Biomedical subjects

L A Alvarez

Publications and source records attributed to L A Alvarez.

At least 19 recordsLinked to original sources

PubMed2000

Epilepsy surgery in children with tuberous sclerosis complex: presurgical evaluation and outcome.

PURPOSE: Children with tuberous sclerosis complex (TSC) benefit from excisional surgery if seizures can be localized to a single tuber. We evaluated the role of noninvasive studies to localize the epileptogenic tuber/region (ET/R) and the outcome of focal resection. METHODS: We identified 21 children with TSC, ages 3 months to 15 years (mean 4.8 years). All had video-(electroencephalogram) EEG and magnetic resonance imaging (MRI) scans, and 18 also had ictal single photon emission-computed tomography (SPECT) studies. An ET/R was localized in 17 patients. Thirteen patients underwent resection guided by intraoperative electrocorticography (n = 7) or subdural monitoring (n = 6). RESULTS: Interictal EEG revealed a principal spike focus (PSF) that corresponded to the ET/R in 14 children. In seven, PSFs occurred in rhythmic runs. PSFs were not observed remote from the ET/R. Focal polymorphic slowing and attenuation occurred in the region of the PSF in 11 patients. Sixteen patients demonstrated an ictal focus corresponding to the ET/R. Ictal SPECT revealed focal hyperperfusion correlating with the ET/R in 10 patients. Although the MRIs in all children revealed multiple tubers, the ET/R corresponded to a large discrete tuber in 8 patients and a calcified tuber in 13 patients. Patchy calcified tubers were also seen elsewhere in six patients. At a mean follow-up of 26 months, 9 of the 13 children who underwent surgery were seizure-free, one had greater than 75% reduction in seizures, two were unchanged, and one was lost to follow-up. New seizures developed in one child from a contralateral tuber. CONCLUSIONS: Surgical resection of an ET/R alleviates seizures in most children with TSC and intractable epilepsy. The scalp EEG and MRI help define the ET/R and improve case selection when ictal SPECT is nonlocalizing.

Adolescent↗

PubMed2000

Intravenous valproate dosing in neonates.

The loading dosage of intravenous valproate required to achieve a desired serum concentration in neonates is not known. Two neonates with seizures received loading doses of intravenous valproate over 30 minutes. Serum valproate concentrations were measured 45 minutes and 3 hours after initiation of the infusion. Both neonates had received phenobarbital and phenytoin before the loading infusions. In the first patient, a loading dose of intravenous valproate of 10 mg/kg increased the 45-minute postinfusion serum valproate concentration to 41 microg/mL with a 3-hour postinfusion serum valproate concentration of 33 microg/mL. In the second patient, a loading dose of 25 mg/kg increased the 45-minute postinfusion serum valproic acid concentration to 100 microg/mL with a 3-hour postinfusion serum valproic acid concentration of 78 microg/mL. We found that each 1 mg/kg of intravenous valproate increased the 45-minute and 3-hour postinfusion serum valproic acid concentrations by approximately 4 microg/mL and 3 microg/mL, respectively. We suggest that these figures be used to calculate the desirable loading dose of intravenous valproate in neonates until larger studies are conducted. The volume of distribution and the serum clearance of valproate were approximately 0.245 L/kg and 25 mL/h/kg, respectively.

Anticonvulsants↗

PubMed2000

A new meatless diet for adult screwworm (Diptera: Calliphoridae).

Screwworm flies, Cochliomyia hominivorax (Coquerel), were fed on honey and spray dried egg product; honey, molasses, and spray dried egg product; honey and spray dried meat protein; as well as on a control diet of honey and horsemeat, which is the standard diet used for screwworm adult colony in the mass-rearing facility. In general, the weight of eggs laid by females fed on the diet of spray dried egg product was significantly higher than that laid by females fed on the standard horsemeat diet. Egg production declined when spray dried meat protein replaced the egg product. Partial replacement of honey with molasses in the egg diet did not decrease egg production, compared with the control diet. The use of spray dried egg diet has advantages over the horsemeat diet, such as storage, handling, preparation, feeding, and expense. A cost analysis suggests that replacing the horsemeat with spray dried egg product, and half of the honey with molasses, would reduce the cost of the diet by more than US $100,000 annually.

Animal Feed↗

PubMed1998

An alternative source of blood protein for screwworm (Diptera: Calliphoridae) larval diet.

