Possible anti-VGKC autoimmune limbic encephalitis associated with SIADH

Clinical features of anti-leucine-rich glioma-inactivated 1 encephalitis in northeast China

AIM

To examine the clinical characteristics, laboratory tests, imaging and electroencephalography presentation, treatment, and prognosis of anti-leucine-rich glioma-inactivated 1 (anti-LGI1) encephalitis and improve the awareness of this disease.

METHOD

We performed a retrospective analysis of the clinical data of 41 patients who were diagnosed with anti-LGI1 encephalitis. Their clinical characteristics, laboratory tests, and imaging and electroencephalography data were collected, and the treatment results and prognosis were evaluated. The modified Rankin Scale (mRS) was used to evaluate neurological function.

RESULTS

A total of 41 patients were included in the study, the average follow-up time is 33.0 months.The initial symptoms included cognitive impairment (n = 16, 39.0%),faciobrachial dystonic seizures (FBDS) (n = 12, 29.3%), grand mal seizures (n = 5, 12.2%) hallucinations (n = 4, 9.8%), loss of consciousness (n = 2, 4.9%), nausea and vomiting (n = 1, 2.4%),and head discharge-like sensation and radiate one limb (n = 1, 2.4%). There were 20 and 21 patients in the good (mRS ≤ 2) and poor (mRS > 2) prognosis groups, respectively. In the good prognosis group, the initial symptoms included faciobrachial dystonic seizures (FBDS) (n = 6, 30.0%), cognitive impairment (n = 6, 30.0%), hallucinations (n = 4, 20.0%), grand mal seizures (n = 3, 15.0%), loss of consciousness (n = 2, 10.0%), and nausea and vomiting (n = 1, 5.0%). There were 10 patients with hyponatremia. Magnetic resonance imaging (MRI) showed limbic system involvement in 12 patients (60.0%).17 patients (85.0%) recovered, 2 (10.0%) showed significant improvement, and 1 (5.0%) died after a mean follow-up period of 36.9 months. In the poor prognosis group, the initial symptoms included FBDS (n = 6, 28.5%), cognitive impairment (n = 10, 47.6%), grand mal seizures (n = 2, 9.5%), and electric shock-like sensation in the left limbs (n = 1, 4.7%). There were 20 patients with hyponatremia. MRI showed limbic system involvement in 11 patients (52.4%). 11 patients (52.4%) recovered, 8 (38.1%) showed significant improvement, and 2 (9.5%) died after a mean follow-up period of 29.0 months.

CONCLUSIONS

The clinical characteristics of anti-LGI1 encephalitis include hyponatremia, FBDS, epileptic seizures, hallucinations, cognitive impairment, and loss of consciousness, while the rarely seen characteristics are nausea, vomiting, and other autonomic dysfunctions and electric shock-like sensation. The appearance of hallucinations often indicates a good prognosis.Hyponatremia and elevated cerebrospinal fluid protein levels can be used as indicators that affect the prognosis of patients.Limbic system involvement has nothing to do with prognosis.Attention should be paid to early diagnosis and timely first-line immunotherapy.

Psychiatric Manifestation of Anti-LGI1 Encephalitis

Background: Anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis is typically characterized by limbic encephalitis, faciobrachial dystonic seizures and hyponatremia. The frequency with which milder forms of anti-LGI1 encephalitis mimic isolated psychiatric syndromes, such as psychoses, or may lead to dementia if untreated, is largely unknown. Case presentation: Here, the authors present a 50-year-old patient who had suffered from neurocognitive deficits and predominant delusions for over one and a half years. He reported a pronounced feeling of thirst, although he was drinking 10–20 liters of water each day, and he was absolutely convinced that he would die of thirst. Due to insomnia in the last five years, the patient took Z-drugs; later, he also abused alcohol. Two years prior to admission, he developed a status epilepticus which had been interpreted as a withdrawal seizure. In his serum, anti-LGI1 antibodies were repeatedly detected by different independent laboratories. Cerebrospinal fluid analyses revealed slightly increased white blood cell counts and evidence for blood–brain-barrier dysfunction. Magnetic resonance imaging showed hyperintensities mesio-temporally and in the right amygdala. In addition, there was a slight grey–white matter blurring. A cerebral [¹⁸F] fluorodeoxyglucose positron emission tomography (FDG-PET) examination of his brain showed moderate hypometabolism of the bilateral rostral mesial to medial frontal cortices. Treatment attempts with various psychotropic drugs remained unsuccessful in terms of symptom relief. After the diagnosis of probable chronified anti-LGI1 encephalitis was made, two glucocorticoid pulse treatments were performed, which led to a slight improvement of mood and neurocognitive deficits. Further therapy was not desired by the patient and his legally authorized parents. Conclusion: This case study describes a patient with anti-LGI1 encephalitis in the chronified stage and a predominant long-lasting psychiatric course with atypical symptoms of psychosis and typical neurocognitive deficits. The patient’s poor response to anti-inflammatory drugs was probably due to the delayed start of treatment. This delay in diagnosis and treatment may also have led to the FDG-PET findings, which were compatible with frontotemporal dementia (“state of damage”). In similar future cases, newly occurring epileptic seizures associated with psychiatric symptoms should trigger investigations for possible autoimmune encephalitis, even in patients with addiction or other pre-existing psychiatric conditions. This should in turn result in rapid organic clarification and—in positive cases—to anti-inflammatory treatment. Early treatment of anti-LGI1 encephalitis during the “inflammatory activity state” is crucial for overall prognosis and may avoid the development of dementia in some cases. Based on this case, the authors advocate the concept—long established in many chronic inflammatory diseases in rheumatology—of distinguishing between an “acute inflammatory state” and a “state of organ damage” in autoimmune psychosis resembling neurodegenerative mechanisms.

Inappropriate Antidiuretic Hormone Secretion and Cerebral Salt-Wasting Syndromes in Neurological Patients

The differential diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt-wasting syndrome (CSWS) in patients with neurological disorders has been a perplexing clinical controversy. The purpose of this review is to summarize the characteristics and risk factors of patients with different types of neurological disorders complicated by hyponatremia (HN) and review various methods to distinguish SIADH from CSWS. Common neurological disorders with high rates of HN include subarachnoid hemorrhage (SAH), traumatic brain injuries, stroke, cerebral tumors, central nervous system (CNS) infections, and Guillain-Barré syndrome (GBS), which have their own characteristics. Extracellular volume (ECV) status of patients is a key point to differentiate SIADH and CSWS, and a comprehensive assessment of relevant ECV indicators may be useful in differentiating these two syndromes. Besides, instead of monitoring the urinary sodium excretion, more attention should be paid to the total mass balance, including Na⁺, K⁺, Cl^-, and extracellular fluid. Furthermore, the dynamic detection of fractional excretions (FE) of urate before and after correction of HN and a short-term infusion of isotonic saline solution may be useful in identifying the etiology of HN. As for brain natriuretic peptide (BNP) or N-terminal prohormone of BNP (NT-proBNP), more prospective studies and strong evidence are needed to determine whether there is a pertinent and clear difference between SIADH and CSWS.