Autoimmune Limbic Encephalitis With GAD Antibodies

Anti-Glutamic Acid Decarboxylase (GAD) 65 Encephalitis Mistaken for Herpes Encephalitis and Hashimoto’s Encephalitis (HE): A Case Report

Autoimmune encephalitis is increasingly recognized in clinical practice. We are presenting a 72-year-old female patient who initially presented with a new onset seizure with temporal lobe abnormality on imaging. This was initially attributed to herpes encephalitis although herpes polymerase chain reaction (PCR) was negative. The patient was treated with acyclovir and antiepileptic medication (AEM) with some clinical improvement. She presented again with refractory seizure evolving to status epilepticus. Escalation of AEMs was pursued and positive anti-thyroid peroxidase (TPO) antibody prompted consideration of Hashimoto's encephalitis (HE) and treatment with high-dose corticosteroids and intravenous immunoglobulin (IVIG). However, poor response to steroid argued against HE, and extended autoimmune encephalitis panel revealed positive anti-glutamic acid decarboxylase (GAD) antibody. This case raises the clinical pearl that anti-thyroid antibodies, e.g anti-TPO antibody, can be seen in those with autoimmune encephalopathies other than HE and HE remains a diagnosis of exclusion. It also helps to remind clinicians that a new onset refractory seizure even with temporal lobe changes is not pathognomonic for herpes encephalitis, and although negative serology does not rule out the diagnosis, it is recommended to rule out autoimmune encephalitis as it shares similar clinical and radiological picture.

Nonparaneoplastic Anti-GAD Limbic Encephalitis: Seizure Outcome and Long-term Neuropsychological Follow-up After Immunotherapy

Antibodies against glutamate decarboxylase (GAD-Abs), especially GAD65 antibodies, are associated with limbic encephalitis (LE) manifested by temporal lobe epilepsy and neuropsychological deficits. We present the case of a 42-year-old Greek woman with nonparaneoplastic anti-GAD LE, discussing the therapeutic management and highlighting the role of neuropsychological assessment. The patient underwent functional and structural brain studies and was investigated longitudinally over a 6-year period with a battery of neuropsychological tests that were designed to document her intellectual function and verbal and visual memory. The patient suffered from refractory temporal-impaired awareness seizures and memory impairment that was mediated by autoimmune nonparaneoplastic LE and comorbid autoimmune disorders (ie, Hashimoto thyroiditis and vitiligo). Neuroimaging studies demonstrated hyperintensities in the medial temporal lobes bilaterally on T2WI MRI sequences. Serial EEGs showed bitemporal intermittent delta activity as well as epileptiform discharges. Tumor blood markers and onconeural antibodies were negative. Immunological screening revealed extremely high GAD-Abs titers in both serum and CSF, as well as the presence of CSF oligoclonal bands. Neuropsychological testing revealed anterograde amnesia with relative preservation of more remote, premorbid memories. The patient underwent first-line immunotherapy followed by immunosuppressive maintenance treatment that led to a reduction of seizures, EEG improvement, and a significant decline in GAD-Abs titers. Neuropsychological evaluations at 5 months, 1 year, and 6 years posttreatment demonstrated improvement, particularly in recent memory and everyday functionality. In this case of anti-GAD LE, the long-term seizure reduction and the improvement of neuropsychological deficits were most likely related to the immunotherapy.

Brain and Muscle Metabolic Changes by FDG-PET in Stiff Person Syndrome Spectrum Disorders

Objective: To report clinical characteristics and fluorodeoxyglucose positron emission tomography (FDG-PET) findings in the brain and muscles of individuals with stiff person syndrome (SPS) spectrum disorders (SPSSDs).

Methods: Retrospective cohort study from 1997 to 2018 at Johns Hopkins Hospital identified 170 individuals with SPS or cerebellar ataxia (CA) associated with anti-glutamic acid decarboxylase (anti-GAD)-65 antibodies. Fifty-one underwent FDG-PET, with 50 involving the body and 30 with dedicated brain acquisition. The clinical and immunological profiles were extracted via medical record review. The brain scans were analyzed quantitatively using the NeuroQ software, with comparison with an averaged normal database. The body scans were reviewed qualitatively by a blinded nuclear medicine radiologist.

