The effect of levodopa on the habituation of the acoustic-palpebral reflex in Parkinson's disease.

The aim of the present study was to assess the habituation of the blink responses evoked by repetitive auditory stimuli in patients with Parkinson's disease in different clinical states. We studied 28 parkinsonian patients. Eighteen patients without motor fluctuations were studied off and on levodopa, on two different sessions, one week apart. The remaining 10 parkinsonians had the wearing off phenomenon and were studied while being off their medication and while ON and OFF, as determined clinically, after a single dose of levodopa. Twelve age-matched controls were also studied in a single session. Unilateral auditory 1 kHz, 105 dB stimuli were delivered at a frequency of 0.2 Hz. The number of responses (R) from the orbicularis oculi was registered. R values were significantly smaller in controls and in treated parkinsonians than in untreated patients. R was also significantly smaller when ON than at baseline and when OFF in parkinsonians with the wearing off phenomenon. These results suggest a failure of the inhibition of the acoustic-palpebral reflex in Parkinson's disease. The improvement with levodopa and the similarities between the clinical and the electrophysiological changes suggest a dopaminergic role in the inhibition of this brainstem reflex.

[Diagnosis and treatment of myasthenia gravis. Experience 1974-1992]. / Diagnostico y tratamiento de la myasthenia gravis. Experiencia 1974-1992.

Between 1974 and 1992, 118 patients with Myasthenia gravis (MG) were studied in our Hospital; 92 patients, followed up for longer than 6 months, were surveyed for therapeutical results. Patients were categorized according to Osserman criteria; 22 belonged to group I; 77 to group II; 4 to group III and 15 to group IV. MG predominated in females, the ratio was 1.87:1.0. This predominance was more obvious in patients below 35 years of age (2.68:1.0) than above (1.18:1.0). The greatest prevalence was found at the 3rd decade of life. The assessment of the diagnostic test is as follows: 1) edrophonium test was positive in 97% of 93 patients; 2) supramaximal repetitive stimulation performed in 3 different nerves yielded positive results in 83% of 118 patients. It is worth noting that the test was positive in 92% of patients with generalized MG while only 48% of those with ocular MG displayed positive results; 3) sera antiacetycholine receptor antibodies (ACRA) quantification produced positive results in 88% of the patients with generalized MG and in 33% of ocular MG. Altogether the positivity of this test was 83%; 4) passive transfer of patients sera (25 generalized and 2 ocular MG forms) to mice and measurement of mepp's amplitude in the phrenic-diaphragm in vitro preparation yielded positive results in 100% of the tested cases. Once the diagnosis was achieved, the characteristics of the thymus were studied combining pneumomediastinography and linear tomography (PT) in 60 patients. Thorax Computed tomography (CT) was performed in 51 patients. Of those patients who underwent thymectomy, the coherence between radiological and histological diagnosis for PT was 100% while for CT just 60%. More recently 14 patients were studied by combining both procedures. Reliability of this technique is currently under study. Therapeutical assessment was carried out adscribing patients to 5 different groups according to their response after treatment withdrawal; group 2: Improved, neither symptoms nor signs; group 1: Remission, neither symptoms nor signs while on medication or minimal disability without medication; group 3: Unchanged while on medication; group 4: Worse, patients with more severe or frequent signs and symptoms despite being on treatment, group 5: Death, patients who died due to respiratory failure. Groups 1 and 2 were considered successful while 3, 4 and 5 as unsuccessful. Treatment was based on the administration of anticholinesterase drugs (piridostigmine, neostigmine) in 113 patients. Of these, 35 received those drugs as the only medication of whom 39% obtained successful results. Steroids (methylprednisone) were administered to 75 patients, in 40 cases combined with anticholinesterase drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

Diagnostico y tratamiento de la myasthenia gravis. Experiencia 1974-1992. / [Diagnosis and treatment of myasthenia gravis. Experience 1974-1992]

