Biomedical subjects

M Manfredi

Publications and source records attributed to M Manfredi.

At least 145 records · Page 8Linked to original sources

PubMed1995

Inhibition of hand muscle motoneurones by peripheral nerve stimulation in the relaxed human subject. Antidromic versus orthodromic input.

In active muscle, a supramaximal conditioning stimulus to peripheral nerve produces a classic silent period in the EMG. The present experiments examined the effect of this type of conditioning stimulus on motoneurone excitability in relaxed muscle. EMG responses evoked by transcranial magnetic stimulation of the brain were recorded from the first dorsal interosseus muscle (FDI) in 10 healthy subjects and 5 patients with sensory neuropathy. These responses (motor evoked potentials) were conditioned by supramaximal peripheral nerve stimuli given 0-150 msec beforehand. In the normal subjects, the classic silent period in the FDI lasted about 100 msec. The same conditioning stimulus only abolished motor evoked potentials when the conditioning-test interval was so short that the antidromic peripheral nerve volley collided with the orthodromic volley set up by magnetic brain stimulation. At longer conditioning-test intervals, although remarkably inhibited (65% mean suppression between 10 and 40 msec), the test motor potential was never completely abolished and gradually recovered by 100 msec. Inhibition of cortically evoked motor potentials did not depend upon activity set up by the conditioning stimulus in peripheral nerve sensory fibres. The patients with complete peripheral sensory neuropathy had the same extent and time-course of inhibition as the normal subjects. We conclude that in relaxed subjects the inhibitory effect of peripheral conditioning results almost exclusively from the motoneuronal inhibitory mechanisms consequent to antidromic invasion.

Adult↗

PubMed1995

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL). Clinical, neuroimaging, pathological and genetic study of a large Italian family.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a rare hereditary stroke disease. The gene has been recently mapped, in two French families, on chromosome 19q12 between two highly polymorphic genetic markers. We report on a new large Italian family affected with this disease, which is characterized by recurrent stroke episodes, focal neurological deficits progressing to pseudo-bulbar palsy, and dementia. Multiple deep infarcts and diffuse leucoencephalopathy were revealed by MRI and brain histopathology showed abnormalities of arterial media. A genetic study performed with microsatellite markers from region 19q12 showed that the disease locus lies in an interval largely overlapping that already described and is closely linked to two microsatellite markers, D19S212 and D19S222. A joint analysis of genotypic and phenotypic data shows that diffuse leucoencephalopathy is a reliable sign of the disease in otherwise normal 50%-risk subjects over the age 30 years and that penetrance of stroke episodes or dementia is most likely complete around age 60 years.

Adult↗

PubMed1995

Physiological effects produced by botulinum toxin treatment of upper limb dystonia. Changes in reciprocal inhibition between forearm muscles.

Patients with upper limb dystonia have abnormal reciprocal inhibition between flexor and extensor forearm muscles. To see whether botulinum toxin treatment alters segmental motor system function, we studied reciprocal inhibition between forearm flexor and extensor muscles, before and after botulinum toxin injection in forearm muscles in 12 patients with upper limb dystonia. Reciprocal inhibition was studied by conditioning the H reflex in forearm flexors with a radial nerve stimulus delivered at a range of time intervals. Botulinum toxin injection improved upper limb dystonia. Before botulinum toxin injection, the dystonic patients had a decreased second phase of reciprocal inhibition. After botulinum toxin injections this second abnormal phase of reciprocal inhibition increased. Botulinum toxin did not change the first phase of reciprocal inhibition. Botulinum toxin treatment also reduced the M wave and the H reflex by a similar amount but left the Hmax:Mmax ratio unchanged. Ample evidence has shown that the therapeutic effects of botulinum toxin in dystonia depend mainly on its neuromuscular junction blocking action. Our data now suggest a concurrent indirect effect on spinal cord circuitry, probably through the action of botulinum toxin on the intrafusal neuromuscular junction.

Adult↗

PubMed1995

Differential diagnosis of parkinsonism.

The diagnosis of idiopathic Parkinson's disease (PD) is essentially clinical and is reached by exclusion. An akinetic rigid syndrome frequently means PD, although a number of other neurodegenerative diseases can share bradykinesia, rigidity, postural instability, and sometimes tremor. Parkinsonism can be classified as follows: degenerative, metabolic, vascular, iatrogenic, toxic, infectious, traumatic, and secondary to mass effect. The diagnostic approach are discussed.

Atrophy↗

PubMed1994

Electromyographic silent period after transcranial brain stimulation in Huntington's disease.

The silent period evoked by transcranial (TCS) and nerve stimulation was studied in the hand muscles in 13 patients with Huntington's disease and in 11 normal subjects. The duration of the silent period after TCS was longer in patients and correlated significantly with the severity of chorea; in contrast, the duration of the silent period after nerve stimulation was similar in patients and controls. The prolongation of the cortical silent period suggests that the duration of the silent period is a functional correlate reflecting basal ganglia influence over the motor cortex.

