Refractory Status Epilepticus in Suspect Encephalitis

Clinical presentation of new onset refractory status epilepticus in children (the pSERG cohort)

Objective

We aimed to characterize the clinical profile and outcomes of new onset refractory status epilepticus (NORSE) in children, and investigated the relationship between fever onset and status epilepticus (SE).

Methods

Patients with refractory SE (RSE) between June 1, 2011 and October 1, 2016 were prospectively enrolled in the pSERG (Pediatric Status Epilepticus Research Group) cohort. Cases meeting the definition of NORSE were classified as "NORSE of known etiology" or "NORSE of unknown etiology." Subgroup analysis of NORSE of unknown etiology was completed based on the presence and time of fever occurrence relative to RSE onset: fever at onset (≤24 h), previous fever (2 weeks–24 h), and without fever.

Results

Of 279 patients with RSE, 46 patients met the criteria for NORSE. The median age was 2.4 years, and 25 (54%) were female. Forty (87%) patients had NORSE of unknown etiology. Nineteen (48%) presented with fever at SE onset, 16 (40%) had a previous fever, and five (12%) had no fever. The patients with preceding fever had more prolonged SE and worse outcomes, and 25% recovered baseline neurological function. The patients with fever at onset were younger and had shorter SE episodes, and 89% recovered baseline function.

Significance

Among pediatric patients with RSE, 16% met diagnostic criteria for NORSE, including the subcategory of febrile infection‐related epilepsy syndrome (FIRES). Pediatric NORSE cases may also overlap with refractory febrile SE (FSE). FIRES occurs more frequently in older children, the course is usually prolonged, and outcomes are worse, as compared to refractory FSE. Fever occurring more than 24 h before the onset of seizures differentiates a subgroup of NORSE patients with distinctive clinical characteristics and worse outcomes.

Markers in Status Epilepticus Prognosis

Status epilepticus (SE) is a neurologic emergency with high morbidity and mortality. The assessment of a patient's prognosis is crucial in making treatment decisions. In this review, we discuss various markers that have been used to prognosticate SE in terms of recurrence, mortality, and functional outcome. These markers include demographic, clinical, electrophysiological, biochemical, and structural data. The heterogeneity of SE etiology and semiology renders development of prognostic markers challenging. Currently, prognostication in SE is limited to a few clinical scores. Future research should integrate clinical, genetic and epigenetic, metabolic, inflammatory, and structural biomarkers into prognostication models to approach "personalized medicine" in prognostication of outcomes after SE.

New onset refractory status epilepticus (NORSE)

PURPOSE

To summarize the clinical features, suggested work-up, treatment and prognosis of new-onset refractory status epilepticus (NORSE), a condition recently defined as the occurrence of refractory status epilepticus (RSE) in a patient without active epilepsy, and without a clear acute or active structural, toxic or metabolic cause; and of the related syndrome of febrile infection-related epilepsy syndrome (FIRES), also recently defined as a subgroup of NORSE preceded by a febrile illness between 2 weeks and 24 h prior to the onset of RSE.

METHOD

Narrative review of the medical literature about NORSE and FIRES.

RESULTS

NORSE and FIRES mainly affect school-age children and young adults. A prodromal phase with flu-like symptoms precedes the SE onset in two third of NORSE cases, and by definition in all FIRES. Status epilepticus usually starts with repeated focal seizures with secondary bilateralization. Most cases evolve to super RSE (SRSE) and have unfavorable outcome, with short-term mortality of 12-27%, long-term disability and epilepsy. No specific imaging or laboratory abnormalities have been identified so far that allows an early diagnosis and half of adult cases remain of unknown etiology. A standardized diagnostic algorithm is provided and. Autoimmune encephalitis is the most frequent identified cause. In the absence of specific diagnosis, immunotherapy could be tried in addition to antiepileptic treatment.

CONCLUSIONS

This review presents the rare but devastating syndrome of NORSE, including the subcategory of FIRES. Early recognition with complete work-up is primordial to identify the underlying cause and promptly start appropriate treatment.

