Review of 23 patients affected by the stiff man syndrome: clinical subdivision into stiff trunk (man) syndrome, stiff limb syndrome, and progressive encephalomyelitis with rigidity

Atraumatic hip fracture due to stiff person syndrome: Case report and literature review

INTRODUCTION AND IMPORTANCE

Stiff person syndrome (SPS) is a rare autoimmune disorder that affects the central nervous system. Patients with this condition may experience sudden muscle spasms, leading to falls and subsequent fractures. Diagnosis is based on clinical presentation, the presence of anti-GAD antibodies, and electromyography (EMG) findings that show continuous motor unit activity. However, there have been few reports of atraumatic fractures in these patients.

CASE PRESENTATION

In this article, we present a case of a patient with stiff person syndrome who sustained an intertrochanteric fracture without any prior history of trauma. Additionally, we review and discuss previous literature on this subject.

CLINICAL DISCUSSION

SPS is a rare autoimmune neurological disease with muscle rigidity and spasms predominantly in the trunk and lower limbs. The authors mentioned that SPS diagnosis and managing related fractures could be challenging. They recommended optimizing the patient's status with proper medical treatments before surgical interventions to reduce further complications.

CONCLUSION

In conclusion, it appears that stiff person syndrome can lead to recurrent and even atraumatic fractures, and should be considered as an underlying cause. Additionally, uncontrolled spasms in these patients can result in the failure of previous surgical fixations and complicated surgical management. To prevent surgical complications, it is crucial to initiate and maintain appropriate medical treatment to control spasms as soon as the underlying disease is diagnosed.

Stiff Person Syndrome and GAD Antibody-Spectrum Disorders

OBJECTIVE

Antibodies against glutamic acid decarboxylase (GAD), originally associated with stiff person syndrome (SPS), define the GAD antibody-spectrum disorders that also include cerebellar ataxia, autoimmune epilepsy, limbic encephalitis, progressive encephalomyelitis with rigidity and myoclonus (PERM), and eye movement disorders, all of which are characterized by autoimmune neuronal excitability. This article elaborates on the diagnostic criteria for SPS and SPS spectrum disorders, highlights disease mimics and misdiagnoses, describes the electrophysiologic mechanisms and underlying autoimmunity of stiffness and spasms, and provides a step-by-step therapeutic scheme.

LATEST DEVELOPMENTS

Very-high serum GAD antibody titers are diagnostic for GAD antibody-spectrum disorders and also predict the presence of GAD antibodies in the CSF, increased intrathecal synthesis, and reduced CSF γ-aminobutyric acid (GABA) levels. Low serum GAD antibody titers or the absence of antibodies generates diagnostic challenges that require careful distinction in patients with a variety of painful spasms and stiffness, including functional neurologic disorders. Antibodies against glycine receptors, first found in patients with PERM, are seen in 13% to 15% of patients with SPS, whereas amphiphysin and gephyrin antibodies, seen in 5% of patients with SPS spectrum disorders, predict a paraneoplastic association. GAD-IgG from different SPS spectrum disorders recognizes the same dominant GAD intracellular epitope and, although the pathogenicity is unclear, is an excellent diagnostic marker. The biological basis of muscle stiffness and spasms is related to autoimmune neuronal hyperexcitability caused by impaired reciprocal γ-aminobutyric acid-mediated (GABA-ergic) inhibition, which explains the therapeutic response to GABA-enhancing agents and immunotherapies.

ESSENTIAL POINTS

It is essential to distinguish SPS spectrum disorders from disease mimics to avoid both overdiagnoses and misdiagnoses, considering that SPS is treatable if managed correctly from the outset to prevent disease progression. A step-by-step, combination therapy of GABA-enhancing medications along with immunotherapies ensures prolonged clinical benefits.

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.

Therapeutic plasma exchange in the management of stiff person syndrome spectrum disorders: a case series and review of the literature

Background

Stiff person syndrome spectrum disorders (SPSD) are a rare group of disabling neuroimmunological disorders. SPSD often requires immune therapies, especially in the setting of inadequate response to symptomatic treatments. The safety and efficacy of therapeutic plasma exchange (TPE) in SPSD remains uncertain.

Objectives

To describe the safety, tolerability, and efficacy of TPE in patients with SPSD.

Design

A retrospective observational study.

Methods

A retrospective review of SPSD patients seen at Johns Hopkins Hospital (JHH) from 1997 to 2021 was performed. Patient demographics/history, examination/diagnostic findings, treatment response, and TPE-related complications were recorded. Assessment for any associations between clinical characteristics, including age, sex, clinical phenotype, and time on immunotherapy, and response to TPE 3 months after treatment was performed. A subgroup of 18 patients treated with TPE at JHH and 6 patients treated with TPE at outside institutions were evaluated for any change in usage of symptomatic medications 3 months after the TPE treatment. Literature review of SPSD and TPE was also conducted.

