[Stiff-Person Syndrome: Results of the First Nationwide Survey in Japan].

Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder characterized by progressive axial muscle stiffness, central nervous system hyperexcitability, and painful stimulus-sensitive muscle spasms. A nationwide survey performed in 2018 showed the estimated prevalence of SPS was 0.2 per 100,000 population. Most patients with SPS had antibodies against glutamic acid decarboxylase 65, followed by antibodies to the glycine receptor α-subunit. Usually, patients with SPS showed favorable outcomes; however, some studies have reported intractable SPS. Early diagnosis and aggressive immunotherapy are necessary for management of patients with SPS.

Machine learning characterization of a rare neurologic disease via electronic health records: a proof-of-principle study on stiff person syndrome.

BACKGROUND: Despite the frequent diagnostic delays of rare neurologic diseases (RND), it remains difficult to study RNDs and their comorbidities due to their rarity and hence the statistical underpowering. Affecting one to two in a million annually, stiff person syndrome (SPS) is an RND characterized by painful muscle spasms and rigidity. Leveraging underutilized electronic health records (EHR), this study showcased a machine-learning-based framework to identify clinical features that optimally characterize the diagnosis of SPS. METHODS: A machine-learning-based feature selection approach was employed on 319 items from the past medical histories of 48 individuals (23 with a diagnosis of SPS and 25 controls) with elevated serum autoantibodies against glutamic-acid-decarboxylase-65 (anti-GAD65) in Dartmouth Health's EHR to determine features with the highest discriminatory power. Each iteration of the algorithm implemented a Support Vector Machine (SVM) model, generating importance scores-SHapley Additive exPlanation (SHAP) values-for each feature and removing one with the least salient. Evaluation metrics were calculated through repeated stratified cross-validation. RESULTS: Depression, hypothyroidism, GERD, and joint pain were the most characteristic features of SPS. Utilizing these features, the SVM model attained precision of 0.817 (95% CI 0.795-0.840), sensitivity of 0.766 (95% CI 0.743-0.790), F-score of 0.761 (95% CI 0.744-0.778), AUC of 0.808 (95% CI 0.791-0.825), and accuracy of 0.775 (95% CI 0.759-0.790). CONCLUSIONS: This framework discerned features that, with further research, may help fully characterize the pathologic mechanism of SPS: depression, hypothyroidism, and GERD may respectively represent comorbidities through common inflammatory, genetic, and dysautonomic links. This methodology could address diagnostic challenges in neurology by uncovering latent associations and generating hypotheses for RNDs.

Prevalence, Clinical Profiles, and Prognosis of Stiff-Person Syndrome in a Japanese Nationwide Survey.

BACKGROUND AND OBJECTIVES: To elucidate current epidemiologic, clinical, and immunologic profiles and treatments of stiff-person syndrome (SPS) in Japan. METHODS: A nationwide mail survey was conducted using an established method. Data processing sheets were sent to randomly selected departments of internal medicine, neurology, pediatrics, psychiatry, and neurosurgery in hospitals and clinics throughout Japan to identify patients with SPS who were seen between January 2015 and December 2017. RESULTS: Thirty cases were identified as glutamic acid decarboxylase 65 (GAD65)-positive SPS cases on the basis of detailed clinical data of 55 cases. Four patients had α1 subunit of glycine receptor (GlyR) antibodies, and 1 patient had both GAD65 and GlyR antibodies. The total estimated number of patients with GAD65-positive SPS was 140, and the estimated prevalence was 0.11 per 100,000 population. The median age at onset was 51 years (range, 26-83 years), and 23 (76%) were female. Of these, 70% had classic SPS, and 30% had stiff-limb syndrome. The median time from symptom onset to diagnosis was significantly longer in the high-titer GAD65 antibody group than in the low-titer group (13 months vs 2.5 months, p = 0.01). The median modified Rankin Scale (mRS) at baseline was 4, and the median mRS at the last follow-up was 2. Among the 29 GAD65-positive patients with ≥1 year follow-up, 7 received only symptomatic treatment, 9 underwent immunotherapy without long-term immunotherapy, and 13 received long-term immunotherapy such as oral prednisolone. The coexistence of type 1 diabetes mellitus and the lack of long-term immunotherapy were independent risk factors for poor outcome (mRS ≥3) in the GAD65-positive patients (odds ratio, 15.0; 95% CI 2.6-131.6; p = 0.001; odds ratio, 19.8; 95% CI 3.2-191.5; p = 0.001, respectively). DISCUSSION: This study provides the current epidemiologic and clinical status of SPS in Japan. The symptom onset to the diagnosis of SPS was longer in patients with high-titer GAD65 antibodies than in those with low-titer GAD65 antibodies. The outcome of patients with SPS was generally favorable, but more aggressive immunotherapies are necessary for GAD65-positive patients with SPS.

