Recurrent Anti-AMPA Receptor Limbic Encephalitis: A Case Report and Literature Review

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor encephalitis is a relatively rare anti-neuronal surface antigen autoimmune encephalitis (LE). We described a case of a 47-year-old Chinese man having anti-AMPA receptor limbic encephalitis initially presented with cognitive decline, undetectable antibodies, and normal imaging findings in magnetic resonance image (MRI) and then developed into typical autoimmune limbic encephalitis a few months later with a course of multiple relapses. In addition, we found progressive brain atrophy in our case, which was a rare presentation of LE. This report also summarized the characteristics of nine reported cases of anti-AMPA receptor limbic encephalitis with relapse up to date. This case highlighted that autoimmune limbic encephalitis is an important differential diagnosis for patients with typical symptoms even when the MRI and antibodies are normal, and more attention should be paid to the relapse of anti-AMPA receptor encephalitis.

TMOD-20. CASE REPORT: THE ODYSSEY TO THE RIGHT DIAGNOSIS. SURPRISING GLIOBLASTOMA MIMICS

A 57-year-old female presented at the emergency room with acute onset aphasia but unremarkable cCT (incl. angiography and perfusion). Suspecting an ischemic stroke, she received thrombolysis with quick recovery of aphasia. Afterwards, myoclonic jerks of the face and right arm occurred leading to anticonvulsant therapy. Follow-up cMRI surprisingly demonstrated swollen T2w-hyperintense and Gd-enhancing left limbic, temporal and frontal lobes. Suspected herpes-simplex-encephalitis was treated with aciclovir despite unremarkable CSF results (no pleocytosis, no BBB disruption, negative HSV-PCR) on day 2 and follow-up (day 5). Due to persisting cognitive deficits, autoimmune limbic encephalitis was suspected, and intravenous immunoglobulin therapy was added. Three weeks later, she experienced new neurological symptoms (weakness, blurred vision, vomiting, headache). Follow-up brain MRI demonstrated a massive increase of multifocal Gd-enhancing lesions. Partial resection revealed the diagnosis of an IDH-wildtype glioblastoma (GB). Next generation oncogene panel testing demonstrated a GOPC-ROS1 fusion which is rarely found in GB. Due to the gliomatosis-like infiltration of both hemispheres, radiotherapy was deemed to be too toxic. Instead, she received two cycles of lomustine in absence of a MGMT-promotor methylation. Two months later cMRI showed a symptomatic second multilocular progression. 2nd-line therapy with a ROS-inhibitor was rejected, whereupon she died five weeks later. Our case is in several aspects peculiar: It demonstrates that rare GB-mimics (i.e. HSV- and autoimmune limbic encephalitis) can only be ruled out in a fast manner by brain biopsy. Watchful waiting may neglect fast progression of GB leading to the inability to provide optimal treatment (i.e. radiotherapy). Thrombolysis is strictly contraindicated in primary brain tumors, but was unharmful in our case most probably to the early tumor stage without relevant neoangiogenesis. Rare genetic abnormalities like ROS1-fusions which are reported mostly in childhood glioblastoma may be present and serve as a therapeutic target also in adult GB.

Atypical Association of Autoimmune Limbic Encephalitis with Anti-NMDA Receptor Antibodies in a Young Male Patient: Clinical, Imaging, and Neuropsychological Characteristics

The spectrum of autoimmune encephalitis (AE) encompasses several entities characterized by a variable frequency of psychiatric symptoms, cognitive dysfunction, focal deficits, and seizures. Although patients with AE can be categorized in specific syndromes, overlapping manifestations are also common. Furthermore, atypical correlations between clinical phenotypes and autoantibody profiles could occur in rare cases. Here, we report the rare case of a young adult man attending due to new-onset seizures and a history of memory loss, autonomic disturbances, headache, behavioral changes, and visual and olfactory hallucinations. The patient was subjected to a complete diagnostic approach that included a comprehensive laboratory workup, neuropsychological testing, electroencephalogram, cerebrospinal fluid (CSF) analysis, brain MRI, and positron emission tomography/computed tomography scan that revealed a functional and structural compromise of the bilateral medial temporal lobes. Together with the clinical manifestations of the patient, these findings were compatible with the diagnosis of autoimmune limbic encephalitis (ALE). Strikingly, further analysis of the CSF showed autoantibodies against the N-methyl-D-aspartate (NMDA) receptor. We found very few cases of the co-occurrence of anti-NMDA receptor antibodies and nonparaneoplastic ALE in the literature, especially in male patients. Our report exemplifies the complicated differential diagnosis of ALE and adds clinical information of the association with anti-NMDA receptor antibodies.

Feline temporal lobe epilepsy: seven cases of hippocampal and piriform lobe necrosis in England and literature review

Case series summary Seven cases of feline hippocampal and piriform lobe necrosis (FHN) are described, with particular emphasis on clinical, radiographic and histopathological correlations. FHN is an uncommon acute epileptic condition resembling human autoimmune limbic encephalitis and temporal lobe epilepsy. Seizures are typically focal and feature uni- or bilateral orofacial or head twitching, hypersalivation, lip smacking, mydriasis, vocalisation and motionless staring, with inter-ictal behavioural changes such as unprovoked aggression and rapid running. Emerging evidence supports an autoimmune aetiology, although disruption of hippocampal architecture secondary to brain neoplasia has also been recognised. Most commonly, however, the underlying cause remains unknown. Diagnosis is achieved clinically and with brain MRI; electroencephalography and voltage-gated potassium channel-complex autoantibodies are currently the subject of research. Affected cats are frequently refractory to conventional antiepileptic treatment. Relevance and novel information Following a review of the literature, including potential complicating factors and comparisons with human medicine, the hippocampus and piriform lobe are proposed as the neuroanatomical localisation for focal seizures with orofacial involvement in cats, regardless of aetiology.

Rare paraneoplastic syndrome of prostatic cancer: limbic encephalitis: a case report

Introduction Limbic encephalitis is an autoimmune neurologic disorder, often of paraneoplastic origin, that seldom complicates prostatic tumors. The nonspecificity of symptoms makes the diagnosis sometimes difficult to establish. Prognosis is essentially determined by comorbidities and sensorineural and cognitive sequelae. Clinical case A 66-year-old Caucasian patient known to have prostatic small-cell neuroendocrine adenocarcinoma under hormonal therapy developed complex partial epileptic seizures associated with rapidly aggravating severe memory impairment. The tripod of autoimmune limbic encephalitis diagnosis was based on the clinical aspect of brain’s functional deterioration, electroencephalography aspect, and γ-aminobutyric acid type B anti-receptor antibody positivity. Clinical, diagnostic, and therapeutic management as well as evolutionary risks were further analyzed. Conclusion Limbic encephalitis is an extremely rare presentation of neurologic paraneoplastic syndromes. A better knowledge of this entity would help better manage diagnostic and therapeutic difficulties and reduce the risk of possible sequelae.