Biomedical subjects

P A Garcia

Publications and source records attributed to P A Garcia.

At least 19 recordsLinked to original sources

PubMed2005

Limitations of Wada memory asymmetry as a predictor of outcomes after temporal lobectomy.

BACKGROUND: The intracarotid amobarbital (Wada) test can be used to evaluate hemispheric memory capacity before anterior temporal lobectomy (ATL). Most patients demonstrate better memory with injection ipsilateral to planned resection (expected asymmetry [EA]), but a substantial minority show better memory with contralateral injection (unexpected asymmetry [UA]). Both degree and direction of Wada memory asymmetry (WMA) have been associated with worse surgical outcome in small series. Reports also suggest that UA is associated with greater decline in verbal memory after left ATL (L-ATL). METHODS: The relationship between WMA and surgical outcome (at 3 months, 1 year, and last follow-up) was examined in a large group of ATL patients (108 L, 119 R) with both EA and UA. Also, memory in a subgroup (96 L, 108 R) was examined, comparing subscores of the Rey Auditory Verbal Learning Test obtained preoperatively, at 3 months, and at 1 year. RESULTS: Thirty-six percent of L-ATL and 8% of R-ATL patients had UA. UA was associated with worse surgical outcome at 1 year for R-ATL patients but was not associated with worse outcome for L-ATL patients. There was no correlation between WMA and persistent postoperative verbal memory change for patients with L- or R-ATL. CONCLUSIONS: Unexpected asymmetry is uncommon in patients with right anterior temporal lobectomy (R-ATL) and may be a risk marker of poor surgical outcome. This relationship may be obscured by language confounds in patients with L-ATL. The results suggest that Wada asymmetry (using mixed stimuli) does not predict postoperative verbal memory; it is unclear whether this finding is generalizable to centers using only nonverbal stimuli.

Adolescent↗

PubMed2003

Potentially misleading extratemporal lobe lesions in patients with temporal lobe epilepsy.

From a series of 217 consecutive temporal resections for intractable epilepsy between 1993 and 2000, we identified all patients with large non-neoplastic extratemporal lesions. Only patients with known postsurgical outcomes with follow up for more than two years were included. Fifteen patients were identified. All patients had a history of medically refractory epilepsy with clinical and ictal evidence of mesial temporal seizure onset. Eleven patients had extratemporal lesions ipsilateral to the seizure focus, whereas four patients had the lesions contralateral to the seizure focus. Nine of the 15 patients had evidence of hippocampal atrophy on magnetic resonance imaging (MRI). Following temporal resection, nine of these patients (60%) became seizure free (Engel class 1A), two patients were free of disabling seizures only (Engel class 1B), and two patients had a few early seizures but then became seizure free for at least two years (Engel class 1C). Two patients had significant improvement (Engel class 2). Thus, the finding of large extratemporal lesions on MRI was potentially misleading. When clinical semiology and ictal EEG recordings provide evidence of temporal onset seizures, anterior temporal resection should be considered in patients with extratemporal lesions.

Adult↗

PubMed2002

Incidence and mortality of generalized convulsive status epilepticus in California.

BACKGROUND: Few population-based studies of status epilepticus have been performed in the United States. OBJECTIVE: To determine the incidence, case fatality, and demographics of generalized convulsive status epilepticus (GCSE) in the state of California. METHODS: Using a state-wide hospital discharge database, the authors identified all hospitalizations from 1991 through 1998 with a discharge diagnosis of convulsive status epilepticus. They identified the first admission for each individual to estimate the incidence of GCSE. In-hospital case fatality rates were calculated, and multivariate analysis was performed to determine predictors of death during hospitalization. Secondary diagnoses were analyzed by retrieving all discharge diagnoses accompanying the diagnosis of GCSE. RESULTS: The incidence rate of GCSE was 6.2/100,000 population and fell by 42% between the years 1991 and 1998 from 8.5 to 4.9/100,000. The rate of GCSE was highest among children under the age of 5 (7.5/100,000) and among the elderly (22.3/100,000). Blacks also demonstrated a relatively high incidence of GCSE (13.4/100,000). The case fatality for incident admissions was 10.7%, with increasing age being the only significant predictor in multivariate analysis. Case fatality was highest in patients who also carried a diagnosis of anoxia, CNS infection, or stroke. CONCLUSIONS: The incidence of GCSE requiring hospitalization has fallen over the last decade and is lower than that reported in previous studies. The case fatality is also lower than that reported previously. Further studies are needed to determine the cause of this decline in incidence and mortality of GCSE.

