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Biomedical subjects

F Tomasello

Publications and source records attributed to F Tomasello.

At least 55 records · Page 3Linked to original sources
PubMed1998

Radiation-induced blood-brain barrier changes: pathophysiological mechanisms and clinical implications.

The pathophysiology of whole-brain radiation (WBR) toxicity remains incompletely understood. The possibility of a primary change in blood-brain barrier (BBB) associated with microvascular damage was investigated. Rats were exposed to conventional fractionation in radiation (200 +/- cGy/d, 5d/wk; total dose, 4,000 cGy). BBB changes were assessed by means of the quantitative 14C-alpha-aminoisobutyric acid (AIB) technique coupled with standard electron microscopy (EM) and morphometric techniques as well as studies of the transcapillary passage of horseradish peroxidase (HRP). At 15 days after WBR, AIB transport across BBB increased significantly in cerebral cortex. EM disclosed vesicular transport of HRP across the intact endothelium without opening of the tight junctions. Ninety days after WBR, well-defined alterations of the microvasculature were observed. The main feature of cortical microvessels was their collapsed aspect, associated with perivascular edema containing cell debris. Data suggest a possible association between damage of the microvascular/glial unit of tissue injury and development of radiation-induced brain cerebral dysfunction. We hypothesize the following sequence of pathophysiological events: WBR causes an early increase in BBB permeability, which produces perivascular edema and microvascular collapse. The interference with microcirculation affects blood flow and energy supply to the tissue, resulting in structural damage on an ischemic/dysmetabolic basis.

Animals↗
PubMed1998

Reversible cerebral perfusion alterations in children with transient mutism after posterior fossa surgery.

Mutism is an infrequent and transitory complication observed following posterior fossa surgery. Patients become mute in the immediate postoperative period, with restoration of speech within a few weeks in the absence of additional neurological alterations. The anatomical structures thought to be involved are the connections between the cerebellar dentate nucleus, the ventrolateral nucleus of the contralateral thalamus and the supplementary motor area. In an attempt to understand the pathophysiology of this syndrome, and to depict the perfusion of different brain areas semiquantitatively, in two children who had become mute after posterior fossa surgery we performed a Tc99M-HM-PAO SPECT study during the period of mutism and again when normal speech had returned. In one patient, who had a left cerebellar astrocytoma, the SPECT study showed a marked reduction of cerebral perfusion in the right fronto-parietal region, and in the other, who had a medulloblastoma, a left fronto-temporo-parietal perfusion alteration was observed. When the patients regained normal speech, the follow-up SPECT studies revealed normalization of the cerebral perfusion. This study demonstrates the occurrence of a focal dysfunction of cerebral perfusion in children with cerebellar mutism after posterior fossa surgery. These observations are useful in extending our understanding of the pathophysiology of this postoperative clinical syndrome.

Adolescent↗
PubMed1998

Transverse microincisions of the outer layer of the dura mater combined with foramen magnum decompression as treatment for syringomyelia with Chiari I malformation.

Numerous surgical procedures have been proposed for treatment of syringomyelia associated with Chiari I malformation, but the optimal treatment has not yet been uniformly standardised. The main aim of the surgical treatment of syringomyelia/Chiari I complex is directed toward restoration of physiological cerebrospinal fluid dynamic at the craniovertebral junction. We report the surgical results of eight patients, affected by syringomyelia and Chiari I malformation, age range from 18 to 62 years, treated by bony foramen magnum decompression combined with transverse microincisions of the outer layer of the dura mater. In an average postoperative follow-up period of two years neurological symptoms and signs improved in seven patients. Postoperative Magnetic Resonance showed a decrease in size of the syrinx in seven patients. These results suggest that foramen magnum decompression combined with transverse microincisions of the outer layer of the dura 1) is an effective and safe treatment option for syringomyelia and Chiari I malformation, 2) corrects the circulatory disturbances of cerebrospinal fluid dynamic, 3) leads to a decrease in size of the syrinx and to a significant improvement in neurological signs and symptoms, 4) avoids complications of intradural approaches and syringosubarachnoid shunting.

Adult↗
PubMed1998

Does subarachnoid blood extravasation per se induce long-term neuropsychological and cognitive alterations?

