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Biomedical subjects

U Sabatini

Publications and source records attributed to U Sabatini.

34 records · Page 2Linked to original sources
PubMed1995

Abnormal vestibuloocular reflex cancellation in multiple system atrophy and progressive supranuclear palsy but not in Parkinson's disease.

We have measured the gain of the vestibuloocular reflex (VOR) in darkness and its cancellation by fixation in 37 patients with Parkinson's disease (PD), 26 patients with multiple system atrophy (MSA), 11 patients with progressive supranuclear palsy (PSP), and 19 normal volunteers. The capacity to cancel the VOR by fixation (VOR cancellation) was significantly reduced in the MSA and PSP patients compared with the PD and normal subjects (p < 10(-4)). A VOR cancellation < 90% (i.e., the mean VOR cancellation of the normals--2 SD) was present in four PD patients, 23 MSA patients, and 11 PSP patients. This criteria distinguished PD and MSA with a 89% sensitivity and a 89% specificity. Our results demonstrate that the VOR cancellation is impaired in most patients with MSA and PSP but not with PD. In MSA patients, the abnormal VOR cancellation is probably not related to the nigrostriatal dopaminergic deficit and more likely reflects a cerebellar dysfunction. Impaired VOR cancellation is a clinical criteria to differentiate MSA and PSP from PD.

Age Factors↗
PubMed1995

Prolonged muscular flaccidity after stroke. Morphological and functional brain alterations.

Patients with a motor deficit due to ischaemic stroke usually develop muscular spasticity, but in some cases they may remain with a prolonged muscular flaccidity which impairs their recovery. Little is known about the causes of these two different functional outcomes. We correlated CT/MRI and 99mTc HM-PAO SPECT with clinical findings in 42 patients at a mean time interval of 3 months after stroke. The patients were divided into two cohorts with either flaccid (prolonged muscular flaccidity) or spastic (muscular spasticity) hemiparesis. Although patients with prolonged muscular flaccidity had a greater motor deficit, the mean structural volume of the ischaemic lesion was similar to that of the muscular spasticity cohort. There was a significantly higher prevalence of structural involvement of the lentiform nucleus in prolonged muscular flaccidity cases. Relative perfusion in the lentiform nucleus, thalamus and contralateral cerebellar hemisphere was significantly lower in prolonged muscular flaccidity than in muscular spasticity patients. A subgroup with only subcortical structural lesions also showed significantly lower relative perfusion in the ipsilateral frontal association areas. A primary involvement of the lentiform nucleus by the structural lesion seems to be crucial for the persistence of flaccidity after stroke. However, cerebral blood flow (CBF) changes in other structurally intact regions indicate their additional role. It is likely that both subcortical-cortical loops involved in motor control, i.e. cortex-basal ganglia-thalamus-cortex and cortex-pons-cerebellum-thalamus-cortex, are more widely and more severely affected in patients with prolonged muscular flaccidity.

Adult↗
PubMed1994

Naltrexone, an opiate antagonist, fails to modify motor symptoms in patients with Parkinson's disease.

One month of adjunct treatment with naltrexone (100 mg/day) was compared with placebo in a double-blind, randomized, cross-over design in two groups of patients with Parkinson's disease. The first group was composed of 10 patients with a moderate motor impairment insufficiently controlled by monotherapy with bromocriptine. The second group was composed of eight patients with L-dopa-induced peak-dose dyskinesia. Naltrexone as compared with placebo did not demonstrate any significant change in motor function in either group. These negative clinical results do not support a significant role of endogenous opioid systems in the pathophysiology of motor impairment in Parkinson's disease.

Aged↗
PubMed1994

Normal activation of the supplementary motor area in patients with Parkinson's disease undergoing long-term treatment with levodopa.

Regional cerebral blood flow (rCBF) changes in cortical motor areas were measured during a movement of the dominant right hand in 15 patients with Parkinson's disease deprived of their usual levodopa treatment, in 11 patients with Parkinson's disease undergoing long-term treatment with levodopa, and in 15 normal volunteers. The supplementary motor areas were significantly activated in the normal subjects and in the patients receiving levodopa but not in the patients deprived of levodopa. The contralateral primary sensory motor area was significantly activated in all three groups. The ipsilateral primary sensory motor cortex was not activated in the normal subjects and the non-treated patients but was in the patients treated with levodopa. It is concluded that the supplementary motor area hypoactivation which is observed in akinetic non-treated patients with Parkinson's disease is not present in patients undergoing long-term treatment with levodopa. This result suggests that (a) levodopa improves the functional activity of supplementary motor areas in Parkinson's disease and (b) there is no pharmacological tolerance to this effect. The ipsilateral primary motor cortex activation observed in the patients treated with levodopa could be related to levodopa-induced abnormal involuntary movements.

Adult↗
PubMed1994

Motor recovery after early brain damage. A case of brain plasticity.

