. The signals are amplified by two DC amplifiers after a low-pass filtering (50 Hz), sampled at 250 Hz and digitized in a 12-bit form by an analog/digital converter. For each patient's evaluation, a series of 20 sweeps of the target is generated. The data analysis, which is performed automatically by the microcomputer, is based on the calculation of four parameters: average peak eye velocity (APEV); typical target velocity (TTV); percent target matching index after saccade removal (PTMI); typical matching target velocity (TMTV) after saccade removal. APEV is calculated as the average of the peak velocities estimated from the 20 sweeps. The purpose of TTV, which is defined as the value of target velocity at which the percent gain has decreased to slightly more than one third of the maximum percent gain, is to provide an overall index of the rate at which the percent gain decreases as the target velocity increases. PTMI describes the eye performance for each value of target velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Comparison of two nonlinear models for fitting saccadic eye movement data.

Saccadic eye movements are rapid shifts in the direction of gaze which are being studied increasingly for clinical and pharmacological purposes. The evaluation of the relationship between amplitude and peak velocity of these ocular movements (the so-called 'main sequence' plot) is particularly useful for characterising the saccade pattern in individual patients. This relationship is nonlinear and the peak velocity tends to achieve an asymptote for high values of amplitude. Since a standard parametrisation of the main sequence based on specific mathematical models has not yet been achieved, in the present study two simple models based on the Michaelis-Menten equation and on an exponential equation are proposed together with their implementation on a microcomputer. Two microcomputer programs are described which estimate the model parameters from the experimental data of the patients using a weighted nonlinear least-squares fit. The two procedures have been tested and compared in a series of 23 healthy volunteers. The following results (mean +/- S.D.) were obtained: Michaelis-Menten model. Km (degrees) = 31.2 +/- 7.7, Vmax (degrees/s) = 841.0 +/- 165.5, root-mean-squared error(%) = 6.0 +/- 1.6; exponential model. K (degrees) = 23.4 +/- 4.6, Vmax (degrees/s) = 578.0 +/- 97.4, root-mean-squared error(%) = 5.4 +/- 1.6. The two techniques of parametrisation provided similar indices of intra-individual variability in 4 healthy volunteers. In conclusion, our methods for saccade parametrisation can be regarded as simple but efficient tools for facilitating research on these ocular movements.

Adult↗

PubMed1991

Topographic CNV activity mapping, presenile mild primary cognitive decline and Alzheimer-type dementia.

The CNV complex evoked with a standard paradigm (S1-2 sec-S2-motor response) and reaction time (RT) to the imperative signal (S2) were recorded and measured in 12 patients with initial presenile idiopathic cognitive decline (PICD), 12 with presenile Alzheimer-type dementia (PAD) and 10 healthy age-matched controls. Significant group differences were obtained for measures of some CNV components, particularly of the late pre-S2 CNV. No significant CNV activity, very prolonged RTs and sometimes characteristic post-imperative negative variations (PINV) were observed in the majority of patients with PAD. These results suggest that similar CNV complex and RT changes to those observed in our patients may constitute a valuable clue in the study of pathophysiological brain functioning in the early stages of presenile idiopathic mental deterioration.

Aged↗

PubMed1991

Effect of physiological and pathological aging processes on topographic bit-mapped cognitive evoked potentials in presenile subjects.

Bit-mapped multicomponent CNV complex and reaction time (RT) were recorded and measured in 24 presenile patients with initial symptoms of very mild to moderately severe primary mental deterioration without depression, and in 10 age-matched controls. All patients underwent CT and MRI examinations, EEG spectral analysis and a battery of psychometric test. Significant group differences were obtained for measures of some post-S1 ERP and CNV components, particularly of the post-S1 N1b, P300 and early and late pre-S2 CNV. P300 with increased latency, no significant CNV activity, very prolonged RTs, EEG slowing down and diffuse brain atrophy were observed in the majority of patients with probable presenile Alzheimer's dementia. These results suggest that CNV/RT and EEG activity changes similar to those observed in our patients may constitute a valuable clue for the study of brain dysfunction in the early stage of presenile idiopathic cognitive impairment.

Aged↗

PubMedDate not supplied

[Alterations of smooth-pursuit ocular movements in Alzheimer's disease].

Recent findings suggest that patients affected by Alzheimer's disease (AD) have evident alterations of smooth-pursuit ocular movements induced by a sinusoidal predictable target. For a better understanding of the possible modifications of this performance in patients with AD we evaluated, using a quantitative method, the smooth-Pursuit induced by ramps with constant, unpredictable velocities. Twelve patients with probable AD were studied. These patients were compared with twelve age matched healthy volunteers. Visual inspection of our recordings shows that AD patients have frequent, large saccades intrusions which in some cases appeared to disrupt smooth tracking, particularly for low target speeds. Furthermore, the smooth-pursuit eye velocity induced by target of high speed is significantly reduced in respect to that present in our control group. Some significant correlations between altered smooth-pursuit parameters and abnormal psychometric scores were noted.

Aged↗

PubMedDate not supplied

[MRI and HM-PAO SPECT in 20 patients with drug-resistant partial epilepsy].

Twenty consecutive patients with chronic partial seizures with onset before twenty years of age were investigated by means of 0.5 T MRI (20) and HM-PAO (19) in order to identify focal alterations amenable to surgical therapy. MRI evidentiated parenchymal lesions in 7 patients. Findings consistent with unilateral medial temporal sclerosis and cortico-subcortical parietal scars were found in two patients each. Small solid nodular lesions in the temporal lobe were observed in two patients. These and one additional patient with nodular partially cystic lesions in temporal lobe were administered a paramagnetic contrast agent (Gadolinium DPA) intravenously. In one case a contrast enhancement was observed. Histologic examination post surgery revealed a low grade glioma in one patient. HM-PAO SPECT examination showed area of abnormal captation in 9 of 19 patients. Aspects of EEG correlation with the MRI and SPECT findings are discussed. Our data supported the usefulness of magnetic resonance and SPECT imaging in the completion of pre-surgical assessment in this kind of patients.

Adult↗