Larvae of screwworm, Cochliomyia hominivorax (Coquerel), were reared on diets with varying concentrations of spray dried animal blood cells, spray dried inedible egg product, and powdered milk substitute, and compared with those reared on spray dried whole bovine blood-based diet currently used for mass rearing. Mean larval weight, pupal weight, number of pupae, adult emergence, sex ratio, longevity, fecundity, and fertility obtained from the tests with animal blood cell based diets were similar to those from tests with whole bovine blood based diet. The animal blood cell based diet has potential for use in the mass production of screwworm larvae.

Animals↗

PubMed1998

[Epilepsy centers: classification and basic requirements].

Over the last two decades the surgical treatment of epilepsies has become a commonly used and effective method for the treatment of intractable epilepsy. However, because of its wide use in various types of centers throughout the world the methodology involved varies significantly throughout the centers. With this article we propose the bases from which a multidisciplinary team of numerous centers can eventually develop an effective and acceptable international protocol for the surgical treatment of the epilepsies and the classifications of the centers.

Epilepsy↗

PubMed1997

[Neuropathology of refractory epilepsy in children].

INTRODUCTION AND OBJECTIVES: The pathological findings in surgical material from children with refractory epilepsy has not offered yet a clear understanding of its role in this condition. The objective of this paper is to report our findings to further expand our knowledge about refractory epilepsy in children. MATERIAL AND METHODS: Results of microscopic examination of the surgical specimen obtained from 80 children, ages 12 or younger, who had surgery for intractable epilepsy at Miami Children's Hospital between 1990 and 1996 were reviewed. RESULTS: Examination was normal only in one. The rest revealed ectopic neurons (1), dysplastic cells with ectopic neurons (2), dyslamination with large neurons (7), dyslamination with ectopic neurons (18), dyslamination with dysplastic cells (10), pachygyria (2), encephalomalacia (9), gliosis with ectopic neurons (10), gliosis without ectopic neurons (3), developmental ectodermal tumor (6), ganglioglioma (2), tumors (3), and Rasmussen encephalitis (4). Lesions were located to the temporal lobe in 34 children. CONCLUSIONS. Extratemporal lesions are more frequent than temporal one, including hyppocampal sclerosis. Ectopic neurons, the most frequent pathological findings, rather than a cause of seizure may be a marker other highly epileptogenic cortical malformations.

Brain↗

PubMed1996

[Single photon emission computer tomography in the differential diagnosis of the paroxysmal clinical events in newborns].

Conventional computerized cranial tomography by single photon emission (TLCESF) is a nuclear medicine technique which makes use of a radioactive chemical complex to obtain a qualitative image of cerebral, cerebellar and brain-stem vascularization. This technique shows the changes in vascularization which occur between (decrease) and during (increase) the clinical events of paroxysmal epilepsy (ECP) in the area of origin. This technique is indicated in neonates with ECP which does not disappear on etiological treatment, where a non-epileptic cause cannot be ruled out on clinical grounds and where there are no associated encephalographic epileptic changes during the ECP.

Brain↗

PubMed1996

[Results of surgery treatment of epilepsy].

The recent advances in the surgical treatment of epilepsy have resulted in great improvement in the overall outcome of these patients. The pediatric group has probably benefited the most as patients who previously were not candidate for this form of treatment are now able to undergo epilepsy surgery with results which are as good as those of adults. In fact, children may now benefit the most, as the control of their epilepsy and our ability to stop their anticonvulsants may allow them to better develop from a psychosocial aspect. Also, because of their plasticity, young children may tolerate surgery involving loss of eloquent cortex without subsequent permanent deficits. The most recent reported results from different centers indicate that 68-90% of patients undergoing temporal lobectomy remain seizure free while the percentage of patients remaining seizure free after extratemporal resections is approximately 50-66%. However, one of the problems with these results is that they vary significantly from one center to another because of the methodology used to evaluate results and the selection of patients depending on the strength of the centers. At present we do not have an optimal method to evaluate results of epilepsy surgery that takes in consideration not only seizure control but also psychosocial outcome. It is our goal to develop such method which will ultimately help us identify the best surgical candidates and predict their outcome.

Age Factors↗

PubMed1993

Carbamazepine toxicity resulting from generic substitution.

Generic substitution is practiced widely in both hospital and community settings. There have been several reports of reduced serum concentrations and seizure exacerbation following generic substitution of Tegretol. We describe the first 2 cases of carbamazepine toxicity resulting from the substitution of Tegretol with Epitol. Two 6-year-old children experienced increases in the maximum serum carbamazepine concentration, one of 22% and one of 41%. Both became asymptomatic when their serum concentrations were lowered and had no residual effects.

Carbamazepine↗

PubMed1992

A safe and effective paradigm to functionally map the cortex in childhood.