Results: Mean age of symptom onset was 41.5 years (range 12–75 years). Majority were female (68%) and White (64%). Of the patients, 82% had SPS (majority being classic phenotype), and 18% had CA. Three had a paraneoplastic process. Forty-seven had serum anti-GAD, two with anti-amphiphysin, and one with anti-glycine receptor antibodies. Brain metabolic abnormalities were seen in both SPS and CA, with significant differences between the groups noted in the right superior frontal cortex, right sensorimotor cortex, left inferior parietal cortex, bilateral thalami, vermis, and left cerebellum. Of the patients, 62% demonstrated muscle hypermetabolism, most commonly bilateral, involving the upper extremities or axial muscles. Neither brain nor muscle metabolism was correlated with functional outcomes nor treatments.

Conclusions: Metabolic changes as seen by FDG-PET are present in the brain and muscle in many individuals with SPSSD. Future studies are needed to assess whether FDG-PET can help aid in the diagnosis and/or monitoring of individuals with SPSSD.

Treatment of Anti-GAD65 Autoimmune Encephalitis With Methylprednisolone

Background: Anti-glutamic acid decarboxylase 65 (anti-GAD65) antibody encephalitis is a rare form of autoimmune encephalitis that can lead to severe neurologic impairment, coma, and death. Case Report: We present the case of a 54-year-old male with severely altered mental status and profound neurologic impairment who rapidly progressed to a comatose state. Because of the patient's rapidly deteriorating status, lack of yield with diagnostic testing, and lack of clinical improvement with broad empiric treatments, the clinical decision was made to treat the patient with high-dose methylprednisolone, and the treatment returned the patient to his baseline mental status. After the patient's discharge, the autoimmune encephalitis panel returned positive for anti-GAD65 antibodies. Conclusion: This case illustrates the importance of considering a diagnosis of autoimmune encephalitis for patients with rapidly deteriorating mental status. Unless contraindicated, treatment with high-dose glucocorticoids can be successful for these patients. This case also shows a potential association between hypothyroidism and anti-GAD65 antibodies.

Pediatric inflammatory demyelinating disorders and mimickers: How to differentiate with MRI?

Multiple sclerosis (MS) is a chronic, immune-mediated, neurodegenerative disorder of the central nervous system (CNS).While the clinical symptoms of MS most commonly manifest between 20 and 40 years of age, approximately 3 to 10% of all MS patients report that their first inaugural events can occur earlier in life, even in childhood, and thus include the pediatric population. The prevalence of MS onset in childhood/adolescence varies between 2.0% and 4.0% of all MS cases according to several extensive studies. The main imaging patterns of pediatric inflammatory demyelinating disorders and mimicking entities, including multiple sclerosis, neuromyelitis optica spectrum disorders, acute disseminated encephalomyelitis, MOG (myelin oligodendrocyte glycoprotein) antibody-related disorders and differential diagnoses will be addressed in this article, highlighting key points to the differential diagnosis.

Specific B- and T-cell populations are associated with cognition in patients with epilepsy and antibody positive and negative suspected limbic encephalitis

OBJECTIVE

Neuropsychological impairments are major symptoms of autoimmune limbic encephalitis (LE) epilepsy patients. In LE epilepsy patients with an autoimmune response against intracellular antigens as well as in antibody-negative patients, the antibody findings and magnetic resonance imaging pathology correspond poorly to the clinical features. Here, we evaluated whether T- and B-cells are linked to cognitive impairment in these groups.

METHODS

In this cross-sectional, observational, case-controlled study, we evaluated 106 patients with adult-onset epilepsies with a suspected autoimmune etiology. We assessed verbal and visual memory, executive function, and mood in relation to the presence or absence of known auto-antibodies, and regarding T- and B-cell activity as indicated by flow cytometry (fluorescence-activated cell sorting = FACS, peripheral blood = PB and cerebrospinal fluid = CSF).

