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Biomedical subjects

J C Peragut

Publications and source records attributed to J C Peragut.

At least 37 records · Page 2Linked to original sources
PubMed1996

Adenosine and neuropathic pain.

Recent studies have reported the possibilities of relieving neuropathic pain by administering adenosine or its analogs. In order to determine if there exists a metabolic anomaly of this nucleoside in patients with neuropathic pain, circulating adenosine levels were compared in three patient groups. The first was composed of individuals suffering from neuropathic pain, the second of patients with nervous system lesions in the absence of pain, and the third was composed of patients suffering from pain resulting from excessive nociception. The adenosine blood levels of these patients were compared to those of a control group. Finally, adenosine in the cerebrospinal fluid (CSF) of some patients was also assayed. The results show that there are reduced levels of blood and CSF adenosine in patients with neuropathic pain. This adenosine deficiency could explain the potential therapeutic effects of administering adenosine or its analogs.

Adenosine↗
PubMed1996

Pineal region tumors and the role of stereotactic biopsy: review of the mortality, morbidity, and diagnostic rates in 370 cases.

OBJECTIVE: It is classically considered that the morbidity and mortality rates are greater for stereotactic biopsies of pineal region tumors, compared with tumors in other regions. However, to date, the number of cases studied in the literature has been insufficient to evaluate these parameters and compare them with the morbidity and mortality rates for stereotactic biopsies of tumors located elsewhere. METHODS: With the aim of evaluating these parameters, we reviewed 370 stereotactic biopsies of pineal region tumors, from 15 French neurosurgical centers. We statistically verified the absence of heterogeneity of the different French centers with regard to diagnostic, mortality, and morbidity rates. In contrast, statistical heterogeneity was clearly seen for the large stereotactic biopsy series (for all tumor locations) in the literature. RESULTS: The mortality rate was 1.3% (5 patients of 370), and 3 patients suffered severe neurological complications. This study is the first to clearly demonstrate that the mortality, morbidity, and diagnostic rates for stereotactic biopsies are not different in the pineal region. CONCLUSION: Our conclusion is that stereotactic biopsy must remain a main diagnostic modality for tumors of the pineal region.

Adolescent↗
PubMed1996

First biochemical evidence of differential functional effects following Gamma Knife surgery.

Clinical experience with radiosurgery for epilepsy on lesions located in highly functional areas has suggested the possibility of Gamma-Knife-induced functional effects without deterioration of the underlying cerebral cortex. To investigate these hypothetical functional changes, we have developed a special frame dedicated to small-animal radiosurgical experimental models, allowing purely atlasguided protocols. The left striatum of the first series of rats was targeted with high doses (200 Gy maximum) for validation of this new device. The same target was used with lower doses (50 Gy at the 50% isodose) in the second series to evaluate the biochemical changes and their chronology. The main biochemical changes occurred between 59 and 90 days after Gamma Knife irradiation, with different amplitudes depending on the biochemical parameter observed. Differential effects were first observed between glutamate decarboxylase and choline acetyltransferase, and secondarily between excitatory amino acids (AAs) and non-excitatory AAs, particularly gamma-aminobutyric acid. These preliminary results need to be confirmed and completed by further experimental studies. However, Gamma-Knife-induced differential biochemical effects provide the basis for a promising new concept for functional radiosurgery and particularly the Gamma Knife surgery of epilepsy.

Animals↗
PubMed1996

Pineal region tumors: the role of stereotactic radiosurgery.

Between July 1992 and August 1995, 11 patients with pineal region tumors (PRTs) were treated at our center. Ages ranged from 8 to 72 years (median 21). Diagnosis was confirmed by histological examination in 7 patients. The remaining cases had strong neuroradiological and marker evidence of the diagnosis, so that a stereotactic biopsy could be avoided. The pathological diagnoses were pinealocytoma (n = 1), tectal astrocytoma (n = 1), germinoma (n = 2), pinealoblastoma (n = 2), and meningioma (n = 3). The marginal dose of these tumors ranged from 12 to 18-20 Gy. Conventional external radiotherapy was never used in this series. With a median follow-up of 12.3 months (range 2-34), all tumors responded to treatment and disappeared or ceased growing. We observed no mortality or major morbidity. One patient (tectal astrocytoma) had a mild radiation-induced reaction, with headache and transient worsening of an abducent nerve palsy, which were controlled with steroids. In germinomas and pinealoblastomas, recovery of normal cerebrospinal fluid circulation was observed in less than 7 days, in parallel with major tumor shrinkage. In this study we confirm that radiosurgery can be an effective and safe alternative for the treatment of pinealocytomas and low-grade tectal gliomas. Moreover, we consider that the characteristics of the radiosurgery technique suggest the method should be evaluated for the treatment of malignant PRTs.

