Search PubMed⌕ Search

Biomedical subjects

E S Tolosa

Publications and source records attributed to E S Tolosa.

At least 19 recordsLinked to original sources
PubMed2005

Bilateral subthalamotomy in Parkinson's disease: initial and long-term response.

We conducted an open label pilot study of the effect of bilateral subthalamotomy in 18 patients with advanced Parkinson's disease. In seven patients, the first subthalamotomy pre-dated the second by 12-24 months ('staged surgery'). Subsequently, a second group of 11 patients received bilateral subthalamotomy on the same day ('simultaneous surgery'). Patients were assessed according to the CAPIT (Core Assessment Program for Intracerebral Transplantation) protocol, a battery of timed motor tests and neuropsychological tests. Evaluations were performed in the 'off' and 'on' drug states before surgery and at 1 and 6 months and every year thereafter for a minimum of 3 years after bilateral subthalamotomy. Compared with baseline, bilateral subthalamotomy induced a significant (P < 0.001) reduction in the 'off' (49.5%) and 'on' (35.5%) Unified Parkinson's Disease Rating Scale (UPDRS) motor scores at the last assessment. A blind rating of videotape motor exams in the 'off' and 'on' medication states preoperatively and at 2 years postoperatively also revealed a significant improvement. All of the cardinal features of Parkinson's disease as well as activities of daily living (ADL) scores significantly improved (P < 0.01). Levodopa-induced dyskinesias were reduced by 50% (P < 0.01), and the mean daily levodopa dose was reduced by 47% at the time of the last evaluation compared with baseline (P < 0.0001). Dyskinesias occurred intraoperatively or in the immediate postoperative hours in 13 patients, but were generally mild and short lasting. Three patients developed severe generalized chorea that gradually resolved within the next 3-6 months. Three patients experienced severe and persistent postoperative dysarthria. In two, this coincided with the patients exhibiting large bilateral lesions also suffering from severe dyskinesias. No patient exhibited permanent cognitive impairment. The motor benefit has persisted for a follow-up of 3-6 years. This study indicates that bilateral subthalamotomy may induce a significant and long-lasting improvement of advanced Parkinson's disease, but the clinical outcome was variable. This variability may depend in large part on the precise location and volume of the lesions. Further refinement of the surgical procedure is mandatory.

Activities of Daily Living↗
PubMed2000

Postural and action myoclonus in patients with parkinsonian type multiple system atrophy.

Patients with a parkinsonian syndrome and features of multisystem atrophy (pMSA) may exhibit abnormal movements of the hands and fingers, which are reported in the literature either as "jerky" tremor or myoclonus. We studied clinically and electrophysiologically these movements in 11 consecutive patients with pMSA. No abnormal movements were observed when the patients were at complete rest, except for a characteristic parkinsonian "pill-rolling" tremor in one patient. Abnormal small-amplitude, nonrhythmic movements involving just one or a few fingers, or more rarely the whole hand, were observed in nine patients when holding a posture or at the beginning of an action. Accelerometric recordings showed small-amplitude irregular oscillations which, contrary to those of patients with tremor, had no predominant peak in the Fast Fourier frequency spectrum analysis. Electromyographic recordings in the forearm and hand muscles showed brief jerks of less than 100 ms duration which were synchronous in antagonist muscles of the forearm and alternated with brief periods of silence. Electrical stimulation of the digital nerves evoked consistent reflex responses in the wrist flexor and extensor muscles at a latency of 55.3+/-4.1 ms (range, 50-63 ms). Routine electroencephalographic (EEG) and somatosensory evoked potentials to median nerve stimulation were normal. Back-averaging of the EEG activity time-locked to the jerks was performed in two patients with no evidence of abnormal cortical activity. Two patients had episodes of transient respiratory failure related to pneumonia. This caused a long-lasting enhancement of the abnormal hand and finger movements, which became larger and more widespread, with features of posthypoxic myoclonus. We conclude that the abnormal hand and finger movements of patients with pMSA are a form of postural and action myoclonus, and can be described as mini-polymyoclonus.

Aged↗
PubMed2000

Metabolic effects of nigrostriatal denervation in basal ganglia.

In the past, functional changes in the circuitry of the basal ganglia that occur in Parkinson's disease were primarily analyzed with electrophysiological and 2-deoxyglucose measurements. The increased activity of the subthalamic nucleus (STN) observed has been attributed to a reduction in inhibition mediated by the external segment of the globus pallidus (GPe), secondary to the loss of dopaminergic-neuron influence on D2-receptor-bearing striato-pallidal neurons. More recently, in situ hybridization studies of cytochrome oxidase subunit I have confirmed the overactivity of the STN in the parkinsonian state. In addition, this technique has provided evidence that the change in STN activity is owing not only to decreased inhibition from the GPe but to hyperactivity of excitatory inputs from the parafascicular nucleus of the thalamus and the pedunculopontine nucleus in the brainstem.

