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Biomedical subjects

J W Wheless

Publications and source records attributed to J W Wheless.

47 records · Page 3Linked to original sources
PubMed1997

Corpus callosotomy for medically intractable seizures.

To identify factors influencing outcome and morbidity in patients selected for corpus callosotomy, we retrospectively reviewed 23 patients with intractable generalized seizures who underwent corpus callosotomy between 1991 and 1994. Three patients had a complete corpus callosotomy, while 20 had an anterior callosotomy. Three of those patients subsequently had completion of the anterior callosotomy. Overall, 41% of patients were nearly or completely free of the seizure types targeted for surgical treatment, while another 45% had seizures less than half as frequently. Four patients developed simple partial motor seizures after callosotomy. A transient disconnection syndrome was observed in 57% of patients. The best predictor of good outcome was a normal preoperative MRI. Mentally retarded patients had poorer outcomes. Outcome was not predicted by extent of callosal section or lateralization on neurological examination, EEG, MRI, and SPECT. Completion of anterior callosotomy resulted in significant reductions in seizure frequency. Though most patients do not become seizure-free after corpus callosotomy, worthwhile palliation of an otherwise intractable illness can be achieved. An analysis of prognostic factors should lead to better selection of patients for surgery.

Adolescent↗
PubMed1997

On the surgical treatment of refractory epilepsy in tuberous sclerosis complex.

The role of surgery in the treatment of refractory epilepsy (RE) in tuberous sclerosis complex (TSC) is poorly defined. Four patients with RE and TSC were evaluated for epilepsy surgery from 1994 to 1996. Three of four patients developed infantile spasms within 5 months of birth. These progressed to frequent complex partial and generalized tonic/myoclonic seizures refractory to antiepileptic drug therapy. Neuroimaging revealed typical findings of TSC including calcified lesions consistent with hamartomas. Clinical and EEG evidence suggested an epileptic focus near a prominent lesion in each child. This was confirmed using magnetic source imaging in 1 case. All patients underwent inpatient continuous video-EEG monitoring followed by temporal lobectomy or focal cortical resection with intraoperative EEG. Age at operation ranged from 5 to 13 years. Three out of 4 patients experienced a greater than 90% decrease in seizure activity. One patient continues to have rare complex partial seizures, and 1 has rare simple partial seizures. Tumor DNA analysis revealed mutations in the TSC1 gene in case 1 and the TSC2 gene in case 2; no mutations have been identified yet in cases 3 and 4. Temporal lobectomy and focal cortical resection can result in improved seizure control in patients with TSC and RE.

Adolescent↗
PubMed1997

Effects of duration of epilepsy on the uncoupling of metabolism and blood flow in complex partial seizures.

We derived interhemispheric asymmetry indices (AIs) in interictal glucose uptake and blood flow in the temporal lobes of patients with intractable complex partial seizures from 18F and 15O positron emission tomograms. All patients subsequently underwent either left (n = 16) and right (n = 18) temporal lobectomy. We determined the effects on AIs of clinical seizure variables, including duration of seizure disorder, age at seizure onset, frequency of complex partial seizures, history of secondary generalization, history of febrile seizures, and magnetic resonance imaging evidence for mesial temporal sclerosis. Duration of seizure disorder produced the only significant effects. Degree of interhemispheric asymmetry in both glucose uptake and blood flow increased with duration of seizure disorder. However, the rate of increase in asymmetry was significantly greater for glucose uptake than for blood flow. These results indicate that uncoupling of metabolism and blood flow is a progressive process that results from the differential response of glucose metabolism and blood flow to chronic seizure activity. The results also suggest that duration of seizure disorder may be an important variable to consider in the interpretation of PET studies for evaluation of seizure surgery candidates.

Adult↗
PubMed1996

Lateralization of memory for music: evidence from the intracarotid sodium amobarbital procedure.

The present study was conducted to determine whether material-specific memory for unfamiliar tonal patterns could be demonstrated for the right temporal lobe during the intracarotid sodium amytal procedure (IAP). Thirty-one patients with intractable complex partial seizures associated with either left temporal lobe epilepsy (LTLE) or right temporal lobe epilepsy (RTLE) underwent assessment of memory for tonal patterns during a baseline phase and right and left cerebral hemisphere anaesthesia during the IAP. Patients were presented unfamiliar tonal patterns which were later selected from a set of distracter patterns. Findings indicated that there was no difference between the LTLE and RTLE patients during injection of the right cerebral hemisphere suggesting no specific involvement of left mesial temporal structures. However, a significant effect was noted during left injection with the LTLE group performing significantly better than the RTLE group. This latter finding supports a specific role of right mesial temporal lobe structures in mediating memory for music.

