Magnetic resonance imaging of patients with epilepsy

New MRI Finding in Migraineurs: Mesial Temporal Sclerosis

Background:

Based on our experience, a noticeable number of migraineurs without history of epilepsy disclose mesial temporal sclerosis (MTS) on their brain MRI.

Objective:

This prospective study was conducted to assess the frequency of MTS in migraineurs and also determine the ratio of unilateral and bilateral cases.

Material and Methods:

In this cross sectional study, the frequency of MTS in MRI of 84 migraine patients, who had symptoms for at least 2 years, assessed. Brain MRI was done with T1 and T2 weighted protocols. Two radiologists separately interpreted findings, defining MTS as presence of any of hippocampal atrophy, increased T2 signal of hippocampus, decreased T1 signal of hippocampus or loss of internal architecture. Patients who radiologists had not agreement on their diagnoses excluded. Stat analysis done using ‘N - 1’ chi squared test.

Results:

Eleven patients were excluded due to non-accordant interpretation of MRI findings by the two examining radiologists. MTS was detected in 14 out of 73 patients (19%). Bilateral involvement of mesial temporal lobe was seen in 6 (8%) patients (M 67%, F 33%). Five cases (7%) had unilateral left MTS (M 67%, F 33%) while 3 (4%) were affected with right-sided MTS (M 33%, F 67%). These findings highly suggest association of MTS and Migraine (P-value <0.0001).

Conclusion:

While MTS is a prevalent finding in migraineurs, incidental finding of MTS in MRI should suspect physicians of migraine as well as temporal lobe epilepsy. MTS can be proposed as an etiology of migraine but most likely, consequence of it.

Comparison of electroencephalographic findings with hippocampal magnetic resonance imaging volumetry in dogs with idiopathic epilepsy

BACKGROUND

In humans, temporal lobe epilepsy (TLE), is a type of focal epilepsy occurring mainly in the mesial TLE (mTLE), commonly associated with hippocampal sclerosis (HS).

OBJECTIVES

According to recent studies, TLE might also occur in dogs and could be associated with hippocampal atrophy (HA)/HS. To date, hippocampal lesions have not been correlated with electroencephalographic (EEG) findings in epileptic dogs.

ANIMALS

An EEG examination, brain magnetic resonance imaging, and volumetric assessment of the hippocampus were performed in 16 nonepileptic and 41 epileptic dogs.

METHODS

In this retrospective study, the presence and localization of EEG-defined epileptiform discharges (EDs) was blindly evaluated. The hippocampus was measured and assessed for unilateral atrophy. The results of EEG and volumetric findings were correlated to determine whether the functional epileptic focus is equivalent to structural changes.

RESULTS

The median hippocampal asymmetric ratio (AR) in epileptic dogs was significantly greater than in the control group (P < .001). Using a cut-off threshold AR of >6%, 56% (23/41) of the dogs were characterized with unilateral HA. Of those animals, 35% (8/23) had EDs in the temporal leads and 26% (6/23) had no EDs. In 88% (7/8) of dogs with EDs in the temporal leads that had unilateral HA, the EDs correlated with the side of the decreased hippocampal volume.

CONCLUSIONS AND CLINICAL IMPORTANCE

The results indicate an association between the presence of EDs detectable on EEG and a decrease in the unilateral hippocampal volume in some cases of canine idiopathic epilepsy that might reflect features of human mTLE.

Yield of Brain MRI in Clinically Diagnosed Epilepsy in the Kingdom of Bhutan: A Prospective Study

BACKGROUND

People with epilepsy (PWE) in low- and middle-income countries may not access the health resources that are considered optimal for epilepsy diagnosis. The diagnostic yield of magnetic resonance imaging (MRI) has not been well studied in these settings.

OBJECTIVES

To report the diagnostic yield of brain MRI and identify clinical associations of abnormal MRI findings among PWE in a neurocysticercosis-endemic, resource-limited setting and to identify the proportion and putative structural brain causes of drug-resistant epilepsy.

METHODS

PWE were prospectively enrolled at the Jigme Dorji Wangchuck National Referral Hospital in Bhutan (2014-2015). Each participant completed clinical questionnaires and a 1.5-Tesla brain MRI. Each MRI was reviewed by at least 1 radiologist and neurologist in Bhutan and the United States. A working definition of drug-resistant epilepsy for resource-limited settings was given as (a) seizures for >1 year, (b) at least 1 seizure in the prior year, and (c) presently taking 2 or more antiepileptic drugs (AEDs). Logistic regression models were constructed to test the cross-sectional association of an abnormal brain MRI with clinical variables.

