Infections as causative factors of epilepsy

Functional neuroimaging in Rasmussen syndrome

PURPOSE

For a diagnosis of Rasmussen syndrome (RS), clinical course together with electroencephalography (EEG) and magnetic resonance imaging (MRI) findings are considered important, but there are few reports on functional neuroimaging. This study investigated cerebral blood flow (CBF)-single photon emission computed tomography (SPECT), central benzodiazepine receptor (BZR)-SPECT, and fluorine-18 fluorodeoxy glucose-positron emission tomography (FDG-PET) in RS patients, and correlated neuroimaging results with MRI and pathological findings.

METHODS

Twenty-three patients diagnosed with RS according to Bien's (2005) diagnostic criteria (including 12 patients with a histological diagnosis) were studied. CBF-SPECT, BZR-SPECT and FDG-PET images were visually evaluated, and the findings correlated with MRI and histological findings.

RESULTS

Hypoperfusion areas were observed in 16 of 22 patients by interictal CBF-SPECT. Hyperperfusion areas were observed in 10 of 12 patients by ictal CBF-SPECT, which correlated with ictal onset area by ictal EEG (IOAE). In the limited data of BZR-SPECT in nine patients, lowered uptake was detected in all nine patients, including two with no MRI abnormalities. Lowered glucose metabolism was observed in affected areas in all five patients by FDG-PET. Histological examination revealed findings of chronic encephalitis in all 12 patients examined, concomitant with focal cortical dysplasia in five patients.

CONCLUSION

In RS patients, functional neuroimaging reveals clear abnormal findings, even before the appearance of MRI abnormalities. BZR-SPECT and FDG-PET could detect the IOAE efficiently even in the absence of MRI abnormalities, while interictal CBF-SPECT occasionally failed to detect IOAE if MRI was normal. Based on BZR-SPECT, refractory epileptic seizures in RS may suggest possible impairment of inhibitory neurons.

Weather as a risk factor for epileptic seizures: A case-crossover study

OBJECTIVE

Most epileptic seizures occur unexpectedly and independently of known risk factors. We aimed to evaluate the clinical significance of patients' perception that weather is a risk factor for epileptic seizures.

METHODS

Using a hospital-based, bidirectional case-crossover study, 604 adult patients admitted to a large university hospital in Central Germany for an unprovoked epileptic seizure between 2003 and 2010 were recruited. The effect of atmospheric pressure, relative air humidity, and ambient temperature on the onset of epileptic seizures under temperate climate conditions was estimated.

RESULTS

We found a close-to-linear negative correlation between atmospheric pressure and seizure risk. For every 10.7 hPa lower atmospheric pressure, seizure risk increased in the entire study population by 14% (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.01-1.28). In patients with less severe epilepsy treated with one antiepileptic medication, seizure risk increased by 36% (1.36, 1.09-1.67). A high relative air humidity of >80% increased seizure risk in the entire study population by up to 48% (OR 1.48, 95% CI 1.11-1.96) 3 days after exposure in a J-shaped association. High ambient temperatures of >20°C decreased seizure risk by 46% in the overall study population (OR 0.54, 95% CI 0.32-0.90) and in subgroups, with the greatest effects observed in male patients (OR 0.33, 95% CI 0.14-0.74).

SIGNIFICANCE

Low atmospheric pressure and high relative air humidity are associated with an increased risk for epileptic seizures, whereas high ambient temperatures seem to decrease seizure risk. Weather-dependent seizure risk may be accentuated in patients with less severe epilepsy. Our results require further replication across different climate regions and cohorts before reliable clinical recommendations can be made.

Immunomodulatory therapy versus surgery for Rasmussen syndrome in early childhood

We examined seizure, cognitive, and motor outcomes in patients with Rasmussen syndrome or Rasmussen encephalitis (RS), after recent initiation of immunomodulatory therapies. Among 53 patients with a diagnosis of RS referred from all over Japan, 49 patients (male 22, female 27) with symptoms and findings characteristic of RS were evaluated. Regular intravenous immunoglobulin (IVIg) therapy was administered at a dose of 100mg/kg/day, etc. Regular steroid pulse therapy was conducted with methylprednisolone at a dose of 30mg/kg/day (children) or 1000mg/day (adults) for 3days. Tacrolimus was given at an initial dose of 0.1mg/kg/day (children). Mean onset age was 8.7±10.5years. Seizure-free rate was 71% after treatment by functional hemispherectomy (FH), and response rate for seizures was 81% by regular steroid pulse therapy, 42% by tacrolimus therapy, and 23% by regular IVIg therapy. Rate of patients with IQ higher than 80 (R80) was 50% by regular steroid pulse therapy, 43% by regular IVIg therapy, 29% by tacrolimus therapy, and 0% by FH. R80 after regular steroid pulse therapy was 100% in patients without MRI lesions, and 37% in those with advanced MRI lesions. Improvement of motor function (paresis) was observed only by immunomodulatory therapy. Motor function was aggravated in 100% of patients treated by FH, 62% by regular IVIg, and 10% by regular steroid pulse therapy. We suggest a new treatment strategy for RS using early immunomodulatory therapy: initiation of regular steroid pulse therapy after early diagnosis indicated by biomarkers, then switching to tacrolimus therapy after several months.

