Dystonic Seizures and Intense Hyperperfusion of the Basal Ganglia in a Patient with Anti-N-Methyl-D-Aspartate Receptor Encephalitis

This report describes a rare case presenting with dystonic seizures due to anti-N-methyl-D-aspartate (NMDA) receptor encephalitis. The patient was an 18-year-old woman with repeated right-dominant dystonic seizures even under sedation. Single-photon emission computed tomography (SPECT) showed intense hyperperfusion of the caudate nuclei, putamen, globus pallidus, thalamus, and insula on the left side, suggesting encephalitis. Antibodies against NMDA receptors were detected in the sera and cerebrospinal fluids. Immune-mediated treatments were administered. Three months later, the dystonic seizures disappeared. We diagnosed her with anti-NMDA receptor encephalitis. SPECT suggested that the main region of encephalitis was the basal ganglia. Therefore, we propose that the patient's dystonic seizures may originate from the insula and be generated by intense hyperactivity of the basal ganglia.

Semi-quantitative analyses of antibodies to N-methyl-d-aspartate type glutamate receptor subunits (GluN2B & GluN1) in the clinical course of Rasmussen syndrome

OBJECTIVE

In Rasmussen syndrome (RS), in addition to the predominant involvement of cytotoxic T cells, heterogeneous autoantibodies against neural molecules are also found, but their function has not been elucidated. We examined antibodies to N-methyl-d-aspartate (NMDA) type glutamate receptor (GluR) subunits (GluN2B & GluN1) semi-quantitatively in cerebrospinal fluid (CSF) samples from RS patients, and evaluated their changes over time and their roles in immunopathogenesis.

METHODS

Autoantibodies against N-terminal and C-terminal of GluN2B and GluN1 were examined in 40 CSF samples collected from 18 RS patients 5 to 180 months after the onset of RS. Epileptic patients without infectious etiology or progressive clinical course served as disease controls (n=23). Synthesized peptides encoding the extracellular and intracellular domains of human GluN2B and GluN1 subunits were used as antigens in ELISA. We defined the cut-off for these antibodies as mean +2 standard deviations (optimal density) of the disease controls. MRI were evaluated according to the MRI staging proposed by Bien et al. (2002b, Neurology 58, 250).

RESULTS

CSF levels of antibodies against N-terminal and C-terminal of GluN2B were higher in RS patients than in disease controls (p<0.01). Likewise, CSF levels of antibodies against N-terminal and C-terminal of GluN1 were also higher in RS patients than in disease controls (p<0.01). All four antibodies tested were below cut-off levels in almost all CSF samples collected within one year from epilepsy onset. The proportions of CSF samples with these antibodies above cut-off levels were highest from 12 to 23 months after epilepsy onset, and declined after 24 months. CSF levels of these antibodies were higher when seizure occurred daily than when seizure occurred less frequently (p<0.01), and were higher at MRI stage 3 than at MRI stages 0, 2 and 4 (p<0.05), except for anti-GluN1-CT antibody at stage 2.

CONCLUSIONS

Broad epitope recognition spectrum and delayed production of autoantibodies to NMDA type GluR in CSF of RS patients suggest that the autoantibodies are produced against NMDA type GluR antigens derived from cytotoxic T cell-mediated neuronal damages. These antibodies may impact the pathophysiology of RS in the most active stage, and could be a marker for active inflammation in the clinical course of RS. Further studies including passive transfer of the antibodies to mice may reveal the pivotal roles of the antibodies in RS.

Anti-glutamate ∊2 receptor antibody-positive and anti-N-methyl-d-aspartate receptor antibody-negative lobar encephalitis presenting as global aphasia and swallowing apraxia

Background

Little is known about the difference between anti-N-methyl-D-aspartate receptor (NMDAR) antibody-positive encephalitis and anti-glutamate receptor (GluR) antibody-positive encephalitis.

Objectives

To characterize anti-GluR antibody-positive encephalitis.

Methods

We report a 33-year-old man with nonparaneoplastic anti-GluR ∊2, ζ1 and δ2 antibody-positive and anti-NMDAR antibody-negative encephalitis, using neuropsychological tests and imaging studies including magnetic resonance imaging and single photon emission computed tomography (SPECT) with a ^99mTc-ethylcysteinate dimer.

Results

The patient exhibited global aphasia and swallowing apraxia (inability to transfer food to the pharyngeal cavity without sialorrhea). He was treated with 3 courses of corticosteroid pulse therapy and had recovered markedly 3 weeks after onset. Magnetic resonance diffusion-weighted images revealed hyperintensity in the bilateral frontal and left parietal cortices. Seven months later, a small area of hyperintensity in the left supramarginal gyrus remained. SPECT revealed hypoperfusion in extensive regions of the bilateral frontal lobes and left supramarginal gyrus. Thirteen months later, blood flow reduction was restricted to diffuse areas in the frontal lobes.