FINDINGS

A total of 217 participants (125 [57%] female; 54 [25%] < 18 years old; 199 [92%] taking AEDs; 154 [71%] with a seizure in the prior year) were enrolled. There was a high prevalence of abnormal brain MRIs (176/217, 81%). Mesial temporal sclerosis was the most common finding (n = 115, 53%, including 24 children), exceeding the number of PWE with neurocysticercosis (n = 26, 12%, including 1 child) and congenital/perinatal abnormalities (n = 29, 14%, including 14 children). The number of AEDs (odds ratio = .59, P = .03) and duration of epilepsy (odds ratio = 1.11, P = .02) were significantly associated with an abnormal MRI. Seizure in the prior month was associated with the presence of mesial temporal sclerosis (odds ratio = .47, P = .01). A total of 25 (12%) participants met our definition of drug-resistant epilepsy, with mesial temporal sclerosis (n = 10), congenital malformations (n = 5), and neurocysticercosis (n = 4) being the more common findings.

CONCLUSIONS

The prevalence of abnormalities on brain MRI for PWE in resource-limited settings is high as a result of a diffuse range of etiologies, most commonly mesial temporal sclerosis. Drug-resistant epilepsy accounted for 12% of the referral population in a conservative estimation.

Hippocampal volumetry: Normative data in the Indian population

BACKGROUND

Mesial temporal sclerosis (MTS) is the most common cause of temporal lobe epilepsy. Quantitative analysis of the hippocampus using volumetry is commonly being used in the diagnosis of MTS and is being used as a marker in prognostication of seizure control. Although normative data for hippocampal volume (HV) is available for the western population, no such data is available for the Indian population.

AIM

The aim of the study was to establish normative data for HV for the Indian population, which can aid in the accurate diagnosis of MTS.

MATERIALS AND METHODS

Magnetic resonance imaging (MRI) scans of 200 healthy volunteers were acquired using a 3 Tesla (3T) MRI scanner. Manual segmentation and volumetry was done using Siemens Syngo software. The data was analyzed using two tailed t-test to detect associations between HV and age, gender, and education. The data so obtained was also correlated with the data available from the rest of the world.

RESULTS

A mean HV of 2.411 cm(3) (standard deviation -0.299) was found in the study, which was significantly smaller when compared to the data from the western population. The right hippocampus was larger than the left, with a mean volume of 2.424 cm(3) and 2.398 cm(3), respectively. HV was detected to be significantly higher in males. No association was found between HV and age and education.

CONCLUSION

The values obtained in this study may be adopted as a standard in the evaluation of patients with intractable epilepsy.

Proton magnetic spectroscopy agreed better with magnetic resonance image to lateralization of epileptogenic zone than with surface electroencephalography

OBJECTIVE

To analyze the agreement rate of proton magnetic spectroscopy with magnetic resonance image (MRI) and surface electroencephalography (EEG) in extratemporal neocortical epilepsies.

METHODS

A cross-sectional study, type series of cases included 33 patients, age range 13-59 years old, of both gender, presenting structural alteration identified by MRI (75.8%) or by neurophysiologic techniques (72.7%). The variables were alterations of N-acetyl-aspartate/choline, N-acetyl-aspartate/creatine, choline/creatine, and N-acetyl-aspartate/cho-line+creatine coefficient of asymmetry.

RESULTS

Agreement rates of lateralization by coefficient of asymmetry of NAA/Cho, NAA/Cr, Co/Cr, and NAA/Cho+Cr with MRI, independent of alteration of surface EEG, were equal to 93.3, 57.9, 15.4, and 93.3%, respectively, modifying to 100, 33.3, 0, and 100%, in 16 patients, with lateralization agreement of MRI and surface EEG.

CONCLUSION

Proton magnetic spectroscopy agreed better with MRI to lateralization of epileptogenic zone than with surface EEG.

Diagnostic methods for extra-temporal neocortical focal epilepsies: present and future

The progress of epilepsies diagnosis has been great, but, amongst the diagnostic detailing that demand research, one of the most important is the essential lateralization and localization of epileptogenic zone, considered as the cerebral cortex region, that removed, will result in a free state of seizures. The present study aims to analyze the possible uses of proton spectroscopy for clinical and pre-surgical evaluation of focal extratemporal epilepsies, since this group presents the highest difficulty degree for lateralizing and locating epileptogenic zones. In almost all cases, a non invasive diagnosis can be performed using routine electroencephalography, video-electroencephalography - considered as gold standard, and magnetic resonance imaging. However, when the results of these exams are contradictory, some patients need invasive techniques, as the intra-cranial video-EEG, using deep electrodes, sub-dural strip and grid, that are associated with increased diagnostic cost and risk of complications, as cerebral hemorrhages and intra-cranial infections. Proton spectroscopy appears as a possibility, given its capacity to evaluate cerebral metabolism, by N-acetyl-aspartate (NAA), creatine (Cre) and choline (Cho) concentrations, amongst other metabolites. This non invasive method may provide time reduction of this evaluation and reliable level improvement for this topographical diagnosis.

