RESUMO

OBJECTIVE: We developed an in vitro model for vasospasm post subarachnoid hemorrhage that was suitable for investigating brain vessel autoregulation. We further investigated the effects of iodinated contrast medium on the vascular tone and the myogenic response of spastic cerebral vessels. METHOD: We isolated and perfused the superior cerebellar arteries of rats. The vessels were pressurized and studied under isobaric conditions. Coagulated blood was used to simulate subarachnoid hemorrhage. The contrast medium iodixanol was applied intraluminally. RESULTS: Vessels exposed to blood developed significantly stronger myogenic tone (65.7 ± 2.0% vs 77.1 ± 1.2% of the maximum diameter, for the blood and the control group, respectively) and significantly decreased myogenic response, compared with the control groups. The contrast medium did not worsen the myogenic tone or the myogenic response in any group. CONCLUSION: Our results show that deranged myogenic response may contribute to cerebral blood flow disturbances subsequent to subarachnoid hemorrhage. The contrast medium did not have any negative influence on vessel tone or myogenic response in this experimental setting.

Assuntos

RESUMO

Objective We developed an in vitro model for vasospasm post subarachnoid hemorrhage that was suitable for investigating brain vessel autoregulation. We further investigated the effects of iodinated contrast medium on the vascular tone and the myogenic response of spastic cerebral vessels. Method We isolated and perfused the superior cerebellar arteries of rats. The vessels were pressurized and studied under isobaric conditions. Coagulated blood was used to simulate subarachnoid hemorrhage. The contrast medium iodixanol was applied intraluminally. Results Vessels exposed to blood developed significantly stronger myogenic tone (65.7 ± 2.0% vs 77.1 ± 1.2% of the maximum diameter, for the blood and the control group, respectively) and significantly decreased myogenic response, compared with the control groups. The contrast medium did not worsen the myogenic tone or the myogenic response in any group. Conclusion Our results show that deranged myogenic response may contribute to cerebral blood flow disturbances subsequent to subarachnoid hemorrhage. The contrast medium did not have any negative influence on vessel tone or myogenic response in this experimental setting. .

Objetivo Desenvolvemos um modelo in vitro para vasoespasmo subsequente à hemorragia subaracnóide que foi adequado para investigar a autorregularão dos vasos cerebrais. Em seguida investigamos os efeitos o meio de contraste iodado no tônus vascular e na resposta miogênica dos vasos cerebrais espásticos. Método Isolamos e perfundimos as artérias cerebelares superiores de ratos. Os vasos foram pressurizados e estudados em condições isobáricas. Sangue coagulado foi utilizado para simular hemorragia subaracnóide. O meio de contraste iodixanol foi aplicado intraluminarmente. Resultados Os vasos expostos ao sangue desenvolveram aumento significativo do tônus miogênico (65.7 ± 2.0% vs 77.1 ± 1.2% do maior diâmetro, para o grupo de sangue e o grupo controle, respectivamente) com resposta miogênica significativamente menor do que aquela dos controles. O meio de contraste iodado não piorou o tônus miogênico ou a resposta miogênica em nenhum dos grupos. Conclusão Nossos resultados mostram que uma resposta miogênica pode contribuir para as alterações de fluxo sanguíneo cerebral subsequentes à hemorragia subaracnóide. O meio de contraste iodado não teve nenhuma influência negativa no tônus vascular ou na resposta miogênica neste modelo experimental. .

Assuntos

Assuntos

Assuntos

Assuntos

RESUMO

We used microneurography to measure muscle sympathetic nerve activity (MSNA) in 25 hypertensive subjects and correlated these results with the presence or absence of signs of neurovascular compression (NVC) at the rostral ventrolateral (RVL) medulla on MRI. Subjects were divided into 3 groups based on MRI findings: NVC-, no MRI evidence of NVC (N=9); NVC+contact, image showing artery in contact but not compressing the RVL medulla (N=8); and NVC+compression, image showing arterial compression of the RVL medulla (N=8). The MSNA measurements were performed at rest, after a hypothermic stimulus, and during isometric exercise. The MSNA during rest in the NVC+compression group was significantly higher than that in the NVC+contact and NVC- groups (30.4+/-3.4 versus 17.5+/-1.1 and 21.4+/-3.2 spikes per minute, respectively). However, the blood pressure in the NVC+compression group was slightly but not significantly higher than that in the other 2 groups (183+/-7/115+/-8, 174+/-6/108+/-7, and 171+/-5/110+/-5 mm Hg, respectively). The increases in MSNA, blood pressure, and heart rate during the cold pressor and isometric exercise tests were similar. Our results show that, although resting MSNA is elevated in patients with true NVC of the RVL medulla, patients without NVC or with arterial contact but not overt compression of the RVL medulla have similar MSNA. These findings are important for identifying, among hypertensive patients with NVC, individuals who may have associated physiological repercussions, such as increased sympathetic activity.