Respiratory symptoms are common in stiff person syndrome spectrum disorders and are associated with number of body regions involved.

BACKGROUND AND PURPOSE: Stiff person syndrome (SPS) spectrum disorders (SPSSD) cause spasms and rigidity throughout different body regions and can be associated with apnea and acute respiratory failure. There are limited data on the prevalence and predictors of respiratory symptoms with spasms (RSwS) in SPSSD. We sought to characterize the spirometry patterns and the frequency and predictors of RSwS in a large SPSSD cohort. METHODS: Participants were recruited from the Johns Hopkins SPS Center between 1997 and 2021, as part of an ongoing, longitudinal observational study. Medical records were reviewed to assess demographics and clinical characteristics. Data were analyzed using descriptive statistics and multivariable logistic regression models. RESULTS: One-hundred ninety-nine participants (mean age = 53.4 ± 13.6 years, median time to diagnosis = 36 [IQR 66] months, 74.9% women, 69.8% White, 62.8% classic SPS phenotype) were included in final analyses; 35.2% of participants reported RSwS, of whom 24.3% underwent spirometry as part of routine clinical care. Obstructive (23.5%) and restrictive (23.5%) patterns were most commonly observed in those with SPSSD. An increasing number of body regions involved predicted the presence of RSwS (odds ratio [OR] = 1.95, 95% confidence interval [CI] = 1.50-2.53); those with ≥5 body regions involved (vs. ≤4) had higher odds (OR = 6.19, 95% CI = 2.81-13.62) of experiencing RSwS in adjusted models. Two patients died from SPSSD-associated respiratory compromise. CONCLUSIONS: RSwS are common in SPSSD and may be predicted by an increasing number of body regions involved by SPSSD. Close clinical monitoring and having a low threshold to obtain spirometry should be considered in people with SPSSD.

Hereditary Hyperekplexia in Saudi Arabia.

BACKGROUND: Hyperekplexia is a rare disorder characterized by exaggerated startle responses to unexpected sensory stimuli, recurrent apneas, and stiffness. Only few studies have been published on this disorder in populations with high rates of consanguinity. METHODS: We retrospectively reviewed Saudi patients with genetically confirmed hereditary hyperekplexia using a standard questionnaire that was sent to nine major referral hospitals in Saudi Arabia. RESULTS: A total of 22 Saudi patients (11 males, 11 females) from 20 unrelated families who had hereditary hyperekplexia were included. Based on molecular studies, they were classified into different subtypes: SLC6A5 variant (12 patients, 54.5%), GLRB variant (seven patients, 31.8%), and GLRA1 variant (three patients, 13.7%). All patients were homozygous for the respective causal variant. The combined carrier frequency of hereditary hyperekplexia for the encountered founder mutations in the Saudi population is 10.9 per 10,000, which translates to a minimum disease burden of 13 patients per 1,000,000. CONCLUSION: Our study provides comprehensive epidemiologic information, prevalence figures, and clinical characteristics of a large cohort of patients with hereditary hyperekplexia.

Amphiphysin-IgG autoimmune neuropathy: A recognizable clinicopathologic syndrome.