BACKGROUND: Motor recovery is remarkable when the brain is damaged early in life. We describe a case of early damage to the right hemisphere with remarkable reorganization and plastic functional changes, studied by computed neuroimaging. CASE DESCRIPTION: A 31-year-old man had a left-sided hemiplegia at the age of 12, followed by good motor recovery despite a large right cortical-subcortical lesion. Single-photon emission computed tomography with motor activation study showed cerebral blood flow increase in the left premotor and sensorimotor cortices irrespective of the hand he was moving, without flow changes in the right hemisphere. CONCLUSIONS: A remarkable reorganization and plastic brain functional changes occurred in a patient after early diffuse damage of the right hemisphere. The study points to a potential role of ipsilateral cortical efferent pathways in subserving hand movements after early cerebral damage.

Adult↗
PubMed1993

Effect of side and rate of stimulation on cerebral blood flow changes in motor areas during finger movements in humans.

We measured, using single photon emission computed tomography, the regional CBF (rCBF) changes in the motor areas of 24 right-handed normal volunteers during the performance of a motor task consisting of sequential finger-to-thumb opposition. Twelve of them performed the task with their right and their left hands consecutively with a fast frequency and large amplitude. The other 12 subjects performed the task with their right hand only at a slow frequency and small amplitude. The contralateral primary sensorimotor areas (S1/M1), supplementary motor area (SMA), and ipsilateral cerebellum were significantly activated during right and left finger movements performed at fast frequency and large amplitude. No significant difference was found between the rCBF changes induced by the right dominant and left nondominant hands. When the task was performed with a slow rate and small amplitude, the SMA was significantly activated while no significant changes were observed in the contralateral S1/M1 or in the ipsilateral cerebellum. These results demonstrate (a) that hand dominance evokes no differences in the activation of the main motor areas and (b) that the frequency and amplitude of the movement have a major effect on the quantitative and qualitative aspect of activation of motor areas in humans.

Adult↗
PubMed1992

Supplementary and primary sensory motor area activity in Parkinson's disease. Regional cerebral blood flow changes during finger movements and effects of apomorphine.

We have measured with single-photon emission tomography the regional cerebral blood flow changes that occurred in the supplementary motor areas and in the primary sensory motor areas during sequential finger-to-thumb opposition movements of the right hand in seven akinetic patients with Parkinson's disease and in nine normal volunteers. Parkinsonian patients were studied before ("off" condition) and after a subcutaneous injection of apomorphine hydrochloride which was able to switch them "on" (on condition). In normal volunteers and parkinsonian patients in the on condition, regional cerebral blood flow significantly increased in the supplementary motor areas and in the contralateral primary sensory motor cortex but not in the ipsilateral primary sensory motor cortex. On the contrary, no significant regional cerebral blood flow change was observed in these areas in parkinsonian patients in the off condition. These results support the hypothesis that a functional cortical motor area deafferentation is involved in the pathophysiological makeup of akinesia and that this abnormality is reversed by dopaminergic drugs.

Aged↗
PubMed1991

Subcutaneous apomorphine increases regional cerebral blood flow in parkinsonian patients via peripheral mechanisms.

1. We have measured regional cerebral blood flow (rCBF) and motor function before and after the subcutaneous (s.c.) injection of apomorphine in parkinsonian patients deprived of their usual treatment for at least 48 h. 2. Nineteen patients, pretreated with domperidone (20 mg three times daily for 48 h), received a mean dose of 5.8 mg s.c. apomorphine. All patients switched 'on'. The mean motor score was significantly improved (-65%, P less than 0.01) but no significant change in rCBF was observed. 3. Seven other patients, not pretreated with domperidone, received a lower dose (0.3 mg) of s.c. apomorphine. No change in motor score was observed while the mean rCBF significantly increased (+12%, P less than 0.05). 4. We conclude that s.c. apomorphine increases rCBF in parkinsonian patients. This effect is independent of the central therapeutic effects of the drug. It is mediated by the stimulation of dopaminergic receptors of the cerebral vessels. These receptors are located outside the cerebral blood brain barrier and can be considered as 'peripheral' ones.

Aged↗
PubMed1991

Square wave jerks in parkinsonian syndromes.

The frequency of square wave jerks (SWJ) was compared in eight patients with progressive supranuclear palsy (PSP), 25 patients with multiple system atrophy or Parkinson's disease plus (MSA/PP), 85 patients with idiopathic Parkinson's disease (PD) and 20 age-matched normal volunteers. In the control group, the mean (SD) SWJ frequency (SWJ larger than 1 degree amplitude) was 2.3 (2.4)/min. Abnormal ocular fixation (SWJ frequency greater than 10/min) was observed in a large proportion of PSP patients (7/8) and of MSA/PP patients (16/25) but in few PD patients (13/85). In the group of PD patients with abnormal ocular fixation, freezing of gait, falls and instability were more severe than in the group of PD patients with normal fixation. The study of ocular fixation may help to differentiate PD clinically from other Parkinsonian syndromes. SWJ are probably not related to the central degeneration of the dopaminergic nigrostriatal pathway observed in PD.