Basal Ganglia↗
PubMed1998

The 'geste antagonistique' induces transient modulation of the blink reflex in human patients with blepharospasm.

The mechanism of action of the 'geste antagonistique', or sensory trick, used by patients with dystonic blepharospasm (BSP) to transiently diminish their symptoms is presently unknown. In this paper we examined the effects induced by a sensory trick consisting of finger contact with the face on the electrically induced blink reflex and the blink reflex excitability recovery curve to paired stimuli. The results were compared with those obtained in a group of six healthy volunteers who mimicked the manoeuvre used by the patients as a sensory trick. In all subjects, the area of R2 was significantly reduced, and the amplitude of R1 was significantly enhanced, during a mean of 10 min after the onset of finger-face contact in comparison to rest. However, there were no changes in the blink reflex excitability recovery curve. The contact-induced effect on the magnitude of the R2 component of the blink reflex is probably caused by sensory gating on trigeminal afferents. Such a reduction in the gain of trigemino-facial reflexes may partly underly the transient benefit experienced by patients with BSP with the use of sensory tricks.

Blepharospasm↗
PubMed1997

Neurophysiological investigations in patients with head tremor.

We studied 30 patients whose primary complaint was head tremor in an attempt to characterize neurophysiological aspects of their abnormal movement. Based on family medical history and physical examination, 23 patients had definite or probable essential tremor (essential head tremor, EHT). The remaining seven had mild dystonic signs accompanying their head tremor (head tremor plus dystonic signs, HT + DS). We recorded head movement and the electromyographic (EMG) activity of the sternomastoid and splenius capitis muscles, determined the spontaneous blinking rate, and measured the excitability recovery curve of the blink reflex and of the masseteric inhibitory reflex. All patients had tremor bursts at a frequency ranging between 3 and 9 Hz in at least one of the muscles examined. The predominant pattern seen when patients were sitting relaxed and facing forward was that of synchronized EMG bursts in both splenius capitis muscles. Maintenance of extreme head postures demonstrated two types of additional abnormalities: type 1 (enhancement of tremor), which was observed in 11 patients (47.8%) with EHT and in two (28.5%) with HT + DS; and type 2 (activation of neck muscles not required for maintenance of the posture), which was observed in two patients (8.7%) with EHT and in five (71.5%) with HT + DS (chi 2 = 26.4; p < 0.001). Mean blinking rate per minute was 24.9 +/- 14.6 in patients with EHT and 42.3 +/- 10.5 in patients with HT + DS (paired t test, p = 0.001). The blink reflex and masseteric inhibitory reflex excitability recovery curves showed an abnormal interneuronal excitability enhancement in seven (30.4%) of the 23 patients with EHT and in two (28.5%) of the seven with HT + DS (chi 2 = 3.1; p > 0.05). Abnormal patterns of EMG activity of the neck muscles correlated well with the presence of mild dystonic signs. However, the analysis of brainstem interneuronal excitability did not enable recognition of those patients with head tremor who could potentially develop cervical dystonia. The enhancement of brainstem interneuronal excitability found in approximately 30% of patients with head tremor could be related to plastic changes triggered by increased activity of the cranial muscles.

Adult↗
PubMed1995

Reaction time and acoustic startle in normal human subjects.

We studied the effects of collision between a voluntary command and the startle response by interrupting a simple visual reaction time task with an acoustic startle. We observed two main effects. First, the reaction time was markedly shortened when the startle was delivered at intervals of 0-75 ms after the 'go' signal. Second, the startle response elicited when the subject's attention was focused onto reacting to the visual 'go' signal involved more muscles and induced larger EMG responses than when the startling stimulus was delivered unexpectedly. Startle response and voluntary commands may share a number of structures along the motor path. Reaction time can be shortened up to the latency of a startle response if the voluntary command is issued a short time after the startling stimulus. Facilitation of the startle responses during motor preparation may be due to the excitability enhancement that occurs in various neural structures along the motor path before the onset of EMG activity.

Acoustic Stimulation↗
PubMed1995

Striated anal sphincter denervation in patients with progressive supranuclear palsy.