Conventional cortical stimulation based on pulses of fixed duration briefer than the chronaxie rarely elicit responses in infants and young children. We developed a stimulation paradigm that relies on increments in both stimulus intensity and pulse duration. This approach ensures that stimulation parameters converge to the chronaxie by mathematically minimizing the energy required to elicit a response. In six patients, this paradigm successfully elicited clinical responses and/or afterdischarges at thresholds 5-8 mA below the standard paradigm and at up to 64% lower energy levels. Furthermore, three patients under age 5 years who did not respond to maximal fixed duration stimulation demonstrated afterdischarges and clinical responses when longer pulse durations were utilized. These findings indicate that a paradigm based on dual increments is effective for cortical mapping in children. Furthermore, by ensuring responses at lower energy levels, it may be more efficient for mapping the cortex at all ages.

Brain Mapping↗

PubMed1991

Localization of epileptogenic foci using a simple reference-subtraction montage to document small interchannel time differences.

We present a modified EEG montage that detects small interchannel time differences and assists in localizing the epileptogenic focus. Regions with apparently synchronous epileptic discharges are displayed simultaneously in referential and subtraction derivations. The subtraction derivation is a bipolar configuration of two regions of interest that are not necessarily adjacent. The referential derivation reveals the polarity, voltage, and morphology of the two discharges, and the subtraction derivation detects asynchrony; the combined reference-subtraction derivation thus indicates the region that is activated first.

Electroencephalography↗

PubMed1991

Localization of seizure foci: pitfalls and caveats.

The pitfalls and difficulties in accurately localizing seizure foci are reviewed. Basic issues regarding modeling, volume conduction, inhomogeneities, and corticocortical propagation are discussed, and the limitations of scalp and intracranial recordings are outlined. The ambiguities in interpreting patterns and their significance are highlighted with a concluding commentary on pitfalls in defining the epileptogenic region.

Brain↗

PubMed1991

Advanced colorectal carcinoma. A prospective randomized trial of sequential methotrexate, 5-fluorouracil, and leucovorin versus 5-fluorouracil alone.

One hundred and twenty-five previously untreated patients bearing metastatic or advanced recurrent (inoperable) colorectal carcinoma and measurable disease were prospectively randomized. Those in arm A received 5-fluorouracil (5-FU), 1,200 mg/m2 i.v. infusion over 2 h, while those in arm B received methotrexate (MTX), 200 mg/m2 i.v. (push injection), followed 20 h later by 5-FU, 1,200 mg/m2 i.v. infusion over 2 h, plus calcium leucovorin (LV), 25 mg i.m. every 6 h for eight doses beginning 24 h after MTX administration. Cycles were repeated every 15 days. All patients receiving treatment were evaluable for toxicity and survival, and 118 patients were evaluable for response. The objective regression rate (complete plus partial response) was 12% (7 of 58) in arm A and 28% (17 of 60) in arm B (p = 0.049). No change was observed in 24% (14 of 58) in arm A and in 35% (21 of 60) in arm B (p = 0.28), while progressive disease was registered in 64% (37 of 58) and 37% (22 of 60) in arms A and B, respectively (p = 0.006). Median duration of response was 3 months in arm A and 5 months in arm B (p = 0.39). The median survival was 8.3 months in arm A and 11.2 months in arm B (p = 0.25). No statistically significant differences were found when objective regression and survival were related to site of primary tumor, performance status, and number of involved organs. There were two drug-related deaths in arm B due to severe myelosuppression followed by mucositis and sepsis. Of nonhematologic toxicities, diarrhea was more frequently observed in arm B, as were mucositis and infectious complications. Our results indicate that the sequential schedule MTX-5-FU-LV with 20-h intervals between MTX and 5-FU is superior in terms of objective regression to 5-FU alone given at the dose and schedule used in the present study. However, MTX-5-FU-LV did not have a significant impact on survival.

Adult↗

PubMed1990

Phase II trial of cytarabine, cisplatin and vindesine for advanced non-small cell lung cancer.