Neuroglucopenia and Metabolic Distress in Two Patients with Viral Meningoencephalitis: A Microdialysis Study

Introduction

Viral encephalitis is an emerging disease requiring intensive care management in severe cases. Underlying pathophysiologic mechanisms are incompletely understood and may be elucidated using invasive multimodal neuromonitoring techniques in humans.

Methods

Two otherwise healthy patients were admitted to our neurological intensive care unit with altered level of consciousness necessitating mechanical ventilation. Brain imaging and laboratory workup suggested viral encephalitis in both patients. Invasive neuromonitoring was initiated when head computed tomography revealed generalized brain edema, including monitoring of intracranial pressure, brain metabolism (cerebral microdialysis; CMD), brain tissue oxygen tension (in one patient), and cerebral blood flow (in one patient).

Results

Brain metabolism revealed episodes of severe neuroglucopenia (brain glucose <0.7 mM/l) in both patients, which were not attributable to decreased cerebral perfusion or hypoglycemia. CMD-glucose levels changed depending on variations in insulin therapy, nutrition, and systemic glucose administration. The metabolic profile, moreover, showed a pattern of non-ischemic metabolic distress suggestive for mitochondrial dysfunction. Both patients had a prolonged but favorable clinical course and improved to a modified Rankin Scale Score of 1 and 0 three months later.

Conclusion

Invasive multimodal neuromonitoring is feasible in poor-grade patients with viral meningoencephalitis and may help understand pathophysiologic mechanisms associated with secondary brain injury. The detection of neuroglucopenia and mitochondrial dysfunction may serve as treatment targets in the future.

Status Epilepticus and Beyond: A Clinical Review of Status Epilepticus and an Update on Current Management Strategies in Super-refractory Status Epilepticus

Status epilepticus and refractory status epilepticus represent some of the most complex conditions encountered in the neurological intensive care unit. Challenges in management are common as treatment options become limited and prolonged hospital courses are accompanied by complications and worsening patient outcomes. Antiepileptic drug treatments have become increasingly complex. Rational polytherapy should consider the pharmacodynamics and kinetics of medications. When seizures cannot be controlled with medical therapy, alternative treatments, including early surgical evaluation can be considered; however, evidence is limited. This review provides a brief overview of status epilepticus, and a recent update on the management of refractory status epilepticus based on evidence from the literature, evidence-based guidelines, and experiences at our institution.

Survey of the diagnostic and therapeutic approach to new-onset refractory status epilepticus

PURPOSE

We conducted a survey of providers to assess for practice patterns in diagnosing and treating new-onset refractory status epilepticus (NORSE). NORSE is the occurrence of prolonged seizures that are not responsive to initial therapies in otherwise healthy individuals without obvious cause on initial presentation. This entity is thought to have multiple etiologies, including autoimmune.

METHOD

A 29-question electronic survey was sent to providers included in the Neurocritical Care Society emailing list. Questions regarded responders' demographics, existing institutional practice protocols, diagnostic work-up, therapeutic management and expected outcomes in NORSE. Responses were collected from October 23, 2014, to November 25, 2014.

RESULTS

There were 107 respondents out of 1334 (8%). CT head, continuous EEG, lumbar puncture and microbe serologies were suggested within 24h of presentation as part of a diagnostic work-up. MRI brain, autoimmune work-up (systemic and anti-neuronal antibodies) and cytology/flow cytometry were favored later in the course. About 25% of providers would never perform an autoimmune work-up in this setting. Initial treatment included up to 3 anticonvulsants (including one anesthetic), followed by additional anticonvulsants/anesthetics along with antimicrobials, followed by steroids, plasma exchange, hypothermia and ketogenic diet. Many respondents would never use IV immunoglobulin or steroid-sparing immunosuppressants (29% and 42%, respectively) for NORSE.

CONCLUSIONS

This survey could serve as the foundation for development of a standardized approach for the diagnosis and treatment of NORSE.