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

Reliability among neurologists in the severity assessment of blepharospasm and oromandibular dystonia: a multicenter study.

The reliability of a scale of 0 to 4 (where 0 is normal) in rating the severity of blepharospasm (BS) and oromandibular dystonia (OMD) was evaluated by the concordance among six neurologists from different neurological institutions. As expressed by k index, interobserver agreement was moderate either for BS or for OMD according to the Landis classification. Neurologists showed different rating attitude toward BS and OMD. In fact, the category analysis showed that raters were inclined to overestimate BS and to underestimate OMD. The familiarity with dystonia influenced reliability more than the length of professional experience in neurology. In fact, when examiners were subdivided into subgroups (each of three raters) according to the former criteria, the level of interobserver agreement increased significantly. Almost perfect agreement was obtained in intrarater comparisons. These results may be of value with regard to the conduct of multicenter epidemiologic and clinical studies on focal dystonias.

Adult↗

PubMed1994

Effects of transcranial magnetic stimulation on single and sequential arm movements.

We studied in humans the effects of transcranial stimulation of cortical motor areas on the execution of single and sequential rapid arm movements. In a reaction time paradigm with an auditory "go" signal, stimulation given after an auditory tone and before the start of movements delayed the onset but did not affect the subsequent performance of single or sequential movements; high intensities of cortical stimulation determined a long-lasting inhibition of movements. Cortical stimulation given during the execution of a sequential movement temporarily interrupted the movements. Reaction time was not prolonged and movements were not inhibited when cortical stimulation was delivered before the auditory tone and the start of movement. Neither electrical stimulation of the corticospinal tracts at the cervico medullary junction nor magnetic stimulation of the cervical roots delayed the onset or interrupted the execution of movements. Transcranial stimulation affects the performance of both single and sequential movements, through cortical mechanisms that interfere with the transfer of the motor program from other cortical structures to the motor cortex.

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↗

PubMed1994

Pathophysiology of hemimasticatory spasm.

Two patients aged 21 and 50 years presented with facial hemiatrophy and unilateral spasms of the masticatory muscles. Masticatory muscle biopsy showed normal findings in both patients and facial skin biopsy specimens only showed atrophy, although morphoea (localised facial scleroderma) had been diagnosed nine years previously in the second patient. The involuntary movements consisted of brief twitches and prolonged contractions clinically and electromyographically similar to those of hemifacial spasm and cramps. The jaw jerk and the silent periods were absent in the affected muscles. Direct stimulation of the muscle nerve and transcranial stimulation of the trigeminal root demonstrated slowing of conduction and after-activity due to autoexcitation. Observations in other reported cases and these two patients suggest that hemimasticatory spasm is produced by ectopic activity secondary to focal demyelination of the trigeminal motor nerve fibres. The proposed cause of the neuropathy is focal damage to the masticatory nerves caused by compression, possibly resulting from the deep tissue changes that occur in facial hemiatrophy.

Adolescent↗

PubMed1994

Transcranial electrical stimulation in patients with apallic syndrome.

Muscle responses (MEPs) to transcranial electrical stimulation were studied in 7 patients with apallic syndrome. All the patients showed clinical signs of upper motor neurone impairment in the upper and lower limbs. MEPs were absent or markedly delayed in 4 of the 7 patients. Since patients with apallic syndrome show only minimal voluntary movement, transcranial stimulation is the only way to demonstrate abnormalities of fast corticospinal axons in these patients. Even though these patients often look similar clinically, with tetraplegia and decorticate or decerebrate posture, only some cases showed dysfunction of fast corticospinal neurons.

Adolescent↗

PubMed1994

Clinical implications of sustained dopaminergic stimulation.

Fluctuations in motor performance are the major problems in chronic management of Parkinson's disease. Most of these fluctuations reflect the decline of levodopa availability. As a consequence, levodopa dosage might be increased and the interdose interval progressively shortened. The postsynaptic dopamine receptors at this point are exposed to a nonphysiologic shift in dopamine level, which may induce changes at the receptor site and contribute to the appearance of "on-off" phenomena and dyskinesias. We compared a group of 18 patients treated for 60 consecutive months with continuous subcutaneous lisuride infusion with a group of 20 patients treated with conventional oral levodopa treatment. The clinical evaluations performed during the study showed in the lisuride group only a worsening of dyskinesias, whereas the other symptoms remained unchanged. In the other group the evaluation scores showed a significant worsening of all long-term treatment complications. The slow-release preparations of levodopa may ensure a more continuous dopaminergic stimulation than standard formulations. However, the use of these compounds is difficult in severely fluctuating patients because the lack of a plasma peak level usually leads to a very long delay before patients turn "on." We studied the pharmacokinetic and clinical effects of the two slow-release preparations of levodopa [Madopar HBS and Sinemet controlled-release (CR)] and a combination of Sinemet CR plus standard Sinemet in 13 fluctuating parkinsonian patients. The results of this study show that the combination of standard Sinemet and Sinemet CR ensures a more prolonged clinical effect with a very short latency to the "on" phase.