Environmental risk factors for attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is the most common cognitive and behavioural disorder diagnosed among school children. It is characterized by deficient attention and problem solving, along with hyperactivity and difficulty withholding incorrect responses. This highly prevalent disorder is estimated to affect 5-10% of children and in many cases, persists into adulthood, leading to 4% prevalence among adults. Converging evidence from epidemiologic, neuropsychology, neuroimaging, genetic and treatment studies shows that ADHD is a valid medical disorder. The majority of studies performed to assess genetic risk factors in ADHD have supported a strong familial nature of this disorder. Family studies have identified a 2- to 8-fold increase in the risk for ADHD in parents and siblings of children with ADHD. Various twin and adoption studies have also highlighted the highly genetic nature of ADHD. In fact the mean heritability of ADHD was shown to be 0.77, which is comparable to other neuropsychiatric disorders such as schizophrenia or bipolar disorder. However, several biological and environmental factors have also been proposed as risk factors for ADHD, including food additives/diet, lead contamination, cigarette and alcohol exposure, maternal smoking during pregnancy, and low birth weight. Many recent studies have specifically examined the relationships between ADHD and these extraneous factors. This review describes some of these possible risk factors.

CONCLUSION

Although a substantial fraction of the aetiology of ADHD is due to genes, the studies reviewed in this article show that many environmental risk factors and potential gene-environment interactions also increase the risk for the disorder.

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.

Prevalence, Incidence, and Etiology of Epilepsies in Rural Honduras: The Salama Study

PURPOSE

Determination of epilepsy etiology in population-based studies is difficult because of the high cost of diagnostic tests. However, cost-effectiveness may be proven if preventive public-health strategies can be established from the test results. We report an epilepsy population-based study using clinical and laboratory techniques.

METHODS

A medical team administered an epilepsy survey to 88% of the residents by census in the rural county of Salamá, Honduras. Ninety of 100 participants identified with active epilepsy underwent a neurologic examination, video-electroencephalography (video-EEG), brain computed tomography (CT) scan, and serum enzyme-linked immunoelectrotransfer blot (EITB) for cysticercosis. Final diagnoses were based on the International League Against Epilepsy classifications for seizures and epilepsy syndromes. Combined epidemiologic, clinical, video-EEG, neuroimaging, and serum EITB assays were used for the diagnosis of epilepsy etiologies.

RESULTS

Among 6,473 residents surveyed, 151 persons with epilepsy (prevalence rate, 23.3/1,000) were identified, 100 of whom had active epilepsy (15.4/1,000) on the prevalence day. Incidence was determined to be 92.7/100,000. Partial seizures with or without secondary generalization were common (92.2%). Symptomatic epilepsy (62%) was primarily due to neurocysticercosis (37%), perinatal brain damage (8%), post-traumatic (3%), and poststroke (2%). Eight percent were idiopathic, and 30% were cryptogenic (unknown cause).

CONCLUSIONS

Symptomatic epilepsies primarily explained the high prevalence and incidence of epilepsy in Salamá. Integration of video-EEG and brain CT scan with clinical-epidemiologic evaluation was critical for determination of epilepsy etiology. Establishment of specific programs for continuation of epidemiologic surveillance, education, intervention, and long-term follow-up will benefit the Salamá region.

Neurosurgical management of pediatric epilepsy

Pediatric neurosurgeons are often involved early in the evaluation and management of children with epilepsy. Surgery should not be viewed merely as the end stage of multiple diagnostic decisions made by neurologists and pediatricians. Instead, when a reasonable trial of several AEDs has failed to provide adequate seizure control, a pediatrician can refer the patient directly to a pediatric neurosurgeon with a specialty interest in epilepsy. The diagnosis and treatment of focal versus diffuse epilepsy can be discussed in an honest and educated fashion with the families and the caregivers. Although full seizure control may be impossible, improved neurologic development and avoidance of self-injurious drop attacks may be worthy alternative surgical outcomes.

Bilateral Mesial Temporal Sclerosis and Kernicterus

Two children with mental retardation, choreoathetosis, dystonia, and muscle rigidity are reported. They had a history of severe hyperbilirubinemia after birth as a result of Rh isoimmunization. The history and clinical picture suggested the diagnosis of kernicterus. The magnetic resonance imaging examination showed a bilateral signal intensity increase in the globus pallidus on T2-weighted images. Additionally, our patients showed symmetric bilateral hyperintensity and volume loss in the hippocampus, which is known to be another characteristic area of bilirubin deposition in kernicterus.

Treatment considerations: role of surgery

Patients with developmental disabilities, including retardation and global developmental delay, are not ideal candidates for epilepsy surgery. Because they have an increased likelihood of diffuse brain dysfunction and multifocal or generalized epileptogenic zones, there is an increased chance that a focal cortical resection will not confer a major improvement in their seizure frequency and severity. There is also increased concern that cortical resection will lead to increase in the patient's disability. However, by applying the basic principles of epilepsy surgery selection (i.e., convergence of multiple lines of localizing evidence) to this population, patients with a reasonable likelihood of good seizure control can be identified. Various means of localizing seizure onset are reviewed, including history and examination, electroencephalography, magnetic resonance imaging, position emission tomography, single-photon-emission tomography, and magnetoencephalography.