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Biomedical subjects

M R Magistris

Publications and source records attributed to M R Magistris.

At least 37 records · Page 2Linked to original sources
PubMed2000

Facial palsy in cerebral venous thrombosis : transcranial stimulation and pathophysiological considerations.

BACKGROUND: Cranial nerve palsy in cerebral sinovenous thrombosis (CVT) is rare, its pathophysiology remains unclear, and data from electrophysiological examinations in such patients are missing. CASE DESCRIPTION: We report the case of a 17-year-old woman with familial protein S deficiency who was admitted with extensive multiple CVT. Two weeks after onset of symptoms, she developed isolated right peripheral facial palsy, and MR venography showed segmental occlusion of the ipsilateral transverse sinus. Complete recovery of facial palsy occurred concomitant with recanalization of the transverse sinus. Facial neurography, including transcranial magnetic stimulation of the facial nerve and related motor cortex, ruled out a coincidental idiopathic palsy and revealed conduction block proximal to the facial canal. CONCLUSIONS: Facial palsy in our patient was caused by transient neurapraxia in the intracranial segment of the nerve. We suggest that elevated venous transmural pressure in the nerve's satellite vein, which belongs to the affected drainage territory of the transverse sinus, might have caused venous blood-brain barrier dysfunction in the intrinsic vascular system of the nerve, with leakage of fluids and ions into the endoneurial space and thus an increase in interstitial resistance.

Adolescent↗
PubMed1999

Rapid cortical motor output map changes assessed by the triple stimulation technique.

The amplitudes of motor evoked potentials (MEPs) were mapped by transcranial magnetic stimulation (TMS) using the triple stimulation technique (TST) in 11 normal individuals. Stimuli were given while the subjects were (a) distracted, (b) concentrating on their target (recorded) hand, and (c) concentrating on their contralateral hand. Within seconds, the proportion of excited motor units increased, similarly in all subjects, by an average of 70% from (a) to (b), and by 48% from (a) to (c). At the optimal stimulation site, results obtained with the TST were compared to those of conventional MEPs. The TST proved superior in detecting the rapid changes of the motor output caused by the non-specific mental tasks studied.

Adult↗
PubMed1999

Cerebrospinal fluid in acute peripheral facial palsy.

Cerebrospinal fluid (CSF) is rarely analyzed in peripheral facial palsy, and reports in the literature are scarce. We report the CSF findings in 265 patients with acute isolated peripheral facial palsy. The CSF findings were abnormal in 11% of 230 patients with idiopathic peripheral facial palsy, in 60% of 17 patients with Ramsay Hunt syndrome (pleocytosis), in 25% of 8 patients with Lyme disease, in all of 8 patients with HIV infection, and in 2 other patients (sarcoidosis and herpes simplex). We conclude from this large series that the CSF is usually normal in idiopathic peripheral facial palsy. If the CSF is abnormal, a specific cause should be sought.

Adolescent↗
PubMed1999

A clinical study of motor evoked potentials using a triple stimulation technique.

Amplitudes of motor evoked potentials (MEPs) are usually much smaller than those of motor responses to maximal peripheral nerve stimulation, and show marked variation between normal subjects and from one stimulus to another. Consequently, amplitude measurements have low sensitivity to detect central motor conduction failures due to the broad range of normal values. Since these characteristics are mostly due to varying desynchronization of the descending action potentials, causing different degrees of phase cancellation, we applied the recently developed triple stimulation technique (TST) to study corticospinal conduction to 489 abductor digiti minimi muscles of 271 unselected patients referred for possible corticospinal dysfunction. The TST allows resynchronization of the MEP, and thereby a quantification of the proportion of motor units activated by the transcranial stimulus. TST results were compared with those of conventional MEPs. In 212 of 489 sides, abnormal TST responses suggested conduction failure of various degrees. By contrast, conventional MEPs detected conduction failures in only 77 of 489 sides. The TST was therefore 2.75 times more sensitive than conventional MEPs in disclosing corticospinal conduction failures. When the results of the TST and conventional MEPs were combined, 225 sides were abnormal: 145 sides showed central conduction failure, 13 sides central conduction slowing and 67 sides both conduction failure and slowing. It is concluded that the TST is a valuable addition to the study of MEPs, since it improves detection and gives quantitative information on central conduction failure, an abnormality which appears to be much more frequent than conduction slowing. This new technique will be useful in following the natural course and the benefit of treatments in disorders affecting central motor conduction.