Between 1974 and 1992, 118 patients with Myasthenia gravis (MG) were studied in our Hospital; 92 patients, followed up for longer than 6 months, were surveyed for therapeutical results. Patients were categorized according to Osserman criteria; 22 belonged to group I; 77 to group II; 4 to group III and 15 to group IV. MG predominated in females, the ratio was 1.87:1.0. This predominance was more obvious in patients below 35 years of age (2.68:1.0) than above (1.18:1.0). The greatest prevalence was found at the 3rd decade of life. The assessment of the diagnostic test is as follows: 1) edrophonium test was positive in 97

of 93 patients; 2) supramaximal repetitive stimulation performed in 3 different nerves yielded positive results in 83

of 118 patients. It is worth noting that the test was positive in 92

of patients with generalized MG while only 48

of those with ocular MG displayed positive results; 3) sera antiacetycholine receptor antibodies (ACRA) quantification produced positive results in 88

of the patients with generalized MG and in 33

of ocular MG. Altogether the positivity of this test was 83

; 4) passive transfer of patients sera (25 generalized and 2 ocular MG forms) to mice and measurement of mepps amplitude in the phrenic-diaphragm in vitro preparation yielded positive results in 100

of the tested cases. Once the diagnosis was achieved, the characteristics of the thymus were studied combining pneumomediastinography and linear tomography (PT) in 60 patients. Thorax Computed tomography (CT) was performed in 51 patients. Of those patients who underwent thymectomy, the coherence between radiological and histological diagnosis for PT was 100

while for CT just 60

. More recently 14 patients were studied by combining both procedures. Reliability of this technique is currently under study. Therapeutical assessment was carried out adscribing patients to 5 different groups according to their response after treatment withdrawal; group 2: Improved, neither symptoms nor signs; group 1: Remission, neither symptoms nor signs while on medication or minimal disability without medication; group 3: Unchanged while on medication; group 4: Worse, patients with more severe or frequent signs and symptoms despite being on treatment, group 5: Death, patients who died due to respiratory failure. Groups 1 and 2 were considered successful while 3, 4 and 5 as unsuccessful. Treatment was based on the administration of anticholinesterase drugs (piridostigmine, neostigmine) in 113 patients. Of these, 35 received those drugs as the only medication of whom 39

obtained successful results. Steroids (methylprednisone) were administered to 75 patients, in 40 cases combined with anticholinesterase drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

[Cerebellar syndrome caused by amiodarone]. / Síndrome cerebeloso por amiodarona.

Amidarone (AMD) is an antiarrhythmic drug with side effects on the nervous system. Cerebellum is seldom involved: We describe the case of a 56 years old male patient with a history of 4 month of cerebellar involvement characterized by gait unsteadiness, ataxia, nistagmus and vertigo. He was on treatment with AMD because of ventricular arrythmia. The cerebellar syndrome progressively disappeared after drug withdrawal and he was symptoms-free 4 months later. Similar symptoms appeared after another one month of automedication with the same drug. Structural lesions, metabolic, nutritional deficiencies or toxics were excluded. Mechanisms of cerebellar toxicity of AMD are yet unknown. The knowledge of the toxic effects of this drug, widely used in our country, would allow its early recognition.

A micrometric multiple electrode array for the exploration of gasserian and retrogasserian trigeminal fibers: preliminary report. Technical note.

The determination of the target for percutaneous thermocoagulation of the trigeminal rootlets has been generally based on the analysis of subjective clinical verbal and motor responses as assessed by freehand displacement of an electrode active at its straight or curved distal tip. In a previous report, we demonstrated that sensory and motor trigeminal evoked potentials are of practical value when attempting to localize the position of trigeminal electrodes. This report describes the technical features of a multiple electrode array designed to provide simultaneous access to various segments along a chosen trigeminal division or divisions, correlating at each segment clinical and electrophysiological data with radiological landmarks in the individual patient. The system consists of an outer needle with four windows at a distance of 15 mm from the tip. A multiple electrode array occludes the windows with four isolated caps for stimulation and recording. After correlating clinical verbal and motor responses with sensory and motor evoked potentials at each window and inter se, a target window is selected. A thermocouple fitted with a micromanipulator allows the accurate placement of the center of the active tip at the center of the chosen window. Preliminary data from 25 patients indicate that the technique provides a reliable sequential analysis of clinical, electrophysiological, and radiological data along the explored tract.

Sensory and motor trigeminal evoked potentials to localize the position of trigeminal electrodes.

Analysis of verbal responses to electrical stimulation of the trigeminal ganglion and rootlets has been the only method available so far to localize the electrode tip in the most appropriate trigeminal division or division segment, prior to thermocoagulation during percutaneous treatment for trigeminal neuralgia. A diversity of factors may lead to unreliable verbal responses, resulting in increased morbidity or even therapeutic failure. In an attempt to enhance the accuracy of electrode localization during Sweet's procedure, we describe an electrophysiological method complementary to clinical responses. Sensory trigeminal evoked potentials (STEPs) induced by separate successive orthodromic cutaneous stimulation of the three trigeminal divisions and recorded by the isolated tip of a transoval thermocouple electrode, together with motor trigeminal evoked potentials (MTEPs) elicited by stimulation of the trigeminal ganglion and recorded in the ipsilateral temporal muscle, were sequentially examined in six patients undergoing percutaneous tic treatment during gradual rostro-caudal electrode withdrawal. STEPs and MTEPs showed appropriate correlation with verbal and clinical motor responses at each electrode site. General anaesthesia failed to affect STEPs. Systematic exploration in the awake patient of both verbal and clinical motor responses, together with STEPs and MTEPs, is therefore recommended prior to the induction of radiofrequency lesions in the course of percutaneous treatment for trigeminal neuralgia.