OBJECTIVE: To define the clinicopathologic features of amphiphysin-immunoglobulin G (IgG)-mediated neuropathy. METHODS: Patients examined at our institution from January 1, 1995, to September 30, 2018, with amphiphysin-IgG by indirect immunofluorescence and Western blot, were reviewed. Their phenotypes were compared to cases of coexisting collapsin response-mediator protein-5 (CRMP5)-IgG or anti-neuronal nuclear antibody type 1 (ANNA1-IgG) and CRMP5-IgG autoimmunity. Improvement in modified Rankin Scale (mRS) (≥1) on follow-up was considered a favorable outcome. Amphiphysin RNA expression was assessed in healthy nerves. RESULTS: Fifty-three amphiphysin-IgG-positive cases were identified. Of 33 (60%) patients with neuropathy, 21 had amphiphysin-IgG alone, and 12 had coexisting autoantibodies (ANNA1-IgG, n = 8; CRMP5-IgG, n = 2; ANNA1-IgG and CRMP5-IgG, n = 2). The neuropathies in isolated amphiphysin-IgG autoimmunity included polyradiculoneuropathy (62%), diffuse sensory neuronopathy (35%), and facial neuropathy with gastroparesis (3%). Among these, pain (80%), breast cancer (63%), and CNS (57%) involvements commonly coexisted, and neuropathy frequently prompted breast cancer diagnosis (76%). Stiff-person spectrum disorder was the most common CNS accompaniment (45%). Nerve biopsies showed axonal loss (n = 6/6), subperineurial edema (n = 4/6), and CD4 predominant inflammation (n = 2/6). Median mRS score at last follow-up was 3.5; 58% of patients were immunotherapy-responsive. Patients with amphiphysin-IgG alone had more favorable immunotherapy response than patients with CRMP5-IgG polyneuropathy (n = 45) (44% vs 16%, p = 0.028, odds ratio 4.2, 95% confidence interval 1.1 to 15.5). Only 1/9 (11%) patients with amphiphysin-IgG with coexisting CRMP5-IgG or ANNA1-IgG had immunotherapy response. RNA amphiphysin expression occurred at low levels in nerve. CONCLUSION: Amphiphysin-IgG autoimmune neuropathy has a recognizable phenotype, is frequently immune responsive, and can prompt early diagnosis of breast cancer.

SPS: Understanding the complexity.

INTRODUCTION: Stiff-person syndrome (SPS), first described in 1956 by Moersch and Woltman, is a progressive autoimmune disorder with core features of chronic fluctuating progressive truncal and limb rigidity and painful muscle spasms leading to gait difficulties, falls and an appearance that resembles tin soldiers. The syndrome is a rare, highly disabling disorder of the central nervous and frequently results in significant disability. Understanding of the etiology, clinical spectrum, diagnostic workup and therapeutic modalities for this painful and disabling disorder has vastly evolved over the past few years with more confidence in classifying and treating the patients. The purpose of this review is to increase the awareness, early detection, and treatment of this disabling disease. METHOD: PubMed was searched, all date inclusive, using the following phrases: stiff person syndrome,anti-Glutamic acid decarboxylase (Anti-GAD) antibody syndrome, Progressive encephalomyelitis with rigidity and myoclonus (PERM), and Paraneoplastic Stiff Person syndrome. No filters or restrictions were used. A total of 888 articles were identified. RESULTS: The results were narrowed to 190 citations after excluding non-English and duplicate reports. Clinical presentation, laboratory testing, treatment, and prognosis were categorized and summarized. DISCUSSION: In this article we will discuss the epidemiology, presentation and classification. Explain the pathophysiology of SPS and the autoimmune mechanisms involved. Discuss the diagnostic approach and treatments available, as well as, the prognosis and outcome.

Stiff person syndrome with Anti-GAD65 antibodies within the national veterans affairs health administration.