RESULTS

56% of the patients were antibody-negative. In the other patients, auto-antibodies were directed against intracellular antigens (GAD65, paraneoplastic: 38%), or cellular surface antigens (LGI1/CASPR2/NMDA-R: 6%). Excluding LGI1/CASPR2/NMDA-R, the groups with and without antibodies did not differ in disease features, cognition, or mood. CD4+ T-cells and CD8+ T-cells in blood and CD4+ T-cells in CSF were prominent in the auto-antibody positive group. Regression analyses indicated the role education, drug load, amygdala and/or hippocampal pathology, and CD4+ T-cells play in verbal memory and executive function. Depressed mood revealed no relation to flow cytometry results.

CONCLUSION

Our results indicate a link between T- and B-cell activity and cognition in epilepsy patients with suspected limbic encephalitis, thus suggesting that flow cytometry results can provide an understanding of cognitive impairment in LE patients with autoantibodies against intracellular antigens.

Super refractory status epilepticus secondary to anti-GAD antibody encephalitis successfully treated with aggressive immunotherapy

Antibodies against glutamic acid decarboxylase are reported in association with a number of neurological conditions including limbic encephalitis. We report a case of anti-GAD-antibody associated encephalitis presenting with super-refractory status epilepticus. We describe the clinical course, management, and the outcome. In addition, we review the presentation and outcomes of reported cases of anti-GAD encephalitis. Similar to the reported cases of anti-GAD encephalitis, our case was refractory to treatment with conventional antiseizure medication. Treatment with intravenous immune globulin (IVIG), high dose corticosteroids, and plasmapheresis had partial response, but escalation of treatment to the use of tocilizumab was associated with significant clinical improvement.

Psychiatric symptoms in anti glutamic acid decarboxylase associated limbic encephalitis in adults: a systematic review

Autoimmune Limbic Encephalitis (LE) is a relatively new category of immune-mediated diseases with a wide range of neuropsychiatric symptoms. LE associated with Glutamic Acid Decarboxylase (GAD) antibodies is difficult to diagnose due to its possible atypical presentation with neuropsychiatric and behavioral features. We performed a systematic review of literature and retrieved 21 cases of anti GAD-associated LE with neuropsychiatric signs. Median age at onset was 27 years with a female predominance (81.0 %) and median diagnostic delay of 6 months. Clinical presentation included typical LE symptoms such as anterograde amnesia (95.2 %) and temporal lobe or tonico-clonic seizures (95.2 %). Psychiatric symptoms were described in 61.9 % of patients, presenting as anxiety, depressive symptoms, apathy and behavioral changes. Extra-limbic symptoms were present in 14.3 % of patients. No neoplasia associated was found. Some patients had poor epileptic, cognitive and psychiatric outcomes requiring prolonged immunosuppressive treatment. The description of the neuropsychiatric spectrum of anti-GAD LE and its specificities aims to improve our understanding of this entity, and may lead to earlier diagnosis as well as better outcome.

Immune-mediated epilepsy with GAD65 antibodies

Anti-GAD65 antibodies have been identified in both acute/subacute seizures (limbic encephalitis and extralimbic encephalitis) and chronic isolated epilepsy. The evidence of high serum titers and intrathecal synthesis play a fundamental role in diagnosis but poorly correlate with disease severity or response to therapies. It remains controversial whether anti-GAD65 Abs are the pathogenic entity or only serve as a surrogate marker for autoimmune disorders mediated by cytotoxic T cells. Unlike other immune-mediated epilepsy, although multiple combinations of therapeutics are used, the efficacy and prognosis of patients with GAD65-epilepsy patients are poor. Besides, GAD65-epilepsy is more prone to relapse and potentially evolve into a more widespread CNS inflammatory disorder. This article reviews the recent advances of GAD65-epilepsy, focusing on the diagnosis, epidemiology, pathophysiology, clinical features, and treatment, to better promote the recognition and provide proper therapy for this condition.

Intravenous methylprednisolone or immunoglobulin for anti-glutamic acid decarboxylase 65 antibody autoimmune encephalitis: which is better?

BACKGROUND

Patients positive for anti-glutamic acid decarboxylase 65 (GAD65) antibodies have attracted increasing attention. Their clinical manifestations are highly heterogeneous and can be comorbid with tumors. Currently, there is no consensus on the therapeutic regimen for anti-GAD65-associated neurological diseases due to the clinical complexity, rarity and sporadic distribution. We reported six anti-GAD65 autoimmune encephalitis (AE) patients who received intravenous methylprednisolone (IVMP) or immunoglobulin (IVIG) or both. Then, we evaluated the therapeutic effect of both by summarizing results in previous anti-GAD65 AE patients from 70 published references.

