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Biomedical subjects

G Avanzini

Publications and source records attributed to G Avanzini.

At least 127 records · Page 7Linked to original sources
PubMed1980

Brain stem projections in the pulvinar-lateralis posterior complex of the cat.

The present experiments were undertaken to define the areas of projection of pretectum and superior colliculus to the pulvinar and n. lateralis posterior, respectively, and to define other brain stem structures projecting to these thalamic nuclei in cats. For this purpose of technique of retrograde transport of horseradish peroxidase (HRP) has been used. After injection of the enzyme in the pulvinar, neurons were labeled in all subdivisions of the pretectal area. The majority of the labeled cells were located in the n pretectalis anterior pars compacta and area pretectalis medialis. Neurons projecting to the pulvinar were also found in the periaqueductal gray, reticular formation and locus coeruleus. When HRP was injected in the n. lateralis posterior, labeled neurons were present in the II and III subdivisions of the second layer of the superior colliculus. The location of these cells shifted from medial to lateral as the injections were shifted from posterior to anterior within the lateralis posterior. Neurons projecting to this nucleus were also present in the intermediate layers of the superior colliculus, lateral hypothalamus and parabigeminal nucleus. The possible role of the pretectal area and superior colliculus in mediating somesthetic input to the pulvinar and lateralis posterior, respectively, and the role of these structures in the control of ocular movements, are discussed.

Animals↗
PubMed1980

Oculomotor abnormalities in patients with lesions involving the tectal region.

An analysis of ocular movements was performed in four patients with retraction nystagmus and paralysis of the upward gaze. The clinical and radiological data indicate that the lesion were relatively limited to the most rostral and dorsal portion of the mesencephalon. The electrooculographic examination disclosed not otherwise obvious abnormalities of horizontal ocular movements. The most prominent defect was a tendency to perform hypometric saccades followed by multiple corrective movements. This tendency was particularly evident in saccadic movements toward a light spot unexpectedly displaced in the visual field of the subject. It is suggested that lesions responsible for retraction nystagmus can also affect the visuomotor integration mechanisms; the foveation of the target is then obtained through a typical modification of the motor strategy.

Adult↗
PubMed1980

Segmental action and stimuli-sensitive myoclonus with acute onset. A case report.

A 23-year old man developed action and stimulus-sensitive myoclonus involving neck and proximal arm muscles. The finding of abnormally long and tortuous vertebral and carotid arteries and the abrupt onset of symptomatology suggest a possible hemodynamic mechanism. The electrophysiological characters and the sensitivity to serotonin precursors are consistent with the definition of "reticular reflex myoclonus".

5-Hydroxytryptophan↗
PubMed1980

Multisensory convergence and interaction in the pulvinar-lateralis posterior complex of the cat's thalamus.

Responsiveness to visual, acoustic and somesthesic stimuli was studied in 260 units recorded within the associative thalamic nuclei of the cat (pulvinar-lateralis posterior complex and posterior group). Of the 123 units responding to one or more stimuli 41 (corresponding to 15% of the total) showed multisensory convergence. Bimodal, visual-somesthesic convergence was the most common finding, occurring in 33 units. Visual-somesthesic inhibitory interaction was observed only in the pulvinar nucleus, suggesting a peculiar synaptic organization of multisensory input to this nucleus.

Animals↗
PubMed1980

Cherry-red spot myoclonus syndrome and alpha-neuraminidase deficiency: neurophysiological, pharmacological and biochemical study in an adult.

A 22 year old patient with non-familial progressive myoclonus, macular cherry-red spot, moderate cerebellar syndrome and normal intelligence is described. The myoclonus began at the age of 18 years. Focal myoclonus could easily be elicited by voluntary and passive movements, and by touch and electrical stimulation of median nerve. Somatosensory evoked potentials showed a high voltage early component. Jerk-locked averaging of the EEG preceding action myoclonus detected an otherwise hidden, time-related, EEG spike. The myoclonus responded partially but clearly to L-5 hydroxytryptophan plus carbidopa treatment. Biochemical study showed an alpha-neuraminidase deficiency in cultured fibroblasts: the decrease in this enzyme activity was compared to that found in a patient affected by mucolipidosis III.

Adult↗
PubMed1980

Effect of L-5HTP and drugs acting on serotonin metabolism in various myoclonic syndromes.