Although recent advances in medical and management strategies have reduced the mortality and morbidity rates related to subarachnoid haemorrhage (SAH), patients who survive a SAH may remain nevertheless affected by persistent cognitive and neuropsychological disturbances. The presence of these deficits has been attributed to the neurotoxic effects of the widespread subarachnoid blood. To assess the long-term neuropsychological and cognitive outcome related to subarachnoid blood extravasation per se we evaluated 20 patients affected by an unknown origin subarachnoid haemorrhage, and having SAH characteristics generally considered predictive of a favourable outcome. Patients were enrolled after a one-year interval from the initial insult, and were selected accordingly to a pre-designed protocol. We employed a complete battery of tests, assessing general cognitive and language functions, memory and construction ability, attention and vigilance, anxiety and depression. The results were compared with normal reference values and with performances of a socio-demographically homogenous sample of control volunteers. This study did not evidence any significant long-term cognitive and neuropsychological alteration after subarachnoid blood extravasation. These results indicate that the presence of subarachnoid blood initiate a number of secondary mechanisms of pathology.

Adult↗
PubMed1998

Supratentorial dorsal cistern epidermoid cyst in childhood.

Epidermoid cysts (ECs) are rare developmental lesions occurring anywhere along the central nervous system. Usually affecting adult patients, the occurrence of supratentorial dorsal cistern ECs has been reported in only 1 certain case of pediatric age. An additional pediatric case is presented. An 11-year-old boy had an 8-year history of petit mal seizures. Neurologic examination on admission was negative. T1-weighted magnetic resonance images demonstrated homogenous, hypointense, intradural, extracerebral, right frontal, precentral, parasagittal mass with relatively high signal intensity on T2-weighted images. The lesion was completely removed using a microneurosurgical technique with special care taken with regard to the adjacent nervous and vascular structures. Histologically, an EC was diagnosed. The patient had no recurrence for 2 years and seizures were significantly reduced. This case suggests the need to include ECs in the differential diagnosis of intradural supratentorial extracerebral lesions in childhood.

Brain Diseases↗
PubMed1998

Antivasospastic and brain-protective effects of a hydroxyl radical scavenger (AVS) after experimental subarachnoid hemorrhage.

OBJECT: The radical scavenger (+/-)-N,N'-propylenedinicotinamide (AVS) was shown recently to ameliorate delayed neurological deficits resulting from ischemia in patients who have had an aneurysmal subarachnoid hemorrhage (SAH). The aim of this study was to evaluate the effect of AVS administration after experimental SAH on 1) behavioral deficits; 2) angiographically confirmed basilar artery (BA) spasm; and 3) blood-brain barrier (BBB) permeability changes. METHODS: These parameters were measured by 1) using a battery of well-characterized chronic assessment tasks over a 5-day observation period; 2) assessing in vivo the mean vessel diameter 2 days after SAH; and 3) evaluating the extravasation of protein-bound Evans Blue dye by using a spectrophotofluorimetric technique 2 days after SAH. Groups of eight to 10 rats received injections of 400 microl of autologous blood into the cisterna magna. Within 5 minutes after the surgical procedures were completed the rats were treated with an intravenously administered continuous infusion of saline (Group III) or AVS (1 mg/kg/minutes, Group IV). Results were compared with those in sham-operated animals treated with intravenously administered saline (Group I) or AVS (Group II). The AVS-treated rats had significantly improved balance beam scores on Days 1 to 2 (p < 0.05), shorter beam traverse times on Day 1 (p < 0.05), and better beam walking performance on Days 1 to 4 (p < 0.01), but no significant effect was seen in terms of SAH-related changes in body weight. Treatment with AVS also attenuated the SAH-induced BA spasm (p < 0.05) and decreased BBB permeability changes in frontal, temporal, parietal, occipital, and cerebellar cortices, and in the subcortical and cerebellar gray matter and brainstem (p < 0.01). CONCLUSIONS: These results demonstrate useful antivasospastic and brain-protective actions of AVS after induction of experimental SAH and provide support for observations of beneficial effects of AVS made in the clinical setting.

Animals↗
PubMed1998

Primary cervical melanoma with brain metastases. Case report and review of the literature.

Primary intramedullary melanoma is a very rare tumor that occurs most frequently in the middle or lower thoracic spinal cord. The authors present a case of primary cervical cord melanoma that developed in a 62-year-old man who was surgically treated and subsequently underwent radiation therapy. Clinical and histogenetic features of this neoplasm and results of chemo-. radio-, and immunotherapy are reported. Both "dysembryogenetic" and "mesodermal" hypotheses on the origin of primary spinal melanoma are discussed.

Brain Neoplasms↗
PubMed1998

[The prevention and treatment of vasospasm in subarachnoid hemorrhage].

The overall data concerning the incidence of angiographic and clinical vasospasm are reported. Furthermore, the pathogenetic mechanisms of vasospasm with regard to vasotoxic agents, vasogenic agents and CSF blockage are discussed together with the mechanisms affecting platelet aggregation, decrease of prostacyclins, and increase of endothelin. At present, therapeutic golden standard, i.e. (triple H therapy), calcium-antagonist, fibrinolytics and antioxidizing agents are debated concerning their clinical applications, first, during and after any possible surgical or endovascular treatment of the source of bleeding, i.e., the aneurysm.

