Kevan E. VanLandingham

Hippocampal MRI signal hyperintensity after febrile status epilepticus is predictive of subsequent mesial temporal sclerosis.

OBJECTIVE The objective of our study was to test the hypothesis that the finding of hyperintense hippocampal signal intensity on T2-weighted MR images soon after febrile status epilepticus is associated with subsequent hippocampal volume loss and persistent abnormal signal intensity on T2-weighted images (i.e., mesial temporal sclerosis). SUBJECTS AND METHODS Eleven children (mean age, 25 months) underwent initial MRI that included coronal temporal lobe imaging within 72 hours of febrile status epilepticus and follow-up imaging from 3 to 23 months later (mean, 9 months). A neuroradiologist blinded to clinical history graded initial and follow-up hippocampal signal intensity on a scale from 0 (normal) to 4 (markedly increased). Two blinded observers measured hippocampal volumes on initial and follow-up MR studies using commercially available software and volumes from 30 healthy children (mean age, 6.3 years). Initial signal intensity and hippocampal volume changes were compared using Kendall tau correlation coefficients. RESULTS On initial imaging, hyperintense signal intensity ranging from 1 (minimally increased) to 4 (markedly increased) was seen in seven children. Four children had at least one hippocampus with moderate or marked signal abnormality, three children had a hippocampus with mild or minimal abnormality, and four children had normal signal intensity. The Kendall tau correlation coefficient between signal intensity increase and volume change was -0.68 (p < 0.01). Five children (two with temporal lobe epilepsy and two with complex partial seizures) had hippocampal volume loss and increased signal intensity on follow-up imaging, meeting the criteria for mesial temporal sclerosis. CONCLUSION MRI findings of a markedly hyperintense hippocampus in children with febrile status epilepticus was highly associated with subsequent mesial temporal sclerosis.

Do prolonged febrile seizures produce medial temporal sclerosis? Hypotheses, MR1 evidence and unanswered questions

Whether or not severe febrile seizures in infancy cause hippocampal injury and subsequent medial temporal sclerosis is an often debated question in epilepsy. Recent magnetic resonance imaging (MRI) of infants suffering from febrile seizures has provided preliminary evidence that abnormally increased T2 signal intensity can be seen in the hippocampi of infants following prolonged and focal febrile seizures. Follow-up MRIs in a few of these infants have confirmed that medial temporal sclerosis can develop following these acute MRI signal changes. In this article, we review the hypotheses and MRI evidence relating to hippocampal injury during prolonged febrile seizures and the later development of medial temporal sclerosis.

Fast Spin-Echo, Magnetic Resonance Imaging-Measured Hippocampal Volume: Correlation with Neuronal Density in Anterior Temporal Lobectomy Patients

Summary: To assess the value of magnetic resonance imaging (MRI)‐measured hippocampal volume in the detection of hippocampal sclerosis, we studied 28 patients undergoing anterior temporal lobectomy for medically intractable mesial temporal lobe epilepsy. Hippocampal volumetry and visual analysis of T2 signal change were performed using fast spin‐echo T2‐weighted MRI. Quantitative neuronal density measurements were performed in the resected hippocampal specimens. There was a significant correlation between MRI‐measured absolute hippocampal volume (AHV) and neuronal density in CA1, CA2, and CA3 subfields (p<0. 0001, p < 0.01, and p < 0.05, respectively). Differential hippocampal volume (side‐to‐side volume difference) failed to detect bilateral atrophy in three patients, but the bilateral hippocampal atrophy was recognized by considering AHV in these patients. This study suggests that MRI‐measured AHV can be of value in evaluating patients with mesial temporal lobe epilepsy, especially when there is no side‐to‐side difference in hippocampal volumetry.

Characteristics of valproic acid resistant juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is often exquisitely responsive to treatment with valproic acid (VPA). However, a subset of patients does not respond to this medication and often has intractable seizures. We wanted to identify differences between these two subsets of JME patients. Charts of all JME patients followed at the Duke Epilepsy Center were reviewed. Clinical parameters, electroencephalogram (EEG) findings and magnetic resonance imaging (MRI) data were reviewed. These features were compared between patients with VPA sensitive and VPA resistant JME. Thirty-three patients with JME were identified: 23 (70%) were VPA sensitive (13 females, 10 males; mean age of onset 15.9 years) and 10 (30%) were VPA resistant (5 females, 5 males; mean age of onset 14.1 years). The VPA resistant group had a higher frequency of EEG asymmetries (40% vs. 10%); atypical seizure characteristics including auras and post-ictal confusion (30% vs. 4%); and intellectual deficiency (20% vs. 0%). Clinical characteristics combined with EEG data may help in predicting which JME patients will respond favorably to VPA. This study also raises the issue whether VPA resistant JME is in fact a localization-related epilepsy.

Slow wave sleep rebound and REM rebound following the first night of treatment with CPAP for sleep apnea: correlation with subjective improvement in sleep quality.

Objective: The purpose of this study was to correlate changes in PSG parameters between the diagnostic polysomnogram (dPSG) and the first night of treatment with continuous positive airway pressure (CPAP) (cpapPSG) to subjective improvement in sleep quality.Background: In patients with obstructive sleep apnea syndrome (OSAS), therapy with CPAP results in reduction of sleep latency, stage 1 sleep, arousal index (Al) and respiratory disturbance index (RDI), and increase in stage 2 sleep, REM sleep and REM density. No data exists on the differences in polysomnographic (PSG) parameters in patients who have subjective improvement in sleep quality and those who do not.Methods: We retrospectively reviewed PSG studies of 44 patients with OSAS who presented to the Sleep Disorders Center at Duke University Medical Center. Patients qualitative assessment of sleep was noted using a Likert-type scale administered the morning after the dPSG and cpapPSG. PSG indices of patients noting subjective improvement were compared to those with no improvement.Results: Patients noting a subjective improvement in sleep quality showed a decrease in the percentages of stage 1 sleep (P<0.001) and an increase in percentages of stages 3 and 4 sleep (slow wave sleep rebound; P<0.007) and stage REM sleep (REM rebound; P<0.008).