Thirty-two patients with advanced non-small cell lung cancer (NSCLC) were entered in this study to evaluate the efficacy and toxicity of a chemotherapy schedule including cisplatin (C) 40 mg/m2 intravenously (i.v.) on days 1-3; vindesine (V) 3 mg/m2 i.v. on day 1, and cytarabine (ara-C) 15 mg/m2 subcutaneously every 12 hours on days 1-3 (total dose: 90 mg/m2). Cisplatin was administered simultaneously with one dose of ara-C. Cycles were repeated every 28 days. Five patients out of 28 (18%) fully evaluable for response presented partial remissions. No complete response was observed. Median survival was 8 months and median duration of response was 4 months. Hematologic toxicity was severe in 3 patients. There were no toxicity-related deaths. Other adverse reactions included nausea and vomiting, alopecia and peripheral neuropathy. We conclude that this chemotherapy combination is marginally effective against NSCLC showing in this group of patients a low number of responses of short duration without a significant impact on survival.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1990

Bone-only versus visceral-only metastatic pattern in breast cancer: analysis of 150 patients. A GOCS study. Grupo Oncológico Cooperativo del Sur.

The medical records of 510 patients with metastatic breast cancer were retrospectively reviewed. Seventy-seven patients with metastases confined to skeleton and 73 patients bearing visceral-only disease were identified. All patients had a disease-free interval greater than or equal to 6 months and received systemic therapy with any of the following modalities: chemotherapy, hormonotherapy, or chemohormonotherapy. The clinical features, response to treatment, and survival were analyzed and compared for both groups. Median survival of patients with osseous metastases was 28 months, while it was 13 months for those patients with a visceral pattern (p less than 0.001). Response rates to first and second line systemic therapy for both metastatic patterns showed no significant differences, suggesting a similar degree of sensitivity or resistance in both groups. Objective regression to first therapy was 45% in the group with bony disease and 41% among patients with visceral involvement; median duration of response was 16 months and 13 months, respectively. In both groups progressive disease conserved the original metastatic pattern in most patients. We conclude that although a superiority in survival was evident for the osseous metastatic pattern, for these patients efforts should be made to select the least aggressive therapy in order to avoid excessive toxicity. Further studies are needed to confirm our findings.

Adenocarcinoma↗

PubMed1990

Focal resection for malignant partial seizures in infancy.

There is little experience with excisional surgery for drug-resistant partial seizures in very young patients. We describe our experience with 5 infants under 1 year of age with malignant partial seizures and deteriorating developmental status. All were experiencing frequent daily seizures that did not respond to 1st-line antiepileptic medications at high therapeutic serum levels and considerable medication toxicity. Three infants had complete resection of epileptic tissue (frontal corticectomy and prefrontal lobectomy) and are seizure-free. Two underwent partial resection (lateral temporal lobectomy, frontal corticectomy with anterior callosotomy) and have experienced a significant reduction in seizure frequency. Surgery did not result in any significant neurologic deficit or lead to compromise of developmental status. From these data, we tentatively conclude that excisional surgery can be performed safely in selected infants with medically uncontrolled malignant partial seizures and may significantly improve long-term seizure status. Referral to a tertiary center specializing in early childhood epilepsy surgical evaluation may be considered in these circumstances.

Cerebral Cortex↗

PubMed1989

Opsoclonus-myoclonus syndrome: correlation of radiographic and pathological observations.

We report a case of a child with opsoclonus-myoclonus syndrome. Neuroradiological studies indicated a lesion in the cerebellar vermis. A cerebellar biopsy revealed changes consisting of Purkinje and granular cell loss with gliosis. This case report documents the correlation of radiologic and pathological findings in a patient with opsoclonus-myoclonus syndrome.

Biopsy↗

PubMed1989

Low morbidity and mortality of status epilepticus in children.

In an ongoing study of status epilepticus, 193 children with status epilepticus of varying causes have been followed up for a mean period of 13.2 months. Of these, 97 patients were recruited prospectively. The patients' ages ranged from 1 month to 18 years (mean, 5.0 years). The cause of the status epilepticus was classified as idiopathic in 46 cases, remote symptomatic in 45, febrile in 46, acute symptomatic in 45, and progressive neurologic in 11. The mortality and incidence of sequelae following status epilepticus was low and primarily a function of etiology. Seven children died within 3 months of having the seizure. New neurologic deficits were found in 17 (9.1%) of the 186 survivors. All of the deaths and 15 of the 17 sequelae occurred in the 56 children with acute or progressive neurologic insults. Only two of the 137 children with other causes sustained any new deficits (P less than .001). Duration of the status epilepticus affected outcome only within the acute symptomatic group (P less than .05). Neurologic sequelae occurred in 29% of infants younger than 1 year of age, 11% of children 1 to 3 years of age, and 6% of children older than 3 years of age. However, this was a reflection of the greater incidence of acute neurologic disease in the younger age groups. Within each cause, age did not affect outcome. Of the 193 children, 61 (32%) had a history of prior unprovoked seizures. Of the 125 surviving children with no history of prior unprovoked seizures, 37 (30%) had subsequent unprovoked seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