Autoimmune and paraneoplastic seizures

Seizures are a common feature of autoimmune encephalitis and are especially prevalent in patients with the commonest autoantibodies, against LGI1, CASPR2 and the NMDA, GABAB, and GABAA receptors. In this chapter, we discuss the classification, clinical, investigation, and treatment aspects of patients with these, and other autoantibody-mediated and -associated, illnesses. We highlight distinctive and common seizure semiologies which, often alongside other features we outline, can help the clinical diagnosis of an autoantibody-associated syndrome. Next, we classify these syndromes by either focusing on whether they represent underlying causative autoantibodies or T-cell-mediated syndromes and on the distinction between acute symptomatic seizures and a more enduring tendency to autoimmune-associated epilepsy, a practical and valuable distinction for both patients and clinicians which relates to the pathogenesis. We emphasize the more effective immunotherapy response in patients with causative autoantibodies, and discuss the emerging evidence for various first-, second-, and third-line immunotherapies. Finally, we highlight available clinical rating scales which can guide autoantibody testing and immunotherapy in patients with seizures of unknown etiology. Throughout, we relate the clinical and therapeutic observations to the immunobiology and neuroscience which drive these seizures.

What Is Different about Teratoma-Associated Anti-LGI1 Encephalitis? A Long-Term Clinical and Neuroimaging Case Series

INTRODUCTION

Anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis is clinically heterogeneous, especially at presentation, and though it is sometimes found in association with tumor, this is by no means the rule.

METHODS

Clinical data for 10 patients with anti-LGI1 encephalitis were collected including one case with teratoma and nine cases without and compared for clinical characteristics. Microscopic pathological examination and immunohistochemical assay of the LGI1 antibody were performed on teratoma tissue obtained by laparoscopic oophorocystectomy.

RESULTS

In our teratoma-associated anti-LGI1 encephalitis case, teratoma pathology was characterized by mostly thyroid tissue and immunohistochemical assay confirmed positive nuclear staining of LGI1 in some tumor cells. The anti-LGl1 patient with teratoma was similar to the non-teratoma cases in many ways: age at onset (average 47.3 in non-teratoma cases); percent presenting with rapidly progressive dementia (67% of non-teratoma cases) and psychiatric symptoms (33%); hyponatremia (78%); normal cerebrospinal fluid results except for positive LGI1 antibody (78%); bilateral hippocampal hyperintensity on magnetic resonance imaging (44%); diffuse slow waves on electroencephalography (33%); good response to immunotherapy (67%); and mild residual cognitive deficit (22%). Her chronic anxiety and presentation with status epilepticus were the biggest differences compared with the non-teratoma cases.

CONCLUSION

In our series, anti-LGI1 encephalitis included common clinical features in our series: rapidly progressive dementia, faciobrachial dystonic seizures, behavioral disorders, hyponatremia, hippocampal hyperintensity on magnetic resonance imaging, and residual cognitive deficit. We observed some differences (chronic anxiety and status epilepticus) in our case with teratoma, but a larger accumulation of cases is needed to improve our knowledge base.

Long-term evolution and prognostic factors of epilepsy in limbic encephalitis with LGI1 antibodies

OBJECTIVE

To characterize the evolution of epilepsy in patients with leucine-rich glioma inactivated 1 antibody-associated (LGI1ab) limbic encephalitis, including factors associated with drug-resistant epilepsy (DRE).

METHODS

Retrospective analysis of patients with LGI1 encephalitis managed at two tertiary epilepsy centers between 2005 and 2019 and whose samples were confirmed by the French Reference Center of Paraneoplastic Neurological Syndromes. Raw clinical, biological, EEG, and MRI data were reviewed. Two endpoints were defined: (i) Epilepsy remission: patients seizure free and in whom anti-seizure medications (ASM) have been stopped for at least 1 year at the last follow-up visit (ii) DRE: patients with persistent seizures at the last follow-up despite at least two ASM used at efficacious daily dose.

