Biomedical subjects

R Edward Hogan

Publications and source records attributed to R Edward Hogan.

12 recordsLinked to original sources

PubMed2006

Composite SISCOM perfusion patterns in right and left temporal seizures.

OBJECTIVE: To compare composite subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance imaging (also known as SISCOM) patterns between right and left medial temporal-onset seizures to document neuroanatomical involvement in perfusion patterns. DESIGN: A retrospective comparative survey. SETTING: Epilepsy monitoring unit in a tertiary care referral center. PARTICIPANTS: Subjects with temporal lobe epilepsy (TLE) who underwent ictal single-photon emission computed tomography studies. MAIN OUTCOME MEASURES: Comparison of ictal perfusion pattern changes in subjects with right and left temporal seizures. RESULTS: Composite subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance images showed similar regions of hyperperfusion change in the ipsilateral anteromedial temporal-corpus striatum-insula region in both groups. In the midbrain reticular formation, there was a significant difference in hyperperfusion between the left and right TLE groups. In addition, the right, but not the left, TLE group shows contralateral hypoperfusion of the temporoparietal junction. CONCLUSIONS: While anteromedial temporal-corpus striatum-insula perfusion patterns are similar, there are brainstem and hemispheric perfusion pattern differences in right and left TLE seizures, confirming pathophysiological differences between the groups. These findings help define neuronal network involvement in TLE seizures, and may explain the differences in clinical symptoms of right and left TLE seizures.

Adult↗

PubMed2005

Three-dimensional deformation-based hippocampal surface anatomy, projected on MRI images.

The objectives of the present study were to illustrate three-dimensional hippocampal surface anatomy using deformation-based composite segmentations, superimposed on two-dimensional MRI (magnetic resonance images) in standard and oblique planes. The hippocampi from five normal volumetric MRI studies were segmented using a semiautomated, deformation-based technique. Segmentations were then processed to combine hippocampal surfaces, generating a composite (or average) deformation for each of the five left and five right hippocampi. Composite hippocampal surfaces were then projected on two-dimensional MRIs, with verification of projections using three-dimensional coordinate data. Composite hippocampal surfaces show anatomical details of hippocampal substructures, including the pes hippocampi, intralimbic gyrus, and uncinate gyrus. Projection on two-dimensional MRI helps to define hippocampal anatomy in relationship to surrounding structures. Composite images highlight specific features of normal hippocampal surface anatomy, and demonstrate the structural relationship of the hippocampus to surrounding structures on MRI.

Anatomy↗

PubMed2005

Quantitative analysis of cerebral blood flow patterns in mesial temporal lobe epilepsy using composite SISCOM.

UNLABELLED: Our objective was to demonstrate common patterns of ictal cerebral blood flow changes in a group of patients with mesial temporal lobe epilepsy (MTLE) using the technique of composite subtraction ictal SPECT coregistered to MRI (SISCOM). METHODS: We retrospectively reviewed the video electroencephalography recordings, SPECT studies, and MR images of 32 MTLE patients and of a subgroup of 11 patients with pathologically verified mesial temporal sclerosis (MTS). Composite SISCOM studies were performed as previously described. The patients were grouped for analysis into those with right seizure onset and those with left seizure onset. The images of the right and left MTS subgroups were combined for analysis by rotating right MTS images to show changes on the left side. The SPECT subtractions were segmented to show regions of hyperperfusion at 1 SD above the mean. A rainbow color map was applied to the final composite SISCOM images to assist in the interpretation of results. Binomial probability was calculated to demonstrate the level of significance of perfusion changes. RESULTS: All patients demonstrated typical seizure semiology of MTLE. Seventeen patients had left MTLE and 15 patients had right MTLE. The levels of significance were set at 6 of 17 (P = 0.042) for the left MTLE group, 6 of 15 (P = 0.022) for the right MTLE group, and 5 of 11 (P = 0.021) for the MTS subgroup. Results among all groups were similar. The most-contiguous area of hyperperfusion was the anterior temporal area extending to include the insular cortex and basal ganglia, lateralizing to the side of seizure onset. CONCLUSION: Composite SISCOM studies in patients with well-localized MTLE most commonly show a region of hyperperfusion in the anterior temporal region, which often also involves the basal ganglia and insula, likely representing the primary regions of seizure propagation. Identifying this pattern of hyperperfusion as typical for mesial temporal onset seizures should assist in clinical interpretation and localization of ictal SPECT studies.

