Stiff-person spectrum disorder (SPSD) is a rare autoimmune neurological disorder characterised by progressive rigidity, muscle co-contractions and spasms; 5%-10% are paraneoplastic. Few infection-related SPSD cases have been reported. We describe a 56-year-old woman who developed SPSD after herpes zoster. Eight days after rash onset, she experienced persistent lower-limb tonic spasms with co-contractions, autonomic symptoms and elevated anti-glutamic acid decarboxylase antibodies in serum and cerebrospinal fluid. Immunotherapy with repeated high-dose intravenous immunoglobulin and methylprednisolone pulses, along with continuous benzodiazepines and epidural analgesia, led to gradual improvement over 3 months. Pain from herpes zoster may have amplified muscle co-contractions via withdrawal and crossed extension reflexes, exacerbating impaired reciprocal inhibition in SPSD. Clinicians should consider optimal pain control in addition to immunotherapy for SPSD triggered by infection.

To investigate the clinical characteristics, immunotherapeutic responses, and long-term outcomes of glutamic acid decarboxylase-65 (GAD65)-associated neurological syndromes, and to identify potential factors linked to poor outcomes. We conducted a retrospective cohort study of patients diagnosed with anti-GAD65-associated neurological syndromes at West China Hospital from August 2019 to March 2024. The clinical characteristics, laboratory and imaging findings, response to immunotherapy and prognosis of the patients were systematically analyzed. 37 patients were included in this study. Predominant clinical phenotypes included epilepsy (Ep) (n = 12, 32.4 %), stiff-person spectrum disorder (SPSD) (n = 8, 21.6 %), limbic encephalitis (LE) (n = 7, 18.9 %), cerebellar ataxia (CA) (n = 3, 8.1 %). Among them, 26 (70.3 %) were female, with a median age of onset at 39 years (IQR 30; range 9-65). Concomitant systemic autoimmune diseases were observed in 10 patients (27.0 %), 15 (40.0 %) were positive for coexisting autoantibodies. Anxiety disorders were documented in 11 patients (29.7 %). 35 patients (94.6 %) received immunotherapy, with symptom remission observed in 30 patients. The follow-up data over a median duration of 16 months (IQR 31.0; range 12.0-67.0), anxiety disorders, elevated cerebrospinal fluid (CSF) protein, delayed treatment and disease relapse are associated with poor outcomes. Neurological syndromes related to GAD65 antibodies exhibited marked clinical heterogeneity. Although most patients responded to immunotherapy, early intervention was critical for improving outcomes. Anxiety disorders, elevated CSF protein, treatment delay, and disease relapse were associated with adverse prognosis.

Influenza A (H1N1) virus infection has been associated with various immune-mediated neurological disorders. Previous studies have reported cases of stiff person spectrum disorder (SPSD) subsequent to viral infections. We report a case of a 4-year-old boy who developed SPSD following H1N1 infection. The patient primarily presented with axial and limb muscle rigidity, painful spasms, and exaggerated startle responses. Electromyography (EMG) revealed continuous synchronous discharges in agonist and antagonist muscles, consistent with the characteristic manifestations of stiff person syndrome (SPS), meanwhile, repetitive compound muscle action potentials (R-CMAPs) following stimulation of the median, common peroneal and tibial nerves were observed on electroneurography (ENG). Symptoms markedly improved following benzodiazepine therapy, and complete remission was achieved after combined treatment with IVIG and glucocorticoids.