RESULTS

39 patients with LGI1 encephalitis were included with a median follow-up duration of 42 months (range 13-169). All of them reported seizures at the acute phase, with faciobrachial dystonic seizures (FBDS) in 23 (59%) and other focal seizures in 38 (97%), including 4 patients (10%) with de novo status epilepticus. At the last follow-up visit, 11 patients (28%) achieved epilepsy remission. Among the 28 patients with persistent epilepsy, eight (29%) fulfilled criteria of DRE. The only factor significantly associated with epilepsy remission was the time from clinical onset of the encephalitis to initiation of the first immunomodulatory treatment, with longer delay in patients with persistent epilepsy (7.5 ± 8.9 vs 2.4 ± 1.7 months, p = 0.006). Evolution to DRE was only driven by MRI evolution. Eight of the 15 patients (53%) who developed hippocampal atrophy (p = 0.007) also suffered from drug-resistant seizures at the last follow-up.

SIGNIFICANCE

In patients with LGI1 encephalitis, rapid initiation of immunomodulatory treatment favors long-term epilepsy remission. Evolution to DRE might primarily reflect the anatomical lesion of limbic structures. Determining what modalities of immune treatment may alter these outcomes requires prospective studies with long-term follow-up.

Faciobrachial Myoclonus as the Presenting Manifestation of Diabetic Keto-Acidosis

Background:

Chorea and ballism are well-recognized acute potentially reversible movement disorders as the presenting manifestation of non-ketotic hyperglycemic states among older type-2 diabetics. Myoclonus as the form of presentation of diabetic keto-acidosis (DKA) in previously undiagnosed type-1 diabetic has never been reported before.

Case report:

We herein report the case of a 36-year-old previously healthy patient who presented with acute onset incessant faciobrachial myoclonus for 10 days. The patient was found to be suffering from DKA and eventually diagnosed as type-1 diabetes mellitus. Myoclonus disappeared with achieving euglycemia and did not recur.

Discussion:

Apart from expanding the spectrum of acute movement disorder among diabetics, this case reiterates the importance of rapid bedside measurement of capillary blood glucose in all patients presenting with acute onset abnormal movements irrespective of their past glycemic status. This simple yet life-saving approach can clinch the diagnosis at the earliest and thus will avoid costly investigations and mismanagement.

Electroencephalographic findings in antileucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis: A systematic review

BACKGROUND

Antileucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis is a distinct syndrome of early onset faciobrachial dystonic seizures (FBDS) and other focal seizures followed by neuropsychiatric symptoms. The electroclinical syndrome of this condition is yet to be fully understood. The main objective of this study was to determine the frequencies of electroencephalogram (EEG) findings in patients diagnosed with anti-LGI1 autoimmune encephalitis through a systematic review of published relevant articles.

METHODS

Major electronic healthcare databases were searched for relevant published articles until July 2020.

RESULTS

From 327 articles, 23 case reports and 14 case series were included in the review after satisfying the eligibility criteria. Data from a total of 151 cases of definite anti-LGI1 encephalitis were analyzed in this systematic review. Epileptiform discharges were the most frequent finding at 57.3%. Focal electroencephalographic abnormalities including slow wave (59.3%) and epileptiform activities (53.5%) most commonly arise from the temporal region. Faciobrachial dystonic seizures often have no ictal electroencephalographic correlate but would show electrodecremental events when seizure duration is prolonged.

CONCLUSION

Electroencephalogram abnormalities are seen in anti-LGI1 autoimmune encephalitis with epileptiform discharges as the most common finding followed by focal slowing. These findings were most frequently seen arising in the temporal region. Further studies using a standardized protocol focusing on electroencephalographic findings in anti-LGI1 encephalitis with clinical correlation to disease stage and treatment outcomes in terms of seizure control and memory and cognitive function are needed. Particular attention on ictal electrodecremental activity during FBDS should be done in studies with a larger sample size.

The exploration of the spectrum of motor manifestations of anti-LGI1 encephalitis beyond FBDS

PURPOSE

The purpose of this study was to characterize the spectrum of motor events in patients with acute anti-leucine-rich glioma-inactivated protein 1 (anti-LGI1) encephalitis through video-electroencephalogram (VEEG) recordings.