Adolescent↗
PubMed1996

Stereotactic radiosurgery for trigeminal neuralgia: a multiinstitutional study using the gamma unit.

A multiinstitutional study was conducted to evaluate the technique, dose-selection parameters, and results of gamma knife stereotactic radiosurgery in the management of trigeminal neuralgia. Fifty patients at five centers underwent radio-surgery performed with a single 4-mm isocenter targeted at the nerve root entry zone. Thirty-two patients had undergone prior surgery, and the mean number of procedures that had been performed was 2.8 (range 1-7). The target dose of the radiosurgery used in the current study varied from 60 to 90 Gy. The median follow-up period after radiosurgery was 18 months (range 11-36 months). Twenty-nine patients (58%) responded with excellent control (pain free), 18 (36%) obtained good control (50%-90% relief), and three (6%) experienced treatment failure. The median time to pain relief was 1 month (range 1 day-6.7 months). Responses remained consistent for up to 3 years postradiosurgery in all cases except three (6%) in which the patients had pain recurrence at 5, 7, and 10 months. At 2 years, 54% of patients were pain free and 88% had 50% to 100% relief. A maximum radiosurgical dose of 70 Gy or greater was associated with a significantly greater chance of complete pain relief (72% vs. 9%, p = 0.0003). Three patients (6%) developed increased facial paresthesia after radiosurgery, which resolved totally in one case and improved in another. No patient developed other deficits or deafferentation pain. The proximal trigeminal nerve and root entry zone, which is well defined on magnetic resonance imaging, is an appropriate anatomical target for radiosurgery. Radiosurgery using the gamma unit is an additional effective surgical approach for the management of medically or surgically refractory trigeminal neuralgia. A longer-term follow-up review is warranted.

Adult↗
PubMed1996

[Treatment of choroid melanoma by Gamma-Knife radiosurgery].

Conservative treatment of uveal melanomas by Gamma Knife Radiosurgery is based on the use of cross fire technique with 201 Cobalt60 sources. A following of 13 months is available for the first case operated by Gamma-Knife Surgery in France. Technical baselines and one year preliminary results are reported. The diagnosis of uveal melanoma T3NOMO was established by converging results of clinical examination, angiography and echography. The definition of the target was based on stereotactic MRT examination. We delivered a dose of 50 Gys to the marginal isodose (50%). Today, one year after treatment the tumor decreased, the visual function was preserved. There were no side effect or complication.

Choroid Neoplasms↗
PubMed1996

[Experimental radiosurgery in rats using gamma a "gamma knife". Description of a stereotactic device for small laboratory animals].

To allow the experimental use in rats of a Gamma Knife Radiosurgical Unit, a stereotactic device adapted from the conventional Kopf's device was developed. To control the accuracy of the coordinate system based on the De Groot's rat stereotactic atlas, experimental radiosurgical lesions were made on the left striatum. The isodose curve distribution of the 4 mm collimator was calculated with the dose planning software used in Gamma Knife and superimposed on the left striatum target. Doses of 200 Gy were administered to the left striatum in six rats. The results were evaluated 21, 34 and 47 days later. At 34 and 47 days necrotic lesions were exactly as targeted. In a second group of 48 rats receiving a doses of 100 Gy, no lesions were observed after 7, 15, 24, 31, 45 days. However, in all rats sacrificed 59, 72 and 90 days after day radiation, a necrotic lesion was always present and confirmed that at each time the lesions were precisely targeted. This apparatus allows precise and reproducible gamma irradiation lesion in rat brain without expensive and time consuming imaging techniques. This device provides a useful system to observe the experimental effects of radiosurgery on the central nervous system in rats.

Animals↗
PubMed1995

Effect of the Gamma Knife on trigeminal neuralgia.

The Gamma Knife radiosurgical treatment of 20 patients suffering from trigeminal neuralgia is reported. Eleven patients received radiosurgical treatment with the goal of pain relief. Six had secondary trigeminal neuralgia due to AVM, large cavernous sinus and petrous bone meningiomas, trigeminal neurinoma, or chordoma; 5 others had essential trigeminal neuralgia. Radiosurgical treatment was considered only after the failure of conventional medical and surgical treatment. For the other 9 patients, the control of the tumor was the main objective (four acoustic and one trigeminal neurinoma, one petroclival chordoma, and three tumors of the cavernous sinus: one hemangiopericytoma, one metastasis, one meningioma). We have not been using this method for sufficient time to evaluate long-term results. However, we believe that a large majority of our patients benefited greatly from this technique with a rapid clinical improvement, which is a reflection of the relevance of the chosen target.

