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Biomedical subjects

F Isamat

Publications and source records attributed to F Isamat.

At least 19 recordsLinked to original sources
PubMed1999

Dysembryoplastic neuroepithelial tumor.

Dysembryoplastic neuroepithelial tumors (DNTs) were first described in 1988. A DNT is a cortical tumor that produces enlargement of a gyrus, forming a megagyrus that exceeds the normal thickness of the cortex. This tumor is generally seen in young patients with a long-standing history of drug-resistant and disabling seizures mostly of the complex partial type. No neurological deficits are found between the interictal periods in the majority of the reported cases. A general agreement exists over the clinical and radiological manifestations of a DNT as well as the benign biological behavior. Two pathological variants of DNT have been recognized: the single form, composed only of the so-called specific glioneuronal element, and the complex form that additionally shows glial nodules and foci of cortical dysplasia. Nevertheless, and despite the benign biological course, nuclear atypias, cellular monstruosities, foci of necrosis and mitosis can also be found. Surgical eradication of the tumor will usuallly have a good prognosis, without recurrences and with a positive control to seizure-free clinical outcome. Controversy continues to exist over a hamartomatous or a neoplastic origin of this lesion. The DNT has been placed among the neuronal and mixed neuronal-glial neoplasms in the revised World Health Organization (WHO) brain tumor classification, a category that includes the gangliogliomas and the central neurocytomas. Ultrastructural studies and immunostaining techniques may suggest that these three lesions represent different spectrums of the same condition. This paper reviews the most recent publications to offer a better understanding of DNTs and their implications in diagnosis and management.

Journal Article↗
PubMed1998

Clinical application of functional magnetic resonance imaging in presurgical identification of the central sulcus.

OBJECT: The authors sought to evaluate the advantages and limitations of functional magnetic resonance (fMR) imaging when it was used regularly in the clinical context to identify the central sulcus. METHODS: A 1.5-tesla MR system comprising a spoiled gradient recalled acquisition in the steady-state functional sequence and a cross-hand cancellation analysis method were used to evaluate 50 surgical candidates with centrally located space-occupying lesions in the brain. Three-dimensional (3-D) models of the patient's head and brain showing the relative position of the tumor and the eloquent cortex were obtained in each case. A selective and reproducible focal activation was found, indicating the probable central sulcus position in 41 patients (82%). Direct cortical stimulation confirmed the fMR findings in 100% of 22 intraoperatively assessed patients. Failure to identify the central sulcus occurred in 18% of cases and was mainly a consequence of intrinsic damage in the primary sensorimotor region that resulted in severe hand paresis. CONCLUSIONS: Although specific factors were identified that contributed to reduced sensitivity of fMR imaging in the clinical context, the present study supports functional assessment and 3-D representation of specific surgical situations as generally feasible in common practice.

Adolescent↗
PubMed1996

Presurgical identification of the primary sensorimotor cortex by functional magnetic resonance imaging.

The ability of functional magnetic resonance (MR) imaging to detect a selective sensorimotor cortex activation in healthy subjects and the feasibility of motor activation in patients with lesions around the central sulcus were investigated. Twenty-five healthy volunteers performed 100 motor activation trials, using a variety of motor tasks, which were monitored by several image analysis methods. The functional images were obtained using a 1.5-tesla standard MR imaging system magnet with blood oxygenation level-dependent contrast. Four patients were assessed using functional MR imaging and invasive cortical mapping. Rolandic cortex activation was observed in 98% of the trials performed on healthy subjects in which no head motion occurred. Nevertheless, the cortical response was not selective in a task-rest analysis due to concurrent activation of neighboring regions. Across-task comparison analyses were useful in cancelling nonrelevant activity in most cases (86%). In the patient group, the region identified as the sensorimotor cortex by invasive means corresponded accurately to the area that was activated in functional MR imaging. Present data support the feasibility of detecting selective activation of the rolandic cortex, even in the clinical setting, leading the authors to suggest the usefulness of this widely available technique in surgical planning.

Adult↗
PubMed1994

Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease) and its relation to the multiple hamartoma syndrome (Cowden disease).