METHOD

We collected data retrospectively from 16 patients diagnosed with anti-LGI1 encephalitis who had completed VEEG recording during hospitalization.

RESULTS

VEEG monitoring lasted a median of 11.0 h (range 4.5∼20). Fourteen types of seizures were recorded in 9 patients (56.3 %). Eight of the 14 types of seizures demonstrated typical ictal EEG evolution (including 2 subclinical seizures), 3/14 demonstrated EEG electrodecremental events (EDE) at onset but without further evolution, and 3/14 could be only judged by analyzing semiology. FBDS was recorded in 6 patients (37.5 %), and all these attacks were followed by epileptic seizures. Simple hyperkinetic movements (HMs), such as jerk-like or twisting movements, were found in 8 (50 %) patients, and 6 of them had complex HMs, such as manipulating movements or mimics of daily activities, during sleep.

CONCLUSIONS

1. Atypical seizures, for instance, seizures without EEG evolution, are not rare but likely to be overlooked. 2. FBDS is closely linked with epileptic seizures, revealing FBDS to be a part of epileptic attacks. 3. HMs could expand the spectrum of motor manifestations, overlapping with sleep disorders. 4. The high prevalence of these motor events might be due to the disrupted cortical-subcortical network, which is critical in motor control and sleep.

Antiepileptic drug therapy in autoimmune epilepsy associated with antibodies targeting the leucine-rich glioma-inactivated protein 1

Objective

To characterize seizure semiology and the utility of antiepileptic drug (AED) therapy in leucine‐rich glioma inactivated‐1 ( LGI1‐Ab) autoimmune epilepsy (AE).

Methods

Patients with voltage‐gated potassium channel complex (VGKCc) titers higher than 0.02 nmol/L who were evaluated between May 2008 and June 2016 at the 3 Mayo Clinic sites (Arizona, Florida, or Minnesota) were identified. We then performed a retrospective review of those who were LGI1‐Ab positive and were treated for seizures.

Results

A total of 1,095 patients with VGKCc titers higher than 0.02 nmol/L were identified, in which 77 were LGI1 positive. Of these, 56 patients with seizures were included in the analysis. Mean age at symptom onset was 62.9 years; 66% (n = 37) were male. The most common seizure semiology was focal faciobrachial dystonic seizures with preserved awareness (FBDS) (n = 35, 63%), followed by focal with impaired awareness (FIA) (n = 29, 52%), generalized tonic–clonic (GTCs) (n = 28, 50%), and focal non‐motor seizures with preserved awareness (n = 28, 50%). The majority had more than one seizure type (n = 49, 88%; median = 2.5). Thirty‐eight patients (68%) became seizure free: 29 (76%) with immunotherapy, 3 (5%) with AEDs alone, 2 (3%) with AEDs before any immunotherapy, and 4 (7%) with AEDs after immunotherapy. Levetiracetam (n = 47, 84%) and valproic acid (n = 21, 38%) were the most commonly used AEDs, but neither were associated with seizure freedom. Sodium channel blocking (NCB) AEDs were associated with seizure freedom in 4 patients compared to none treated with non‐NCB AEDs. Regardless of class, AEDs prior to or apart from immunotherapy were associated with seizure freedom in only five patients (9%). In patients with FBDS, seizure freedom was more often associated with immunotherapy than AEDs (20/30 vs. 3/34, p = 0.001).

Significance

Although FBDS are the most characteristic seizure type seen in LGI1‐Ab AE, other seizure types including FIA and GTCs also occur. Immunotherapy was the treatment most frequently associated with seizure freedom in LGI1‐Ab AE. In general, AEDs seemed to confer a very low chance for seizure freedom, although AEDs with NCB‐blocking properties were associated with seizure freedom in a limited number. Levetiracetam in particular appears to be ineffective in this patient population.