Adolescent↗

PubMed2001

False lateralization by subdural electrodes in two patients with temporal lobe epilepsy.

The authors present two patients with medically refractory partial seizures who had invasive recordings with stereotactic depth EEG (SEEG) and subdural electrodes (SDE) as part of their presurgical workup. SDE recordings were falsely lateralizing in both of these patients with pathologically proven mesial temporal sclerosis. In temporal lobe epilepsy, SEEG electrodes should be considered when presurgical studies are discordant.

Electrodes, Implanted↗

PubMed2001

New process for simultaneous removal of nitrogen and sulphur under anaerobic conditions.

A granular activated carbon (GAC) anaerobic fluidised-bed reactor treating vinasse from an ethanol distillery of sugar beet molasses was operated for 90 days, the first 40 days of start-up followed by 50 days of operation at constant organic loading rate of 1.7g COD/Ld. The reactor showed good performance in terms of organic matter removal but an anomalous behaviour in terms of unusual high concentrations of molecular nitrogen in the biogas. The analysis of the different nitrogenous and sulphur compounds and the mass balances of these compounds in the liquid and gas phases clearly indicated an uncommon evolution of nitrogen and sulphur in the reactor. About 50% of the nitrogen entering the reactor as total Kjeldahl nitrogen (TKN) was removed from the liquid phase appearing as N2 in the gas phase. Simultaneously, only 20% of the S-SO4(2-) initially present in the influent appears as S-S2- in the effluent or S-H2S in the biogas, indicating that 80% of the sulphur is removed. This behaviour has not been reported previously in the literature. These observations may suggest a new anaerobic removal process of ammonia and sulphate according to an uncommon mechanism involving simultaneous anaerobic ammonium oxidation and sulphate reduction.

Anaerobiosis↗

PubMed2001

Selective loss of cholinergic neurons projecting to the olfactory system increases perceptual generalization between similar, but not dissimilar, odorants.

The neuromodulator acetylcholine is thought to modulate information processing in the olfactory system. The authors used 192 IgG-saporin, a lesioning agent selective for basal forebrain cholinergic neurons, to determine whether selective lesions of cholinergic neurons projecting to the olfactory bulb and cortex affect odor perception in rats. Lesioned and sham-operated rats were tested in an olfactory generalization paradigm with sets of chemically related odorants (n-aliphatic aldehydes, acids, and alcohols). Lesioned rats generalized more between chemically similar odorants but did not differ from controls in their response to chemically unrelated odorants or in acquisition of the conditioned odor. Results show that cholinergic inputs to the olfactory system influence perceptual qualities of odorants and confirm predictions made by computational models of this system.

Acetylcholine↗

PubMed2001

Vagus nerve stimulation for the treatment of bilateral independent temporal lobe epilepsy.

PURPOSE: We studied the effect of vagus nerve stimulation (VNS) on seizure reduction in patients with intractable epilepsy with bilateral independent temporal lobe foci. METHODS: Ten patients who met the criterion of the presence of two distinctive clinical and ictal EEG seizure patterns were identified and followed up for 1 year. RESULTS: Six patients had >50% reduction in their seizure frequency that persisted up to > or =1 year of follow-up, whereas four patients reported small or no reduction in their partial seizures. CONCLUSIONS: VNS is often effective and well tolerated in this select group of intractable epilepsy patients.

Adolescent↗

PubMed1998

Management of seizures and epilepsy.

While the evaluation and treatment of patients with seizures or epilepsy is often challenging, modern therapy provides many patients with complete seizure control. After a first seizure, evaluation should focus on excluding an underlying neurologic or medical condition, assessing the relative risk of seizure recurrence and determining whether treatment is indicated. Successful management of patients with recurrent seizures begins with the establishment of an accurate diagnosis of epilepsy syndrome followed by treatment using an appropriate medication in a manner that optimizes efficacy. The goal of therapy is to completely control seizures without producing unacceptable medication side effects. Patients who do not achieve complete seizure control should be referred to an epilepsy specialist, since new medications and surgical treatments offer patients unprecedented options in seizure control.

Adult↗

PubMed1997

Correlation of seizure frequency with N-acetyl-aspartate levels determined by 1H magnetic resonance spectroscopic imaging.