Adolescent↗

PubMed2004

MRI-based high-dimensional hippocampal mapping in mesial temporal lobe epilepsy.

MRI-based evaluation of the hippocampus is important in the assessment and treatment of patients with mesial temporal lobe epilepsy (MTLE). Using MRI-based large-deformation high-dimensional mapping (HDM-LD), which allows structural evaluation of regions of the hippocampus, we document the HDM-LD-defined pattern of hippocampal deformation in MTLE patients compared with matched controls. In 30 subjects with MTLE and confirmed medial temporal lobe sclerosis (MTS), we performed measurements of intracranial area, brain parenchymal volume and deformation-based hippocampal segmentations, and then grouped patients into right and left MTS groups (resulting in 15 subjects in each group). Using HDM-LD techniques, we compared the right and left MTS groups with a group of 15 matched controls. Analysis included both the MTS and contralateral hippocampi, and covariance for changes in brain parenchymal volume. Final results were interpreted using a segmentation showing normal hippocampal surface subfield anatomy. Comparing the MTS groups with controls, after covarying with brain parenchymal volume, the MTS hippocampi showed significant volume loss (P < 0.0001), contralateral hippocampi showed no significant volume loss. HDM-LD techniques showed significant shape changes, with marked inward deviation in the Sommer sector of the MTS hippocampi. In the contralateral hippocampi, the inferior surface of the hippocampal body showed inward deformation in the medial aspect of the subiculum, with minimal involvement of the Sommer sector. HDM-LD shows involvement of subregions of the hippocampus which are consistent with MTS histopathology. Contralateral hippocampi show different HDM-LD changes, suggesting that the underlying disease process in the contralateral hippocampi is different from MTS.

Adult↗

PubMed2004

Composite SISCOM images in mesial temporal lobe epilepsy: technique and illustration of regions of hyperperfusion.

OBJECTIVE: To outline and validate a technique for subtraction ictal single photon emission tomography (SPET) co-registered to magnetic resonance imaging (MRI) (SISCOM), which allows non-linear co-registration of groups of subtraction SPET images to a single, template image. METHODS: In patients with mesial temporal lobe epilepsy, we used linear and non-linear transformation steps to co-register ictal and interictal images to a template SPET, then used the resultant ictal and interictal images to produce subtraction images. Statistical changes in subtraction SPET before and after the transformation steps in individual subjects were documented to validate the technique. Subtraction SPET images were thresholded to include pixel values 1 standard deviation (SD) above zero, and converted to binary. Images were combined by simple addition of images to form the final composite image. Final results were co-registered to a template MRI to demonstrate the regions most commonly hyperperfused in mesial temporal lobe epilepsy. RESULTS: Linear and non-linear transformation steps induced only small changes in standard deviations of subtraction SPET, typically approximately 1 pixel value. The final composite SISCOM images showed the anterior temporal lobe, insula and basal ganglia as the most commonly hyperperfused regions during mesial temporal lobe epileptic seizures. CONCLUSION: Our technique resulted in only small changes in statistical characteristics of individual subtraction SPET studies, and was acceptable for the purpose of creating composite SISCOM images.

Algorithms↗

PubMed2004

John Hughlings-Jackson's writings on the auditory aura and localization of the auditory cortex.

PURPOSE: To relate John Hughlings-Jackson's findings of the auditory aura to his ideas about the "dreamy state," and localization of primary auditory cortex. METHODS: We reviewed Hughlings-Jackson's writings on the auditory aura and his integration of the auditory aura into his description of the "dreamy state." To integrate Hughlings-Jackson's postulations about the auditory aura and David Ferrier's localization of primary auditory cortex, we also reviewed Ferrier's localization of auditory cortex in animals. RESULTS: Hughlings-Jackson described three cases of the auditory aura, which he integrated with his concept of the "dreamy state" (now known as mesial temporal epilepsy). In doing so, he described the current concept of elementary and complex auditory auras. Hughlings-Jackson also associated the auditory aura with seizures that began in the "auditory centre of Ferrier." Whereas Ferrier showed respect and admiration for Hughlings-Jackson's work as a whole, he did not integrate Hughlings-Jackson's ideas of localization of the auditory epileptic aura with his work in localizing the primary auditory cortex in animals. CONCLUSIONS: Hughlings-Jackson outlined the modern concept of elementary and complex auditory auras and correctly correlated it with primary auditory cortex. The history of Hughlings-Jackson's auditory aura reflects the history of his ideas of epilepsy as a whole, which closely parallel our modern concepts of focal epilepsy.