Extrahippocampal Involvement in Human Herpesvirus 6 Encephalitis Depicted at MR Imaging

PURPOSE To test the hypothesis that patterns of signal intensity abnormality in human herpesvirus 6 (HHV6)-positive patients would allow distinction from patients who did not test positive for HHV6 encephalitis. MATERIALS AND METHODS This retrospective study was performed with institutional review board committee approval by using a waiver of informed consent. Sixteen immunocompromised patients (nine males, seven females; age range, 2-39 years) underwent magnetic resonance (MR) imaging and cerebrospinal fluid polymerase chain reaction (PCR) testing for HHV6 DNA on the basis of clinical findings suspicious for encephalitis. MR images acquired during acute illness were examined without knowing PCR results. RESULTS Nine patients were HHV6 positive. Seven showed signal intensity abnormalities, with prominent involvement of the hippocampus, and six showed additional involvement of the amygdala. Three HHV6-positive patients showed signal intensity abnormality in extrahippocampal divisions of the olfactory cortex and cortical and subcortical structures that maintain prominent connections with the hippocampal formation. Among the seven HHV6-negative patients, six had abnormalities in the hippocampus but only two showed extrahippocampal involvement, which was restricted to the amygdala. CONCLUSION Most patients with HHV6 encephalitis have signal intensity abnormalities in the hippocampal formation and amygdala and, contrary to prior reports, some also have involvement of limbic structures outside of the medial temporal lobe. The presence of MR signal intensity abnormality in the medial temporal lobe should raise the diagnosis of HHV6 encephalitis in immunosuppressed patients, especially when hyperintense lesions are seen in the insular region and inferior frontal lobe.

Migratory leptomeningeal inflammation with relapsing polychondritis

We report a case of relapsing polychondritis with focal sensorimotor seizures, aseptic meningitis, and migratory leptomeningeal enhancement on contrast MRI. These abnormalities on imaging studies correlated accurately with laterality of the patients seizures, facilitating early aggressive management of his neurologic symptoms.

Self‐sustaining limbic status epilepticus.: II. Role of hippocampal commissures in metabolic responses

In prior work, we developed a model of self-sustaining limbic status epilepticus (SSLSE) induced by continuous hippocampal stimulation (CHS). Previous electrographic studies showed that SSLSE was synchronized between the cerebral hemispheres. On the basis of this initial work, we postulated that hippocampal commissures were critical for the initiation and maintenance of SSLSE. In the current experiments, we tested this hypothesis by applying CHS in animals with (CMX) or without (— CMX) hippocampal commissurotomies. In the — CMX group, electrographic SSLSE was synchronized between the stimulated and contralateral sides. In the CMX group, SSLSE developed only on the stimulated sides. Regional cerebral glucose utilization (RCGU) was also studied acutely (1 hour) after CHS using 2-deoxyglucose autoradiography. In the — CMX group, there was symmetrically increased RCGU in the hippocampus, retrohippocampal structures, and associated limbic and subcortical nonlimbic regions. In the CMX group, a similar pattern was found, but confined to the side of stimulation. CMX alone did not change RCGU values from those in control (— CMX, nonstimulated) brain in any of the regions studied. Areas of bilateral neocortical hypometabolism were found in both (CMX and —CMX) SSLSE groups. These results lead to rejection of the hypothesis that hippocampal commissures play an essential role in the initiation and maintenance of SSLSE. Instead, a feedback circuit involving the hippocampus and its adjacent structures seems to be the critical anatomic substrate for SSLSE. The presence of neocortical hypometabolism after CMX indicates that the structures other than the hippocampal commissure (eg, the thalamus or other forebrain commissures) mediate this effect.

Lateralized seizure termination: relationship to outcome following anterior temporal lobectomy☆

Determination of side of seizure onset is critical for a successful outcome following epilepsy surgery. Little is known about the significance of lateralized seizure termination. Sustained seizure activity contralateral to side of seizure onset, following termination of ictal activity ipsilateral to side of onset, may suggest the presence of an independent focus. Such activity, if present, should predict a poor outcome. We studied side of seizure termination in 13 patients undergoing monitoring with bitemporal depth electrodes and correlated this to outcome following anterior temporal lobectomy (ATL). Side of seizure onset was determined for all seizures during that evaluation. Based on side of final cessation of ictal activity, patients were classified as having ipsilateral final termination or simultaneous termination (Group 1; N=6) or contra-lateral or mixed final termination (Group 2; N=7). The Duke outcome classification system was used. At the end of 2 years follow-up, 6/6 patients in Group 1 and 3/7 patients in Group 2 were seizure free. We conclude that lateralized seizure termination during evaluation with depth electrodes may be useful in predicting outcome following ATL. Continued seizure activity contralateral to side of seizure onset (following termination of ictal activity ipsilateral to side of onset) predicts a poor outcome. This may indicate the presence of an independent seizure focus opposite to the side of surgery.

Succinylcholine induced hyperkalemia and cardiac arrest death related to an EEG study.

Changes in EEGs during cardiac arrest have been described in detail by many authors; however, mortality because of an EEG has never been reported. The authors report the case of a patient who developed cardiac arrest causally related to administration of succinylcholine for reduction of excessive amounts of myogenic artifact during an EEG. This case indicates the need for caution when doing an EEG study in an intensive care unit setting.