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Biomedical subjects

M Manfredi

Publications and source records attributed to M Manfredi.

18 recordsLinked to original sources
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↗
PubMed1992

Hemimegalencephaly and normal intellectual development.

Hemimegalencephaly is a rare congenital malformation characterised by overgrowth of one hemisphere. Although it is commonly thought to be associated with neurological deficits, developmental delay, and intractable epilepsy, the clinical expression of hemimegalencephaly, can vary widely. This patient was neurologically and neuropsychologically normal apart from rare partial seizures.

Adult↗
PubMed1979

[Multielectronic computerized EMG: technical notes on the recording and parallel off-line elaboration].

A Multielectrodic EMG analysis program is developing. The purpose is to get as short as possible the main EMG parameters (amplitude, duration, frequency) of most motor units, and to reach an estimation of the anatomical extent of single units. According to the muscle extent a variable number of electrodes are inserted crosswise the fibers. EMG signals are simultaneously recorded on a multichannel AMPEX FR1300 and then off-line processed by a 21MX HP minicomputer connected with a 5Mbytes disc drive. Some technical problems had to be solved:channel amplification adjustment to avoid any difference among preamplifiers calibration and filtering, severe hum filtering of main power that is specially strong in nultielectrodic recording systems, the need of sampling at the same Nyquist time the signals of different channels. The computer is instructed to identify the "sinchronous" units i.e. the motor units recorded from more than one channel. These motor units are detected, counted and deleted from all the channels, except the one where they show the maximum amplitude. The percentage of these sinchronous units depends upon the interelectrodic distance and their anatomical area, thus it can support an evaluation of motor unit anatomical spread.

Computers↗
PubMed1977

Selective Activation of peripheral nerve fibre groups of different diameter by triangular shaped stimulus pulses.

1. The differential block of cutaneous nerve fibres has been achieved with a simple method of electrical stimulation, employing a single pair of active electrodes. 2. The method allows the selective activation of 95% of small myelinated (delta) axons, without activation of the larger (beta) ones; and activation of unmyelinated (C) fibres, without A fibre activation. Asynchronous firing of myelinated axons was absent in the majority of the experiments. 3. The method employs triangularly shaped electrical pulses, with a steep rise front and a slow exponential decay. The outward flow of current at the cathode fires conducted impulses in both larger and smaller axons, and the inward flow inactivates differentially the conduction in the smaller ones. 4. The differential effect of anodal currents rests upon the greater internal conductance and greater conduction velocity of larger fibres. 5. The method has the advantage over the conventional polarization block of simpler surgical preparation, longer nerve survival and minimal latency distortion. However, it cannot be applied in experiments requiring physiological stimulation of peripheral receptors.

Action Potentials↗
PubMed1975

Treatment of epileptic seizures with clonazepam. A reappraisal.

The therapeutic efficacy of orally administered clonazepam has been evaluated in 32 epileptic patients, with substantial improvement in 22. The drug is active in all types of seizures, particularly in myoclonus, petit mal absences, and partial complex epilepsy; it seems the drug of choice in generalized infantile organic epilepsy, although the treatment of these patients is still unsatisfactory. In some patients, the drug seemed less effective after months of therapy. Drowsiness is the main side effect.

Administration, Oral↗
PubMed1975

The tonic ambulatory foot response. A clinical and electromyographic study.

Three cases with "pyramidal" symptoms in which standing and/or walking evoked a tonic flexion of the toes and sole of the affected foot, have been studied from the clinical and electrophysiological standpoint. The phenomenon, for which the definition of tonic ambulatory foot respone (TAFR) is proposed, appeared to be triggered by cutaneous stimuli travelling along fibres lying in the range of nociceptive afferents, and to depend on a background of complex sensorimotor patterns of standing posture and/or stepping movements against resistance. The relationship of TAFR to other flexor foot responses described in the literature is discussed.

Cerebrovascular Disorders↗
PubMed1975

[Relationship between circadian rhythms and blood pressure and the pathogenesis of cerebrovascular insufficiency].

Cerebrovascular accidents occur more frequently during the morning, less frequently during the night, whether due to thrombosis or embolism. In cases with hypertension, however, there have been noted a more uniform distribution of these complications throughout the day. The preponderance in the morning of the number of accidents in non-embolic subjects, depends probably on the state of the autonomic nervous system during the night, which gives rise to a dilated and hypotonic microcirculation. Autoregulation is, in this way, reduced and the physiological increase in blood pressure during the morning may induce a break through of autoregulation. In embolic subjects, on the other hand, an important role may be played by heart arrhythmias which occur usually during the waking hours. In hypertensives, the microcirculatory bed is restricted and cerebro-vascular resistance relatively constant. The brain, paradoxically, is thus better defended against any moderate increase in blood pressure and fluctuations in blood pressure throughout 24 hours, which may leave cerebral autoregulation unchanged, which probably explains the more uniform distribution of cerebro-vascular accidents throughout the 24 hour period.

Blood Pressure↗