Results

Thirty-nine SPSD patients were treated with TPE (21 at JHH and 18 at outside institutions); median age 48 years, 77% female, median modified Rankin Scale 3; mean initial anti-GAD65 antibody titer was 23,508 U/mL. Twenty-four patients (62%) had classic SPS, 10 (26%) had SPS-plus, 2 (5%) had progressive encephalomyelitis with rigidity and myoclonus, and 3 (8%) had pure cerebellar ataxia. All patients were on symptomatic treatments, 30 (77%) previously received IVIg, and 3 (8%) previously received rituximab. Four patients (10%) had a TPE-related adverse event. One developed asymptomatic hypotension, another had both line thrombosis and infection, and two had non-life-threatening bleeding events. Twenty-three (59%) patients reported improvement in symptoms after TPE. Of the subgroup of 24 patients evaluated for any change in usage of symptomatic medications 3 months after the TPE treatment, 14 (58%) required fewer GABAergic symptomatic medications. Literature review identified 57 additional patients with SPSD; 43 (75%) reported temporary improvement after TPE.

Conclusion

The majority of patients treated with TPE had improvement. Moreover, most patients evaluated for any change in usage of symptomatic medications after the TPE treatment no longer required as much symptomatic medications months after TPE. TPE appears safe and well-tolerated in SPSD. Further studies are needed to assess the long-term efficacy of TPE in SPSD and identify which patients may benefit the most from TPE.

Stiff person syndrome in a Nepalese man with uncontrolled diabetes mellitus and ketonuria: A rare case report

Stiff Person Syndrome (SPS), a progressive Central Nervous System disorder is accompanied by progressive muscle rigidity, hyperreflexia, and spasms mainly in truncal and proximal leg muscles mainly associated with autoimmune disorders. Here, we report a rare case of SPS in a middle-aged Nepalese man with uncontrolled diabetes mellitus and ketonuria.

Stiff-person Syndrome and GAD Antibody-spectrum Disorders: GABAergic Neuronal Excitability, Immunopathogenesis and Update on Antibody Therapies

Although antibodies against Glutamic Acid Decarboxylase (GAD) were originally associated with Stiff Person Syndrome (SPS), they now denote the "GAD antibody-spectrum disorders (GAD-SD)" that include Cerebellar Ataxia, Autoimmune Epilepsy, Limbic Encephalitis, PERM and eye movement disorder. In spite of the unique clinical phenotype that each of these disorders has, there is significant overlapping symptomatology characterized by autoimmune neuronal excitability. In addition to GAD, three other autoantibodies, against glycine receptors, amphiphysin and gephyrin, are less frequently or rarely associated with SPS-SD. Very high serum anti-GAD antibody titers are a key diagnostic feature for all GAD-SD, commonly associated with the presence of GAD antibodies in the CSF, a reduced CSF GABA level and increased anti-GAD-specific IgG intrathecal synthesis denoting stimulation of B-cell clones in the CNS. Because anti-GAD antibodies from the various hyperexcitability syndromes recognize the same dominant GAD epitope, the clinical heterogeneity among GAD-SD patients remains unexplained. The paper highlights the biologic basis of autoimmune hyperexcitability connected with the phenomenon of reciprocal inhibition as the fundamental mechanism of the patients' muscle stiffness and spasms; addresses the importance of high-GAD antibody titers in diagnosis, pinpointing the diagnostic challenges in patients with low-GAD titers or their distinction from functional disorders; and discusses whether high GAD-antibodies are disease markers or pathogenic in the context of their association with reduced GABA level in the brain and CSF. Finally, it focuses on therapies providing details on symptomatic GABA-enhancing drugs and the currently available immunotherapies in a step-by-step approach. The prospects of future immunotherapeutic options with antibody therapies are also summarized.

Unusual presentation of stiff-person syndrome in a patient with type 1 diabetes mellitus

Stiff-person syndrome (SPS) is a rare, autoimmune, neurological disorder that often occurs concurrently with other autoimmune disorders, such as type 1 diabetes mellitus, pernicious anaemia, vitiligo and Hashimoto's thyroiditis. It also can manifest as a paraneoplastic syndrome. Although SPS classically presents with truncal and appendicular stiffness and lumbar hyperlordosis, it can present focally in a single limb (termed stiff-limb syndrome). Here, we describe a woman with stiff-limb syndrome who initially presented with concerns about right foot swelling and pain. She also was positive for anti-GAD65 (anti-GAD2) antibodies. With treatment, she regained the ability to drive and ambulate without a walker, and she had a noted reduction in stimulus-induced spasms.

Stiff-person syndrome: an atypical presentation and a review of the literature

Introduction: Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder associated with muscle rigidity and spasms. A number of antibodies have been associated with disorder, including anti-glutamic acid decarboxylase and anti-amphiphysin.Case report; In this report, we present a rare case of a 79-year-old woman who presented with bilateral lower extremity weakness who was ultimately diagnosed with stiff-limb syndrome, a rare variant of SPS. Extensive laboratory and CSF studies were unrevealing. Electromyography showed significant peroneal motor neuropathy and complex repetitive discharges in the left tibialis anterior muscle. Antibodies to glutamic acid decarboxylase were significantly elevated at 124 units/mL. She was subsequently started on oral diazepam with significant improvement in her symptoms.Conclusion: The presentation of SPS can vary based on epidemiologic factors, clinical symptoms, and associated disorders. These forms can have overlapping features which may make the categorization of patients into one of these forms challenging.

Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM)-like Symptoms Associated with Anti-ganglionic Acetylcholine Receptor Antibodies

This report describes a 59-year-old woman who presented with progressive encephalomyelitis with rigidity and myoclonus (PERM)-like symptoms and severe dysautonomia, including orthostatic hypotension, sinus bradycardia, dysuria, and prolonged constipation. Her neurological symptoms improved after immunotherapy, but the dysautonomia persisted. Anti-ganglionic acetylcholine receptor (gAChR) α3 subunit antibodies, which are frequently identified in patients with autoimmune autonomic ganglionopathy, were detected in the pre-treatment serum. The central distribution of the nicotinic acetylcholine receptors, a target of anti-gAChR antibodies, and immunotherapeutic efficacy observed in this case indicate that anti-gAChR α3 subunit antibodies are associated with the PERM-like features accompanied by autonomic manifestations.

The Interdisciplinary Stem Cell Institute's Use of Food and Drug Administration-Expanded Access Guidelines to Provide Experimental Cell Therapy to Patients With Rare Serious Diseases

The U.S. Food and Drug Administration (FDA) provides guidance for expanded access to experimental therapies, which in turn plays an important role in the Twenty-first Century Cures Act mandate to advance cell-based therapy. In cases of incurable diseases where there is a lack of alternative treatment options, many patients seek access to cell-based therapies for the possibility of treatment responses demonstrated in clinical trials. Here, we describe the use of the FDA’s expanded access to investigational new drug (IND) to address rare and emergency conditions that include stiff-person syndrome, spinal cord injury, traumatic brain stem injury, complex congenital heart disease, ischemic stroke, and peripheral nerve injury. We have administered both allogeneic bone marrow-derived mesenchymal stem cell (MSC) and autologous Schwann cell (SC) therapy to patients upon emergency request using Single Patient Expanded Access (SPEA) INDs approved by the FDA. In this report, we present our experience with 10 completed SPEA protocols.

Surgical Treatment for Toe Deformities in Stiff-Person Syndrome: A Case Report

CASE

Stiff-person syndrome is a rare neurological disorder characterized by rigidity and painful spasms of the trunk and limbs, and patients sometimes have difficulty in walking due to rigid toe deformities. This is a case report of a 76-year-old woman suffering from stiff-person syndrome with painful rigid toe deformities regained walking ability after metatarsal osteotomy and cutting of the toe extensors for all toes in the left foot.

CONCLUSION

For patients with stiff-person syndrome, surgical intervention is a powerful treatment option when they have developed rigid and painful toe deformities despite adequate pharmacological treatment.

Efficacy and safety of therapeutic plasma exchange in stiff person syndrome

The stiff person syndrome (SPS) is an extremely rare neurological disorder with primarily immune-mediated etiology. The cardinal symptoms are progressive, fluctuating axial/proximal limb muscle stiffness and spasms. The diagnosis is based on the clinical picture, electromyography examination and detection of antibodies to glutamic acid decarboxylase (anti-GAD). Adverse effects of medications might preclude its use or increase in dosing, therefore symptomatic and/or immunomodulatory medical therapy might be ineffective in acute exacerbation of the disease. We present a case of a 49-year-old female with exacerbation of SPS, in whom some standard pharmacotherapy could not be introduced (clonazepam, baclofen used in the past) and doses of existing standard medications could not be increased (diazepam, gabapentin, and levetiracetam) due to adverse effects. Moreover, a newly introduced medication (methylprednisolone) also led to a serious adverse effect (severe hyperglycemia). The patient underwent therapeutic plasma exchange (TPE) with good effect and no complications. We review the literature regarding the efficacy and safety profile of TPE in exacerbation of SPS unresponsive to medical therapy. The procedure seems to have a good safety profile as an adjunct therapy for exacerbation of SPS not responding to standard medical therapy in this patient population.

GAD antibody-spectrum disorders: progress in clinical phenotypes, immunopathogenesis and therapeutic interventions

Antibodies against glutamic acid decarboxylase (GAD), originally linked to stiff person syndrome (SPS), now denote the "GAD antibody-spectrum disorders" (GAD-SD) that also include autoimmune epilepsy, limbic encephalitis, cerebellar ataxia and nystagmus with overlapping symptomatology highlighting autoimmune neuronal excitability disorders. The reasons for the clinical heterogeneity among GAD-antibody associated syndromes remain still unsettled, implicating variable susceptibility of GABAergic neurons to anti-GAD or other still unidentified autoantibodies. Although anti-GAD antibody titers do not correlate with clinical severity, very high serum titers, often associated with intrathecal synthesis of anti-GAD-specific IgG, point to in-situ effects of GAD or related autoantibodies within the central nervous system. It remains, however, uncertain what drives these antibodies, why they persist and whether they are disease markers or have pathogenic potential. The review, focused on these concerns, describes the widened clinical manifestations and overlapping features of all GAD-SD; addresses the importance of GAD antibody titers and potential significance of GAD epitopes; summarizes the biologic basis of autoimmune hyperexcitability; highlights the electrophysiological basis of reciprocal inhibition in muscle stiffness; and provides practical guidelines on symptomatic therapies with gamma-aminobutyric acid-enhancing drugs or various immunotherapies.

