Frontal intermittent rhythmic delta activity (FIRDA): is there a clinical significance in children and adolescents?

BACKGROUND: Frontal intermittent rhythmic delta activity (FIRDA) has been studied extensively in adults but published literature about its clinical correlates in children and adolescents is comparatively limited. AIMS: This study was performed to find more evidence regarding the clinical significance of this electrographic pattern in the pediatric population. METHODS: All electroencephalograms (EEGs) with FIRDA between 07/01/2006 and 12/31/2009 at our institution were identified. Clinical data were collected from charts of patients with FIRDA. A comparison group consisting of patients matched for age and location was assembled. RESULTS: We identified 26 EEGs in 22 patients with this electrographic pattern from a total of 4627 EEGs. All 26 EEGs were performed because of a history of seizures or to rule out seizures. Two of the 22 patients did not have evaluable clinical data. Of the remaining, 18 had seizures. The events in 2 patients were determined to be non epileptic. Amongst the 18 patients with seizures, 10 had associated epileptiform discharges and only 2 were without epileptiform activity or localizing or lateralizing features. Two patients had brain tumor. Six patients had hydrocephalus. Three patients had encephalopathy due to anoxic, metabolic or infectious etiology. There was no statistically significant difference between the study and the comparison group for occurrence of brain tumor, hydrocephalus or encephalopathy. CONCLUSIONS: FIRDA was uncommonly observed. It was associated with a variety of conditions and was not a specific marker of brain tumor, hydrocephalus or encephalopathy.

Clinical associations of occipital intermittent rhythmic delta activity.

Association of occipital intermittent rhythmic delta activity with absence seizures has been well documented in the published literature. Two recent studies have also described an association with focal seizures. After obtaining approval from our Institutional Review Board, all electroencephalograms with occipital intermittent rhythmic delta activity at our institution between July 1, 2006 and December 31, 2009 were identified. Charts of these patients were reviewed to collect clinical data. A matched comparison group was assembled. Thirty-one of the patients who met criteria had evaluable clinical data. Fifteen had generalized seizures (9 absence; 2 tonic-clonic; 3 absence and tonic-clonic; 1 absence, tonic-clonic, myoclonic, and atonic). Eleven had focal seizures. One had both generalized tonic-clonic and focal seizures. Events in 1 were nonepileptic in nature. Documentation was inadequate for seizure classification in 3. There was a statistically significant difference between the study and comparison groups for absence seizures, but not for focal seizures.

5-HT1A receptor binding in temporal lobe epilepsy patients with and without major depression.

BACKGROUND: Major depressive disorder (MDD) is the most common comorbid psychiatric condition associated with temporal lobe epilepsy (TLE). Preclinical and clinical studies suggest that 5-HT(1A) receptors play a role in the pathophysiology of both TLE and MDD. There is preliminary evidence for an association between decreased 5-HT(1A) receptor binding in limbic brain areas and affective symptoms in TLE patients. The objective of this study was to compare 5-HT(1A) receptor binding between TLE patients with and without MDD. For the first time, 5-HT(1A) receptor binding was measured in a sample large enough to permit sensitive comparisons between TLE patients with and without comorbid MDD diagnosed by clinical and structured psychiatric interviews. METHODS: Thirty-seven epilepsy patients with temporal lobe foci confirmed by ictal video-electroencephalogram (EEG) monitoring were recruited from the Clinical Epilepsy Section, National Institute of Neurological Disorders and Stroke. We performed interictal positron emission tomography scanning, with [(18)F]FCWAY, a fluorinated derivative of WAY100635, on a GE Medical Systems (Waukesha, Wisconsin) Advance scanner with continuous EEG monitoring. The 5-HT(1A) receptor binding was estimated by partial volume-corrected [(18)F]FCWAY V/f(1) values. RESULTS: In addition to decreased 5-HT(1A) receptor binding in the epileptic focus itself, comorbid MDD was associated with a significantly more pronounced reduction in 5-HT(1A) receptor binding in TLE patients, extending into non-lesional limbic brain areas outside the epileptic focus. Focus side and the presence of mesial temporal sclerosis were not associated with the presence of comorbid depression. CONCLUSIONS: Reductions in 5-HT(1A) receptor binding might help elucidate the neurobiological mechanisms underlying the TLE-MDD comorbidity.

5-HT 1A receptors are reduced in temporal lobe epilepsy after partial-volume correction.

