Analysis of the clinical characteristics of 10 cases of serum anti-glutamic acid decarboxylase-65 antibody-positive autoimmune neurological diseases
Authors: Wu Yujun , Wang Meng-meng , Jin Kai-li , Gu Li-yan , Wu Min-lu , Chen Ying , Han Yi , Wei Jie 
Published: November 2024

Objective
To study the clinical characteristics of patients with anti-glutamic acid decarboxylase-65 (GAD-65) antibody-positive autoimmune neurological diseases.
Methods The clinical data of 10 patients with anti-GAD-65 antibody-positive autoimmune neurological diseases who were admitted to the department of neurology of NO. 905 Hospital of PLA Navy from November 2014 to November 2023 was retrospectively analyzed.
Results The age of onset of 10 patients was 15 to 72 (44.9 ± 21) years old and the confirmed age was 21 to 73 (47.3 ± 20.1) years old. The ratio of male to female was 1:9. In three cases, symptoms were easily triggered by mental stress, fatigue and around the time of menstruation, and in one case, symptoms of muscle spasms were obvious at night. Clinical manifestations: 3 cases of single or double lower limb spasm with or without abdominal cramps, 3 cases of limb stiffness with swallowing or dyspnea or diplopia, 2 cases of unconsciousness, limb convulsions with memory loss, 1 case of dizziness, limb numbness and olfactory hallucinations, and 1 case of hiccups, nausea and vomiting. The final diagnosis was as follows: 6 cases of stiff-person syndrome (SPS), 2 cases of limbic encephalitis (LE) with seizures, 1 case of autoimmune encephalitis with cerebellar ataxia (CA), and 1 case of autoimmune brainstem cerebellum. In the auxiliary examination, 10 patients were positive for different titers of GAD65 in blood and/or cerebrospinal fluid (CSF), including 1 with GAD67 positive in CSF at the same time; 5 with abnormal blood autoimmune antibodies, 4 with abnormal thyroid function, 3 had diabetes and 2 with thymoma or thymic hyperplasia. Imagological examinations of the brain indicated that 3 patients had abnormal signals in hippocampus or temporal lobe; 2 had mild abnormal electroencephalogram (EEG) with no epileptiform discharge. In 6 cases, electromyography (EMG) showed continuous muscle motor unit electrical activity in the group of muscles at rest. 1 case had positive peroneal sensation in the right lower limbs, and 1 case showed cervicofacial abnormality and left ulnar nerve sensory positive.
Treatments Except for the first patient who only received symptomatic treatment, the remaining 9 patients were immunoreacted. Among them, 3 patients were treated with first-line treatment alone, 6 patients received first-line combined with second-line treatment, and 4 patients with seizures were treated with antiepileptic drugs. Ten patients were followed up, one died half a year later, and the remaining nine had symptoms improved (mRS score ≧ 1 point). Conclusion Anti-GAD65 antibody encephalitis is more common in young and middle-aged people, more women than men. Its clinical manifestations mainly include SPS, CA, LE and so on. Given that single or multiple symptoms exist at the same time, high titer of GAD65 antibody in serum is the gold standard for diagnosis. Though epilepsy is often difficult to control, immunotherapy has a good effect on the vast majority of patients, and it should be started as soon as possible, which helps to improve the recovery.