An Appraisal of Electrodiagnostic Studies in Stiff Person Syndrome

A literature review was performed on the use of electrodiagnostic (EDX) tests including nerve conduction study, electromyography, exteroceptive reflex, blink reflex, and late response in the evaluation of patients with stiff person syndrome (SPS). A web survey was conducted to report the extent of EDX testing usage in the evaluation of SPS among laboratories accredited by the American Academy of Neuromuscular and Electrodiagnostic Medicine. Coactivation of selected agonist and antagonist muscles was performed in 5 healthy subjects to determine its specificity for SPS. Observation of continuous motor unit activity on electromyography and elicitation of exteroceptive reflexes by electric stimulation are informative in assisting a diagnosis of SPS, but further studies focusing on their sensitivities in diagnosing SPS and specificities in differentiating SPS from other movement disorders are needed. The value of EDX testing in SPS lies in ruling out other neuromuscular disorders.

Sex differences in movement disorders

A number of studies reported the possible differences between men and women in movement disorders. Evidence shows that estrogens may have a neuroprotective effect and may modulate the neurodevelopment of the different brain structures. Movement disorders including Parkinson's disease, dementia with Lewy body, Huntington's disease, Tourette's syndrome, and dystonia among others display significant clinical differences between sexes, with structural differences in the dopaminergic pathways between men and women. Here we summarize the most relevant clinical aspects of some of the most common movement disorders, highlighting the differences in disease onset, clinical presentation, therapy, and outcomes. Increased recognition of these differences may help physicians better understand the pathophysiology of these conditions and provide a tailored therapeutic approach.

Paraneoplastic Stiff Person Syndrome in Early-Stage Breast Cancer with Positive Anti-Amphiphysin Antibodies

Stiff person syndrome (SPS) is a rare neurologic disorder, characterized by muscle rigidity and spasms. Anti-glutamic acid decarboxylase (anti-GAD) antibodies are associated with the classic form of SPS, while antibodies against amphiphysin are associated with the paraneoplastic form of the disease. We present the case of a patient with paraneoplastic SPS, presenting with muscle cramps of lower extremities that progressed to severe muscle rigidity and spasms, associated with a right breast tumor and positive anti-amphiphysin antibodies. Paraneoplastic SPS is a rare neurological disorder, challenging for the physicians both to diagnose and treat.

Autologous haematopoietic stem cell transplantation for refractory stiff-person syndrome: the UK experience

Abstract

Stiff Person Syndrome (SPS) is a rare immune-mediated disabling neurological disorder characterised by muscle spasms and high GAD antibodies. There are only a few case reports of autologous haematopoietic stem cell transplantation (auto-HSCT) as a treatment for SPS.

Objective

To describe the UK experience of treating refractory SPS with auto-HSCT.

Methods

Between 2015 and 2019, 10 patients with SPS were referred to our institution for consideration of auto-HSCT. Eight patients were deemed suitable for autograft and four were treated. Of the treated patients, three had classical SPS and one had the progressive encephalomyelitis with rigidity and myoclonus variant. All patients were significantly disabled and had failed conventional immunosuppressive therapy. Patients were mobilised with Cyclophosphamide (Cy) 2 g/m² + G-CSF and conditioned with Cy 200 mg/kg + ATG followed by auto-HSCT.

Results

Despite their significantly reduced performance status, all patients tolerated the procedure with no unexpected toxicities. Following autograft, all patients improved symptomatically and stopped all forms of immunosuppressive therapies. Two patients were able to ambulate independently from being wheelchair dependent. One patient’s walking distance improved from 300 meters to 5 miles and one patient’s ambulation improved from being confined to a wheelchair to be able to walk with a frame. Two patients became seronegative for anti-GAD antibodies and normalised their neurophysiological abnormalities.

Conclusions

Auto-HSCT is an intensive but well tolerated and effective treatment option for patients with SPS refractory to conventional immunotherapy. Further work is warranted to optimise patient selection and establish the efficacy, long-term safety, and cost-effectiveness of this treatment.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-10054-8) contains supplementary material, which is available to authorized users.

Effectiveness of Combined Immunoglobulin and Glucocorticoid Treatments in a Patient With Stiff Limb Syndrome: Case Report and Review of the Literature

Stiff limb syndrome (SLS) is a rare autoimmune-related central nervous system disorder, resulting in stiffness and spasms of limbs since onset with rare involvement of the truncal muscles. However, SLS patients will gain notable effects by appropriate therapy focusing on symptomatic treatment and immunotherapy. We reported on a 55-year-old female who showed typical painful spasms in both lower limbs and abduction of the right eyeball that partially responded to low-dose diazepam and had high-titer anti–glutamic acid decarboxylase (anti-GAD) antibody. Electromyography (EMG) only showed continuous motor unit activity (CMUA) in the anterior tibialis and right triceps. Eventually, our patient was diagnosed with SLS and treated with intravenous immunoglobulin (IVIG) and glucocorticoid combined simultaneously. She obtained notable effects. We also review and summarize the current literature on clinical characteristics, coexisting disease, treatment, and outcome of 40 patients with SLS. We hope that this report will provide a basis for further understanding of SLS and promote the formation of more advanced diagnosis and treatment processes.