Ten patients affected by various myoclonic syndromes were tested with drugs acting on cerebral serotonin metabolism and with clonazepam (CZP). After L5HTP or serotonergic drugs administration a clear cut improvement was observed in the 2 patients affected by Ramsay-Hunt syndrome, while the patients with myoclonic epilepsy have shown no effect (3 cases) or negative response (1 case). Methysergide was active only in 1 patient affected by progressive erratic myoclonus who had a striking worsening of clinical picture. The main side effects observed were: gastrointestinal distress (L5HTP--4 patients, fenfluoramine--2, quipazine--1, methysergide--2) and cutaneous rash (quipazine--1 case). These results support the possible implication of the serotonergic system in the pathogenesis of myoclonus other than post-anoxic.

5-Hydroxytryptophan↗
PubMed1979

Alterations of ocular motility in cerebellar pathology. An electro-oculographic study.

Saccadic as well as smooth pursuit movements were studied by means of electro-oculograms in a group of 14 patients affected by cerebellar diseases. Ten patients had cerebellar atrophies, and four had undergone surgery for cerebellar tumors. Loss of gain of the pursuit system and metric alteration of saccades were the most striking abnormalities observed. Dysmetria was shown to be related to the amplitude of the movement and to the sector of the perimeter within which the movement occurs (movements occurring in the more eccentric sector were more disturbed). A tendency to produce saccades slower than normal was noted in patients affected by olivopontocerebellar atrophy. The clinical and pathophysiological significance of this finding is discussed with particular reference to Wadia-Swaami hereditary ataxia.

Adult↗
PubMed1979

Oculomotor disorders in Huntington's chorea.

Electro-oculographic recordings were obtained from 11 patients with Huntington's disease. Significant reduction of saccadic velocity was constantly found. In all the patients vertical saccades were much more impaired than horizontal. When present, vertical saccades showed long latency, low amplitude, low velocity, and disturbances related to blinking. Following movements were jerky, and ability to perform repeated rhythmic movements was impaired. These results are in agreement with previous observations and underline the selective defect of rapid movements as a characteristic feature of Huntington's disease. Further, they suggest a possible correlation between the difficulty in performing repeated ocular movements and the impaired execution of gestural sequences involving a succession of different fundamental movements.

Adult↗
PubMed1977

Intention and action myoclonus from thalamic angioma. Report of a case.

Clinical electrophysiological and neuroradiological examination of a case of unilateral intention and action myoclonus is reported. Brachial arteriography revealed an angioma located mainly in the lateral portion of the right posterior thalamus. Clinical and electrophysiological findings suggesting involvement of nonthalamic structures were absent. Our case, together with some cases previously described, raises the possibility that volitional myoclonus may be related to a relatively circumscribed damage of some diencephalic and/or mesencephalic structures. The rare occurrence of a hyperkinetic syndrome as principal symptom of a cerebral vascular malformation should be borne in mind in view of the potential risk of a stereotactic surgical procedure designated to alleviate the involuntary movements.

Adult↗
PubMed1977

Pharmacology of Huntington's chorea. Personal experience.

Dipropylacetic acid (DPA), gamma-aminobutyric acid (GABA), physostigmine, CB 154 and butyrophenones were administered to 26 patients affected by Huntington's chorea. The evaluation of the pharmacologic activity of the different drugs was determined by means of some clinical parameters and motor performance tests. Butyrophenones succeeded to ameliorate the hyperkinesias and the motor dexterity, CB 154 provoked a worsening of the motor signs of the disorder, while DPA, GABA and physostigmine did not modify the clinical pattern. The relationship between these results and the Hungtington's chorea physiopathology is discussed and a hypersensitivity of DA receptors is suggested.

Acetates↗
PubMed1976

Study of the excitability cycle of the blink reflex in Huntington's chorea.

The trigemino-facial reflex was studied in 7 patients affected by Huntington's chorea and in 10 patients affected by Parkinson's disease. The results show a different behavior of the habituation phenomenon in the two groups of patients: it is enhanced in the choreic and abolished in the parkinsonian patients. The main changes concern the time course of the second phase (the first inhibitory phase) of the reflex excitability cycle, in fact, the inhibitory phase appears very pronounced and prolonged in huntingtonian patients and reduced or abolished in parkinsonian patients. Some pathophysiological mechanisms involved in the control of the trigeminofacial reflex excitability are discussed with particular regard to the role of the hemispheric structures.

Adult↗