Limbic Encephalitis and Related Cortical Syndromes

A single center retrospective study of paraneoplastic neurological syndromes with positive onconeural antibodies

Paraneoplastic neurological syndromes (PNS) are rare immune-mediated disorders, and the detection of onconeural antibodies is helpful for PNS diagnosis. The aim of this study was to investigate the clinical characteristics of patients with PNS with positive onconeural antibodies in a single center in Hubei, China. We retrospectively analyzed the clinical characteristics of 54 patients with positive onconeural antibodies from January 2016 to September 2020. Among 780 patients with suspected PNS, 54 (6.9%) had positive onconeural antibodies. Of those 54 patients, 28 (51.8%) were diagnosed with definite PNS and 13 (24.1%) with possible PNS. Eighteen (33.3%) patients were confirmed with cancer. Ten PNS syndromes were detected among the 28 patients with definite PNS, and they had either classical (12/28, 42.8%) or non-classical syndromes (17/28, 60.7%). Peripheral neuropathy (9/28, 32.1%), subacute cerebellar degeneration (4/28, 14.3%), and limbic encephalitis (4/28, 14.3%) were the most common PNS syndromes. The anti-CV2/CRMP5-antibody was observed most frequently. Lung cancer was the most common tumor type. For patients with possible PNS, peripheral neuropathy was the most common PNS syndrome, and the anti-Tr-antibody was the most frequent onconeural antibody. Immunotherapy was effective in treating PNS. The anti-CV2/CRMP5-antibody was the most subsequently observed antibody. The manifestations of PNS are diverse and include peripheral neuropathy, subacute cerebellar degeneration, and limbic encephalitis. In patients with PNS, lung cancer was the most common tumor.

Paraneoplastic Limbic Encephalitis Associated with Anti-CV2/CRMP5 Antibodies Secondary to Thymoma in an Adolescent

Paraneoplastic neurological syndromes (PNS) associated with anti-CV2/CRMP5 antibodies are rare in the literature. Various clinical manifestations can occur including paraneoplastic limbic encephalitis (PLE). Thymoma is one of the rare causes that can be associated with this syndrome. It has not been reported in the literature in children or adolescents to the best of our knowledge. We report a case of PLE in a 19-year-old male patient secondary to thymoma that was diagnosed after 5 years of onset. Anti-CV2/CRMP5 antibodies were positive in the serum and became negative after thymectomy. Diagnosis of PNS should be evoked in cases with atypical neurological manifestation and can be confirmed by the presence of onconeuronal antibodies. We report the first pediatric PLE secondary to thymoma associated with anti-CV2/CRMP5 antibodies.

Application of Plasma Exchange in Steroid-Responsive Encephalopathy

Plasma exchange has been widely used in autoimmune neurological diseases and is the standard treatment for myasthenia gravis crisis and Guillain-Barre syndrome. A growing body of research suggests that, in the clinical application of steroid-responsive encephalopathy, such as for Hashimoto's encephalopathy, limbic encephalitis, systemic lupus erythematosus encephalopathy, ANCA-associated vasculitis encephalopathy, and acute disseminated encephalomyelitis, plasma exchange is a safe, and effective option when steroids or other immunosuppressive therapies are ineffective in the short term or when contraindications are present. Additionally, plasma exchange can also be used alone or in combination with steroids, immunoglobulins, or other immunosuppressive agents to treat steroid-responsive encephalopathy. This paper reviews the clinical application of plasma exchange in steroid-responsive encephalopathy, including its indications, onset time, course, curative effects, and side effects.

Acute Encephalitis in an Adult with Diffuse Large B-Cell Lymphoma with Secondary Involvement of the Central Nervous System: Infectious or Non-Infectious Etiology?