RESULTS

Our six patients all achieved clinical improvements in the short term. Unfortunately, there was no significant difference between IVMP and IVIG in terms of therapeutic response according to the previous references, and the effectiveness of IVMP and IVIG was 45.56% and 36.71%, respectively. We further divided the patients into different subgroups according to their prominent clinical manifestations. The response rates of IVMP and IVIG were 42.65% and 32.69%, respectively, in epilepsy patients; 60.00% and 77.78%, respectively, in patients with stiff-person syndrome; and 28.57% and 55.56%, respectively, in cerebellar ataxia patients. Among 29 anti-GAD65 AE patients with tumors, the response rates of IVMP and IVIG were 29.41% and 42.11%, respectively. There was no significant difference in effectiveness between the two regimens among the different subgroups.

CONCLUSION

Except for stiff-person syndrome, we found that this kind of AE generally has a poor response to IVMP or IVIG. Larger prospective studies enrolling large numbers of patients are required to identify the optimal therapeutic strategy in the future.

Distinct Effects of Stereotactically Injected Human Cerebrospinal Fluid Containing Glutamic Acid Decarboxylase Antibodies into the Hippocampus of Rats on the Development of Spontaneous Epileptic Activity

Background: The conversion of glutamic acid into γ-aminobutyric acid (GABA) is catalyzed by the glutamic acid decarboxylase (GAD). Antibodies against this enzyme have been described in neurological disorders, but the pathophysiological role of these antibodies is still poorly understood. We hypothesized that anti-GAD autoantibodies could diminish the GABA content in the slice and facilitate epileptic activity. Methods: Cerebrospinal fluids (CSF) from two patients containing anti-GAD (A and B) were injected into the rat hippocampus in vivo. Hippocampal slices were prepared for electrophysiological field potential recordings in order to record recurrent epileptic discharges (REDs) in the CA1 region induced by the removal of Mg2+ and/or by adding gabazine. As control groups, we injected an anti-GAD-negative human CSF or saline solution, and we used non-operated naive animals. Results: RED frequencies were significantly higher in the Mg2+-free solution than in the gabazine-containing solution. The average frequency of REDs in the last 10 min and the average duration of REDs in the last 5 min did not show significant differences between the anti-GAD-B-treated and the control slices, but in the Mg2+-free solution, anti-GAD-A had significantly higher epileptic activity than anti-GAD-B. Conclusions: These results indicate that anti-GAD has distinct effects on the development of spontaneous epileptic activity.

Steroids: A Wake-Up Call in TBI Induced Hypersomnolence

ABSTRACT

Hypersomnolence is one of the more common symptoms reported after mild traumatic brain injury (TBI) and often one of the most difficult to treat. This case series presents a cohort of patients with TBI related hypersomnolence associated with a de novo autoimmune process that successfully resolved with pulse dose corticosteroid treatment. When associated with an autoimmune inflammatory process, corticosteroids may serve to stabilize the blood brain barrier leading to the successful and sustained resolution of TBI induced sleepiness.

A Survival Case of Super-refractory Status Epilepticus due to Glutamic Acid Decarboxylase Antibodies-associated Limbic Encephalitis

Limbic encephalitis (LE) is a neurological syndrome that mainly affects mesial temporal lobes. It may present in association with cancer or infection. Limbic encephalitis associated with glutamic acid decarboxylase antibodies (anti-GAD) is rare. Here, we report a case of anti-GAD limbic encephalitis to heighten the awareness of this rare cause of autoimmune encephalitis. Anti-GAD-associated epilepsy is often poorly responsive to seizure medications. Treatment is challenging. Early initiation of immunotherapy is important.