Humans↗
PubMed1998

Asymptomatic aneurysms. Literature meta-analysis and indications for treatment.

Autopsy and angiographic studies indicate that cerebral aneurysms occur in an estimated 0.2% to 8.9% of the general population. Modern noninvasive imaging techniques now detect these lesions in ever increasing numbers, and neurosurgeons are faced with a difficult decision about whether to recommend surgical treatment of incidentally discovered asymptomatic unruptured aneurysms (AA). While in the past an expectant management was generally recommended for AA, elective surgery is now advocated because of the risk of bleeding of the untreated aneurysm and the low operative morbidity and mortality rates of modern microneurosurgery. We performed a meta-analysis of the literature on morbidity and mortality from elective surgery for AA to obtain a more generalizable estimate of operative risk than is currently available. Our meta-analysis contained 19 series consisting of 343 cases of elective surgery for AA. There was a total of 3 deaths for a combined mortality rate of 0.87%, and a total of 15 deficits for a combined morbidity rate of 4.3%. These results compare favorably with the 10.3% natural history cumulative risk of mortality for unruptured aneurysms. The authors' personal experience with AA management was also reviewed and a particularly significant illustrative case is briefly reported. We recommend treatment for all asymptomatic aneurysms incidentally discovered particularly if: a) the aneurysm size is greater than 5 mm and arterial hypertension is present; b) the patient is otherwise healthy; c) the estimated life expectancy is > or = 10 years.

Aged↗
PubMed1997

Is there a group of early surgery aneurysmal SAH patients who can expect to achieve a complete long-term neuropsychological recovery?

There is a significant controversy regarding the effect of early surgical intervention for microsurgical aneurysm clipping on long-term cognitive recovery. Although new strategies in surgical and medical management have progressively reduced the morbidity and mortality rates related to subarachnoid haemorrhage (SAH), the overall quality of life of aneurysm patients has been reported to remain unsatisfactory. In fact, even in the presence of a good neurological recovery following an aneurysmal SAH, patients may show persistent emotional and psychological disturbances. The aim of this study was to analyse the long-term cognitive, neuropsychological and emotional status of a group of patients, subjected to early surgery aneurysm treatment, and having SAH characteristics generally considered predictive of a favourable outcome. Patients were submitted to a complete battery of neuropsychological tests designed to assess a full range of cognitive and attentional functions. The results of the neuropsychological evaluation did not detect evidence of any significant cognitive deterioration as compared to control volunteers and to the published age-adjusted test norms. These results indicate that early aneurysm surgery, coupled with modern microneurosurgical techniques and aggressive medical management is associated with a good neurological outcome and a full recovery of cognitive, neuropsychological and emotional performances in a subset of patients with favourable clinical characteristics.

Adult↗
PubMed1997

Do spinal meningiomas penetrate the pial layer? Correlation between magnetic resonance imaging and microsurgical findings and intracranial tumor interfaces.

OBJECTIVE: To study the relationships between spinal dura-arachnoid and tumor-cord interfaces in spinal meningiomas and to investigate whether a disruption of the pial layer and penetration of the tumor in the spinal cord occurs. METHODS: Fifteen patients with histologically proven meningiomas underwent magnetic resonance imaging (MRI) preoperatively. All patients underwent microsurgery. The histological characteristics of the tumors were compared with MRI and microsurgical findings. RESULTS: At surgery, the peritumoral hypointense rim revealed by MRI in 10 of 15 patients corresponded to a well-defined cerebrospinal fluid-containing space confined between the outer arachnoidal layer and the inner leptomeningeal layer. In those patients in whom the hypointense peritumoral rim was absent, the inner layer was either difficult to identify or clearly absent, and the blood vessels were extremely adherent to the tumor, requiring a more cautious dissection. Penetration of the tumors through disruption of the pial surface was not documented. CONCLUSION: Previous anatomic and electron microscopy studies demonstrated, in human spinal meninges, the presence of an intermediate layer attached to the inner aspect of the arachnoid, extending laterally over the dorsal surface of the spinal cord and arborizing over the nerve roots and blood vessels. The intermediate layer is not present in human cerebral leptomeninges. The presence/absence of this layer might explain the hypointense rim detected by MRI and might also explain why no penetration and no peritumoral edema is observed in spinal meningiomas as compared with intracranial meningiomas.

Adult↗
PubMed1997

Chronic encapsulated intracerebral hematoma: contribution of thallium-201 single photon emission computed tomography in preoperative diagnosis: case report.