Adult↗
PubMed1996

Effects of temporal lobe epilepsy on spatial and figural aspects of memory for a complex geometric figure.

The preoperative delayed memory performance on the Rey-Osterrieth Complex Figure (Lezak, 1983) of 54 patients with complex partial seizures of temporal lobe origin was analyzed using 3 different indices. One index (composite) was derived using a common scoring method that included both spatial and figural aspects of memory in its score. The other two indices were derived emphasizing either spatial or figural aspects of memory for the elements of the figure separately. All 3 indices distinguished between individuals with right-sided (RTLE) and left-sided (LTLE) seizure onset. However, spatial memory was significantly lower than figural memory in individuals with RTLE as compared to those with LTLE. Both the spatial and figural memory indices were significantly lower in the presence of magnetic resonance imaging (MRI) evidence for hippocampal sclerosis in individuals with RTLE. Results suggest that while both the spatial and figural aspects of nonverbal memory are sensitive to right hippocampal dysfunction, figural memory may be less vulnerable to the effects of RTLE.

Adult↗
PubMed1996

Memory tests distinguish between patients with focal temporal and extratemporal lobe epilepsy.

We examined the ability of preoperative memory performance to distinguish between patients who had been diagnosed as having left (LTLE, n = 31), right (RTLE, n = 37), and extra-(ETLE, n = 17) temporal lobe focal epilepsy. All patients eventually underwent surgical resections. Analyses indicated that the ETLE group performed better than the RTLE group on nonverbal memory measures and better than the LTLE group on verbal memory measures. Discriminant function analyses indicated that use of a combination of measures that assess different aspects of memory were of significant value in distinguishing between patients with focal TLE and ETLE. This approach, as compared the use of single measures, improved classification rates of all three groups. The best single predictor of group membership, an index of verbal learning, yielded a 47% overall correct classification rate, with sensitivities ranging from 25 to 59%, and performed at worse than chance levels in classifying RTLE patients. A multivariate approach, which included an index of verbal and nonverbal learning, incidental nonverbal memory, and consolidation of organized and rote verbal material, yielded a 65% correct classification rate, with sensitivities ranging from 57 to 75%. This compares favorably with the other noninvasive techniques for lateralizing epileptogenic lesions.

Adolescent↗
PubMed1993

Variability of expression in tuberous sclerosis.

We present three families in whom a diagnosis of tuberous sclerosis is difficult to secure and we review published reports about similar cases. Tuberous sclerosis has been reported to affect as many as 1 in 9400 subjects in the population. The manifestations of this disease vary not only between but also within families. Currently no reliable method of prenatal diagnosis is available. For these reasons, subjects known to be at 50% risk should be assessed scrupulously to clarify their status. These cases illustrate the difficulties in the clinical diagnosis of tuberous sclerosis and further reinforce the need for a molecular method of determining whether an at risk subject has the disease.

Adolescent↗
PubMedDate not supplied

[Insights into brain function though magnetic source imaging: A review of research and clinical applications].

INTRODUCTION AND DEVELOPMENT: The paper presents a brief outline of the rationale behind the use of non invasive functional imaging and of the features that any imaging technique should display in order to make a substantial contribution to the search of the brain mechanisms responsible for cognitive functions. One such technique, magnetic source imaging (MSI), that meets these specifications, is described in more detail. Advantages of MSI include the capacity to provide direct measures of regional neurophysiological activity, a millisecond range temporal resolution, and the capacity to provide images of brain activity on an individual basis. We then describe applications of MSI to the study of brain mechanisms involved in various language functions such as oral comprehension and reading. Among these applications, the accuracy of MSI protocols in determining hemispheric dominance for language functions and in identifying the precise location and extent language specific cortex (Wernicke s area) has been verified through comparison with standard invasive techniques (Wada procedure and electrocortical stimulation mapping) in over 60 consecutive cases. In another series of studies we combined data from MSI and direct cortical stimulation to determine the role of temporoparietal areas in phonological analysis of spoken language and in phonological decoding of print. Finally, we have used MSI to gain unique insights into the brain mechanisms that support reading in developmental reading disability. CONCLUSION: Results from over 21 children diagnosed with this disorder suggest that impaired reading is associated with aberrant functional connections between temporal and temporoparietal areas of the left hemisphere that are normally engaged in reading.

Brain Mapping↗