Aged↗
PubMed1991

Quantitative assessment of cerebral blood volume by single-photon emission computed tomography.

We implemented a technique for measuring regional cerebral blood volume using single-photon emission computed tomography and in vivo technetium-99m-labeled red blood cells and then evaluated it in nine normal human volunteers (controls) and seven patients with bilateral occlusion or severe stenosis of the internal carotid artery. We also measured regional cerebral blood flow using single-photon emission computed tomography and intravenous xenon-133 in the same subjects. We studied regional cerebral blood flow, regional cerebral blood volume, and their ratio before and after the intravenous injection of 1 g acetazolamide. Mean +/- SD baseline regional cerebral blood volume was higher in the patients than in the controls (4.1 +/- 0.6 versus 3.2 +/- 0.3 ml/100 g, p less than 0.01), and mean +/- SD baseline regional cerebral blood flow was lower in the patients than in the controls (40.5 +/- 11 versus 55.6 +/- 11 ml/100 g/min, p less than 0.05). Acetazolamide induced similar mean +/- SD increases in regional cerebral blood volume in both the controls and the patients (0.3 +/- 0.1 and 0.3 +/- 0.2 ml/100 g), while the mean +/- SD regional cerebral blood flow reactivity was significantly less in the patients than in the controls (12.6 +/- 7.6 versus 24.5 +/- 9.6 ml/100 g/min, p less than 0.05). Our study shows that single-photon emission computed tomography can provide quantitative estimates of both regional cerebral blood volume and regional cerebral blood flow in humans.

Acetazolamide↗
PubMed1991

[Cerebral blood volume, endarterectomy and SPECT].

Cerebral blood flow and cerebral blood volume were measured and quantified using single photon emission computed tomography before and after unilateral endarterectomy in 3 patients with bilateral severe lesions of the internal carotid artery. These parameters were measured using an intravenous injection of 133 Xenon and 99m Technetium respectively. Before endarterectomy cerebral blood volume was high in all patients suggesting a focal vasodilatation in response to a reduced cerebral perfusion pressure. After endarterectomy a decrease of cerebral blood volume and an increase of cerebral blood flow were observed. These preliminary results confirm that the hemodynamic adaptative mechanisms secondary to carotid occlusion are reversible when the stenosis is removed and demonstrate that these changes can be accurately measured using single photon emission computed tomography. Positron emission tomography was previously considered to be the only method able to quantify cerebral blood volume in man. Single photon emission computed tomography can also be considered a reliable technique to measure both cerebral blood flow and cerebral blood volume. This technique can then be used to assess individual cerebral vascular adaptative states and to evaluate the influence of cerebral hemodynamic changes on stroke occurrence in large longitudinal studies.

Aged↗
PubMedDate not supplied

Turbo-Proton Echo Planar Spectroscopic Imaging (t-PEPSI) MR technique in the detection of diffuse axonal damage in brain injury. Comparison with Gradient-Recalled Echo (GRE) sequence.

PURPOSE: Diffuse axonal injury (DAI) is a common type of primary neuronal injury in patients with severe traumatic brain injury, and is frequently accompanied by tissue tear haemorrhage. The T2*-weighted gradient-recalled echo (GRE) sequences are more sensitive than T2-weighted spin-echo images for detection of haemorrhage. This study was undertaken to determine whether turbo-PEPSI, an extremely fast multi-echo-planar-imaging sequence, can be used as an alternative to the GRE sequence for detection of DAI. MATERIALS AND METHODS: Nineteen patients (mean age 24,5 year) with severe traumatic brain injury (TBI), occurred at least 3 months earlier, underwent a brain MRI study on a 1.5-Tesla scanner. A qualitative evaluation of the turbo-PEPSI sequences was performed by identifying the optimal echo time and in-plane resolution. The number and size of DAI lesions, as well as the signal intensity contrast ratio (SI CR), were computed for each set of GRE and turbo-PEPSI images, and divided according to their anatomic location into lobar and/or deep brain. RESULTS: There was no significant difference between GRE and turbo-PEPSI sequences in the total number of DAI lesions detected (283 vs 225 lesions, respectively). The GRE sequence identified a greater number of hypointense lesions in the temporal lobe compared to the t-PEPSI sequence (72 vs 35, p<0.003), while no significant differences were found for the other brain regions. The SI CR was significantly better (i.e. lower) for the turbo-PEPSI than for the GRE sequence (p<0.00001). CONCLUSIONS: Owing to its very short scan time and high sensitivity to the haemorrhage foci, the turbo-PEPSI sequence can be used as an alternative to the GRE to assess brain DAI in severe TBI patients, especially if uncooperative and medically unstable.

Journal Article↗