INTRODUCTION: Stiff person syndrome (SPS) is a neurological disorder characterized by muscle rigidity primarily in the truncal muscles, commonly associated with autoantibodies to the glutamic acid-decarboxylase 65 kD receptor (GAD65). There is limited epidemiological information on patients with SPS. METHODS: We performed a retrospective case review using the National United States Veterans Affairs Health Administration electronic medical record system. We analyzed prevalence, demographics, disease characteristics, and treatment outcomes in SPS patients who were anti-GAD65 antibody positive. RESULTS: Fifteen patients met our criteria. Point prevalence was 2.06 per million, and period prevalence was 2.71 per million. Men to women ratio was 14:1. All patients benefitted from treatment with symptomatic antispasmodic agents. Ten of 15 patients received intravenous immunoglobulin, with a majority demonstrating stable or improved modified Rankin scores. DISCUSSION: This investigation was a large North American epidemiological study of SPS with predominantly male patients. Symptomatic therapy was beneficial for most patients, with less clear sustained benefit of immunotherapy. Muscle Nerve 58:801-804, 2018.

Glycine receptor antibodies in PERM and related syndromes: characteristics, clinical features and outcomes.

The clinical associations of glycine receptor antibodies have not yet been described fully. We identified prospectively 52 antibody-positive patients and collated their clinical features, investigations and immunotherapy responses. Serum glycine receptor antibody endpoint titres ranged from 1:20 to 1:60 000. In 11 paired samples, serum levels were higher than (n = 10) or equal to (n = 1) cerebrospinal fluid levels; there was intrathecal synthesis of glycine receptor antibodies in each of the six pairs available for detailed study. Four patients also had high glutamic acid decarboxylase antibodies (>1000 U/ml), and one had high voltage-gated potassium channel-complex antibody (2442 pM). Seven patients with very low titres (<1:50) and unknown or alternative diagnoses were excluded from further study. Three of the remaining 45 patients had newly-identified thymomas and one had a lymphoma. Thirty-three patients were classified as progressive encephalomyelitis with rigidity and myoclonus, and two as stiff person syndrome; five had a limbic encephalitis or epileptic encephalopathy, two had brainstem features mainly, two had demyelinating optic neuropathies and one had an unclear diagnosis. Four patients (9%) died during the acute disease, but most showed marked improvement with immunotherapies. At most recent follow-up, (2-7 years, median 3 years, since first antibody detection), the median modified Rankin scale scores (excluding the four deaths) decreased from 5 at maximal severity to 1 (P < 0.0001), but relapses have occurred in five patients and a proportion are on reducing steroids or other maintenance immunotherapies as well as symptomatic treatments. The glycine receptor antibodies activated complement on glycine receptor-transfected human embryonic kidney cells at room temperature, and caused internalization and lysosomal degradation of the glycine receptors at 37°C. Immunoglobulin G antibodies bound to rodent spinal cord and brainstem co-localizing with monoclonal antibodies to glycine receptor-α1. Ten glycine receptor antibody positive samples were also identified in a retrospective cohort of 56 patients with stiff person syndrome and related syndromes. Glycine receptor antibodies are strongly associated with spinal and brainstem disorders, and the majority of patients have progressive encephalomyelitis with rigidity and myoclonus. The antibodies demonstrate in vitro evidence of pathogenicity and the patients respond well to immunotherapies, contrasting with earlier studies of this syndrome, which indicated a poor prognosis. The presence of glycine receptor antibodies should help to identify a disease that responds to immunotherapies, but these treatments may need to be sustained, relapses can occur and maintenance immunosuppression may be required.

Efficacy of therapeutic plasma exchange for treatment of stiff-person syndrome.

BACKGROUND: The efficacy of therapeutic plasma exchange (TPE) in stiff-person syndrome (SPS) is unclear. STUDY DESIGN AND METHODS: A retrospective analysis of patients diagnosed with SPS who underwent TPE and a systematic literature review were conducted. RESULTS: Nine patients with the presumptive diagnosis of SPS who underwent TPE were identified. The mean age was 55 years (range, 34-72 years) and 78% (n = 7) were female. Anti-GAD65 was present in 89% (n = 8) of the patients (range, 1.9-40,000 U/mL), and 33% (n = 3) had a history of diabetes. Forty-four percent (n = 4) of patients had previously received immunosuppressive medication and 67% (n = 6) received intravenous immune globulin. The main indication for TPE was worsening of symptoms despite treatment with first-line therapy. Seventy-eight percent of the patients (n = 7) had five TPE procedures. Seventy-eight percent (n = 7) of patients demonstrated at least minimal clinical improvement and 56% (n = 5) had a significant response. Most of the patients who demonstrated a significant response to treatment improved and their symptoms stabilized. Two patients (22%) developed adverse events, including catheter-associated infection and transient hypotension. Eighteen publications were found from the literature review, which resulted in a total of 26 patients diagnosed with SPS. Forty-two percent (n = 11) of patients had a significant symptomatic improvement after TPE treatment, and two patients (8%) developed adverse events. CONCLUSION: TPE may benefit patients with SPS who are not responsive to first-line therapy, and it is well tolerated.