New-Onset Refractory Status Epilepticus: More Investigations, More Questions

A 27-year-old previously healthy woman was admitted to the hospital with recurrent seizures. Status epilepticus developed that became refractory to third-line therapy with propofol and barbiturates. The patient had a very extensive diagnostic workup including autoimmune, viral and genetic investigations. A tentative immune therapy was proposed with high doses of steroids and plasma exchanges. Our patient had an inherited heterozygous single nucleotide variant in the sequence c.1280A>G [p.Lys427Arg] of the SMC3 gene that was insufficient to explain the seizures. Surprisingly, IgM antibodies against Japanese encephalitis virus were positive on the serum drawn 11 days after symptom onset, as detected by ELISA and the immunofluorescence antibody (IFA) technique. IgG antibodies were also positive using the IFA technique, but not with ELISA. The same investigations as well as the detection of the viral genome by the q-RT-PCR technique were negative on cerebrospinal fluid. Despite the suspicion of a viral infection, we concluded that our patient had a new-onset refractory status epilepticus of cryptogenic origin. Termination of the status epilepticus was obtained after 47 days, with a possible benefit from the introduction of ketamine.

Encephalitis Surveillance through the Emerging Infections Program, 1997-2010

A 3-state syndromic surveillance system documented reduction and emergence of neurologic infectious diseases.

Encephalitis is a devastating illness that commonly causes neurologic disability and has a case fatality rate >5% in the United States. An etiologic agent is identified in <50% of cases, making diagnosis challenging. The Centers for Disease Control and Prevention Emerging Infections Program (EIP) Encephalitis Project established syndromic surveillance for encephalitis in New York, California, and Tennessee, with the primary goal of increased identification of causative agents and secondary goals of improvements in treatment and outcome. The project represents the largest cohort of patients with encephalitis studied to date and has influenced case definition and diagnostic evaluation of this condition. Results of this project have provided insight into well-established causal pathogens and identified newer causes of infectious and autoimmune encephalitis. The recognition of a possible relationship between enterovirus D68 and acute flaccid paralysis with myelitis underscores the need for ongoing vigilance for emerging causes of neurologic disease.

New-onset refractory status epilepticus: Etiology, clinical features, and outcome

OBJECTIVES

The aims of this study were to determine the etiology, clinical features, and predictors of outcome of new-onset refractory status epilepticus.

METHODS

Retrospective review of patients with refractory status epilepticus without etiology identified within 48 hours of admission between January 1, 2008, and December 31, 2013, in 13 academic medical centers. The primary outcome measure was poor functional outcome at discharge (defined as a score >3 on the modified Rankin Scale).

RESULTS

Of 130 cases, 67 (52%) remained cryptogenic. The most common identified etiologies were autoimmune (19%) and paraneoplastic (18%) encephalitis. Full data were available in 125 cases (62 cryptogenic). Poor outcome occurred in 77 of 125 cases (62%), and 28 (22%) died. Predictors of poor outcome included duration of status epilepticus, use of anesthetics, and medical complications. Among the 63 patients with available follow-up data (median 9 months), functional status improved in 36 (57%); 79% had good or fair outcome at last follow-up, but epilepsy developed in 37% with most survivors (92%) remaining on antiseizure medications. Immune therapies were used less frequently in cryptogenic cases, despite a comparable prevalence of inflammatory CSF changes.

CONCLUSIONS

Autoimmune encephalitis is the most commonly identified cause of new-onset refractory status epilepticus, but half remain cryptogenic. Outcome at discharge is poor but improves during follow-up. Epilepsy develops in most cases. The role of anesthetics and immune therapies warrants further investigation.

Status epilepticus and refractory status epilepticus management

Status epilepticus (SE) describes persistent or recurring seizures without a return to baseline mental status and is a common neurologic emergency. SE can occur in the context of epilepsy or may be symptomatic of a wide range of underlying etiologies. The clinician's aim is to rapidly institute care that simultaneously stabilizes the patient medically, identifies and manages any precipitant conditions, and terminates seizures. Seizure management involves "emergent" treatment with benzodiazepines followed by "urgent" therapy with other antiseizure medications. If seizures persist, then refractory SE is diagnosed and management options include additional antiseizure medications or infusions of midazolam or pentobarbital. This article reviews the management of pediatric SE and refractory SE.