Limited Utility for Benzodiazepines in Chronic Pain Management: A Narrative Review

INTRODUCTION

Controversy and uncertainty exist about the use of benzodiazepine receptor agonists (BZRAs) in pain management. This article curates available research to determine the appropriate role of BZRAs in the course of pain management, and how prescribers might address these challenges.

METHODS

A narrative review was performed to determine the appropriate role of BZRAs in pain management and to develop practice recommendations. Publications were identified by a search of PubMed, references of retrieved reports, guidelines, and the author's personal files.

RESULTS

BZRAs were found to have analgesic benefit for two pain conditions: burning mouth syndrome and stiff person syndrome. Absence of research, heterogeneity of trials, and small sample sizes precluded drawing conclusions about efficacy of BZRAs for the other 109 pain conditions explored. Data supports the use of BZRAs to treat co-occurring insomnia and anxiety disorders but only when alternatives are inadequate and only for short periods of time (2-4 weeks). The utility of BZRAs is limited by loss of efficacy that may be seen with continued use and adverse reactions including physiologic dependence which develops in 20-100% of those who take these agents for more than a month.

CONCLUSIONS

BZRAs are often used inappropriately in pain management. Their initiation and duration of use should be limited to a narrow range of conditions. When prescribed for 4 weeks or more, patients should be encouraged to discontinue them through a supported, slow tapering process that may take 12-18 months or longer.

Glycine receptor autoantibodies disrupt inhibitory neurotransmission

Chloride-permeable glycine receptors have an important role in fast inhibitory neurotransmission in the spinal cord and brainstem. Human immunoglobulin G (IgG) autoantibodies to glycine receptors are found in a substantial proportion of patients with progressive encephalomyelitis with rigidity and myoclonus, and less frequently in other variants of stiff person syndrome. Demonstrating a pathogenic role of glycine receptor autoantibodies would help justify the use of immunomodulatory therapies and provide insight into the mechanisms involved. Here, purified IgGs from four patients with progressive encephalomyelitis with rigidity and myoclonus or stiff person syndrome, and glycine receptor autoantibodies, were observed to disrupt profoundly glycinergic neurotransmission. In whole-cell patch clamp recordings from cultured rat spinal motor neurons, glycinergic synaptic currents were almost completely abolished following incubation in patient IgGs. Most human autoantibodies targeting other CNS neurotransmitter receptors, such as N-methyl-d-aspartate (NMDA) receptors, affect whole cell currents only after several hours incubation and this effect has been shown to be the result of antibody-mediated crosslinking and internalization of receptors. By contrast, we observed substantial reductions in glycinergic currents with all four patient IgG preparations with 15 min of exposure to patient IgGs. Moreover, monovalent Fab fragments generated from the purified IgG of three of four patients also profoundly reduced glycinergic currents compared with control Fab-IgG. We conclude that human glycine receptor autoantibodies disrupt glycinergic neurotransmission, and also suggest that the pathogenic mechanisms include direct antagonistic actions on glycine receptors.

Neurological Syndromes Associated with Anti-GAD Antibodies

Glutamic acid decarboxylase (GAD) is an intracellular enzyme whose physiologic function is the decarboxylation of glutamate to gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter within the central nervous system. GAD antibodies (Ab) have been associated with multiple neurological syndromes, including stiff-person syndrome, cerebellar ataxia, and limbic encephalitis, which are all considered to result from reduced GABAergic transmission. The pathogenic role of GAD Ab is still debated, and some evidence suggests that GAD autoimmunity might primarily be cell-mediated. Diagnosis relies on the detection of high titers of GAD Ab in serum and/or in the detection of GAD Ab in the cerebrospinal fluid. Due to the relative rarity of these syndromes, treatment schemes and predictors of response are poorly defined, highlighting the unmet need for multicentric prospective trials in this population. Here, we reviewed the main clinical characteristics of neurological syndromes associated with GAD Ab, focusing on pathophysiologic mechanisms.

Pseudoagoraphobia, a Diagnostic Clue in Stiff-Limb Syndrome

BACKGROUND

Stiff-limb syndrome is part of stiff person spectrum, presenting with fluctuating gait disorders attributed to leg stiffness, spasms, and posturing. It could also manifest with anxiety and specific phobias such as pseudoagoraphobia. We aimed to describe the importance of specific gait phobia as a diagnostic clue to anti-glutamic acid decarboxylase stiff-limb syndrome.

CASES

We reported on 2 cases of stiff-limb syndrome sharing a similar diagnostic path and phenomenology. Both were featured by pseudoagoraphobia, which has documented to typically cover organic conditions, and a remarkable diagnostic delay attributed to misdiagnoses. Presence of pseudoagoraphobia should not point to the diagnosis of a functional disorder-although a negative instrumental workup is documented.

