Antiphospholipid and glutamic acid decarboxylase antibodies in patients with focal epilepsy

Evaluation of Glutamic Acid Decarboxylase Antibody Levels in Patients with Juvenile Myoclonic Epilepsy and Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

INTRODUCTION

Several clinical studies have been conducted to investigate the role of autoantibodies and immunological mechanisms in the etiology of treatment-resistant epilepsy in recent years. Some immunological treatments have been suggested as a result of these studies. In this study, we aimed to investigate the role of autoimmunity in partial and idiopathic generalized epilepsy and determine the relationship between drug resistance and autoimmune antibodies.

METHODS

Twenty-eight patients (24 treatment-responsive and 4 treatment-resistant) with juvenile myoclonic epilepsy (JME), 26 patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLEHS) resistant to antiepileptic drug treatment, and 26 age-matched healthy control subjects were included in a two-year cross sectional study. Glutamic acid decarboxylase antibody (GADA) levels were measured with a radioimmunoassay method in the serum of the included subjects.

RESULTS

High GADA titers were detected in 2 patients with JME (7.1%), 1 patient with MTLEHS (3.8%), and 1 healthy subject (3.8%). There was no statistically significant difference among the groups regarding the serum GADA level. Although a limited number of drug-resistant patients with JME our study did not show relationships among anti-GADAs, both epileptic syndromes and drug resistance.

CONCLUSION

Because we did not determine any significant relationship between GADA levels and JME or MTLEHS, we do not recommend analysis of serum GADA levels in routine examinations where there is no evidence to suggest risk factors for autoimmunity.

Hughes syndrome and epilepsy: when to test for antiphospholipid antibodies?

Epilepsy and seizures are reported among the neurological manifestations of antiphospholipid syndrome (APS) at a prevalence rate of approximately 8%, which is nearly 10 times the prevalence of epilepsy in the general population. The association of seizures with antiphospholipid antibodies (aPL) is even more significant in the presence of systemic lupus erythematosus (SLE). In this review, we discuss the epidemiological, pathophysiological, laboratory, clinical, and radiological aspects of this association, and derive suggestions on when to consider testing for aPL in epileptic patients and how to manage seizures secondary to APS based on literature data. Epilepsy due to APS should be considered in young patients presenting with seizures of unknown origin. Temporal lobe epilepsy seems to be particularly prevalent in APS patients. The pathogenesis is complex and may not only involve micro-thrombosis, but also a possible immune-mediated neuronal damage. Patients with seizures and positive aPL tend to develop thrombocytopenia and livedo racemosa more frequently compared with those without aPL. Magnetic resonance imaging (MRI) remains the imaging modality of choice in these patients. The presence of SLE and the presence of neurological symptoms significantly correlate with the presence of white matter changes on MRI. In contrast, the correlation between aPL positivity and the presence of white matter changes is very weak. Furthermore, MRI can be normal in more than 30–40% of neuropsychiatric lupus patients with or without aPL. aPL testing is recommended in young patients presenting with atypical seizures and multiple hyper-intensity lesions on brain MRI in the absence of other possible conditions. New MRI techniques can better understand the pathology of brain damage in neuro-APS. The therapeutic management of epileptic APS patients relies on anti-epileptic treatment and anticoagulant agents when there is evidence of a thrombotic event. In the absence of consensual recommendations, the decision of lifelong anticoagulation is discussed on a case-by-case basis. The anti-thrombotic benefit of hydroxychloroquine and statins is supported by several studies.

Epilepsy as part of systemic lupus erythematosus and systemic antiphospholipid syndrome (Hughes syndrome)

The antiphospholipid syndrome (APS) is defined by the presence of antiphospholipid antibodies (aPL), demonstrated by ELISAs for antibodies against phospholipids and associated phospholipid-binding cofactor proteins and/or a circulating lupus anticoagulant (LA) together with diverse systemic clinical manifestations such as thrombosis, and recurrent spontaneous abortions. According to the criteria set out in Sydney1 the only neurological manifestations that can be suitable as APS classification criteria are ischemic events (stroke and transient ischemic attacks). However, other neurological manifestations, including seizures in particular, have been repeatedly reported in APS patients.2

The present review will summarize recent research on the association of aPL, as well as other autoantibodies, with seizure disorders, with or without concomitant SLE.