Animals↗

PubMed2003

Continuous or emergent EEG: can bedside caregivers recognize epileptiform discharges?

OBJECTIVE: When emergent or continuous EEG monitoring is carried out to detect subclinical seizures, expert interpretation of the results is usually not immediately available. We assessed the ability to recognize epileptiform discharges among various nonexpert bedside caregivers. A second objective was to determine whether such skill improves with a simple educational intervention. DESIGN AND SETTING: A prospective cohort study with an educational intervention in a university-based tertiary medical center. PARTICIPANTS: All 125 neurology and neurosurgery residents, intensive care fellows, critical care and neurological floor nurses, and EEG technicians were offered participation. Of these, 50 completed the study and provided 2,398 EEG responses. INTERVENTIONS: A computer-based PowerPoint lecture designed to teach recognition of epileptiform discharges. MEASUREMENTS AND RESULTS: (a) Average number of correct responses in identifying epileptiform discharges in a computer-based pre-test consisting of 24 EEG questions. (b) Impact of the educational intervention as measured by change in the mean average score in a similar post-test. The rate of correct responses by group ranged from 46% for medical critical care nurses to 94% for EEG technicians. Overall mean correct response rate was 14.72 (61%) for the pre-test, and increased to 16.06 (67%) in for post-test (p=0.002). CONCLUSIONS: Recognition of epileptiform discharges by bedside caregivers is disturbingly low. A simple educational intervention only modestly improved such ability. Therefore we should not rely on nontrained personnel to interpret emergent or continuous recordings. EEG technicians are an exception, and their skill could be utilized during emergent studies.

Cohort Studies↗

PubMed2003

Tolerability and effects on quality of life of twice-daily extended-release carbamazepine in adults with seizure disorders: an open-label, 12- to 36-month continuation study.

BACKGROUND: An earlier 6-month, multicenter, open-label study in patients with complex partial seizures found that a switch from multiple daily doses of conventional carbamazepine (CBZ) to twice-daily CBZ extended-release capsules(CBZ-ERC) was well tolerated, with maintenance of seizure control over the study period and significant improvements in quality of life (P < 0.001). OBJECTIVE: The goal of the present study was to assess the tolerability and effects on quality of life of twice-daily CBZ-ERC over the longer term in patients with seizure disorders. METHODS: This was a multicenter, open-label assessment of the long-term(12-36 months) tolerability and quality-of-life effects of twice-daily CBZ-ERC given at a daily dose equivalent to the daily dose of CBZ taken before study en-try. The regimen could be adjusted as clinically indicated up to a daily dose of 1600 mg. Patients could receive up to 2 other antiepileptic drugs during the study. RESULTS: One hundred eighteen patients were enrolled. In patients completing>12 months of study therapy, a significant decrease in the highest mean 2-day frequency of generalized tonic-clonic seizures was observed over the first 12 months (P = 0.005). The significant improvements in quality of life achieved in the earlier study were maintained during the present study. Of 37 patients who were discontinued from the study, 9 met criteria mandating withdrawal from the study due to exacerbation of seizures. Three patients were discontinued from the study for adverse events judged to be unrelated to study drug. Low incidences of rash (3.4%) and weight gain (0.8%) were reported. CONCLUSIONS: In this population of adults with seizure disorders, CBZ-ERC twice daily was well tolerated during 12 to 36 months of open-label treatment,with no increase in seizure frequency or decrease in quality of life.

Adolescent↗

PubMed2003

Hippocampal deformation-based shape analysis in epilepsy and unilateral mesial temporal sclerosis.

PURPOSE: To assess shape changes in patients with mesial temporal sclerosis (MTS) and temporal lobe epilepsy (TLE), by using deformation-based hippocampal shape analysis. METHODS: We retrospectively reviewed magnetic resonance imaging (MRI) studies in 30 subjects with unilateral MTS (15 right-sided MTS, 15 left-sided MTS) and TLE. We defined the "average" hippocampus in the right- and left-MTS groups by generating a mean transformation for the 15 deformation images in each group. Further to quantify the difference between the hippocampi, we coregistered the mean transformation of the involved hippocampus (with MTS) to the contralateral hippocampus, considering the left- and right-MTS groups independently. We generated a color "flame" scale showing degrees of outward and inward deviation of the coregistered hippocampi. RESULTS: Both the right- and left-MTS groups showed similar shape changes, with maximal inward deformation in the medial and lateral hippocampal head and the hippocampal tail. However, more extensive involvement was seen in the lateral hippocampal body in the right-MTS group as compared with the left. CONCLUSIONS: Deformation-based hippocampal shape analysis shows specific regions of hippocampal surface anatomy that are most affected in MTS. This technique may aid in detection of clinically significant anatomic abnormalities of the hippocampus in patients with epilepsy.