[Acute encephalitis with refractory partial status epilepticus treated with early immunotherapies including plasma exchange: a case report]

We describe a patient of acute encephalitis with refractory partial status epilepticus who was successfully treated with early immunotherapy. A 35-year-old male presented with generalized seizures a week after febrile upper respiratory illness. He developed refractory multifocal and generalized seizures despite multiple antiepileptic drug therapies, thereby requiring intubation on the 8(th) day after admission. No significant improvement was observed after steroid pulse and intravenous immunoglobulin (IVIG) therapies. On the 18(th) day, he received plasma exchange (PE) therapy in combination with intravenous thiamylal and lidocaine to achieve burst-suppression coma. This multidisciplinary treatment led to remission of refractory status epilepticus and subsequent withdrawal from general anesthesia. Although anti-N-methyl-D-aspartate receptor antibodies in cerebrospinal fluid were negative, other neural surface antibodies may responsible for the development of status epilepticus in this case. Clinical features in this case, including previous good health, an antecedent febrile illness, and prolonged treatment-resistant status epilepticus, were similar to those of the acute phase of new-onset refractory status epilepticus (NORSE) syndrome. Consecutive use of glucocorticoids, IVIG, and PE in the early phase was speculated to ameliorate seizures by suppressing abnormal activation of humoral immunity. This indicates that early aggressive immunotherapy may prevent complications resulting from immune-mediated treatment-resistant status epilepticus.

Is pentobarbital safe and efficacious in the treatment of super-refractory status epilepticus: a cohort study

Introduction

Seizures refractory to third-line therapy are also labeled super-refractory status epilepticus (SRSE). These seizures are extremely difficult to control and associated with poor outcome. We aimed to characterize efficacy and side-effects of continuous infusions of pentobarbital (cIV-PTB) treating SRSE.

Methods

We retrospectively reviewed continuous electroencephalography (cEEG) reports for all adults with RSE treated with cIV-PTB between May 1997 and April 2010 at our institution. Patients with post-anoxic SE and those receiving cIV-PTB for reasons other than RSE were excluded. We collected baseline information, cEEG findings, side-effects and functional outcome at discharge and one year.

Results

Thirty one SRSE patients treated with cIV-PTB for RSE were identified. Mean age was 48 years old (interquartile range (IQR) 28,63), 26% (N = 8) had a history of epilepsy. Median SE duration was 6.5 days (IQR 4,11) and the mean duration of cIV-PTB was 6 days (IQR 3,14). 74% (N = 23) presented with convulsive SE. Underlying etiology was acute symptomatic seizures in 52% (N = 16; 12/16 with encephalitis), remote 30% (N = 10), and unknown 16% (N = 5). cIV-PTB controlled seizures in 90% (N = 28) of patients but seizures recurred in 48% (N = 15) while weaning cIV-PTB, despite the fact that suppression-burst was attained in 90% (N = 28) of patients and persisted >72 hours in 56% (N = 17). Weaning was successful after adding phenobarbital in 80% (12/15 of the patients with withdrawal seizures). Complications during or after cIV-PTB included pneumonia (32%, N = 10), hypotension requiring pressors (29%, N = 9), urinary tract infection (13%, N = 4), and one patient each with propylene glycol toxicity and cardiac arrest. One-third (35%, N = 11) had no identified new complication after starting cIV-PTB. At one year after discharge, 74% (N = 23) were dead or in a state of unresponsive wakefulness, 16% (N = 5) severely disabled, and 10% (N = 3) had no or minimal disability. Death or unresponsive wakefulness was associated with catastrophic etiology (p = 0.03), but none of the other collected variables.

Conclusions

cIV-PTB effectively aborts SRSE and complications are infrequent; outcome in this highly refractory cohort of patients with devastating underlying etiologies remains poor. Phenobarbital may be particularly helpful when weaning cIV-PTB.