Ophthalmoplegia and flaccid paraplegia in a patient with anti-NMDA receptor encephalitis: a case report and literature review

We herein report the case of a 26-year-old woman with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis presenting with ophthalmoplegia and flaccid paraplegia. She developed disorientation and hallucination after fever and vomiting. Hypothermia, hypoventilation, hypertension, paralytic ileus and hyponatremia were present. Neurological examination showed mild consciousness disturbance and bilateral ophthalmoplegia on admission, flaccid paraplegia with leg areflexia on Day 4. Anti-NMDAR antibodies were detected in the serum and cerebrospinal fluid samples. Motor nerve conduction velocity was decreased in the tibial and peroneal nerves. F-wave amplitudes were reduced in the tibial nerve. MRI disclosed lesions in the callosal splenium, hippocampus and cerebral subarachnoid regions. In addition to various encephalitic symptoms, physicians should pay more attention to peripheral nerve damage in patients with anti-NMDAR encephalitis.

Nationwide survey (incidence, clinical course, prognosis) of Rasmussen's encephalitis

PURPOSE

Rasmussen's encephalitis (RE) is a progressive and catastrophic epileptic disorder caused by chronic localized encephalitis. We performed a nationwide survey of RE to assess the clinical picture, treatment effect, and prognosis of Japanese RE patients.

SUBJECTS & METHODS

The subjects were 27 patients (male:12; female:15) from 13 medical facilities. All of them satisfied the clinical and neuroimaging criteria for RE, including 14 pathologically proven cases.

RESULTS

They were divided into the childhood-onset rapidly progressive type (CORP, n=19), and late-onset slowly progressive type (LOSP, n=8). The mean age at epilepsy onset was 4 years and 4 months in CORP, and 16 years in LOSP. The mean period between the onset age of epilepsy and development of frequent seizures was 1 year and 4 months in the former, and 3 years and 4 months in the latter. The immunomodulatory treatment including high-dose steroid (n=14) and high-dose intravenous immunoglobulin therapies (IVIgG, n=12) achieved more than a 50% reduction in the seizure frequency in 5 (36%) and 4 (33%) patients, respectively. Eight and seven patients underwent focal cortical resection and functional hemispherectomy, leading to significant improvement in 5 of the 8 patients and excellent seizure control in all 7 patients, respectively.

CONCLUSION

Although the high-dose steroid and IVIG therapies may have alleviated the exacerbation of seizures in those with RE, they could not halt the disease progression. Functional hemispherectomy is still the only curative therapy for RE, despite the fact that the early introduction of this procedure remains controversial.

Acute encephalitis with refractory, repetitive partial seizures (AERRPS): a peculiar form of childhood encephalitis

OBJECTIVE

We conducted a nationwide multicenter study in Japan to elucidate the clinical and laboratory characteristics of acute encephalitis with refractory, repetitive partial seizures (AERRPS).

MATERIALS AND METHODS

Clinical and laboratory features, treatment, and outcome were assessed using a structured questionnaire.

RESULTS

Twenty-nine children were enrolled in the study. Refractory and repetitive partial seizures accompanied by fever were the cardinal clinical features. Partial seizures consisted principally of eye deviation or facial twitching, being periodically repeated during the acute phase. These seizures were refractory to conventional anticonvulsants and were only suppressed by high-dose intravenous barbiturate administration. Rhythmic activities on electroencephalography and non-specific cerebral atrophy on neuroimaging were common. Serum or cerebrospinal antibodies against GluRepsilon2 were positive in six patients. General prognosis was unfavorable due to intractable epilepsy and cognitive deficits.

CONCLUSION

Based on the peculiar and homogenous features, AERRPS can be regarded as a distinct clinical entity.

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.