Stiff-man syndrome and variants: clinical course, treatments, and outcomes.

BACKGROUND: Little information is available about the incidence of stiff-man syndrome (SMS) (the classic form or its variants) or about long-term treatment responses and outcomes. OBJECTIVE: To comprehensively describe the characteristics of a cohort of patients with SMS. DESIGN: Observational study. SETTING: Mayo Clinic, Rochester, Minnesota. PATIENTS: Ninety-nine patients with classic SMS vs variants of the disorder, both glutamic acid decarboxylase 65 kD isoform (GAD65) antibody seropositive and seronegative. MAIN OUTCOME MEASURES: Neurological, autoimmune, serological, and oncological findings; treatments; and outcomes between January 1984 and December 2008. RESULTS: The median follow-up duration was 5 years (range, 0-23 years). Seventy-nine patients (59 having classic SMS, 19 having partial SMS, and 1 having progressive encephalomyelitis with rigidity and myoclonus [PERM]) were GAD65 antibody seropositive. Sixty-seven percent (53 of 79) of them had at least 1 coexisting autoimmune disease, and 4% (3 of 79) had cancer. GAD65 antibody values at initial evaluation were significantly higher among patients with classic SMS (median value, 623 nmol/L) than among patients with partial SMS (median value, 163 nmol/L) (P < .001). The initial GAD65 antibody value was positively correlated with the last follow-up Rankin score (P = .03). Among 20 patients who were GAD65 antibody seronegative (6 with classic SMS, 12 with partial SMS, and 2 with PERM), 15% (3 of 20) had at least 1 coexisting autoimmune disease, and 25% (5 of 20) had cancer (3 with amphiphysin autoimmunity and breast carcinoma and 2 with Hodgkin lymphoma). Excluding patients with PERM, all patients but 1 had sustained improvements with at least 1 γ-aminobutyric acid agent, usually diazepam; the median dosage for patients with classic SMS was 40.0 mg/d. Additional improvements occurred among 14 of 34 patients (41%) who received immunotherapy (intravenous immune globulin, azathioprine, prednisone, mycophenolate mofetil, or cyclophosphamide). Sixteen of 25 patients (64%) with extended follow-up duration remained ambulatory. CONCLUSIONS: Recognition of classic SMS vs variants is important because appropriate therapy improves symptoms in most patients. Classification by anatomical extent and by GAD65 antibody serostatus gives important diagnostic and prognostic information.

GAD antibodies associated neurological disorders: incidence and phenotype distribution among neurological inflammatory diseases.

We investigated the prevalence and the clinical association of high titer of antibodies against glutamic acid decarboxylase (hGADAb) among unselected patients with inflammatory/autoimmune disorders of the nervous system. By indirect immunofluorescence examination of samples from 1435 patients, we identified 7 cases (0.48%) with hGADAb. Although stiff-person plus syndrome was the commonest clinical accompaniment, most of the patients presented with a combination of different symptoms, including psychiatric disturbances and intestinal motility disorders. Diagnosis delay and chronic evolution were common findings. In two cases persistently high values of hGADAb over the years were observed. The rarity and the phenotype heterogeneity of hGADAb clinical association should not discourage clinicians from antibody screening, at least in selected cases, as an early immunotherapy can change the otherwise chronic progression of this complex disorder spectrum.

The occurrence of stiff person syndrome in a patient with thymoma: case report and literature review.