Assuntos

RESUMO

Hypertension (HTN) has been controversially related to neurovascular compression (NVC) at the rostral ventrolateral (RVL) medulla in anatomical, surgical, and radiological reports. Our objective was to investigate the association between primary HTN and signs of NVC at the medulla oblongata on magnetic resonance imaging (MRI) and to explore a new classification based on image criteria. Subjects with (n=64) and without (n=29) HTN were studied. Three-millimeter slices, with 1-mm intervals in between, were performed on T2-weighted images in axial and coronal views. Attention was focused on the relationship between the upper medulla and the surrounding arteries. The findings were divided into three categories: 1) non-NVC: absence of signs of NVC, 2) NVC type I: an artery in contact with the RVL medulla but not compressing it, and 3) NVC type II: evident compression of the RVL medulla by an artery. Signs of NVC were observed in 65.7% (42/64) of the HTN group (type I: 39.1%, 25/42 patients; type II: 26.6%, 17/42 patients). Among the normotensive subjects, 27.6% (8/29) had signs of NVC; only one (3.3%) of these had NVC type II (evident compression), and the rest were NVC type I. We conclude that the presence of NVC at the RVL medulla on MRI is related to HTN. More importantly, the finding of frank compression (NVC type II) is present almost exclusively in hypertensive subjects; only one individual (3.3% of our normotensive population) had NVC type II.

Assuntos

RESUMO

A microneurografia foi usada para investigar a atividade simpática periférica (ASP) em 25 indivíduos hipertensos, investigados quanto à presença de compressão neurovascular (CNV) no bulbo com a técnica de ressonância magnética (RM). De acordo com a RM, foram formados três grupos: CNV-, sem sinais de CNV (n=9); CNV Tipo I, com imagem vascular junto ao bulbo mas sem deformação anatômica (n=8); e CNV Tipo II, com imagem vascular causando compressão no bulbo (N=8). O grupo CNV Tipo II apresentou ASP mais elevada que os grupos CNV Tipo I e CNV-, tanto no repouso, quanto após estímulos hipotérmico e exercício isométrico. A demonstração de ASP diferenciada dependendo do tipo de CNV é um fato importante, pois pode identificar um subgrupo de hipertensos nos quais a CNV possa ter alguma implicação fisiopatológica.Sympathetic activity in hypertension with neurovascular compression in humans. /Microneurography was used to measure peripheral muscle sympathetic nerve activity (MSNA) in 25 subjects with hypertension, who were submitted to magnetic resonance imaging (MRI) to detect neurovascular compression (NVC) at the medulla. Three groups were formed according to MRI: NVC-, without signs of NVC (N=9); NVC Type I, with a vessel nearby medulla but not compressing it (N=8); NVC Type II, with a vessel compressing the medulla (N=8). Group NVC Type II had higher MSNA than other groups during rest period and after stimuli with cold and isometric exercise. These results show different values of PSA in subjects with different findings of NVC, and are important to the identification of subgroups whose image of NVC really have clinical relevance...

Assuntos

RESUMO

OBJECTIVE AND IMPORTANCE: To highlight arterial hypertension as an additional factor favoring surgical indication in neurovascular compression syndromes such as trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia. CLINICAL PRESENTATION: A 52-year-old woman with trigeminal neuralgia concomitant with systemic arterial hypertension, submitted initially to unsatisfactory conservative treatment, presents tortuousness and enlargement of the vertebral artery (VA) topography on magnetic resonance imaging (MRI). A microsurgical neurovascular decompression of the trigeminal nerve and the medulla was performed, revealing that the compression was due to the superior cerebellar artery instead of the VA. Both the neuralgia and the hypertension were controlled with no need of medication during a 1-year follow-up. CONCLUSION: Surgical indication in neurovascular compression disorders should be reinforced in the presence of concomitant arterial hypertension and a compatible MRI examination.

Assuntos

RESUMO

Plasmacytomas are tumors that may arise in a wide variety of locations, because of the universal distribution of plasma cells. They are rare within the cranial vault and rarely present as extramedullary lesions, arising from the intracranial soft tissues usually without affecting neighboring bony structures. The presentation may resemble a meningioma, both clinically and radiologically. The most commonly recommended therapeutic strategy is complete surgical resection followed by radiotherapy. We report a case of a 47 -years-old man presenting with a median parietal plasmacytoma, submitted to subtotal surgical resection and radiotherapy, with good results

Assuntos