Adolescent↗

PubMed2003

The "dreamy state": John Hughlings-Jackson's ideas of epilepsy and consciousness.

OBJECTIVE: The authors review John Hughlings-Jackson's writings on the "dreamy state" and his subsequent derivation of degrees of consciousness. METHOD: They reviewed the publications of Hughlings-Jackson from his initial description of the "dreamy state" in 1876 until his writing about the "uncinate group of fits" in 1899. They then examined Hughlings-Jackson's use of the associated signs and symptoms of the "dreamy state" to formulate his ideas about human consciousness. RESULTS: Hughlings-Jackson defined the "dreamy state" as "over-consciousness," or a heightened intellectual state. He described associated symptoms of "crude sensations" of smell and taste, an unusual epigastric sensation, chewing and lip smacking, automatisms, postictal symptoms, and at least some degree of alteration of consciousness. Using his observations of the "dreamy state" as a model, Hughlings-Jackson proposed three degrees of consciousness, each with an object and subject component. CONCLUSIONS: Through his description of the "dreamy state," Hughlings-Jackson accurately characterized and localized medial temporal epilepsy. Correlating the ictal semiology of the "dreamy state" with consciousness, he developed a theory of consciousness that remains relevant to current understanding of the mind-brain relationship.

Brain↗

PubMed2002

The usefulness of subtraction ictal SPECT coregistered to MRI in single- and dual-headed SPECT cameras in partial epilepsy.

PURPOSE: To prove the clinical usefulness of SISCOM and compare SISCOM images derived from single- and dual-headed single-photon computed tomography (SPECT) cameras for localization of partial epileptic seizures. METHODS: We retrospectively studied 38 partial epilepsy patients, using subtraction SPECT coregistered to magnetic resonance imaging (MRI; SISCOM). SPECT imaging of the first 15 patients was performed by single-headed camera, and the next 23 patients by dual-headed camera. Side-by-side ictal-interictal SPECT evaluation and SISCOM images were blindly reviewed and classified as either localizing to one of 16 sites or nonlocalizing. A third reviewer evaluated cases of disagreement between primary reviewers. Results were compared with seizure localization by any of the following three traditional techniques: surgical outcome, invasive, and noninvasive video-EEG monitoring. The results from the single- and dual-headed SPECT cameras were compared. RESULTS: Reviewers localized areas of hyperperfusion with SISCOM images more often than with side-by-side SPECT evaluation (71.0 vs. 47.4%; p = 0.01). When we compared results of SPECT evaluation with traditional techniques, SISCOM showed greater concordance than side-by-side SPECT evaluation (60.53 vs. 36.84%; p = 0.006). There were no differences in localization between images derived from single- and dual-headed cameras. Concordance of seizure localization, compared with traditional techniques, also was not different between these groups [kappa = 0.38, 95% confidence interval (CI), 0.18-0.58] vs. kappa = 0.63, 95% CI (0.45-0.81)]. CONCLUSIONS: SISCOM is a worthwhile technique for preoperative evaluation in partial epilepsy patients and improves the sensitivity and specificity of seizure localization of SPECT images derived from both single- and dual-headed SPECT cameras.

Adolescent↗

PubMedDate not supplied

Hippocampal shape analysis in status epilepticus associated with acute encephalitis.

We performed MR imaging deformation-based hippocampal shape analysis in a 28-year-old woman in whom status epilepticus developed after acute encephalitis. Hippocampal shape analysis revealed severe global bilateral hippocampal atrophy. Regional volume loss was most accentuated in the medial and lateral aspects of the hippocampal head; the loss was similar to shape changes in hippocampal sclerosis of chronic temporal lobe epilepsy. This deformation pattern may reflect a common pathologic process that causes hippocampal volume loss in both of these conditions.

Adult↗