Glycine receptor antibodies in PERM: a new channelopathy

Inspiratory laryngeal stridor as the main feature of progressive encephalomyelitis with rigidity and myoclonus: a case report and literature review

Background

Progressive encephalomyelitis with rigidity and myoclonus (PERM) is an acute, potentially life-threatening, yet curable neuro-immunological disease characterized by spasms, muscular rigidity, and brainstem and autonomic dysfunction. The clinical features of glycine receptor (GlyR) antibody-positive PERM may be overlooked, particularly with some unusual symptoms.

Case presentation

A 52-year-old man was admitted to the hospital for evaluation of tension headache for 20 days and mild dysarthria. These symptoms were followed by panic, profuse sweating, severe dysarthria, dizziness, unsteady gait, and paroxysmal muscle spasms. Brain magnetic resonance imaging and cerebrospinal fluid analysis were normal. The patient’s condition steadily deteriorated. He repeatedly presented with rigidity, panic attacks, severe anxiety, paroxysmal inspiratory laryngeal stridor, cyanosis of the lips, and intractable epilepsy. Electromyography showed multiple myoclonic seizures, a single generalized tonic-clonic seizure, and a single generalized tonic seizure. Screening for autoimmune encephalitis antibodies revealed anti-GlyR antibodies in his cerebrospinal fluid. Immunomodulatory pulse therapy with steroids and immunoglobulin resulted in expeditious improvement of the symptoms within 2 weeks, and a follow-up at 5 weeks showed consistent clinical improvement.

Conclusion

Our case highlights that inspiratory laryngeal stridor is an important symptom of PERM. Our observation widens the spectrum of the clinical presentation of anti-GlyR antibody-positive PERM, where early identification is a key to improving prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02555-y.

Clinical features of paediatric and adult autoimmune encephalitis: A multicenter sample

BACKGROUND

Autoimmune encephalitis (AE) is a heterogeneous class of inflammatory diseases of the brain that can present with a wide spectrum of neuropsychiatric symptoms. Patients may be negative for CSF anti-neuronal antibodies, which can make the diagnosis of AE challenging. Distinguishing features between paediatric and adult patients with AE are not well characterized.

OBJECTIVE

Describe the clinical presentation, seizure type, EEG and sleep patterns in paediatric and adult patients with AE.

METHODS/DESIGN

Retrospective review of clinical data from paediatric and adult patients diagnosed with AE from three medical centers between 1/2008-12/2019.

RESULTS

We included 100 patients with AE, including 65 children. Median age at presentation was 14 years (1-88years). Fifty-five patients had positive CSF autoantibody results (NMDAR 36%, VGKC Ab 10%, anti-GAD65 4%, miscellaneous 3%), and 47 patients were autoantibody-negative. Paediatric patients were more likely to present with psychiatric symptoms, focal seizures and/or status epilepticus, and sleep disturbances compared to adult patients (p < 0.05). There was a higher incidence of NMDA-R encephalitis in children compared to adults.

CONCLUSION

Paediatric patients with AE were more likely to present with psychiatric symptoms, sleep disturbances, focal seizures, and/or status epilepticus compared to adults (p < 0.05). Insomnia and hypersomnia are common sleep problems associated with AE that should be screened early in the diagnostic evaluation. Further studies can be performed to explore the relationship between sleep disturbances and long-term cognitive effects and the incidence of chronic epilepsy in this subset of patients.

Relevance of Surface Neuronal Protein Autoantibodies as Biomarkers in Seizure-Associated Disorders

The detection of neuronal surface protein autoantibody-related disorders has contributed to several changes in our understanding of central nervous system autoimmunity. The clinical presentation of these disorders may be associated (or not) with tumors, and often patients develop an inexplicable onset of epilepsy, catatonic or autistic features, or memory and cognitive dysfunctions. The autoantigens in such cases have critical roles in synaptic transmission and plasticity, memory function, and process learning. For months, patients with such antibodies may be comatose or encephalopathic and yet completely recover with palliative care and immunotherapies. This paper reviews several targets of neuronal antibodies as biomarkers in seizure disorders, focusing mainly on autoantibodies, which target the extracellular domains of membrane proteins, namely leucine-rich glioma-inactivated-1 (LGI1), contactin-associated protein-like 2 (CASPR2), the N-methyl-D-aspartate receptor (NMDAR), γ-aminobutyric acid receptor-B (GABA_BR), the glycine receptor (GlyR), and a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). In order to restore health status, limit hospitalization, and optimize results, testing these antibodies should be done locally, using internationally certified procedures for a precise and rapid diagnosis, with the possibility of initiating therapy as soon as possible.