Adult↗
PubMed1995

Generic model for the localization of the cerebral cortex and preoperative multimodal integration in epilepsy surgery.

In cerebral cortex neurosurgery and particularly in epilepsy surgery, the recognition of individual cortical anatomic landmarks is necessary for presurgical evaluation and planning. To overcome the classical great variability in the superficial aspect of the human cerebral cortex, we have developed an original generic description of the cerebral cortex in a three-dimensional structure. The result is a generic model matching the cortical topography of each brain regardless of inter- and intra-individual variability. In this model, sulcal roots (fundi) are separated by more or less superficial annectent gyrus, and buried by operculization during the gyrification. This original generic model of the cerebral cortex enabled us to develop a mathematical methodology for the construction of a structural representation of the cortical topography from a T1-weighted three-dimensional MR image. This program can provide automatic detection and recognition of the main cortical sulci.

Algorithms↗
PubMed1994

Intervertebral disk vacuum phenomenon secondary to vertebral collapse: prevalence and significance.

PURPOSE: To evaluate the prevalence of the intervertebral vacuum phenomenon in disks adjacent to vertebral collapses of various causes. MATERIALS AND METHODS: The authors retrospectively studied 310 consecutive patients who had at least one vertebral collapse. The vacuum phenomena were divided into collapse-related (ie, adjacent to a collapse) and degenerative (ie, not associated with a vertebral fracture) ones. Plain radiography was performed in all patients, and, in addition, conventional tomography, computed tomography, and/or magnetic resonance imaging was performed in 175 patients. RESULTS: Collapse-related vacuum phenomena were seen in 15% of patients with plain radiography and in 21% when all of the imaging modalities were considered. They occurred in association with all of the causes of collapse (ie, osteoporosis, multiple myeloma, metastasis, acute trauma, and vertebral osteomyelitis), although the prevalence was lower in association with metastasis or trauma (P = .008). The occurrence of collapse-related vacuum phenomenon was correlated with age (P = .001) and with the coexistence of degenerative disk-related vacuum phenomenon in the same patient (P = .0002). CONCLUSION: Occurrence of a vacuum cleft in disks adjacent to a vertebral collapse is common and appears as the second cause of vacuum phenomenon after degenerative disk disease.

Adult↗
PubMed1994

Cavernous angiomas and arteriovenous malformations of the spinal epidural space: report of 11 cases.

We have retrospectively studied 11 cases of solitary cavernous and arteriovenous malformations of the spinal epidural space. The acute or subacute onset of symptoms was found in all cases, with a neurological deficit in five cases. A plain x-ray study revealed abnormal calcification in one case. Hyperdensity with no iodine enhancement was found on computed tomographic scans in all cases. Magnetic resonance imaging studies showed ovoid or round lesions with isosignal and gadolinium enhancement on T1-weighted images and hypersignal on T2-weighted images, except in one case with hypersignal on T1 and T2 before the administration of a contrast medium. Four lumbar cases were localized in the posterior vertebral ligament; all the thoracic cases were posterior with foraminal extension. The other cases were anterolateral. The surgical findings revealed a dark vascularized epidural lesion associated in two cases with a localized epidural hematoma. A pathological examination revealed seven cavernous angiomas and four arteriovenous malformations. These arteriovenous malformations were all lumbar, and two of four localized within the posterior ligament. The pathophysiology of these vascular malformations is discussed. In light of the good postoperative prognosis of these lesions, surgical removal is recommended for all the symptomatic cases.

Adult↗
PubMed1994

[Meningioma of the floor of the temporal fossa. Anatomo-clinical study of 11 cases].

The authors present eleven cases of middle fossa floor meningiomas. They describe the anatomical and clinical features of these tumors in this rare localisation. They emphasize the strait anatomical relations with the cranial base, eight cases were inserted above the superior surface of the petrous bone, two above the endocranial face of the horizontal part of the greater sphenoid wing, one above the horizontal part of the temporal squama. Headache (6 cases) and memory loss (4 cases) are the most frequent clinical feature, seizures (2 cases) and neuropsychologic troubles were probably undervalued. Auditory signs were present in three cases. There was no visual defect and cranial nerve impairment. They insist on the necessity to obtain a complete preoperative temporal bone CT scan exploration. They think that a well advised surgical act is sufficient for these meningiomas inserted above weak structures and with good prognosis: there's no recurrence in this study with a follow up from 12 to 132 months.