OBJECTIVE AND IMPORTANCE: Chronic encapsulated intracerebral hematoma is a fairly rare clinical entity. This unique lesion is peculiar for its clinical onset, formation of a capsule, and progressive enlargement. The mechanism for capsule formation and self-perpetuating expansion still remains uncertain, as well as the causal relationship with vascular malformations. Because of their pseudotumoral course and misleading neuroradiological features, these lesions can be misdiagnosed preoperatively as cerebral neoplasms. CLINICAL PRESENTATIONS: A 62-year-old man was referred with a 2-month history of generalized tonicoclonic seizures. There was no history of head injury or arterial hypertension. The results of a neurological examination were normal. Computed tomographic scans revealed a slightly hyperdense roundish area in the right parietotemporal region with ring-like enhancement after contrast medium injection, moderate mass effect, and perifocal low attenuation. With the provisional diagnosis of astrocytoma, the patient was admitted for a craniotomy. Before surgery, a thallium-201 single photon emission computed tomographic study was performed, which showed no abnormal uptake of the tracer, raising significant doubt regarding the presumptive diagnosis of a tumor. INTERVENTION: Intraoperative findings revealed a hematoma, with a well-demarcated, thick, fibrous-elastic capsule. There was evidence of repeated intracapsular hemorrhages. The lesion was totally removed, and the patient recovered fully. No other pathological findings, including vascular malformations, were noted. CONCLUSION: Chronic encapsulated intracerebral hematomas probably occur more frequently than the limited number of reported cases would indicate. This case represents a realistic clinical problem-solving setting in with thallium-201 single photon emission computed tomography was used because of its capacity for functional tumor detection and differential diagnosis.

Cerebral Hemorrhage↗
PubMed1997

Microsurgical excision of a primary isolated hypothalamic eosinophilic granuloma. Case report.

Solitary focal eosinophilic granuloma (EG) is one element in the spectrum of diseases associated with Langerhans' cell histiocytosis (LCH). This report documents the occurrence of a primary isolated hypothalamic EG in a man who presented with diabetes insipidus and panhypopituitarism. His treatment consisted of complete microsurgical excision of the lesion. After a 13-month follow-up period, no residual tumor was evident on magnetic resonance imaging and no other lesions were present in peripheral tissues. This case is unique in several respects: 1) it is the third documented case of a primary isolated hypothalamic LCH granuloma diagnosed in a living patient; 2) it is the only known example of complete microsurgical excision of such a lesion in the hypothalamic region; and 3) it demonstrates the efficacy of direct surgery in this scenario, as compared with other treatment modalities such as biopsy and irradiation, suggesting that complete surgical excision may represent the treatment of choice for isolated intracerebral LCH granulomas, being curative in most instances. Also, the literature is reviewed for information about the diagnosis and treatment of this particular type of unifocal brain lesion.

Eosinophilic Granuloma↗
PubMed1996

Brain energy metabolism in the acute stage of experimental subarachnoid haemorrhage: local changes in cerebral glucose utilization.

An experimental model was used to investigate acute alterations of cerebral metabolic activity in rats subjected to subarachnoid haemorrhage (SAH). Haemorrhages were produced in anaesthetized animals by injecting 0.3 ml of autologous, arterial nonheparinized blood into the cisterna magna. Control rats received subarachnoid injections of mock-cerebrospinal fluid to study the effect of sudden raised intracranial pressure, or underwent sham operation. Three hours after SAH rats were given an intravenous injection of [14C]-2-deoxyglucose. Experiments were terminated by decapitation, and the brains were removed and frozen. Regional brain metabolic activity was studied by quantitative autoradiography. In comparison with sham-operated controls, cerebral metabolic activity was diffusely decreased after SAH. Statistically significant decreases in metabolic rate were observed in 23 of 27 brain regions studied. Subarachnoid injections of mock-cerebrospinal fluid also produced depression of cerebral metabolic activity, but quantitatively these changes were not as pronounced and diffuse as in SAH rats. The present study shows that a widespread depression of brain metabolism occurs in the acute stage after experimental SAH and is probably secondary to the subarachnoid presence of blood itself and/or blood products.

Animals↗
PubMed1996

Nerve regeneration through autogenous vein grafts: an SEM evaluation.

The role of autogenous vein grafts in nerve regeneration was studied in a rat model. Three groups of animals underwent autogenous vein grafting for ischiatic nerve regeneration, and were sacrificed 30, 60, and 90 days after surgery. Samples obtained were processed for S.E.M. study. Nerve regeneration consisted of two stages: the first (up to 60 days) was characterized by the presence of active endothelial cells; the second (after 60 days) by cell disappearance, with the venous wall acting as a protective conduit throughout both steps. Complete qualitative morphologic and functional studies of neural regeneration are presented, confirming previous investigations.

Animals↗