Anal sphincter electromyography may contribute to the differential diagnosis between Parkinson's disease (PD) and other parkinsonisms featuring autonomic dysfunction, such as multiple system atrophy (MSA). Although patients with progressive supranuclear palsy (PSP) do not normally exhibit clinical signs of autonomic dysfunction, a few may be first seen with urinary and fecal incontinence. We performed an electromyographic study of the anal sphincter in 12 patients with clinical criteria of probable or definite PSP, two of them with clinical manifestations of vesical and anal sphincter dysfunction. The results have been compared with those obtained from six patients with PD and six patients with MSA. An abnormal anal sphincter examination was present in five of 12 PSP patients (41.6%). The abnormal motor units of these patients were indistinguishable from those observed in patients with MSA. Patients with MSA had the largest, and patients with PD had the lowest, proportion of abnormal motor units. We conclude that some patients with PSP may have electromyographic signs of denervation in the anal sphincter, which make them indistinguishable by using this test alone from patients with MSA.

Adult↗
PubMed1994

Vibration-induced presynaptic inhibition of the soleus H reflex is temporarily reduced by cortical magnetic stimulation in human subjects.

We have examined the effects of a transcranial magnetic stimulus (TMS) on the H reflex of the soleus muscle during vibration-induced presynaptic inhibition of the reflex, in seven normal volunteers. Without vibration, the H reflex was facilitated at interstimulus time intervals of > or = 5 ms after TMS. With vibration, the H reflex was markedly reduced or completely inhibited in control trials, but facilitation by TMS was noticed at intervals as short as -2.5 ms. These findings indicate an effect of TMS on the spinal interneurons mediating presynaptic vibratory inhibition of the H reflex.

Cerebral Cortex↗
PubMed1994

Responses of the soleus muscle to transcranial magnetic stimulation.

Soleus muscle responses are difficult to elicit by cortical stimulation in normal humans at rest. We have studied in normal volunteers the behavior of the soleus and tibialis anterior muscle responses to maximal intensity transcranial magnetic stimulation (TMS) in the following experimental conditions: lying in supine position, active ankle dorsal flexion, active plantar flexion, standing on the soles, standing on the toes, and standing on the heels. At rest, consistent responses were recorded in the soleus to 61% of the stimuli, only. Maximal facilitation of the response in the soleus occurred when standing on the toes. In this condition, responses were recorded to 100% of the stimuli, at a latency that was, on average, 5.2 msec shorter than the latency of the responses at rest, and similar to the latency of the responses recorded in the tibialis anterior muscle when standing on the heels. Central motor conduction time, calculated in conditions of maximal facilitation, was not different for soleus or tibialis anterior muscles. We conclude that the soleus muscle receives short latency excitatory inputs from cortico-spinal axons activated by TMS, with a conduction time similar to that for the tibialis anterior. Such short latency cortico-spinal connections to the soleus muscle may become functionally effective only during maximum enhancement of motoneuronal excitability by muscle contraction.

Adult↗
PubMed1994

Treatment with botulinum toxin injections does not change brainstem interneuronal excitability in patients with cervical dystonia.

Brainstem interneuronal excitability is enhanced in patients with cervical dystonia. Treatment with local botulinum toxin (BTX) injections temporarily alleviates the pain and weakens the muscle spasms, characteristics of this condition. In 10 patients with cervical dystonia, we studied whether the clinical improvement induced by BTX was associated with modification of the blink reflex excitability recovery curve to paired supraorbital nerve electrical shocks. We found that the mean percentage recovery of the R2 to the test stimulus was abnormally enhanced before treatment and that it did not significantly change after treatment, at the time of maximal clinical improvement, in any of the interstimulus intervals tested. We conclude that the clinical improvement induced by BTX in patients with cervical dystonia is largely symptomatic and is not related to any change of the known abnormalities in brainstem interneuronal excitability that possibly underlie the pathophysiology of cervical dystonia.

Adult↗
PubMed1994

New and emerging strategies for improving levodopa treatment.

Soon after the successful introduction of large oral doses of levodopa or of levodopa plus a decarboxylase inhibitor, such as carbidopa or benserazide, for the treatment of Parkinson's disease, it became evident that several disturbing side effects were limiting the therapeutic efficacy of this amino acid. This paper discusses novel practical approaches for the management of these levodopa-related complications. These approaches include therapeutic strategies for controlled delivery of levodopa to the brain (controlled-release preparations), rescue treatment with subcutaneous, intranasal, or sublingual administration of the dopamine agonist apomorphine, and the administration of an atypical neuroleptic, such as clozapine. Other approaches for prolonging the response of levodopa that are being used or investigated are also reviewed in this paper. These include the use of levodopa prodrugs and blocking the degradation in the brain with inhibitors of monoamine oxidase-B and catechol-O-methyltransferase.