[A case of glioblastoma misdiagnosed initially due to positive finding of anti-glutamate receptor antibody]

A 53-year-old man was admitted to our hospital after suffering four attacks with loss of consciousness and/or topographic agnosia. Three months after the first attack, the cerebrospinal fluid analysis showed no abnormal findings. IgG-autoantibodies and IgM-autoantibodies against glutamate receptor epsilon2 (GluRepsilon2) were detected in cerebrospinal fluid and serum respectively. At that time, we diagnosed him as having limbic encephalopathy. Brain MRI revealed a high intensity lesion on T2-weighted and FLAIR images in the medial regions of the bilateral temporal lobes and splenium. A diffusion-weighted image revealed high intensity lesions which were also weakly enhanced by Gd-DTPA in the deep white matter beside the posterior horns. The patient then developed numbness in the right hand. The cerebralspinal fluid analysis, four months after the onset of the disease, exhibited slight pleocytosis and elevated protein. IgG-autoantibodies against GluRepsilon2 were detected in the serum. The lesions beside the posterior horns were ring-like enhanced more strongly. Brain biopsy led to a diagnosis of glioblastoma. We suggest that patients with autoantibodies against GluRepsilon2 should be carefully diagnosed with limbic encephalopathy associated with autoimmune mechanisms even if radiological findings are typical of the disease.

[Subacute encephalitis associated with anti-glutamate receptor antibodies: serial studies of MRI, 1H-MRS and SPECT]

A 32-year-old man who had experienced fever and a pulsating headache of the right occipital region for a month and a transient left hemianopia and numbness in the left arm two weeks prior to presentation was admitted to our hospital because of a seizure. Fluid-attenuated inversion recovery and diffusion-weighted magnetic resonance imaging (MRI) showed high-intensity signals, without reduction of apparent diffusion coefficient value, in the right temporo-occipital cortices. Proton MR spectroscopy (1H-MRS) indicated a decrease in N-acetylaspartate, and single-photon emission CT (SPECT) showed hyperperfusion in the right temporo-occipital territory. An examination of the cerebrospinal fluid showed an elevation of mononuclear cells and the presence of anti-glutamate epsilon2 receptor antibodies. All abnormalities shown by these imaging techniques were normalized in the clinical course. This report suggests that MRI, 1H-MRS and SPECT studies were useful in understanding the pathogenesis of encephalitis associated with glutamate receptor antibodies.

[Rasmussen encephalitis and non-herpetic acute limbic encephalitis]

Rasmussen syndrome (RS) and non-herpetic acute limbic encephalitis (NHALE) have pathophysiological background related with autoimmunity to glutamate receptors (GluRs) after infections. RS and NHALE were reviewed, depending mainly on our recent studies. RS is the prototype of autoimmune-mediated epilepsy. In patients with RS, several kinds of autoantibodies against neuronal molecules, for example, GluR3, GluRepsilon2 (NMDA-R2B), etc., are reported. These autoantibodies are not specific for RS. About autoantibodies against GluR3, significance and stimulating effects to GluR3 are controversial. Autoantibodies against GluRepsilon2 were detected in all patients within six months from epilepsy onset, and in some patients at chronic stage. These data suggest that autoantibodies against GluRepsilon2 may be involved in the pathological mechanisms in the early stage, but we could not confirm the effect of the autoantibodies from RS patients on excitatory postsynaptic NMDA current using patch clump methods. However, anti-double-stranded DNA antibodies in patients with SLE are reported to cross-react with n-terminal of GluRepsilon2, and cause neuronal apoptosis in rat hippocampus, ensuing memory impairment, and emotional behavior impairment in mice. Therefore, autoantibodies against GluRepsilon2 may contribute to the cognitive and behavioral changes in RS. Concerning about cellular immunity in RS, lymphocytes stimulating tests revealed peripheral lymphocytes sensitized by antigens containing GluRepsilon2. Cytotoxic T cells (CTLs) excreting Granzyme B were reported in resected brain tissue, and we confirmed the elevated levels of Granzyme B, not in sera, but in CSF. These data suggest that CTLs activated by infection invade into CNS, and recognize neural antigens, and excrete Granzyme B. The incidence of NHALE is 4.1/1 million/year in Japanese adults. Our study in 91 adult patients with NHALE revealed the following characteristics. Mean onset age was 35.2 +/- 16.9 years old, and preceding infections existed in 68.7% of patients, and predominant symptoms at the onset were psychiatric symptoms (33.3%) and convulsions (25.0%). CSF showed slightly elevated cell counts (55.5 +/- 139.9), protein levels (48.1 +/- 36.0 mg/dl), and IgG levels (4.5 +/- 3.9 mg/dl). MRI lesions with high intensity were found in 40.8% (DWI) and 54.2% (FLAIR) of patients in various stages after onsets. Autoantibodies against GluRepsilon2 in sera were detected in approximately 60% of NHALE patients from acute to chronic stages, and the autoantibodies in CSF were detected in 51.8% (acute stage), 41.4% (recovery stage), 28.6% (chronic stage) of patients and included epitopes to n-terminal of GluRepsilon2 (NT1). These data suggest that autoantibodies against GluRepsilon2 produced in sera after infection infiltrate into CNS through damaged BBB in acute stages, and affect n-terminal of GluRepsilon2. In chronic stage, recovery of function of BBB reduces levels of the autoantibodies in CSF. Because BBB in hippocampi and amygdala are vulnerable, autoantibodies against GluRepsilon2 including epitopes to n-terminal may contribute to the limbic symptoms around onset. Among several autoantibodies related with NHALE, autoantibodies against GluRepsilon2 were found in patients around 15-34 years old, autoantibodies against VGKC were around 50.4 years old, autoantibodies against NAE were around 59 years old, autoantibodies against Hu were around 61.5 years old. These data suggest that autoantibodies related with NHALE have age-dependent heterogeneity.