Viral encephalitis in the ICU

Viral encephalitis causes an altered level of consciousness, which may be associated with fever, seizures, focal deficits, CSF pleocytosis, and abnormal neuroimaging. Potential pathogens include HSV, VZV, enterovirus, and in some regions, arboviruses. Autoimmune (eg, anti-NMDA receptor) and paraneoplastic encephalitis are responsible for some cases where no pathogen is identified. Indications for ICU admission include coma, status epilepticus and respiratory failure. Timely initiation of anti-viral therapy is crucial while relevant molecular and serological test results are being performed. Supportive care should be directed at the prevention and treatment of cerebral edema and other physiological derangements which may contribute to secondary neurological injury.

New onset refractory status epilepticus (NORSE) as the heralding manifestation of herpes simplex encephalitis

New onset refractory status epilepticus (NORSE) is a relatively novel concept used to describe a cohort of previously healthy young adults mostly women presenting with denovo refractory status epilepticus which has a miserable impact on the outcome. Various infectious and non-infectious causes have been considered to be responsible for this dreaded syndrome; however, many a times the exact cause is not identified. As therapy with antiepileptic and anaesthetic drugs is not so successful, identifying and treating the exact cause could improve the outcome. Here the authors describe a woman who presented with NORSE. Investigations confirmed the diagnosis of herpes simplex encephalitis (HSE) and she responded drastically to acyclovir along with complete control of seizures. In this case, NORSE was the presenting feature of HSE and the refractoriness of her seizures was terminated only after treating the exact cause, that is, encephalitis.

The diagnosis and treatment of limbic encephalitis

The term limbic encephalitis (LE) was first introduced in 1968. While this disease was initially considered rare and is often fatal with very few treatment options, several reports published in the last decade provide a better description of this condition as well as possible causes and some cases of successful treatment. The clinical manifestation of LE is primarily defined by the subacute onset of short-term memory loss, seizures, confusion and psychiatric symptoms suggesting the involvement of the limbic system. In addition, EEG often shows focal or generalized slow wave or epileptiform activity, and MRI findings reveal hyperintense signals of the medial temporal lobes in T2-weighted or FLAIR images. The current literature suggests that LE is not a single disorder but is comprised of a group of autoimmune disorders predominantly affecting the limbic system. Before the diagnosis of LE can be determined, other causes of subacute encephalopathy must be excluded, especially those resulting from infectious aetiologies. LE has previously been regarded as a paraneoplastic phenomenon associated with the classical onconeuronal antibodies that are primarily directed against intracellular antigens. However, recent literature suggests that LE is also associated with antibodies that are directed against cell surface antigens, and these cases of LE display a much weaker association to the neoplasm. The treatment options for LE largely depend on the aetiology of the disease and involve the removal of the primary neoplasm. Therefore, a search for the underlying tumour is mandatory. In addition, immunotherapy has been successful in a significant number of patients where LE is not associated with cancer.

Problems and controversies in status epilepticus: a review and recommendations

Status epilepticus (SE) is a neurologic emergency that require immediate vigorous treatment in order to prevent serious morbidity or even death. Several investigators have suggested that the underlying etiology is the primary determinant of outcome. We believe that this may be true in aggressively treated SE, but not when the treatment is less than optimal. In this article, we will discuss the factors that have been implicated in affecting SE outcomes, and argue, on the basis of both human and experimental animal data, that aggressive treatment is necessary and appropriate for all presentations of SE in order to maximize the probability of a successful outcome even when the etiology suggests a poor prognosis.

TNF-overexpression in Borna disease virus-infected mouse brains triggers inflammatory reaction and epileptic seizures

