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Biomedical subjects

G Paradiso

Publications and source records attributed to G Paradiso.

At least 19 recordsLinked to original sources
PubMed2003

Involvement of the human subthalamic nucleus in movement preparation.

BACKGROUND: Although it has long been recognized that the basal ganglia play a major role in motor control, their precise functions remain unclear. As patients with Parkinson's disease (PD) have difficulties initiating movement, the basal ganglia may be involved in movement preparation. The subthalamic nucleus (STN) is particularly suited to play a role in movement preparation because it receives direct input from the supplementary motor area through the corticosubthalamic pathway. METHODS: Taking advantage of the electrodes surgically implanted in the STN for deep brain stimulation (DBS) treatment in 13 PD patients, we recorded from the DBS electrodes and the scalp simultaneously while the patients were performing self-paced wrist extension movements. RESULTS: Scalp recordings showed a slow, negative movement-related potential (MRP) in all patients studied (onset 1,690 +/- 336 milliseconds before electromyography onset). STN recordings showed premovement MRP in 11 of 13 patients. The STN activity occurred with both ipsilateral and contralateral hand movement. The onset time for STN MRP (contralateral 2,095 +/- 1,005 milliseconds, ipsilateral 2,020 +/- 920 milliseconds) was not significantly different from that for cortical MRP. CONCLUSION: The STN or nearby structures are active before self-paced movement in humans.

Action Potentials↗
PubMed2001

Potentials recorded at the scalp by stimulation near the human subthalamic nucleus.

OBJECTIVE: To record the potentials evoked at the scalp by stimulation through electrodes targeted at the human subthalamic nucleus (STN) and to determine whether the responsible pathways continue to be excited or become blocked with high frequency stimulation. METHODS: We recorded the potentials evoked at the scalp in response to single and multiple stimuli delivered through STN contacts in 6 patients with Parkinson's disease. RESULTS: On 9/11 sides tested, single stimuli elicited a negative potential with latency of approximately 3 ms which was largest over the frontal region. Its short chronaxie (50 micros) and refractory period imply that it arose from the activation of low threshold neural elements, possibly myelinated axons. This potential could follow at 100 Hz. This early potential was sometimes followed by later negative potentials at approximately 5 ms (6/11 sides) and approximately 8 ms (8/11 sides). The responsible neural elements had the same short chronaxie. These potentials were augmented by paired stimuli at separations of 2-7 ms and by trains of stimuli at 200 Hz. CONCLUSIONS: Trains of stimuli delivered to the STN may excite low threshold neural elements which can transmit impulses at frequencies >100 Hz without blocking and which may produce postsynaptic facilitation at the cortex.

Electric Stimulation Therapy↗
PubMed1999

Epidemiological, clinical, and electrodiagnostic findings in childhood Guillain-Barré syndrome: a reappraisal.

We evaluated 61 children with Guillain-Barré syndrome, 14 months to 14 years of age, admitted to the Hospital Nacional de Pediatria in Buenos Aires. According to the electrodiagnostic findings, they fit into two groups, those with acute motor axonal neuropathy (AMAN) (18 patients) and those with acute inflammatory demyelinating polyradiculoneuropathy (AIDP) (43 patients). Ninety percent of the children with AMAN resided in suburban or rural areas without running water, whereas half of the AIDP patients lived in a metropolitan district. Summer and winter months showed a higher incidence of both variants. Children with AMAN were younger, evolved more acutely, reached a higher maximum disability score, required assisted ventilation more often, had lower mean level of cerebrospinal fluid protein, improved more slowly, and had a poorer outcome 6 months and 12 months after onset. Electrophysiological findings in those with AIDP revealed a pattern of severe diffuse slowing in children 5 years old or younger and a multifocal pattern in children 6 years old or older. This difference was not reflected in the clinical picture. In contrast, AMAN showed a uniform pattern with normal sensory conduction, severely reduced compound muscle action potential amplitude, near normal conduction velocity, and early denervation. Epidemiological, clinical, electrodiagnostic, cerebrospinal fluid, and prognostic data indicate that these variants of Guillain-Barré syndrome should be regarded as different entities.

Adolescent↗
PubMed1997

Monomelic amyotrophy following trauma and immobilization in children.

Two children aged 9 and 11 years suffered from left elbow sprain and right anterior tibial tuberosity cortical fracture respectively and were treated with plaster cast immobilization for about 30 days. They regained normal strength afterwards, but 9 and 2 months later developed insidious progressive weakness and wasting in the affected limb, mainly evident in the musculature surrounding the site of injury and sparing hand and foot muscles. Two to three years later the condition stabilized. Sensory abnormalities were not found. Electromyographic examination showed neurogenic pattern confined to the impaired extremity. The focal quality and the unusual disposition of muscle involvement suggest a correlation between trauma and/or immobilization and monomelic amyotrophy.

Adolescent↗
PubMed1997

Prenatal brachial plexus paralysis.

An 18-day-old child with a history of difficult breech delivery presented with wasting and weakness of C5-6-innervated muscles. The EMG examination performed the same day showed high-voltage polyphasic motor unit potentials without abnormal spontaneous activity. Both the EMG pattern and the clinical features suggest an injury taking place several weeks before delivery. This presumption seems confirmed when compared with findings in our series of 100 EMG examinations in 78 children with diagnosis of Erb's palsy. Because of both clinical and medicolegal implications, early EMG testing is advisable in all patients with congenital brachial paralysis.

Brachial Plexus↗
PubMed1996

Familial bulbospinal neuronopathy with optic atrophy: a distinct entity.