Habituación del reflejo acústico-palpebral en la enfermedad de Parkinson / Habituation of the acoustic-blink reflex in Parkinsons disease

La oclusión palpebral ante un estímulo auditivo sorpresivo es una respuesta refleja [RAP] polisináptica de integración mesencefálica que tiende a desaparecer frente a estímulos repetidos. Este reflejo transcurre a través del núcleo coclear, cuerpo trapezoide, collículo inferior y sus conexiones, y está sujeto a influencias supramesencefálicas. En el estudio presente, se evaluaron electrofisiológicamente 6 individuos normales y 6 pacientes con enfermedad de Parkinson de edades similares. Se aplicaron estímulos tonales registrándose la actividad refleja en el orbicular de los párpados. Se midieron latencia [L], duración [D], amplitud [A] y fases [F] de las respuestas reflejas obtenidas por aplicación de estímulos auditivos a intervalos randomizados, y luego de un período de reposo, se midió el número de respuestas obtenidas [R] aplicando los estímulos a una frecuencia fija de 0,2 Hz. No se observaron diferencias significativas en L,D,A y F, viéndose en cambio, un mayor número de R en los enfermos de Parkinson. Esta observación sugiere una alteración en la habituación a los estímulos auditivos posiblemente debida a fallas en la inhibición de este reflejo por compromiso de estructuras supramesencefálicas

Habituación del reflejo acústico-palpebral en la enfermedad de Parkinson / Habituation of the acoustic-blink reflex in Parkinson's disease

La oclusión palpebral ante un estímulo auditivo sorpresivo es una respuesta refleja [RAP] polisináptica de integración mesencefálica que tiende a desaparecer frente a estímulos repetidos. Este reflejo transcurre a través del núcleo coclear, cuerpo trapezoide, collículo inferior y sus conexiones, y está sujeto a influencias supramesencefálicas. En el estudio presente, se evaluaron electrofisiológicamente 6 individuos normales y 6 pacientes con enfermedad de Parkinson de edades similares. Se aplicaron estímulos tonales registrándose la actividad refleja en el orbicular de los párpados. Se midieron latencia [L], duración [D], amplitud [A] y fases [F] de las respuestas reflejas obtenidas por aplicación de estímulos auditivos a intervalos randomizados, y luego de un período de reposo, se midió el número de respuestas obtenidas [R] aplicando los estímulos a una frecuencia fija de 0,2 Hz. No se observaron diferencias significativas en L,D,A y F, viéndose en cambio, un mayor número de R en los enfermos de Parkinson. Esta observación sugiere una alteración en la habituación a los estímulos auditivos posiblemente debida a fallas en la inhibición de este reflejo por compromiso de estructuras supramesencefálicas

[Diagnosis and treatment of myasthenia gravis: study of an inpatient population]. / Diagnóstico y tratamiento de la myasthenia gravis: estudio de una población hospitalaria.

Between 1974 and 1987 we have examined 50 patients with the diagnosis of myasthenia gravis. Female preponderance (2.5: 1) was found. Also, it was observed that most of the patients were aged between 20 and 49 years. Beside the clinical examination, the following tests were performed: (1) edrofonium test, (2) supramaximal repetitive nerve stimulation, (3) serum acetylcholine antibodies titers and (4) intraperitoneal passive transference of patient's sera to mice and recording of meepp's amplitude in the phrenic-diaphragm preparation in vitro. These four tests gave positive values for myasthenia in 90 to 100% of the cases. Thymus radiological examination was carried out by pneumomediastinography, which proved to correlate with the histological picture of the gland, and computed tomography, which disclosed some discrepances with the histology. Treatment was based on anticholinesterase drugs, corticosteroids and thymectomy, being the corticosteroids the most valuable therapeutical tool. Nine patients treated with steroids disclosed transitory worsening of their signs and symptoms at very early stages after onset of corticosteroid therapy, 6 of them had a disfavorable course in their follow-up. This observation seem to have value in the early prognosis of the disease.