Faciobrachial dystonic seizures result from fronto-temporo-basalganglial network involvement

•Faciobrachial dystonic seizures (FBDS) are caused by autoantibodies to leucine-rich glioma-inactivated1 proteins, a component of the voltage-gated potassium channel complex (VGKC-complex) and precede the clinical presentation of limbic encephalitis.•The exact pathophysiology of FBDS is not known and whether they are seizures or movement disorder is still debated.•We suggest the fronto-temporo-basal ganglia network involving the medial frontal and temporal regions along with the corpus striatum and substantia nigra being responsible for the clinical phenomenon of FBDS.•The varied clinical, electrical and imaging features of FBDS in our cases and in the literature are best explained by involvement of this network.•Entrainment from any part of this network will result in similar clinical expression of FBDS, whereas other electro-clinical associations and duration depends on the extent of involvement of the network.

Antibody-associated epilepsies: Clinical features, evidence for immunotherapies and future research questions

PURPOSE

The growing recognition of epilepsies and encephalopathies associated with autoantibodies against surface neuronal proteins (LGI1, NMDAR, CASPR2, GABABR, and AMPAR) means that epileptologists are increasingly asking questions about mechanisms of antibody-mediated epileptogenesis, and about the use of immunotherapies. This review summarizes clinical and paraclinical observations related to autoimmune epilepsies, examines the current evidence for the effectiveness of immunotherapy, and makes epilepsy-specific recommendations for future research.

METHOD

Systematic literature search with summary and review of the identified publications. Studies describing the clinical characteristics of autoantibody-associated epilepsies and treatments are detailed in tables.

RESULTS

Literature describing the clinical manifestations and treatment of autoimmune epilepsies associated with neuronal cell-surface autoantibodies (NSAbs) is largely limited to retrospective case series. We systematically summarize the features of particular interest to epileptologists dividing patients into those with acute or subacute encephalopathies associated with epilepsy, and those with chronic epilepsy without encephalopathy. Available observational studies suggest that immunotherapies are effective in some clinical circumstances but outcome data collection methods require greater standardization.

CONCLUSIONS

The clinical experience captured suggests that clusters of clinical features associate well with specific NSAbs. Intensive and early immunotherapy is indicated when patients present with autoantibody-associated encephalopathies. It remains unclear how patients with chronic epilepsy and the same autoantibodies should be assessed and treated. Tables in this paper provide a comprehensive resource for systematic descriptions of both clinical features and treatments, and highlight limitations of current studies.

Jerking & confused: Leucine-rich glioma inactivated 1 receptor encephalitis

This is a case of autoimmune encephalitis with features of faciobrachial dystonic seizures (FBDS) pathognomonic for Leucine Rich Glioma inactivated (LGI)1 antibody encephalitis. This voltage-gated potassium channel complex encephalitis is marked by rapid onset dementia, FBDS and hyponatremia, which is sensitive to management with immunotherapy including steroids, IVIG and other agents. In this case report we review the clinical features, imaging and management of this condition.

Natural course of LGI1 encephalitis: 3-5 years of follow-up without immunotherapy

Antibodies against LGI1 (leucin-rich glioma-inactivated 1 protein) are associated with limbic encephalitis (LE), which is characterized by a favorable outcome following immunotherapy. Here, we present two cases, where antibodies against LGI1 were detected in the sera 36 and 53 months after acute LE, respectively, and none of the patients received immunotherapy. LE showed characteristics of LGI1 encephalitis in both cases, including low sodium content in the sera; disorientation, hallucination, short-term memory loss; and epileptic seizures. One patient had faciobrachial tonic seizures. MRI indicated bilateral inflammation of the hippocampus in one case. We reviewed longitudinal clinical and MRI data covering 53 and 36 months after LE without immunotherapy, respectively. Both patients became seizure-free and spontaneously recovered with mild/moderate cognitive impairment. No relapses have been observed. Follow-up brain MRI indicated early hippocampal sclerosis and global brain atrophy in one case characterized by more pronounced cognitive deficit. Memory and verbal fluency were affected most during the natural course of LGI1 encephalitis. LGI1 encephalitis had a monophasic course and spontaneously improved, suggesting that a relatively benign natural course may contribute to the favorable outcome observed after immunotherapy. Our data also indicate that LGI1 antibodies can be present in the sera without clinical disease activity.