Both infectious and non-infectious etiologies of acute encephalitis have been described, as well as their specific presentations, diagnostic tests, and therapies. Classic findings of acute encephalitis include altered mental status, fever, and new lesions on neuroimaging or electroencephalogram (EEG). We report an interesting case of a 61-year-old male with a history of diffuse large B-cell lymphoma with secondary involvement of the central nervous system (SCNS-DLBCL). He presented with acute encephalitis: altered mental status, fever, leukocytosis, neuropsychiatric symptoms, multiple unchanged brain lesions on computed tomography scan of the head, and EEG showed mild to moderate diffuse slowing with low-moderate polymorphic delta and theta activity. With such a wide range of symptoms, the differential diagnosis included paraneoplastic and autoimmune encephalitis. Infectious and autoimmune/paraneoplastic encephalitis in patients with SCNS-DLBCL are not well documented in the literature, hence diagnosis and therapy becomes challenging. This case report describes the patient’s unique presentation of acute encephalitis.

Immune-Mediated Diseases of the Central Nervous System: A Specificity-Focused Diagnostic Paradigm

Immune-mediated diseases of the central nervous system show wide variability both symptomatically and with respect to underlying pathophysiology. Recognizing aberrant immunologic activity as the cause of neurologic dysfunction requires establishing as precise a neuroanatomic and functional phenotype as possible, and a diagnostic and therapeutic strategy that stabilizes the patient, excludes broad categories of disease via rapidly available diagnostic assays, and maintains a broad differential diagnosis that includes immune-mediated conditions. This process is aided by recognizing the appropriate clinical circumstances under which immune-mediated disease should be suspected, and how to differentiate these conditions from other causes of similar neurologic dysfunction.

Autoimmune limbic encephalitis detected on FDG brain scan performed for the evaluation of dementia

Most diagnostic imagers are familiar with the classic patterns of altered metabolism seen in Alzheimer disease, frontal temporal dementia, and dementia with Lewy bodies. However, awareness of other conditions that can cause cognitive impairment is crucial when interpreting FDG brain PET studies. This is particularly true of infectious and inflammatory processes, such as viral encephalitis, which should be diagnosed and treated on an emergent basis. In addition, altered metabolism can be caused by autoimmune paraneoplastic and encephalitic syndromes. We report a case of autoimmune limbic encephalitis encountered as part of evaluation for atypical onset cognitive impairment.

Isolated Chorea Associated with LGI1 Antibody

Background

Leucine-rich glioma inactivated 1 (LGI1) antibody produces a syndrome of limbic encephalitis, hyponatremia, and facio-brachial dystonic seizures that is non-paraneoplastic and responsive to corticosteroids. Parkinsonism, tremor, and generalized chorea are rare manifestations of LGI1, but, when present, commonly accompany other signs of limbic encephalitis.

Case Report

We present a case of LGI1-related isolated chorea in a 53-year-old Japanese male. His chorea responded to high-dose steroids, suggesting a potential role for this synaptic antibody in triggering chorea.

Discussion

This case highlights a new treatable etiology of chorea.

VGKC-complex/LGI1-antibody encephalitis: clinical manifestations and response to immunotherapy

Leucine-rich glioma inactivated 1 (LGI1) was recently identified as a target protein in autoimmune synaptic encephalitis, a rare condition associated with autoantibodies against structures in the neuronal synapse. Studies dealing with LGI1 are small in number and the various outcomes of different therapeutic regimens are not well studied. Here, we analyzed clinical characteristics of 14 patients with LGI1 antibodies, and outcomes according to therapeutic strategies. Most patients exhibited abnormal brain positron emission tomography and that patients treated with steroids alone were more likely to relapse and had less favorable outcomes than those treated with steroids and intravenous immunoglobulins.

Autoimmune limbic encephalitis presenting as relapsing psychosis

A 34-year-old woman with a history of relapsing psychosis presented with a 15-month history of impassivity and social withdrawal associated with cognitive impairment. The subsequent recurrence of psychomotor agitation, auditory hallucinations and delusional thinking resulted in an emergency admission under psychiatric services. Initial investigations, including MRI of the brain and cerebrospinal fluid studies were unremarkable and she was treated for a primary psychiatric disorder. The diagnosis of autoimmune limbic encephalitis was established after further investigations revealed the presence of antibodies to the NR1 subunit of the N-Methyl-d-aspartate receptor (NMDAR). Immunotherapy resulted in rapid resolution of psychosis and marked improvement in cognitive and social function. This case underlines the importance of considering anti-NMDAR encephalitis within the differential diagnosis of psychosis associated with cognitive impairment even in those with an apparent previous psychiatric history and response to antipsychotics.