Proinflammatory state of the brain increases the risk for seizure development. Neonatal Borna disease virus (BDV)-infection of mice with neuronal overexpression of tumor necrosis factor-α (TNF) was used to investigate the complex relationship between enhanced cytokine levels, neurotropic virus infection and reaction pattern of brain cells focusing on its role for seizure induction. Viral antigen and glial markers were visualized by immunohistochemistry. Different levels of TNF in the CNS were provided by the use of heterozygous and homozygous TNF overexpressing mice. Transgenic TNF, total TNF (native and transgenic), TNF-receptor (TNFR1, TNFR2), IL-1 and N-methyl-D-aspartate (NMDA)-receptor subunit 2B (NR2B) mRNA values were measured by real time RT-PCR. BDV-infection of TNF-transgenic mice resulted in non-purulent meningoencephalitis accompanied by epileptic seizures with a higher frequency in homozygous animals. This correlated with lower weight gain, stronger degree and progression of encephalitis and early, strong microglia activation in the TNF-transgenic mice, most obviously in homozygous animals. Activation of astroglia could be more intense and associated with an unusual hypertrophy in the transgenic mice. BDV-antigen distribution and infectivity in the CNS was comparable in TNF-transgenic and wild-type animals. Transgenic TNF mRNA-expression was restricted to forebrain regions as the transgene construct comprised the promoter of NMDA-receptor subunit2B and induced up-regulation of native TNF mRNA. Total TNF mRNA levels did not increase significantly after BDV-infection in the brain of transgenic mice but TNFR1, TNFR2 and IL-1 mRNA values, mainly in the TNF overexpressing brain areas. NR2B mRNA levels were not influenced by transgene expression or BDV-infection. Neuronal TNF-overexpression combined with BDV-infection leads to cytokine up-regulation, CNS inflammation and glial cell activation and confirmed the presensitizing effect of elevated cytokine levels for the development of spontaneous epileptic seizures when exposed to additional infectious noxi.

Management of refractory status epilepticus in adults: still more questions than answers

Refractory status epilepticus (RSE) is defined as status epilepticus that continues despite treatment with benzodiazepines and one antiepileptic drug. RSE should be treated promptly to prevent morbidity and mortality; however, scarce evidence is available to support the choice of specific treatments. Major independent outcome predictors are age (not modifiable) and cause (which should be actively targeted). Recent recommendations for adults suggest that the aggressiveness of treatment for RSE should be tailored to the clinical situation. To minimise intensive care unit-related complications, focal RSE without impairment of consciousness might initially be approached conservatively; conversely, early induction of pharmacological coma is advisable in generalised convulsive forms of the disorder. At this stage, midazolam, propofol, or barbiturates are the most commonly used drugs. Several other treatments, such as additional anaesthetics, other antiepileptic or immunomodulatory compounds, or non-pharmacological approaches (eg, electroconvulsive treatment or hypothermia), have been used in protracted RSE. Treatment lasting weeks or months can sometimes result in a good outcome, as in selected patients after encephalitis or autoimmune disorders. Well designed prospective studies of RSE are urgently needed.

Encephalitis diagnosis and management in the real world

Significant advances, especially in microbiologic diagnostics and brain imaging, have broadened our understanding of the etiology, pathogenesis, and natural history of acute encephalitis. In some instances this had led to specific therapies and preventive measures. The clinical hallmark of acute encephalitis is the triad of fever, headache, and altered mental status. Common neurologic features include disorientation or depressed level of consciousness; disturbances of behavior, speech, or executive function; and diffuse or focal neurologic signs such as cranial nerve dysfunction, hemiparesis, or seizures. These features distinguish the unusual patient with encephalitis from the more commonly encountered patient with uncomplicated meningitis who has fever, headache, and nuchal rigidity but lacks abnormal global or focal neurologic signs. Etiologies of acute encephalitis are myriad. Most are viral infections. Table 1 shows a robust but not exhaustive list of viral etiologies. Beyond this there is another robust but not exhaustive list (Table 2) of important considerations in the differential diagnosis. These include infectious agents (bacterial, fungal, parasitic, and amebic) as well as non-infectious etiologies (parainfectious, post-infectious, autoimmune, neoplastic, cerebrovascular, systemic, and other conditions). The challenge for the clinician is to rapidly hone the list and make critical management decisions by considering the specific features of the setting of the patient's illness, host susceptibility, clinical and neurologic findings, and results of laboratory and imaging studies.

Less common etiologies of status epilepticus

Status epilepticus is treated as a neurologic emergency and only later are the potential etiologies assessed. While sometimes the cause for status epilepticus is apparent (e.g., antiepileptic drug withdrawal), all too often it is not identified, even after extensive diagnostic testing has been performed. With emphasis on the less-common etiologies, this review will cover various probable and known causes of status epilepticus among adults, children, and those patients with refractory epilepsy.

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.