A 61 year old woman and her 58 year old brother presented with the clinical picture of late onset progressive bulbar and spinal muscular atrophy with family history of involvement in successive generations. The sister also had optic neuropathy and the brother developed diabetes mellitus and sex hormone abnormalities. Neurophysiological and histopathological studies showed a pattern of motor and sensory neuronopathy. There was no abnormal expansion of CAG repeats in the androgen receptor gene. This family seems to have a previously unrecognised entity with the bulbospinal neuronopathy phenotype.

Electromyography↗
PubMed1994

[Neurologic complications by cocaine abuse].

Argentina is facing an increase in cocaine use by adolescents and young adults from every socioeconomic background. It is calculated that up to 10% of all cocaine passing through this country is locally sold and consumed. Nevertheless, local information describing common cocaine-related neurological events is scarce. From August 1988 to March 1993, 13 patients were evaluated with neurological disease associated with cocaine abuse. Among these 13 patients (Table 1), the mean age was 29; 70% were men. Patients most commonly used the nasal route (snorting). Concomitant abuse of other intoxicants, especially alcohol, was frequent (85%). The major neurological complications included one or more seizures (n = 7), ischemic stroke (n = 2) (Fig. 1-2), hemorrhagic stroke (n = 2) associated with arteriovenous malformation (Fig. 3a-b), memory disturbances (n = 1) and paroxysmal dystonia (n = 1). Psychiatric complaints were present in all patients. Mortality was not observed. There was no correlation between the appearance of complications and the amount of cocaine used, or prior experience with this drug. Only one of the 7 patients with seizures had a previous history of seizures. All had generalized tonic-clonic seizures, and one had concomitant absence episodes. Cocaine modulates central neurotransmitters and has direct cerebrovascular effects. The neurological complications appear to be related to cocaine hyperadrenergic effects, striatal dopaminergic receptor hypersensitivity and perhaps vasculitis. Structural changes in the brain of long-term cocaine abusers could explain the persistence of neurologic symptoms after drug withdrawl.

Adolescent↗
PubMed1991

Dopa-responsive dystonia masquerading as idiopathic kyphoscoliosis.

A 19-year-old girl with a long-standing history of kyphoscoliosis misdiagnosed as idiopathic was offered corrective surgery on several occasions but fortunately refused, since neurological examination later found evidence of mild dystonic posturing in the neck and right leg. Symptoms worsened toward evening but improved with rest. Treatment with low doses of levodopa led to total remission within a month. Our case illustrates that dopa-responsive dystonia can manifest spinal curvature as the major symptom and warrants its inclusion in the differential diagnoses of idiopathic kyphoscoliosis.

Adult↗
PubMed1990

[Multifocal demyelinating neuropathy after tetanus vaccine].

A 39 year old man presenting multifocal demyelinating neuropathy (MFDN) is reported. Fifteen days before onset he had been vaccinated with 75 IU of tetanus toxoid. Although recent histories of vaccination or viral infection support the immunological hypothesis proposed for chronic acquired demyelinating neuropathies (CADN) it is reported for the first time in MFDN, suggesting that MFDN and CADN may share common pathophysiological mechanisms.

Adult↗
PubMed1989

Movement disorders and depression due to flunarizine and cinnarizine.

Over the last few years, cases of movement disorders induced by flunarizine and cinnarizine have been increasingly reported. We describe a series of 101 patients, whose ages ranged from 37 to 84 years (mean 69.1), developing abnormal movements frequently associated with depression, secondary to treatment with either or both drugs. Symptoms closely resembled those induced by neuroleptic drugs and remitted on drug discontinuance in all but five cases after 5-22 months' follow-up. Whether or not such undesirable side effects are attributable to calcium antagonism and/or dopamine receptor blockade, long-term treatment with flunarizine or cinnarizine should be discouraged, particularly in the elderly.

Adult↗
PubMed1989

[Clinical and neurophysiologic tests in the normal elderly].

Clinical and neurophysiological examination was performed in 35 normal aged subjects (72 +/- 6.4; range 65-86 years). Seventeen showed abnormal ankle reflex (48.6%), one case had patellar areflexia as well (2.9%), six had malleolar appalesthesia (17%), and five revealed both areflexia and apallesthesia (14%). Electromyography and motor conduction were normal in every case. Sural nerve conduction velocity and the amplitude of the sensory evoked potential showed no differences between subjects with and without clinical abnormalities. It is concluded that a) reflex and vibration sensibility changes in the elderly are not consequence of peripheral nerve involvement and b) there is no reason to believe there is an "aging neuropathy".

Aged↗
PubMed1988

Concurrent hypnogenic and reflex paroxysmal dystonia.

A 29-year-old patient with nocturnal episodes of paroxysmal dystonia is described. In addition, attacks could be provoked by stimulation of his right foot. Treatment with phenytoin resulted in a marked reduction in the frequency of the episodes.

Adult↗
PubMed1988

Continuous dopaminergic stimulation in cranial dystonia.

Meige's disease is a distressing complaint, the treatment of which often poses a challenge to the neurologist. The patient described here had blepharospasm-oromandibular dystonia, which responded transiently to oral lisuride. On three occasions, drug holidays successfully restored efficacy but thereafter further trials proved fruitless. Continuous subcutaneous lisuride administration in 0.35 mg doses per day, by means of a portable infusion pump, led to sustained improvement for 7 months. No major side effects were observed. Our findings suggest that this treatment deserves further trials.

Domperidone↗
PubMed1987

Calcified cerebral hydatid cyst.

A 32-year-old patient with a lifelong history of epileptic attacks is described. A skull X-ray showed a round calcified nonhomogenous left frontotemporal mass. A CT scan confirmed its presence, as well as displacement of the left lateral and the third ventricles. At surgery a calcified inactive hydatid cyst was totally removed. Full recovery took place two months later. A differential diagnosis of hydatic cysts should be made when a calcified brain mass is found in patients from an endemic echinococcosis area.

Adult↗