Refractory epilepsy accompanying acute encephalitis with multifocal cortical lesions: possible autoimmune etiology

We report on a 14-year-old male suffering from acute encephalitis, whose clinical course met the criteria for acute encephalopathy with refractory, repetitive partial seizures (AERRPS). He presented with extremely refractory partial and secondary generalized seizures, and required high-dose barbiturate infusion therapy for 57 days under mechanical ventilation. Seven weeks after onset, the seizures were ameliorated by treatment with sodium bromide, carbamazepine, clobazam, and high-dose phenobarbital. Magnetic resonance imaging on day 14 of admission showed multifocal cortical lesions scattered in the bilateral hemispheres; these disappeared on day 34. Diffuse and mild atrophy of the cerebral cortex, and moderate atrophy of the hippocampus, appeared by day 61. Serum anti-glutamate receptor epsilon2 autoantibodies were detected on day 2. The patient was discharged after 113 days of admission with intractable epilepsy, memory disability, and regression of intelligence. We discuss the etiological significance of the multifocal lesions, which are unusual findings on neuroimaging of AERRPS.

Autoantibodies against Glutamate Receptor ε2-Subunit Detected in a Subgroup of Patients with Reversible Autoimmune Limbic Encephalitis

We investigated the presence of autoantibodies against glutamate receptor (GluR) epsilon2 in serum and cerebrospinal fluid (CSF) samples from 12 consecutive patients with acute encephalitis/encephalopathy by immunoblotting using recombinant GluR epsilon2 as antigen. In 4 patients, IgM autoantibodies against GluR epsilon2 were detected in CSF in the early phase of the disease but were not detectable after several months. Seizures and psychiatric symptoms were noted during the acute phase of the disease in these 4 patients, who showed various degrees of residual amnesia. Immunotherapy was performed on 3 patients (patients 1, 3 and 4), and they showed marked improvements. Immunohistochemistry using these patients' sera showed that immunoreactivity is specifically detected in the cytoplasm of rat hippocampal and cortical neurons. The clinical features and neuroimaging findings of patients with IgM autoantibodies against GluR epsilon2 in CSF resemble those of patients with reversible autoimmune limbic encephalitis.

Vaccination and infection as causative factors in Japanese patients with Rasmussen syndrome: molecular mimicry and HLA class I

Rasmussen syndrome is an intractable epilepsy with a putative causal relation with cellular and humoral autoimmunity. Almost half of the patients have some preceding causative factors, with infections found in 38.2%, vaccinations in 5.9% and head trauma in 8.9% of Japanese patients. In a patient with seizure onset after influenza A infections, cross-reaction of the patient's lymphocytes with GluRε2 and influenza vaccine components was demonstrated by lymphocyte stimulation test. Database analyses revealed that influenza A virus hemagglutinin and GluRε2 molecules contain peptides with the patient's HLA class I binding motif (HLA − A*0201). The relative risks of HLA class I genotypes for Rasmussen syndrome are 6.1 (A*2402), 6.4 (A*0201), 6.3 (A*2601) and 11.4 (B*4601). The relative risks of HLA class I-A and B haplotypes are infinity (A*2601+B*5401), 21.1 (A*2402+B*1501), 13.3 (A*2402+B*4801) and 5.1 (A*2402+B*5201). Some alleles and haplotypes of HLA class I may be the risk factors in Japanese patients. Cross-reactivity of cytotoxic T lymphocytes may contribute to the processes leading from infection to the involvement of CNS.

Paraneoplastic limbic encephalitis caused by ovarian teratoma with autoantibodies to glutamate receptor

We report a rare case of paraneoplastic limbic encephalitis with autoantibodies to glutamate receptor (GluR) in the cerebrospinal fluid (CSF). The 35-year-old woman with consciousness disturbance was diagnosed initially as non-herpetic encephalitis. Her signs and symptoms improved with acyclovir and steroid pulse therapy. However, after the treatment, an ovarian tumor was discovered, and we detected autoantibodies to GluR in the CSF. A possible association between the ovarian teratoma and GluR is suggested.