Conclusions

Frontal lobar encephalitis without medial temporal involvement, marked cognitive impairment with a relatively preserved level of consciousness, and a favorable response to corticosteroid therapy, with nearly reversible cortical damage, may characterize anti-GluR antibody-positive encephalitis.

Fine mapping of a monoclonal antibody to the N-Methyl D-aspartate receptor reveals a short linear epitope

Anti-N-Methyl D-aspartate receptor encephalitis is an autoimmune disease in which autoantibodies are produced against extracellular regions of the N-Methyl D-aspartate receptor (NMDAR). In this study, we used resin-bound peptides equipped with a base labile linker to map the epitope of a monoclonal NMDAR antibody against the NMDAR NR1 subunit. The antigenicity of the synthesized resin-bound peptides was determined by enzyme-linked immunosorbent assay. Distinct reactivity was found to two extracellular overlapping peptides (amino acids, 658-687). Using N- and C-terminally truncated resin-bound peptides, the minimum functional epitope was identified as the NPSDK sequence. The peptide sequence RNPSDK (amino acids, 673-678) was identified as the complete epitope, which was found to be located in the extracellular S2 domain of the NR1 subunit. Especially, the N-terminal arginine residue was found to be essential for reactivity, whereas the remaining amino acids could be replaced with amino acids of similar side-chain functionality, indicating the importance of backbone interaction in antibody reactivity.

Late delirious behavior with 2009 H1N1 influenza: mild autoimmune-mediated encephalitis?

Delirious behavior associated with influenza usually has an onset within a few days after fever and lasts <24 hours. As we encountered several patients with 2009 H1N1 influenza who presented with late-onset and long-standing delirious behavior, we retrospectively evaluated the clinical, radiologic, and laboratory features to elucidate the possible pathophysiology. This information was collected on 5 previously healthy patients (2 boys and 3 girls, aged 10-15 years) with 2009 H1N1 influenza who presented with late onset (>3 days after fever) and long-standing (>48 hours) delirious behavior. Each exhibited mild to moderate drowsiness between the episodes of delirious behavior. Electroencephalography was normal except for 1 patient with high voltage and slow activity bilaterally in the occipital regions. Brain MRI was normal. The outcome was excellent with no neurologic sequel in 4 of the 5 patients. In all 5 patients, autoantibodies against N-methyl-D-aspartate type glutamate receptor were elevated or positive in cerebrospinal fluid or serum; the autoantibody levels normalized in the 3 patients who had follow-up studies. This study indicates that 2009 H1N1 influenza has a tendency to cause late-onset and long-standing delirious behavior, at least in Japanese children. Mild autoimmune-mediated encephalitis should be considered as an underlying cause.

Diversity in anti-N-methyl-D-aspartate receptor encephalitis: case-based evidence

Antibodies against N-methyl-D-aspartate receptor (NMDAR) are identified in the form of immune-mediated encephalitis in which typical manifestations include neuropsychiatric symptoms, seizures, abnormal movements, dysautonomia and hypoventilation. The authors report two cases of anti-NMDAR encephalitis with different presentations and patterns of progression. The first patient presented with status epilepticus and later developed psychosis, pyramidal signs and diffuse encephalopathy. The second patient presented with acute psychosis followed a week later by seizures, dystonia, rigidity, oromandibular dyskinesias and dysautonomia. Possible mechanisms responsible for the clinical manifestations of this disease are discussed in light of recently described additional clinical and laboratory findings.

Atypical Miller Fisher syndrome associated with glutamate receptor antibodies

The present study reports a young woman with acute ataxia, areflexia and ophthalmoplegia, accompanied by psychosis and involuntary movements (IVMs) from disease onset. Anti-GQ1b and anti-GT1a antibodies were detected allowing for a diagnosis of Miller Fisher syndrome (MFS). However, psychosis and IVMs are atypical MFS symptoms and often mimic symptoms of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. Interestingly, the autoantibodies against full-length glutamate receptor-ε2 (GluRε2) and glutamate NR2B- and NR2A-containing heteromers (NR1/NR2) of NMDAR were also detected in the patient serum and cerebrospinal fluid. It was concluded that psychosis and IVMs in this patient were associated with autoantibodies against various GluRs.

The growing recognition of immunotherapy-responsive seizure disorders with autoantibodies to specific neuronal proteins

PURPOSE OF REVIEW

The concept of epilepsy and seizure disorders caused by autoantibodies to specific neuronal membrane proteins has developed significantly during the past few years.

RECENT FINDINGS

Antibodies to cell-surface membrane proteins such as voltage-gated potassium channels or N-methyl-D-aspartate receptors, or to glutamic acid decarboxylase, are found in patients with different forms of limbic encephalitis, and in a few patients with epilepsy as their main or only condition. Many of these patients do not show a good response to conventional antiepileptic drugs, but respond to immunotherapies. By contrast, studies of other antibodies in idiopathic forms of epilepsy, or epilepsy associated with systemic lupus erythematosus or coeliac disease, have not in general disclosed consistent, clinically helpful results.