Adult↗
PubMed1993

[Nociceptive flexion reflex of the leg. Use after surgical treatment of herniated disk].

In patients suffering from acute sciatica due to herniated disk Lasegue's manoeuvre inhibits the leg flexion nociceptive reflex (RIII reflex) in either the ipsilateral or the contralateral limb. This is thought to be due what is called "diffuse noxious inhibitor control" modulating the activity of a group of convergent spinal neurons. The purpose of this study was to determine whether surgical resection of the herniated disk in patients suffering from sciatica might relieve this so-called "counter-irritation". Among 10 patients whose sciatica resulted from herniated disk, the decrease in amplitude of the RIII response observed when Lasegue's manoeuvre is applied disappeared in 7 patients, 6 to 8 days after surgical resection of the herniated disk. These results suggest that this test might be a useful tool for postoperative prediction of radicular compression.

Adult↗
PubMed1992

Value of MRI in the morphological evaluation of tumors of the third ventricle.

The detection or suspicion of a tumoral expansive process in the third ventricule is usually performed by MRI. The contribution of MRI to the diagnosis is unquestionable in view of its accuracy in the topographical characterization of these lesions and in the detection of small formations. The great histological variety of tumours in that region may result in different treatments which can be associated. MRI, therefore, plays an important role in pretherapeutic morphological evaluation. Fifteen patients with tumour of the third ventricle were examined by MRI before treatment. The results of these examinations were compared with the pathological data and the therapeutic procedures: ventricular shunting, stereotactic needle biopsy, radio- or chemotherapy and surgery. MRI cannot provide a formal histological characterization, but it can individualise some categories of tumours, give details on the walls of the third ventricle (notably in the case of bifocal pineal and suprassellar lesions), visualize the paths of CSF flow and predict the need for cisternoventriculostomy, and detect venous structures in the vicinity of the great cerebral vein which might result in post-biopsy and post-surgery complications.

Adolescent↗
PubMed1991

[Microcompression of Gasser's ganglion. A treatment of essential facial neuralgia. Apropos of 70 cases].

Percutaneous micro-compression of the trigeminal ganglion for trigeminal neuralgia, using the technique of Mullan and Lichtor (1983), with some modifications, was performed during the last five years, in our institution in 70 patients. 97.5% of the patients were initially relieved of their pain. There were 14 recurrences (20.5%). 9 of these patients underwent a second micro-compression with 8 excellent results. The follow up examination 6 to 60 months (average: 16.5 months) showed that 88.5% of the patients were free of pain (54 times after one micro-compression and 8 times after two). Sequellae are: --hypoesthesia: 14.3%, --loss of the corneal reflex without keratitis: 11.4%, --dysesthesias without anesthesia dolorosa: 11.4%. We think that this technique should be the first operation considered for trigeminal neuralgia, in the aged and poor cooperative patients, especially when V1 or V1-V2 pain is present, for symptomatic neuralgia (especially multiple sclerosis), or after recurrences after other procedures.

Adult↗
PubMed1991

Brain metastases.

Brain metastases are frequent, accounting for 20% of all brain tumours. The most common primary tumours responsible for brain metastases are lung cancer in man and breast cancer in women. Most metastases are located at the grey matter-white matter junction, in junctional vascular territories and in the rolandic region. Although non-specific, MRI is the most sensitive neuroradiological method for the lesions, especially when accompanied by gadolinium injection. MRI must absolutely be performed before surgical treatment, as gadolinium might detect other metastatic lesions or show metastatic tumours so small that they were not visible at computerized tomography (CT).

Aged↗
PubMed1990

Atypical inflammatory histiocytic tumor of the cerebellum. A histological, immunohistochemical, and ultrastructural study.

We report a primary histiocytic tumor involving the cerebellum. Microscopically, the tumor was composed of nests of pleomorphic cells surrounded by thin vascular septa invaded by lymphocytes. Immunocytochemistry and electron microscopy confirmed the histiocytic origin of the tumor. Although we considered several diagnoses, we ultimately concluded that "atypical inflammatory histiocytic tumor of the cerebellum" best characterized the lesion. This case represents another example of the diversity of histiocytic tumors and shows that they can occur in the central nervous system.

Adult↗