CONCLUSIONS

Both cases are emblematic of the high misdiagnosis rate affecting stiff person syndrome patients. A proper diagnostic process, including the identification of a pseudoagoraphobia, should help in reaching a diagnosis and providing an early and effective treatment.

S1 guidelines "lumbar puncture and cerebrospinal fluid analysis" (abridged and translated version)

Introduction

Cerebrospinal fluid (CSF) analysis is important for detecting inflammation of the nervous system and the meninges, bleeding in the area of the subarachnoid space that may not be visualized by imaging, and the spread of malignant diseases to the CSF space. In the diagnosis and differential diagnosis of neurodegenerative diseases, the importance of CSF analysis is increasing. Measuring the opening pressure of CSF in idiopathic intracranial hypertension and at spinal tap in normal pressure hydrocephalus constitute diagnostic examination procedures with therapeutic benefits.Recommendations (most important 3-5 recommendations on a glimpse): The indications and contraindications must be checked before lumbar puncture (LP) is performed, and sampling CSF requires the consent of the patient.Puncture with an atraumatic needle is associated with a lower incidence of postpuncture discomfort. The frequency of postpuncture syndrome correlates inversely with age and body mass index, and it is more common in women and patients with a history of headache. The sharp needle is preferably used in older or obese patients, also in punctures expected to be difficult.In order to avoid repeating LP, a sufficient quantity of CSF (at least 10 ml) should be collected. The CSF sample and the serum sample taken at the same time should be sent to a specialized laboratory immediately so that the emergency and basic CSF analysis program can be carried out within 2 h.The indication for LP in anticoagulant therapy should always be decided on an individual basis. The risk of interrupting anticoagulant therapy must be weighed against the increased bleeding risk of LP with anticoagulant therapy.As a quality assurance measure in CSF analysis, it is recommended that all cytological, clinical-chemical, and microbiological findings are combined in an integrated summary report and evaluated by an expert in CSF analysis.

Conclusions

In view of the importance and developments in CSF analysis, the S1 guideline "Lumbar puncture and cerebrospinal fluid analysis" was recently prepared by the German Society for CSF analysis and clinical neurochemistry (DGLN) and published in German in accordance with the guidelines of the AWMF (https://www.awmf.org). /uploads/tx_szleitlinien/030-141l_S1_Lumbalpunktion_und_Liquordiagnostik_2019-08.pdf). The present article is an abridged translation of the above cited guideline. The guideline has been jointly edited by the DGLN and DGN.

Stiff limb syndrome with lower limb myoclonus: A case report

RATIONALE

stiff limb syndrome (SLS) is a variant of stiff-man syndrome, primarily affecting a specific limb. Its diagnosis has always been challenging due to the lack of a specific confirmation test. We present a rare case of a patient with lower limb myoclonus and rigidity.

PATIENT CONCERNS

A 53-year-old male presented with a sudden onset of progressive left lower extremity myoclonus and muscle rigidity for 3 days. He rapidly showed signs of right lower limb involvement with severe joint stiffness and inability to walk.

DIAGNOSIS

The symptoms nature, physical examination, careful elimination of differential diagnosis suggested a diagnosis of stiff limb syndrome.

INTERVENTIONS

Intravenous infusion of gamma globulin 0.4 mg/kg coupled with baclofen and clonazepam were given after admission. He also received an injection of botulinum toxin A to relieve his muscle stiffness.

OUTCOMES

The patients' condition improved after the initial treatment with complete disappearance of muscle twitching. Further improvements were seen later on after the local administration of botulinum toxin A.

LESSONS

Stiff limb syndrome shares the same complex symptoms with many other conditions. Its diagnosis relies heavily on clinical presentations and on ruling out other conditions. However, unusual symptoms such as myoclonus can occur in few cases and together with the rarity of the condition, the prevalence of misdiagnosis is high. Therefore, being aware and recognizing the signs and symptoms is crucial for proper management. Additionally, EMG is a very important test if the present condition is suspected. However, a negative EMG result or a negative anti-glutamic acid decarboxylase antibody test should not exclude SLS diagnosis.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

Rituximab improves not only back stiffness but also "stiff eyes" in stiff person syndrome: Implications for immune-mediated treatment

OBJECTIVE

Stiff person syndrome (SPS) is usually characterized by truncal muscle rigidity and episodic painful spasms, but it sometimes appears with ocular symptoms called "stiff eyes". We recorded saccade movements in an SPS patient manifesting with "stiff eyes" conditions with slow saccade velocity and evaluated the effect of immunotherapy including rituximab on saccade parameters.

METHODS

We repeatedly conducted saccade eye recordings using video-based eye tracking system on a 42-year-old male SPS patient with slow saccade. The velocity and onset latency of visual guided saccades (VGS) were measured at each recording. Because VGS velocity is affected by saccade amplitude, estimated peak velocity (Vmax) was also calculated by taking the relationship between the velocity and the amplitude of saccade into account.

RESULTS

The mean VGS velocity improved significantly after two courses of rituximab administration compared with its lowest value. The estimated Vmax decreased as the clinical manifestations worsened, but it increased after rituximab administration. Other neurological symptoms in this patient such as muscle rigidity and gait instability also improved after the treatment.