Fulminant Anti-GAD antibody encephalitis presenting with status epilepticus requiring aggressive immunosuppression

Antibodies against glutamic acid decarboxylase (GAD) are reported in association with numerous neurological conditions including temporal lobe epilepsy and limbic encephalitis. We report a case of Anti-GAD-Antibody associated encephalitis presenting with epilepsia partialis continua (EPC) progressing to a fulminant encephalopathy preferentially affecting the frontal lobes associated with coma and refractory status epilepticus. The abnormalities identified on MRI included marked bilateral frontal lobe involvement which has not been reported in other auto-immune encephalitides and may be specific for Anti-GAD-Antibody associated encephalitis. Similar to the majority of cases of Anti-GAD associated neurological disturbance no underlying malignancy was identified. Treatment with high dose corticosteriods, IVIG and plasmapheresis had minimal response, but escalation of treatment with rituximab and cyclophosphamide was associated with clinical improvement, reducing antibody titers and resolution of MRI changes.

Lesson of the month 2: Autoimmune sequelae of anti-GAD antibodies - thinking outside the box

A 52 year-old female with no significant medical problems presented with left-sided weakness, unsteady gait and speech disturbance. It was thought that she had neuro-inflammation and she remained clinically stable. Several years later, she was diagnosed with latent autoimmune diabetes of adulthood. Her neurological symptoms deteriorated and she was admitted into hospital. The cerebrospinal fluid was normal, as were an array of blood tests. Imaging tests, including magnetic resonance imaging, computerised tomography and positron emission tomography scans were normal. However, her anti-glutamic acid decarboxylase antibody serum level, which had been taken in the diabetes outpatient clinic, returned at 2,000,000 IU/mL (normal range 0-10). This led to the diagnosis of glutamic acid decarboxylase (GAD) positive cerebellar ataxia. She was treated with plasma exchange and intravenous immunoglobulins and over next 12 weeks her symptoms improved. Our case highlights the need for appropriate treatment of patients with GAD positive cerebellar ataxia to achieve good outcomes.

Electroconvulsive therapy and/or plasmapheresis in autoimmune encephalitis?

Autoimmune encephalitis is a poorly understood condition that can present with a combination of neurological and psychiatric symptoms, either of which may predominate. There are many autoantibodies associated with a variety of clinical syndromes - anti-N-Methyl-D-Aspartate receptor (NMDAR) is the commonest. Currently, the most widely used therapy is prompt plasmapheresis and steroid treatment (and tumour resection if indicated), followed by second line immunosuppression if this fails. Given the growing awareness of autoimmune encephalitis as an entity, it is increasingly important that we consider it as a potential diagnosis in order to provide timely, effective treatment. We discuss several previously published case reports and one new case. These reports examined the effects of electroconvulsive therapy (ECT) on patients with autoimmune encephalitis, particularly those in whom psychiatric symptoms are especially debilitating and refractory to standard treatment. We also discuss factors predicting good outcome and possible mechanisms by which ECT may be effective. Numerous cases, such as those presented by Wingfield, Tsutsui, Florance, Sansing, Braakman and Matsumoto, demonstrate effective use of ECT in anti-NMDAR encephalitis patients with severe psychiatric symptoms such as catatonia, psychosis, narcolepsy and stupor who had failed to respond to standard treatments alone. We also present a new case of a 71-year-old female who presented to a psychiatric unit initially with depression, which escalated to catatonia, delusions, nihilism and auditory hallucinations. After anti-NMDAR antibodies were isolated, she was treated by the neurology team with plasmapheresis and steroids, with a partial response. She received multiple sessions of ECT and her psychiatric symptoms completely resolved and she returned to her premorbid state. For this reason, we suggest that ECT should be considered, particularly in those patients who are non-responders to standard therapies.

Type 1 diabetes and GAD65 limbic encephalitis: a case report of a 10-year-old girl

Limbic encephalitis is a rare neurological disorder that may be difficult to recognize. Clinical features include memory impairment, temporal lobe seizures and affective disturbance. We report the case of a 10-year-old girl with type 1 diabetes mellitus that presented with seizures, depressed mood and memory changes. The diagnosis of glutamic acid decarboxylase 65 (GAD65) mediated limbic encephalitis relied on cerebral magnetic resonance imaging lesions and high serological and cerebrospinal fluid GAD65-antibodies titers. High-dose steroidal therapy was started with clinical improvement. Relapse led to a second high-dose steroid treatment followed by rituximab with remission. A correlation between serum GAD65-antibodies levels and symptoms was found, demonstrating GAD65-antibodies titers may be useful for clinical follow-up and immunotherapy guidance. This report raises awareness of this serious neurological condition that may be associated with type 1 diabetes, underlining the importance of an early diagnosis and prompt treatment for a better prognosis.