UNLABELLED: Preclinical studies suggest that serotonin 1A receptors (5-HT 1A) play a role in temporal lobe epilepsy (TLE). Previous PET studies reported decreased 5-HT 1A binding ipsilateral to epileptic foci but did not correct for the partial-volume effect (PVE) due to structural atrophy. METHODS: We used PET with 18F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl-N-(2-pyridyl)cyclohexanecarboxamide (18F-FCWAY), a 5-HT 1A receptor antagonist, to study 22 patients with TLE and 10 control subjects. In patients, 18F-FDG scans also were performed. An automated MR-based partial-volume correction (PVC) algorithm was applied. Psychiatric symptoms were assessed with the Beck Depression Inventory Scale. RESULTS: Before PVC, significant (uncorrected P < 0.05) reductions of 18F-FCWAY binding potential (BP) were detected in both mesial and lateral temporal structures, mainly ipsilateral to the seizure focus, in the insula, and in the raphe. Group differences were maximal in ipsilateral mesial temporal regions (corrected P < 0.05). After PVC, differences in mesial, but not lateral, temporal structures and in the insula remained highly significant (corrected P < 0.05). Significant (uncorrected P < 0.05) BP reductions were also detected in TLE patients with normal MR images (n = 6), in mesial temporal structures. After PVC, asymmetries in BP remained significantly greater than for glucose metabolism in hippocampus and parahippocampus. There was a significant inverse relation between the Beck Depression score and the ipsilateral hippocampal BP, both before and after PVC. CONCLUSION: Our study shows that in TLE patients, reductions of 5-HT 1A receptor binding in mesial temporal structures and insula are still significant after PVC. In contrast, partial-volume effects may be an important contributor to 5-HT 1A receptor-binding reductions in lateral temporal lobe. Reduction of 5-HT 1A receptors in the ipsilateral hippocampus may contribute to depressive symptoms in TLE patients.

Brain incorporation of 11C-arachidonic acid, blood volume, and blood flow in healthy aging: a study with partial-volume correction.

UNLABELLED: PET with 11C-arachidonic acid (AA) can be used to quantify neural signaling related to phospholipase A2 (PLA2). Animal studies suggest reduction in the activity of this signaling system with age. The aim of this study was to evaluate the effect of healthy aging on brain incorporation of 11C-AA, before and after partial-volume correction (PVC). METHODS: Absolute measurements of cerebral blood flow (CBF) were obtained in 8 young and 7 old healthy subjects (mean age +/- SD, 27 +/- 5 y and 65 +/- 9 y) with bolus injection of 15O-water. About 15 min later, dynamic 60-min 3-dimensional scans were acquired after the injection of 11C-AA. Radioactivity frames of 11C-AA were corrected for head motion and registered to magnetic resonance (MR) images. A 3-segment (3S) and a 2-segment (2S) PVC was applied pixel-by-pixel to the activity frames. For the 3S method, the white matter value was estimated using a new automatic method by extrapolating the activity values of pixels with white matter membership > 0.99. Parametric images of the brain incorporation rate of 11C-AA (K*) and cerebral blood volume (Vb), as well as CBF, were generated and regional gray matter values were obtained. RESULTS: Among cortical areas, there were no significant differences (uncorrected P < 0.05) in K* or Vb absolute values between young and old subjects before or after PVC. A significant reduction of CBF was detected in the frontal cortex of the elderly group. After normalization to the global gray average, K*, Vb, and CBF values revealed significant reductions in the frontal lobe of old subjects; none of these differences were significant after PVC. CONCLUSION: These results confirm previous PET findings that brain function at rest is minimally affected by healthy aging. Proper PVC methodology is of critical importance in accurate quantitative assessment of PET physiologic measures.

Epilepsy duration, febrile seizures, and cerebral glucose metabolism.

PURPOSE: Studies using magnetic resonance imaging have shown that reduced hippocampal volume is associated with a history of febrile seizures, the duration of epilepsy, and the number of generalized tonic-clonic seizures. It is uncertain whether these factors have the same influence on functional as on structural measures of the integrity of the epileptogenic zone. METHODS: We used positron emission tomography (PET) with fluorine 18 2-deoxyglucose to study 91 patients with temporal lobe seizure foci localized by ictal video-EEG. PET was performed in the awake interictal resting state with ears plugged and eyes patched. We recorded surface EEG during injection (5 mCi) and the 30-min uptake period. We used a standard template to analyze PET scans. RESULTS: A significant negative relation was found between the duration of epilepsy and hippocampal glucose metabolism ipsilateral to the epileptic focus. Patients with a history of either any febrile seizures, or complex, or prolonged febrile seizures, did not have greater hypometabolism ipsilateral to the epileptic focus than did patients without a febrile seizure history. We found no effect of generalized tonic-clonic seizure history. CONCLUSIONS: Longer epilepsy duration is associated with greater hypometabolism, suggesting that epilepsy is a progressive disease.

Cortical dysplasia and epilepsy: functional imaging using single photon emission computed tomography and positron emission tomography.

Functional imaging using single photon emission CT and positron emission tomography have made important contributions to the evaluation of patients with medically intractable epilepsy and cortical dysplasia by identifying patients who previously were not considered surgical candidates. This article reviews the role of functional imaging in the presurgical evaluation of this patient population.