Animals↗
PubMed1993

Magnetic resonance imaging in patients with concurrent Tourette's disorder and Asperger's syndrome.

OBJECTIVE: The purpose of the study was to examine behavioral/cognitive and neuroradiological features of patients with concurrent Tourette's disorder (TD) and Asperger's syndrome (AS). METHODS: The authors studied the occurrence of structural brain abnormalities using magnetic resonance imaging (MRI) in seven males with concurrent TD and AS, and in nine age-matched males, who had TD but did not have AS. Both groups were tested with an extensive battery of neurological and psychiatric rating scales and cognitive tests. RESULTS: Five of the seven patients with TD and AS had developmental brain anomalies. In contrast, normal MRI scans were found in all but one TD patient without AS. Both groups were not significantly different in the severity of motor and phonic tics, obsessionality, depression and anxiety, or in measures of general intelligence, memory, and language function; but patients with TD and AS had a history of more psychiatric hospitalizations, poor academic achievement, more neurological soft signs and appeared more impaired on complex problem-solving and spatial tests than did TD patients without AS. CONCLUSION: These findings suggest that structural cortical and subcortical abnormalities are more common among individuals with concurrent TD and AS than among sex- and age-matched TD patients without AS. Dysfunction of frontal-subcortical systems may play a role in the pathophysiology of concurrent TD and AS.

Adolescent↗
PubMed1992

Myokymic discharges and enhanced facial nerve reflex responses after recovery from idiopathic facial palsy.

A functional disorder of facial muscle activity commonly occurs in patients after recovery from Bell's palsy with axonal degeneration. The postparalytic facial dysfunction is probably related to the aberrant growing of regenerating axons, although other theories such as ephaptic transmission, spontaneous generation of impulses, and enhancement of motoneuron excitability should also be considered. In this work, we have carried out a comparative electrophysiological study of both sides of the face in 23 patients who had recovered from a unilateral Bell's palsy with axonal degeneration. At rest, spontaneous firing of motor units was observed in muscles of the previously paralyzed side. Direct motor responses to facial nerve stimulation were smaller in the muscles of the previously paralyzed side, but reflex responses obtained in the same muscles by stimulation of either the facial or trigeminal nerve were larger when compared with those of the contralateral side. These data indicate that patients with "postparalytic facial dysfunction" may have an increased background muscle activity, as well as an enhanced recruitment of facial motoneurons to reflex activation in the side of the previous paralysis. These findings are compatible with an enhanced level of motoneuron excitability in the facial nucleus.

Action Potentials↗
PubMed1992

Recurrent hypersomnia in two adolescent males with Asperger's syndrome.

Two individuals with Asperger's syndrome, a rare pervasive developmental disorder, developed recurrent episodes of hypersomnia and abnormal behavior (Kleine-Levin syndrome) during adolescence. The possible etiological role of developmental structural brain anomalies and the differential diagnosis of recurrent hypersomnia and abnormal behavior in patients with pervasive developmental disorders are discussed.

Adolescent↗
PubMed1992

Tics and myoclonus.

This article describes advances occurring over the last year in the pathophysiology, etiology and treatment of tics and myoclonus. Progress is being made in the clinical definition of Tourette syndrome (TS). The search for the TS gene has already excluded more than 50% of the autosomal genome. Progress in the understanding of myoclonus is slow but continuous. Several paper are devoted to clinical aspects but much recent attention has been focused on the pathophysiological mechanisms underlying myoclonus.

Brain↗
PubMed1991

Neurophysiological observations on the effects of botulinum toxin treatment in patients with dystonic blepharospasm.

Botulinum toxin treatment improves dystonic blepharospasm by inducing transient paresis of the orbicularis oculi muscle. It is not known if it also reduces the enhanced brainstem neuronal excitability found in this disorder. We have performed conventional electromyography (EMG) and blink reflex excitability studies on fifteen patients with blepharospasm before and after botulinum toxin treatment. Denervation signs were found with needle EMG in all treated muscles. Amplitude of the facial compound muscle action potential (CMAP) and R1 response was reduced after botulinum toxin injections. In blink reflex excitability studies, the recovery of R2 response was enhanced after treatment even when patients were tested at the time of maximal benefit from botulinum toxin injections. The results suggest that there is little influence of botulinum toxin treatment upon the enhanced excitability of brainstem interneurons in patients with blepharospasm.

Adult↗