The clinical manifestations, surgical treatment and postoperative results of three patients with gangliocytomas of the cerebellum (Lhermitte-Duclos disease) are presented. Particular attention is placed in one of the cases, that of a young woman with a short clinical history of episodic symptoms of intracranial hypertension, dizziness and ataxia, with a concomitant frontal meningioma and in the general context of a multiple hamartoma syndrome (Cowden disease). The possible relationship between both diseases is contemplated, since they can be the extremes of a wide spectrum of a peculiar form of phakomatosis.

Adult↗
PubMed1993

Parvalbumin and calbindin D-28K immunoreactivity in central ganglioglioma and dysplastic gangliocytoma of the cerebellum. Report of two cases.

Calbindin D-28K and parvalbumin immunocytochemistry were used in the study of central ganglionic cell tumors. Most neurons in the ganglioglioma were immunoreactive to calbindin D-28K, but a few cells were labeled with antibodies against parvalbumin. In contrast, most cells in dysplastic gangliocytoma of the cerebellum were parvalbumin immunoreactive, but fewer reacted with anti-calbindin antibodies. These latter cells had two or three dendrites with claw-shaped terminals and axons with recurrent collateral branches and varicose terminals filled with strings and buttons. These observations suggest that central ganglionic cell tumors, including dysplastic gangliocytoma of the cerebellum, are composed of neurons which, on the basis of their calcium-binding protein content, have particular metabolic and electrophysiological properties.

Adolescent↗
PubMed1993

Cavernous angiomas of the brain stem.

Cavernous angiomas in contact with the pial or ependymal surfaces of the brain stem can be totally and safely resected. Such an approach is recommended for symptomatic patients. For asymptomatic patients whose lesions are deeply embedded in the parenchyma, close observation without surgical intervention is recommended.

Adolescent↗
PubMed1990

Studies with the Golgi method in central gangliogliomas and dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease).

The rapid Golgi method, combined with current optical and electronmicroscopical techniques, was used in three central gangliogliomas and in one dysplastic gangliocytoma of the cerebellum to study the morphology of ganglionic cells. Gangliogliomas were composed of bipolar, fusiform and radiate cells with dense core and clear vesicles in the perikaryon and cellular processes, the number of each cellular type varying from one case to another. These features, together with the fact that isodendritic neurons are considered to be phylogenetically old neurons, suggest that these tumours are composed of "primitive" neurons that are not homogeneous with regard to their morphology. In contrast, ganglionic cells in dysplastic gangliocytoma are huge cells with long, stereotyped neurites that establish unique asymmetric contacts with neighbouring perikarya and neurites by means of claw-shaped processes covered with synaptic buttons. These morphological characteristics are different from those of any other neuron of the CNS.

Adolescent↗
PubMed1989

Plasma cell granuloma of the hypothalamic region.

Two patients suffering from diabetes insipidus, with additional symptoms of impaired vision and signs of panhypopituitarism and increased intracranial pressure, showed a normal sella tursica in the X-ray examination of the skull but large, dense space-occupying lesions in the hypothalamus on CT scans of the brain. NMR performed in one patient disclosed suprasellar growth of a hypothalamic lesion. Proliferation of lymphoplasmocytes and mature plasma cells was seen by light microscopic and electromicroscopical examination of biopsy samples in both cases; histiocytes and multinucleated giant cells were absent; tuberculosis, syphilis and sarcoidosis were ruled out by appropriate tests. Plasma cells exhibited polyclonal immunoglobulin expression as revealed by immunocytochemistry using the PAP method. Taken together these features are typical of plasma cell granuloma. Transitory remission after radiotherapy was obtained in one patient.

Adult↗
PubMed1988

Intracranial arachnoid cysts in adults.

Twenty-two cases of intracranial arachnoid cysts in adult patients have been studied and treated surgically. The authors analysed the correlation between the size and the location of the cysts and their clinical manifestations. It seems clear that the symptomatology and the problems of intracranial arachnoid cysts in the adult are quite different from those occurring with infants. The majority of our cases have been diagnosed by CT and NMR, and have been treated by open excision of the cystic membranes with the establishment of a wide communication with the basal cisterns or the subarachnoid space. With this technique the results have been very gratifying, while in cases managed with shunts the morbidity has been high.

Adolescent↗
PubMed1988

Lumbar microdiscectomy: analysis of 100 consecutive cases. Its pitfalls and final results.