Aged↗

PubMed1993

Blink reflex and the masseter inhibitory reflex in patients with dystonia.

The excitatory and inhibitory interneuronal pathways in the brainstem are tested by examining the blink reflex and the masseter inhibitory reflex, respectively. We studied the R2 component of the blink reflex and the SP2 component of the masseter inhibitory reflex and their recovery cycle in 56 patients with various forms of dystonia. In patients with cranial, cervical, and generalized dystonia, but not in patients with extracranial segmental dystonia, the recovery cycle of both reflexes was enhanced. The recovery cycle of R2 and SP2 can demonstrate subclinical changes in excitability of brainstem interneurons. The degree of enhancement of the recovery cycles did not correlate, however, with the severity of clinical facial muscle impairment. In addition, the recovery cycles correlated positively with each other, showing that excitatory as well as inhibitory interneuronal pathways in the brainstem are perturbed in dystonia. Study of the trigemino-facial and trigemino-trigeminal reflexes provides an objective tool for assessing functional abnormalities in dystonia.

Adult↗

PubMed1993

[The development of nursing in Latin America: a strategic view].

Nursing in Latin America is facing a number of serious challenges significantly affecting the contributions its personnel con make to the health of the people they serve. This article presents an overview of nursing as an important component of the health system in Latin America through the prospective and orientation provided by strategic planning. The author, following an analysis of the nursing situation in the Region, identifies several problems and then creates a vision for the future. The article looks at the possibilities of developing and implementing projects and action plans to address the priority problems. It sees strategic thinking as a possible means for nursing to reflect on and maximize its contribution and presence in the solution of the health problems in the current decade and into the next century.

Education, Nursing↗

PubMed1993

Silent period evoked by transcranial stimulation of the human cortex and cervicomedullary junction.

1. The silent period evoked in the first dorsal interosseous (FDI) muscle after electrical and magnetic transcranial stimulation (TCS), electrical stimulation of the cervicomedullary junction and ulnar nerve stimulation was studied in ten healthy subjects. 2. With maximum-intensity shocks, the average duration of the silent period was 200 ms after electrical TCS, 300 ms after magnetic TCS, 43 ms after stimulation at the cervicomedullary junction and 100 ms after peripheral nerve stimulation. 3. The duration of the silent period, the amplitude of the motor-evoked potential, and the twitch force produced in the muscle were compared at increasing intensities of magnetic TCS. When the stimulus strength was increased from 30 to 70% of the stimulator output, the duration of the silent period lengthened as the amplitude of the motor potential and force of the muscle twitch increased. At 70 to 100% of the output, the amplitude of the motor potential and force of the muscle twitch saturated, whereas the duration of the silent period continued to increase. 4. Proximal arm muscle twitches induced by direct electrical stimulation of the biceps and extensor wrist muscles produced no inhibition of voluntary activity in the contracting FDI muscle. 5. The level of background activation had no effect on the duration of the silent period recorded in the FDI muscle after magnetic TCS. 6. Corticomotoneurone excitability after TCS was studied by means of a single magnetic conditioning shock and a test stimulus consisting either of one single magnetic shock or single and double electrical shocks (interstimulus interval 1.8 ms) in the relaxed muscle. A conditioning magnetic shock completely suppressed the response evoked by a second magnetic shock, reduced the size of the response evoked by a single electrical shock but did not affect the response evoked by double electrical shocks. Inhibition of the test magnetic shock was also present during muscle contraction. 7. Our findings indicate that the first 50 ms of the silent period after TCS are produced mainly by spinal mechanisms such as after-hyperpolarization and recurrent inhibition of the spinal motoneurones. If descending inhibitory fibres contribute, their contribution is small. Changes in proprioceptive input probably have a minor influence. From 50 ms onwards the silent period is produced mainly by cortical inhibitory mechanisms.

Adult↗

PubMed1992

Biopsy diagnosis of a case of adult onset orthochromatic leukodystrophy. Clinical and brain biopsy findings.

We report the intra vitam histopathological findings on the brain of a female patient presenting an adult form of orthochromatic leukodystrophy. At 38 years of age the patient began to show progressive dementia and a pseudobulbar syndrome. The pedigree revealed an autosomal dominant pattern of inheritance. The CT scan showed a wide hypodensity of the anterior white matter. Biochemical investigations showed only a slight elevation of serum VLCFA and no alteration of urinary enzymatic activities. Cortical and subcortical biopsy specimens from the right frontal lobe showed: neuronal loss in the gray matter, accumulation of autofluorescent material within residual neurons and sudanophilic material within macrophages and astrocytes, sparing of axons. Electron microscopy showed lamination and fragmentation of the myelin and the presence of electrondense bodies and vesicular material into oligodendrocytes and astrocytes. We discuss the differential diagnosis of OLD forms with adult onset, namely between Löwenberg-Hill disease and the pure form of OLD with pigmented glial cells.

Biopsy↗

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↗