Using 1H MRSI, we measured N-acetyl-aspartate (NAA), a neuronal marker, in the seizure focus of 16 patients with partial epilepsy. Decreasing NAA correlated with increasing seizure frequency in frontal lobe epilepsy (r = -0.72, p < 0.02) and a similar trend was present in temporal lobe epilepsy (r = -.60, p < 0.06). NAA was not related to the duration of epilepsy. We conclude that patients with higher seizure frequency have evidence of greater neuron loss or dysfunction.

Adolescent↗

PubMed1996

Effect of rate of contrast medium injection on hepatic enhancement at CT.

PURPOSE: To determine the effect of the rate of contrast medium injection on liver enhancement at computed tomography (CT). MATERIALS AND METHODS: Forty-five patients who underwent a follow-up CT examination of the liver were included in five different groups according to the compared rates of contrast material delivery: group A, 2 versus 3 mL/sec; group B, 2 versus 4.5 mL/sec; group C, 3 versus 4.5 mL/sec; group D, 3 versus 6 mL/sec; and group E, 4.5 versus 6 mL/sec. RESULTS: Time to peak enhancement was shorter for the faster rates of injection. In each group, maximum enhancement was nearly identical for the paired examinations (group A, 57 vs 58 HU; group B, 48 vs 47 HU; group C, 55 vs 58 HU; group D, 55 vs 54 HU; group E, 62 vs 61 HU, respectively). Mean enhancement in each group was similar when calculated at 3-second intervals. CONCLUSION: Higher rates of injection shorten the time to peak liver enhancement but have no effect on maximum liver enhancement.

Contrast Media↗

PubMed1995

Proton magnetic resonance spectroscopic imaging in patients with frontal lobe epilepsy.

Proton magnetic resonance spectroscopic imaging (1H MRSI) has demonstrated decreased N-acetyl compounds (NA) in the epileptogenic hippocampus in patients with temporal lobe epilepsy. We studied 8 patients with frontal lobe epilepsy and found mean NA/creatine (Cr) in the epileptogenic frontal lobe decreased by 27% compared with that of the contralateral homologous region (1.81 +/- 0.36 vs 2.49 +/- 0.60, p < 0.008). In every patient, NA/Cr was decreased in the epileptogenic region by at least 5%. These findings suggest that 1H MRSI may be useful in the presurgical evaluation of patients with frontal lobe epilepsy.

Aspartic Acid↗

PubMed1995

Application of spectroscopic imaging in epilepsy.

Functional and anatomical neuroimaging has had a dramatic effect on the evaluation of patients for seizure surgery. The demonstration by PET that the epileptogenic focus has interictal metabolic abnormalities has allowed a greater number of patients to come to seizure surgery, with fewer of these patients requiring intracranial electrode evaluations. Metabolic changes have also been demonstrated utilizing single voxel and whole brain 1H and 31P MRS imaging techniques with the interictal focus characterized by increased Pi, pH, and decreased PME and NAA. These findings can be used to accurately lateralize temporal lobe as well as frontal lobe epilepsy. Furthermore, there is evidence that these findings can be used to localize the seizure focus with the changes specific for the epileptogenic region; although, more diffuse changes both ipsilaterally and contralaterally have been seen. In patients with anterior hippocampal seizure foci the pH is significantly alkaline only in the ipsilateral hippocampus, whereas the increased Pi and decreased PME can be seen throughout the ipsilateral temporal lobe. When compared to controls the contralateral hemisphere is acidotic. Decreased NAA concentrations as well as NAA/Cr ratios have been demonstrated in the epileptogenic region in temporal and frontal lobe epilepsy. The decreased NAA has been correlated with the severity of cell loss, and may be a more sensitive measure than qualitative or quantitative measures of the hippocampal atrophy; however, the NAA decrease is more widespread than just the epileptogenic focus but may be maximal at the site of seizure initiation. In preliminary work, NAA maps of deviation from normality have suggested that the maximal change to coincide with the epileptogenic region. These results suggest that in focal epilepsy there is abnormal metabolic activity throughout the brain detectable by MRS, with patterns of metabolic asymmetry that are useful for seizure localization.

Acid-Base Equilibrium↗

PubMed1995

Spatial- and locomotion-related neural representation in rat hippocampus following long-term survival from ischemia.