Adult↗
PubMed1999

Indirect discharges as an early nerve conduction abnormality in the Guillain-Barré syndrome.

Abnormal electrophysiological findings may be delayed in the Guillain-Barré syndrome (GBS). In this study, conducted in 29 GBS patients, 23 patients (group 1) fulfilled the electrodiagnostic criteria for GBS [1]at the time of initial investigation, performed on average 22.3 days after onset of symptoms; whereas the 6 patients (group 2) who did not fulfil the criteria were first seen earlier, on average after 9.7 days. During the initial nerve conduction studies, numerous late responses, distinct from F waves, were observed in 26 of the 29 patients (90%), that is in 20 patients of group 1, and in all patients of group 2. Most of these responses, if not all, were indirect discharges (iDs) caused by proximal re-excitation on motor axons. If the iDs had been included in the electrodiagnostic criteria of GBS, all the patients of this series would have been diagnosed at the initial electrophysiological examination. We conclude that iDs occur frequently in GBS and are observed early in the disease. We recommend adding the presence of multiple iDs to the classical electrodiagnostic criteria of GBS.

Adolescent↗
PubMed1998

Needle muscle biopsy in the investigation of neuromuscular disorders.

We have evaluated needle muscle biopsies in 220 patients with various neuromuscular disorders, using a method developed previously at Tuft's University. The method uses a 14-gauge needle propelled by an automatic device. An average of 3.5 samplings were taken per patient. Muscle samples were used for histological and molecular genetic analysis, and for the isolation of muscle satellite cells for in vitro cultures. The biopsy is well tolerated by the patients who never declined multiple samplings. Complications were few and minor, with no sequelae. In most cases the small size of the muscle specimen (ca. 15 mg per sampling) was sufficient to perform the various procedures and to yield a diagnosis. Specimens were considered insufficient for histological results in 9 patients (4%), due to technical artifacts or insufficient material. We now routinely use this method, which has several advantages over the surgical technique for most muscle biopsies.

Adolescent↗
PubMed1998

Transcranial stimulation excites virtually all motor neurons supplying the target muscle. A demonstration and a method improving the study of motor evoked potentials.

Transcranial stimulation has become an established method in the evaluation of corticospinal tract function. Clinical studies mainly address slowing of conduction through measurement of increased central conduction time (CCT) and 'failures' of conduction through observation of marked reductions in the size of the motor evoked potential (MEP). While CCT is of great interest in detecting subclinical slowing of conduction, the method discloses only gross failures of conduction, since the size of the MEP varies markedly between normal subjects and from one stimulus to another, leading to a broad range of normal values. Furthermore, transcranial stimulation does not appear to achieve depolarization of all spinal motor neurons leading to the target muscles, since in most normal subjects MEPs are smaller in amplitude than the responses evoked by peripheral nerve stimulation. We have developed a triple stimulation technique (TST) which, through two collisions, links central to peripheral conduction and suppresses desynchronization of MEPs. This technique shows that transcranial stimulation does achieve depolarization of all, or nearly all, spinal motor neurons supplying the target muscle in healthy subjects. Our data thus demonstrate that the amplitudes of MEPs are (i) smaller than those of peripheral responses, mostly due to phase cancellation of the action potentials caused by the desynchronization occurring within the corticospinal tract or at spinal cell level and (ii) variable between normal subjects and from one stimulus to another, mostly due to variability of this desynchronization. This technique provides new insights into normal corticospinal tract conduction. It will improve detection and quantification of central motor conduction failures.

Action Potentials↗
PubMed1998

Post-traumatic stimulus suppressible myoclonus of peripheral origin.