CONCLUSION

Slow saccade in a "stiff eyes" patient improved after rituximab administration. Our study also indicated that the saccade eye recording is useful for evaluating the clinical condition of SPS when it is complicated with ocular symptoms.

Association of stiff-person syndrome with autoimmune endocrine diseases

BACKGROUND

Stiff-person syndrome (SPS) and its subtype, stiff limb syndrome (SLS), are rare neurological disorders characterized by progressive muscular rigidity and spasms. Glutamic acid decarboxylase (GAD) is the enzyme that catalyzes the production of γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter of the central nervous system. SPS is an autoimmune disease triggered by anti-glutamic acid decarboxylase antibody (anti-GAD Ab). Clinically, anti-GAD Ab is associated with SPS, type 1 diabetes mellitus (T1DM), and other autoimmune diseases.

AIM

To investigate the link of autoimmune endocrine disorders with anti-GAD Ab in SPS subjects.

METHODS

This retrospective study was approved by the Institutional Review Board of Chang Gung Memorial Hospital, Taiwan. We collected the patients with SPS from January 2001 to June 2018. By reviewing 14 patients from medical records, we analyzed the clinical findings with coexisting autoimmune diseases, particularly diabetes mellitus and thyroid disease, which are associated with anti-GAD antibody titers or other immunological test results (anti-thyroid peroxidase and anti-nuclear antibodies). We also evaluated malignancies, major complications, and reported treatment to improve symptoms. Anti-GAD antibodies were measured using radioimmunoassay and enzyme-linked immunosorbent assay (ELISA). The cut-off values of these tests are < 1 U/mL and < 5 U/mL, respectively.

RESULTS

The median age of all patients was 39.3 (range, 28.0-54.0) years with a median follow-up period of 6.0 (2.7-13.3) years. Five (35.7%) patients were female; twelve (85.7%) were diagnosed with classic SPS and two (14.3%) with SLS. The median age of onset of symptoms was 35.0 (26.0-56.0) years with a median follow-up duration of 9.0 (2.1-14.9) years in the classic SPS group; the SLS group had a median age of onset of 46.7 years and a shorter follow-up duration of 4.3 years. Among nine classic SPS patients who underwent the anti-GAD Ab test, three were anti-GAD Ab seropositive and each of these three patients also had T1DM, latent autoimmune diabetes in adults, and autoimmune thyroid disease, respectively. In contrast, other rare autoimmune diseases co-existed in six anti-GAD Ab seronegative SPS patients. None of the SLS patients had additional autoimmune diseases.

CONCLUSION

While typical clinical symptoms are crucial for the diagnosis of SPS, the presence of anti-GAD autoantibody may consolidate the diagnosis and predict the association with other autoimmune diseases.

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.

Quantitative clinical and autoimmune assessments in stiff person syndrome: evidence for a progressive disorder

BACKGROUND

Stiff Person Syndrome (SPS) is an under-diagnosed disorder that affects mobility and the quality of life of affected patients. The aim of the study is to describe the natural history of SPS, the extent of accumulated disability and the associated clinical and immunological features in patients followed for up to 8 years in a single center.

METHODS

Our collective cohort included 57 SPS patients. Additionally, 32 of these patients were examined every 6 months for a two-year period in a longitudinal study protocol, to assess disease progression using quantitative measures of stiffness and heightened sensitivity.

RESULTS

The most frequent initial symptom was leg stiffness, followed by paraspinal muscle rigidity and painful spasms in 95% of the patients. Although none of the patients required assistance for ambulation during the first 2 years of disease onset, 46 patients (80%) lost the ability to walk independently during our follow-up, despite symptomatic medications. In the longitudinal cohort, the number of stiff areas increased (p < 0.0001), consistent with worsening functional status and quality of life. High-titer anti-GAD antibodies were present in serum and CSF with elevated intrathecal GAD-specific IgG synthesis, but they did not correlate with clinical severity or progression.

CONCLUSIONS

This large study on SPS patients, combining an eight-year follow-up at a single center by the same leading neurologist and his team, is the first to provide longitudinal data in a large patient subgroup using objective clinical measures. One of the main findings is that SPS is a progressive disease leading to physical disability over time.

Progressive Encephalomyelitis with Rigidity and Myoclonus Resolving after Thymectomy with Subsequent Anasarca: An Autopsy Case

Progressive encephalomyelitis with rigidity and myoclonus (PERM) is an autoimmune disorder involving the brainstem and spinal cord and is sometimes associated with thymoma. We encountered a 75-year-old woman with typical PERM features, glycine receptor antibody, and thymoma. Her neurologic symptoms improved after thymectomy, but she unexpectedly developed anasarca with massive pleural effusions and hypoalbuminemia and finally succumbed to death. The autopsy showed edema and mononuclear infiltration in the pleura but no neuropathological findings typical of PERM. Effective treatment of PERM can reverse the neuropathological signs of encephalomyelitis. The autoimmune nature of anasarca is possible but not proven.