100 consecutive microsurgically operated patients suffering lumbar prolapsed disc are analyzed in the present work. Three different groups have been distinguished. Under and over forty years of age, and patients operated on after chemonucleolysis failure. General results after all treatments have been 76% good result, 17% improvement and 7% worsening. Special remark should be given about the chemonucleolysis group, that has a highest worsening percentage which raises 25% of the group patients.

Adult↗
PubMed1987

On posttraumatic intracavernous false aneurysms and arteriovenous fistulas.

Posttraumatic high-flow communications between the intracavernous internal carotid artery (ICA) and the cavernous sinus may give rise to two different pathological entities. A connection between the ICA and one of the adjacent intracavernous veins will result in a carotico-cavernous fistula (CCF). A false aneurysm will develop if the arterialized rent from the injured ICA flows directly into the bare perivenous spaces within the cavernous sinus, without a shunt with one of the veins. A CCF and a false aneurysm can be present in the same patient. Angiographically these two entities may be demonstrated, and clinically have a somewhat different behaviour. Life-threatening massive epistaxis is the most serious complication, particularly in false intracavernous aneurysms. Most high-flow CCFs are the result of a small side-wall laceration of the ICA, while large ICA injuries or even complete transection of the artery are responsible for the origin or false aneurysms.

Carotid Artery Injuries↗
PubMed1986

Direct intracavernous obliteration of high-flow carotid-cavernous fistulas.

Four cases of high-flow carotid-cavernous sinus fistula (CCF), three of them posttraumatic and one spontaneous, have been treated by a direct surgical approach to the cavernous sinus. The CCF's were obliterated by the introduction into the cavernous sinus of muscle fragments and/or fibrin sealant. In the three cases with a preoperatively patent internal carotid artery (ICA), the CCF was occluded and the ICA flow preserved. One of these also had a posttraumatic false aneurysm that enclosed the two avulsed ends of a transected intracavernous ICA. This was treated by cervical ICA ligation following resolution of the CCF. A fourth patient, who had previously undergone an unsuccessful ICA trapping procedure elsewhere, also obtained a good result. The case histories and the surgical technique are presented. Direct intracavernous obliteration with muscle fragments and fibrin sealant fulfills the criteria for treatment of high-flow CCF's: occlusion of the arteriovenous fistula and preservation of the ICA circulation. While this surgical technique is a therapeutic option in some cases, it appears to have precise indications in others.

Adult↗
PubMed1981

Selective percutaneous thermocoagulation rhizotomy in essential glossopharyngeal neuralgia.

Percutaneous radiofrequency (rf) thermocoagulation of the inferior petrous ganglion of Andersch at the jugular foramen has been used to treat three patients with essential glossopharyngeal neuralgia. Two of these patients needed a second rf thermocoagulation, one within 1 week due to an incomplete result, and the other 8 months after the first procedure for recurrence of some neuralgic pain. Thus, a total of five rf thermocoagulations of the ganglion of Andersch have been performed. The patients are now pain-free and without significant side-effects. Deglutition and phonation have remained intact after each rf thermocoagulation. Glossopharyngeal selectivity was obtained by avoiding the risk of injury to the other nerves at the jugular foramen. The surgical technique involves precise x-ray control and constant monitoring of the blood pressure and electrocardiogram findings. Electrode misplacement of any spreading of current to the vagus nerve will be readily detected by bradycardia and hypotension during the physiological testing before a definite rf lesion takes place. This operative technique is described.

Female↗
PubMed1979

A Golgi and electron microscopic study of a dysplastic gangliocytoma of the cerebellum.

The fine structure of a dysplastic gangliocytoma of the cerebellum is studied by means of the Golgi method and electron microscopic examination. Thick proximally unbranched dendrites with terminal arborizations and varicose inflorescences in the form of a basket are stained with the Golgi method. Axons are always descendant to the inner myelinated layer of the redistributed cerebellar cortex, while ascendant collaterals are observed at the level of the outer myelinated layer. Clear and dense-core vesicles and synapses are common in the cellular profiles under electron microscopic examination. From these data and because of the lack of putative connections through the white matter, an organized, self-regulated, catecholamine-mediated complex may be postulated.

Axons↗