A patient is described who presented with myoclonus of the first dorsal interosseus muscle of the right foot. This myoclonus occurred 18 months after trauma of the cutaneous branch of the deep peroneal nerve on the dorsal aspect of the foot. Tactile stimulation in the dermatome of this nerve, or an anaesthetic block of the deep peroneal nerve stopped the myoclonus. The different innervation between the efferent motor activity responsible for the movements and the sensory afference suppressing it points firmly towards involvement of central connections. However, abolition of the movement by anaesthesia suggests the presence of a peripheral ectopic generator. This finding confirms that focal myoclonus can have its origin in the peripheral nervous system and may be modulated by sensory inputs.

Adult↗
PubMed1998

[Brown-Vialetto-Van Laere syndrome: a case with anti-ganglioside GM1 antibodies and literature review].

We report the case of a woman suffering from progressive bulbopontine paralysis in whose the first symptom, bilateral hypoacousia, began in childhood. This clinical picture is that of the Brown-Vialetto-Van Laere (BVVL) syndrome. Anti-ganglioside GM1 antibodies were moderately elevated in this patient. Intravenous immunoglobulins produced little benefit. The main clinical characteristics of 29 BVVL patients reported in literature are reviewed, and the pathological significance of anti-GM1 antibodies is discussed in the context of this disorder.

Adult↗
PubMed1996

Contraction response to muscle percussion is increased in peripheral nerve conduction block.

We studied the contraction of skeletal muscle upon direct percussion in 119 patients presenting with palsies related to focal peripheral nerve disorders. We compared the response of the paralyzed muscles with the response obtained on the contralateral normal side. The cause of the palsy was subsequently assessed by electrophysiological testing which disclosed: conduction block (CB), axonal, or mixed lesions (when both CB and denervation existed in similar proportions). Most of the time, the muscle response to percussion was increased in patients with CB (37/47), decreased in axonal lesions (44/53), and symmetric in mixed lesions (12/19). We conclude that distinction between CB and denervation is often possible on the basis of this simple bedside test.

Adult↗
PubMed1995

Electrophysiological characteristics of lesions in facial palsies of different etiologies. A study using electrical and magnetic stimulation techniques.

Using magnetic stimulation techniques in addition to conventional electrical stimulation, the entire facial motor pathway can be assessed electrophysiologically. To study the diagnostic yield of these examinations, 174 patients with facial palsies of a variety of etiologies were examined (85 Bell's palsies, 24 Guillain-Barré syndrome (GBS), 19 Lyme borreliosis, 17 zoster oticus, 12 meningeal affections, 10 brain-stem disorders and 7 HIV-related facial palsies). The facial nerve was stimulated electrically at the stylomastoid fossa and magnetically within its canalicular portion. Additionally, the face-associated contralateral motor cortex was stimulated magnetically. Recordings were from the nasalis or mentalis muscle, or both, using surface electrodes. Bell's palsy patients showed typically a unilateral local hypoexcitability of the facial nerve to canalicular stimulation. In GBS, bilateral latency prolongations were frequent, as expected for a myelinic disorder. In contrast, in zoster, predominant axonotmesis was unilateral, and in HIV infection sometimes bilateral. The method was very sensitive to detect subclinical dysfunctions in meningo-radiculitis and malignant meningeal diseases, either prior to the onset of palsy, or on the contralateral (clinically unaffected) side. It also distinguished reliably between central and peripheral facial motor pathway lesions. In our experience, these inexpensive and non-invasive electrophysiological techniques contribute substantially to the differential diagnosis of facial palsies.

Adult↗
PubMed1995

[Isolated peripheral facial paralysis and HIV infection: 7 cases].

Human immunodeficiency virus infection frequently involves the peripheral or central nervous system. Seven cases of isolated peripheral facial palsy that occurred at various stages of the disease are reported. The palsy was the first manifestation of the disease in 5 patients, and revealed it in 3 of them. The palsy involved the right side in 6 cases (complete N = 2; incomplete N = 4); it was bilateral in one (complete on both sides). Abnormalities of the cerebrospinal fluid were present in all patients but differed depending on the stage of the retroviral infection. Electroneuromyography defined the type of the palsy, principally due to axonotmesis in 4 patients (including the bilateral one) and principally to neurapraxia in 3 patients. The outcome was good in most cases. The physiopathology remains undetermined.

Adult↗