Presence of GAD65 autoantibodies in the serum of children with autism or ADHD

Antibodies against glutamic acid decarboxylase 65 (GAD65) have been detected in the serum of patients with several neurological disorders. The presence of antibodies against GAD65 has not yet been examined in the serum of patients with neurodevelopmental disorders such as autism or attention-deficit/hyperactivity disorder (ADHD). In this study, GAD65 antibodies and total IgG were assayed in the serum of normal subjects and patients diagnosed with autism or ADHD. GAD65 antibodies were detected in the serum of 15% of children with autism (N = 20), 27% of children with ADHD (N = 15) and of none of the controls (N = 14). The serum of 60% of autistic and 53% of ADHD patients reacted with Purkinje neurons in mouse cerebellum. Serum from 20% of ADHD patients reacted also with the cells in the molecular and granule cell layers and cells in the vicinity of the Purkinje neurons. No association was found between the titer of GAD65 antibodies and total IgG levels, and presence of seizures or mental retardation. None of the ADHD patients were diagnosed with mental retardation. Serum anti-GAD65 antibodies may be a common marker of subgroups of patients with autism and ADHD. Reactions of serum antibodies with the cells in the cerebellum in these patients suggest direct effects on brain function. The subgroup of children with autism and ADHD that tests positive for GAD65 antibodies needs further characterization in a larger study.

Temporal lobe epilepsy and anti glutamic acid decarboxylase autoimmunity

Epilepsy is one of the most impactful diseases on social life. A significant number of epileptic syndromes have been linked to immunological alterations. Elevated levels of antibodies against glutamic acid decarboxylase have been recently found in a significant percentage of patients with temporal lobe epilepsy, the most common epilepsy type. The clinical and pathogenetic relationship of this association is discussed. This link may have important therapeutic implications and merits additional clinical and laboratory research.

Clinical significance of glutamic acid decarboxylase antibodies in patients with epilepsy

PURPOSE

Glutamic acid decarboxylase antibodies (GADAs) have been detected in patients with epilepsy, but the clinical determinants of epilepsy associated with GADA have not been defined.

METHODS

We analyzed GADA with a radioimmunoassay in sera of 253 well-characterized patients with epilepsy and 200 control subjects. The positive samples were confirmed by immunohistochemistry and western blotting (WB). Sera were screened for other autoantibodies.

RESULTS

GADA were detected in 15 patients (5.9%) and in three control subjects (1.5%) (p = 0.026). Seven patients (2.8%) had high GADA titers [>or=1,000 relative units (RUs)/ml], six of whom had temporal lobe epilepsy (TLE). All three GADA-positive control subjects had low titers. Two of the five patients with high GADA titers and available cerebrospinal fluid (CSF) samples had intrathecal synthesis (IS) of GADA; one patient had CSF oligoclonal bands. The prevalence of increased levels of GADA tended to be higher in patients with TLE than in patients with extra-TLE [odds ratio (OR) 1.32, 95% confidence interval (CI) 0.39-4.42; p = 0.657]. The patients with high GADA titers had significantly higher number of other autoantibodies compared to the patients with low GADA titers (p = 0.001) and the patients with normal GADA (p < 0.001).

DISCUSSION

High GADA titers were present in a subgroup of patients; close to 90% had TLE. The immunologic profile of these patients suggests that the most probable origin of their epilepsy is autoimmune. A positive IS of GADA may be a marker of an ongoing immune response that could identify those patients in whom a trial with immunosuppressive therapy might be warranted.

[Neurological manifestations of the antiphospholipid syndrome]

Antiphospholipid syndrome can be associated with several neurological manifestations. The most common symptom is headache. It has also been associated with cognitive dysfunction, probably due to ischemia. A high prevalence of antiphospholipid antibodies has been found in patients with epilepsy and in transverse myelitis. The most common thrombotic manifestation is stroke. Venous thrombosis can also be found, yet it is less frequent. A stroke in a young person obliges to rule out the antiphospholipid syndrome. The neurological manifestations can mimic multiple sclerosis. Thus, determination of antiphospholipid antibodies is recommended in the study of patients with atypical manifestations of multiple sclerosis. Other manifestations associated with antiphospholipid antibodies include chorea, neurosensorial deafness, Guillain-Barre syndrome, and psychotic disorders.