SUMMARY

There are a growing number of specific antibodies associated with new onset epilepsy. These patients are likely to have an immune-mediated disorder that may benefit from immunotherapies. In autoimmune diseases such as systemic lupus erythematosus or coeliac disease, antibodies to specific membrane targets may also prove to be important in the future.

Expression of various glutamate receptors including N-methyl-D-aspartate receptor (NMDAR) in an ovarian teratoma removed from a young woman with anti-NMDAR encephalitis

A 21-year-old woman developed psychiatric symptoms, progressive unresponsiveness, generalized seizures, severe dyskinesia, marked fluctuation of blood pressure, and hypersalivation after a flu-like episode. Anti-glutamate receptor (GluR)ε2 and anti-N-methyl-D-aspartate receptor (NMDAR) antibodies were positive in both her serum and CSF. After she recovered five months later she underwent surgery to remove a right ovarian teratoma. Immunohistochemical examinations of her teratoma disclosed abundant expression of various GluRs including NR2B subunit of NMDAR, GluR1, and GluR2/3. These immunoreactivities of GluRs were seen not only in small areas of neural tissue identified as anti-glial fibrillary acidic protein (GFAP)-immunoreactive areas but also in other large areas of undifferentiated neuroepithelial tissue without GFAP immunoreactivity. Our findings strongly support the recent idea that neural elements in ovarian teratoma play an important role in the production of antibodies to NMDARs in anti-NMDAR encephalitis. Additionally, the study of control ovaries clearly showed NR2B-related immunoreactivity in the cytoplasm of oocytes, indicating that the normal ovary itself has expression of NMDARs. This finding might provide a clue to understand the pathogenesis of this disease in female patients without ovarian teratoma.

Acute encephalitis with refractory, repetitive partial seizures

Acute encephalitis with refractory, repetitive partial seizures (AERRPS) represents a peculiar form of encephalitis mainly affecting children. They usually present abruptly with seizure or impaired consciousness as well as high-grade fever following antecedent infection. Seizures in AERRPS are almost exclusively of localized origin, whose semiology includes eye deviation, hemifacial twitching, hemiclonic convulsion, and autonomic manifestations. Partial seizures are brief, but repeat with increasing frequency and develop status epilepticus at nadir. They are extremely pharmaco-resistant and are only suppressed by intravenous administration of high-dose barbiturates. Although acute seizures are hardly controlled, patients gradually recover with decreasing seizure frequency and continuously evolve into post-encephalitic epilepsy without latent period. Residual cognitive impairment is common. Electroencephalograms in active stage demonstrate electrical seizure activities and interictal periodic discharges. Magnetic resonance imaging reveals late cerebral atrophy with limited signal abnormality. Persistent fever during active stage, cerebrospinal fluid (CSF) pleocytosis, and up-regulation of neopterin raise the hypothesis that inflammatory process is involved in this condition. Furthermore, early production of autoantibody against NMDA receptor 2B in serum and CSF, although its disease specificity is still in controversy, is suggestive of autoimmune etiology. Exploration for definite clinical marker is currently in progress.

[Acute limbic encephalitis and NMDA type-glutamate receptor]

We compared clinical characteristics and autoantibodies against GluRepsilon2 between 95 patients with nonparaneoplastic non-herpetic acute limbic encephalitis (NPNHALE) and 19 patients with non-herpetic acute encephalitis accompanying ovarian teratoma (NHAE-OT). Onset age (mean +/- SD) was 27.7 +/- 18.6 years old in NPNHALE, 27.5 +/- 6.5 in NHALE-OT. Preceding factors were found in 63.8% of patients with NPNHALE and 89.5% of patients with NHALE-OT (Fisher's exact test, p = 0.025), and major preceding factors were upper respiratory infections or fever in both groups. Symptoms at the onset were disorder of behavior and talk > seizures > impairment of consciousness in NPNHALE, and disorder of behavior and talk > seizures > disorientation in NHALE-OT. Symptoms at the acute stage were similar between NPNHALE and NHAE-OT, but duration of hospital stay was longer in NHAE-OT (209.0 days) than NPNHALE (87.5 days) (Mann Whitney test, p<0.0001). At the onset, cell counts in CSF were 51.6 +/- 66.4/mm3 and protein levels were 35.4 +/- 14.7 mg/dl, and IgG levels were 6.6 +/- 4.2 mg/dl in NHAE-OT, and these data were not significantly different between NPNHALE and NHAE-OT. In acute stage, autoantibodies against whole molecule of GluRepsilon2 in CSF were detected in 51.8% (29/56) of adult NPNHALE, and 40% (6/15) of NHAE-OT patients by immunoblot. These autoantibodies in both groups included epitopes to n-terminal of GluRepsilon2. Antibodies against NMDAR complex (Dalmau's method) in CSF were detected in 90.9% (10/11) of NHAE-OT patients.