Spatial and locomotion-related behavioral correlates of hippocampal cell discharge were compared between ischemic and sham-control rats performing a spatial maze. Ischemic rats showed impaired choice accuracy during maze acquisition, but not during asymptote performance. Single-unit correlates during asymptote performance revealed enhanced spatial selectivity of CA2/3 complex-spike cells coincident with attenuated place-specific firing by hilar complex-spike or subicular cells. Responsivity to locomotion state by stratum granulosum interneurons was exaggerated, and locomotion-induced changes in firing of hilar and subicular interneurons was reduced. Ischemic rats showed recovered spatial learning abilities as evidenced by the fact that acquisition of the spatial task in a second environment was not impaired. Because representational reorganization was also observed in ischemic, maze-naive rats, brain injury per se appears to change information coding schemes.

Animals↗

PubMed1995

The frontal N30 component of the median-derived SEP in patients with predominantly unilateral Parkinson's disease.

There are conflicting reports concerning attenuation of the frontal N30 component of the median-derived somatosensory evoked potential in patients with Parkinson's disease (PD). We found that the mean N30 latency (28.03 +/- 2.50 msec) and amplitude (2.30 +/- 1.58 microV) obtained with stimulation of the affected arm of 10 patients with predominantly unilateral PD were not significantly different from those obtained from the unaffected arm (mean latency, 28.14 +/- 2.47 msec; mean amplitude, 2.43 +/- 1.65 microV) or from 10 age-matched controls (mean latency, 29.01 +/- 1.88 msec; mean amplitude, 1.92 +/- 0.64 microV). Three patients had an N30 of abnormal amplitude; in two, responses were absent with stimulation of either side, and in one there was a response asymmetry exceeding the normal range, with the smaller response elicited from the affected arm. Thus, only one of 10 patients had a diminished N30 consistent with the clinical findings. We conclude that the N30 is unlikely to be clinically useful in the assessment of patients with PD.

Aged↗

PubMed1995

Magnetic resonance spectroscopy.

Magnetic resonance spectroscopy, like PET, allows cerebral function to be assessed neuro-anatomically. In addition to being noninvasive and not requiring ionizing radiation, this technique can be performed with equipment available at most medical centers. Initial studies suggest both proton and phosphorous spectroscopy will be useful adjunctive presurgical tests for the localization of the epileptogenic foci in patients with partial epilepsy, especially those with extratemporal foci. Furthermore, MRS imaging may prove to be a useful tool for studying the response to medical treatment and the pathophysiologic basis of epilepsy.

Brain↗

PubMed1994

Phosphorus magnetic resonance spectroscopic imaging in patients with frontal lobe epilepsy.

Phosphorus magnetic resonance spectroscopic imaging has previously demonstrated localized metabolic abnormalities within the epileptogenic region in patients with temporal lobe epilepsy, including alkalosis, increased inorganic phosphate level, and decreased phosphomonoester levels. We studied 8 patients with frontal lobe epilepsy, finding interictal alkalosis in the epileptogenic region compared to the contralateral frontal lobe in all patients (7.10 +/- 0.05 vs 7.00 +/- 0.06, p < 0.001). Seven patients exhibited decreased phosphomonoester levels in the epileptogenic frontal lobe compared to the contralateral frontal lobe (16.0 +/- 6.0 vs 23.0 +/- 4.0, p < 0.01). In contrast to findings in temporal lobe epilepsy, inorganic phosphate level was not increased in the epileptogenic region. Based on values derived from normal control subjects, 5 patients had elevated pH in the seizure focus and 2 patients had decreased phosphomonoesters while none had abnormalities in the contralateral frontal lobe. These data suggest that magnetic resonance spectroscopy will be useful in the presurgical evaluation of patients with frontal lobe epilepsy.

Adolescent↗

PubMed1994

Drug-induced seizures.

Drug-induced seizures are a commonly encountered problem for physicians. In this article, drugs that cause seizures are discussed with regards to the incidence of seizures, associated clinical factors, risk factors, and special treatment considerations. This information should help physicians determine appropriate evaluation and treatment strategies when their patients experience a seizure while using drugs.

Analgesics↗

PubMed1993

Neurological reactions in HIV-infected patients treated with trichosanthin.

Trichosanthin is a ribosome-inactivating protein that is being studied as a possible treatment for patients infected with human immunodeficiency virus (HIV). We report the clinical and pathological features in two patients who experienced neurological reactions to trichosanthin. Both patients were neurologically asymptomatic prior to treatment but developed coma and multifocal neurological deficits after treatment. Neuropathological examination revealed regions of severe, multifocal necrosis with histiocytic infiltrates. These reactions to trichosanthin may be mediated by soluble factors released by HIV-infected macrophages.

Acquired Immunodeficiency Syndrome↗