Correlations of Clusters of Non-Convulsive Seizure and Magnetic Resonance Imaging in a Case With GAD65-Positive Autoimmune Limbic Encephalitis

With the increased availability of laboratory tests, glutamic acid decarboxylase (GAD) antibody-positive limbic encephalitis has become an emerging diagnosis. The myriad symptoms of limbic encephalitis make the diagnosis challenging. Symptoms range from seizures, memory loss, dementia, confusion, to psychosis. We present a case of a 21-year-old female with GAD65 antibody-positive limbic encephalitis. The case is unique because the clinical course suggests that non-convulsive seizures are the major cause of this patient’s clinical manifestations. The following is the thesis: systemic autoimmune disease, associated with the GAD65 antibody, gives rise to seizures, in particular, non-convulsive seizures. Temporal lobes happen to be the most susceptible sites to develop seizures. The greater part of these seizures can be non-convulsive and hard to recognize without electroencephalogram (EEG) monitoring. The variable symptoms mirror the severity and locations of these seizures. The magnetic resonance imaging (MRI) signal abnormities in the bilateral hippocampus, fornix, and mammillary body correlate with the density of these seizures in the similar manner, which suggests it is secondary to post-ictal edema.

Limbic Encephalitis Associated With GAD65 Antibodies: Brief Review of the Relevant literature

Recently, many cases of autoimmune limbic encephalitis with positive GAD65 (glutamic acid decarboxylase) antibodies have been described in the scientific literature. However, it remains an understudied topic of great relevance to practicing neurologists. Thus, we report here a review of published cases, in English, of autoimmune limbic encephalitis with this type of antibodies, focusing on presenting symptoms and signs, associated conditions, and findings upon investigation. We also report treatment responses. We aim to offer a better description of the clinical spectrum of autoimmune limbic encephalitis associated with GAD65 antibodies as well as to expose its paraclinical features and outcome.

Differences in epileptic symptoms depending on the type of autoimmune-mediated limbic encephalitis

Limbic encephalitis (LE) is an inflammatory disease of the central nervous system that is characterized by the selective involvement of limbic structures. The clinical manifestations of LE include the acute or sub-acute onset of recent memory disorders, mental disorders and seizures. Autoimmune-mediated LE is a major type of non-infectious LE; seizure is a hallmark of this type of LE. The treatment of epilepsy, which is a key factor that affects the prognosis of LE patients, warrants special attention. Understanding the characteristics of epilepsy caused by autoimmune-mediated LE and providing the appropriate treatment will help to improve patients' outcomes. In this article, we extensively review the literature related to autoimmune-mediated LE epidemiology, mechanisms, characteristics and seizure frequency and onset, and we discuss the possible diagnosis and treatment of this disease.

Early recognition of anti-N-methyl D-aspartate (NMDA) receptor encephalitis presenting as acute psychosis

OBJECTIVE

We present a case of anti-N-methyl D-aspartate (NMDA) receptor encephalitis that illustrates the dilemma that psychiatrists face in evaluating patients with first episode psychosis.

CONCLUSIONS

The discovery that acute psychosis can be the presenting feature of autoimmune encephalitis (in particular encephalitis caused by anti-NMDA receptor antibodies) has both practical and theoretical consequences. First, this condition is an important, but often overlooked, differential diagnosis of first episode psychosis. Antibody testing is not currently part of routine screening, though delayed (or missed) diagnosis can lead to prolonged hospital stay, medical complications and incomplete or delayed recovery. Widespread screening of patients with first presentation psychosis for anti-NMDA receptor and anti-voltage-gated potassium channel (anti-VGKC) antibodies is warranted for a number of reasons: to expedite appropriate treatment, to determine the true proportion of patients with these conditions presenting as psychosis, and to help elucidate the neurochemical causes of psychosis.