Stiff-person syndrome (SPS) is a rare disorder that affects the central nervous system, being characterized by intermittent episodes of muscle spasms, rigidity, and a significant increase in morbidity and mortality. We report a 29-year-old patient, with left-sided chylothorax and thymoma, who presented with truncal, lower extremities stiffness and painful cramps alleviated by diazepam and opiates. His clinical picture was suggestive of SPS secondary to invasive thymoma. This syndrome is best approached by its early recognition and prompt treatment since a missed diagnosis can have deleterious outcome. An intensive search for the underlying etiology is of utmost importance in the management of SPS. A review of the current literature is also included in this manuscript.

Amphiphysin autoimmunity: paraneoplastic accompaniments.

Amphiphysin-IgG was identified in 71 patients among 120,000 evaluated serologically for paraneoplastic autoantibodies. Clinical information was available for 63 patients. Cancer was detected in 50 (mostly limited), proven histologically in 46, and was imaged intrathoracically in 4 patients (lung, small-cell [27] and non-small cell [1]), breast [16] and melanoma [2]). Neurological accompaniments included (decreasing frequency): neuropathy, encephalopathy, myelopathy, stiff-man phenomena, and cerebellar syndrome. In a case examined neuropathologically, parenchymal T-lymphocyte infiltration (predominantly CD8(+)) was prominent in lower brainstem, spinal cord, and dorsal root ganglion. Coexisting paraneoplastic autoantibodies, identified in 74% of patients, predicted a common neoplasm and indicated other neuronal autoantigen targets that plausibly explained several neurological manifestations; for example, P/Q-type Ca(2+)-channel antibody with Lambert-Eaton syndrome (n = 5), anti-neuronal nuclear antibody type 1 with sensory neuronopathy (n = 7), K(+)-channel antibody with limbic encephalitis (n = 1) or neuromyotonia (n = 1), and collapsin response-mediator protein-5-IgG with optic neuritis (n = 3). Patients with isolated amphiphysin-IgG (n = 19) were more likely to be women (with breast cancer, p < 0.05) and to have myelopathy or stiff-man phenomena (p < 0.01). Overall, a minority of women (39%) and men (12%) had stiff-man phenomena. Only 10% of women (some with lung carcinoma) and 4% of men fulfilled diagnostic criteria for stiff-man syndrome.

Psychiatric consultations in stiff-man syndrome.

BACKGROUND: Stiff-man syndrome is a rare central nervous system disease first described nearly 40 years ago. Its cause has been attributed to both neurologic and psychiatric processes. In recent years, it has been accepted as a neurologic condition in which the gamma-aminobutyric acid (GABA) system malfunctions, probably because of an autoimmune process. Published reports that have described psychiatric manifestations of the disease have relied on descriptions of one or two cases and literature reviews. METHOD: We reviewed the medical records of 24 patients with confirmed stiff-man syndrome, 12 of whom had received psychiatric consultation. This review was done to better determine the psychiatric manifestations of stiff-man syndrome. RESULTS: Retrospective analysis of these 12 cases showed that the most common psychiatric symptoms were anxiety, depression, and alcohol abuse. CONCLUSION: We speculate that the GABA system is involved in both the neurologic and psychiatric symptoms of these patients. Psychiatrists have a significant role in the management of patients with stiff-man syndrome and may be expected to manage anxiety, depression, and substance misuse.

Determination of anti GAD65 autoantibodies with an ELISA before and after standardization with the new international reference serum.

The serum of a stiff-man syndrome patient was declared international GAD reference standard at the "1st GAD Antibody Workshop" held at the "12th International Immunology and Diabetes Workshop" in Orlando, Florida, USA 1993. A comparative study was performed with 123 diabetic and non-diabetic patients to evaluate whether standardization of this reference serum had changed the properties of a commercially available ELISA assay. All samples classified positive with the old test were confirmed with the new assay. Four additional samples with high "normal" values became positive with the new test. One of them was a control person having a family history of diabetes and genetic loci DR4/DR11. These findings might implicate a higher risk for the development of IDDM. The new standardization and adaptation of the ELISA seems to have influenced the sensitivity of the test positively.