A case report of rigidity and recurrent lower limb myoclonus: progressive encephalomyelitis rigidity and myoclonus syndrome, a chameleon

BACKGROUND

Progressive encephalomyelitis with rigidity and myoclonus (PERM) syndrome is a rare neurological condition. Its clinical characteristics include axial and limb muscle rigidity, myoclonus, painful spasms and hyperekplexia. Diagnosis of this disease can be very challenging and optimal long-term treatment is unclear.

CASE PRESENTATION

We report a case of a 62 year old patient admitted for repetitive myoclonus and rigidity in the lower limbs progressing since 10 years, associated with a fluctuating encephalopathy requiring stays in Intensive Care Unit. Multiple diagnostics and treatment were proposed, unsuccessfully, before the diagnosis of PERM syndrome was established. In association with the clinical presentation, a strong positive result for GAD (glutamic acid decarboxylase) antibodies lead to the diagnosis of PERM syndrome.

CONCLUSIONS

PERM syndrome is a rare disease and its diagnosis is not easy. Once the diagnosis is established, the correct treatment should follow and could be lifesaving, regardless of a delayed diagnosis. Maintenance of long-term oral corticotherapy is suggested to prevent relapses.

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.

Stiff person syndrome with elevated titers of antibodies against cardiolipin and β2 glycoprotein 1: a case report and literature review

We reported a Stiff person syndrome (SPS) patient with elevated autoantibodies against cardiolipin and β2 glycoprotein 1 but without glutamic acid decarboxylase (GAD) antibodies. A 40-year male was admitted due to limited mouth opening for 1 week. His blood routine, biochemical, infectious diseases, tumor markers, radiographic examinations were all normal. At day 3 (D3) after admission, he developed paroxysmal systemic muscle rigidity. At D6, the on-duty physician occasionally gave oral clonazepam, which effectively relieved the symptom. At D13, the titers of cardiolipin and β2 glycoprotein 1 autoantibodies elevated but the remaining autoantibodies were all in normal ranges. After clonazepam treatment for 1 week, the symptoms were basically relieved, and the titers of these two antibodies returned to normal range with the relief of symptoms. During the 3 years of follow-up, the symptoms did not present again, and the titers of both antibodies were stable in the normal ranges. He had no tumor and other immune system diseases. In summary, we reported a SPS case with elevated cardiolipin and β2 glycoprotein 1 autoantibodies. The patient was highly responsive to clonazepam therapy, and had favorable outcome in the 3 years follow-up. Our report is helpful for better understand the heterogeneous feature of SPS.

Paraneoplastic movement disorders

Paraneoplastic movement disorders are rare, autoimmune-mediated, nonmetastatic complications of malignant neoplasms. Common paraneoplastic movement disorders include paraneoplastic chorea, dystonia, cerebellar degeneration, different types of encephalitis, opsoclonus-myoclonus syndrome, stiff person syndrome, and neuromyotonia. Syndromes usually develop before tumor diagnosis, have subacute onset, and are associated with serum or cerebrospinal fluid antibodies. Two types of antibodies can be distinguished: antibodies against nuclear and cytoplasmic neuronal antigens (anti-Hu, anti-Ri, anti-Yo, anti-Ma, anti-CV2/CRMP5, anti-Gephrin, and anti-GABATRAP) and antibodies recently identified against cell surface and synaptic proteins (anti-NMDAR, anti-LGI1, and anti-Caspr2). These two types differ from each other in a few important aspects. Antibodies against cell surface and synaptic protein disrupt cell-surface antigens. Clinical symptoms are related to the disruption of antigens and potentially can be reversed by immunotherapy. The association between these antibodies and malignancy is much less consistent. On the other hand, antibodies against nuclear and cytoplasmic neuronal antigens seem to be not pathogenic; however, they most likely indicate a T-cell-mediated immune response against neurons. Due to T-cell-mediated neuronal loss, response to immunotherapy is generally disappointing. Early recognition of all these diseases is crucial because it may lead to the disclosure of occult cancer. This review is focused on paraneoplastic movement disorders with emphasis on clinical presentations, investigational findings, and therapeutic results.

Neurologic disorders associated with anti-glutamic acid decarboxylase antibodies: A comparison of anti-GAD antibody titers and time-dependent changes between neurologic disease and type I diabetes mellitus

To determine clinical features of neurologic disorders associated with anti-glutamic acid decarboxylase antibodies (anti-GAD-Ab), we examined titers and time-dependent changes of anti-GAD-Ab. Six patients, stiff person syndrome (2), cerebellar ataxia (1), limbic encephalitis (1), epilepsy (1), brainstem encephalitis (1), were compared with 87 type I diabetes mellitus (T1DM) patients without neurologic disorders. Anti-GAD-Ab titers and index were higher in neurologic disorders than in T1DM, suggesting intrathecal antibody synthesis. Anti-GAD-Ab titers in T1DM decreased over time, whereas they remained high in neurologic disorders. Immunotherapy improved neurological disorders and anti-GAD-Ab titers and index provide clinically meaningful information about their diagnostic accuracy.

Difficult to Treat Focal, Stiff Person Syndrome of the Left Upper Extremity

Background

Stiff person syndrome (SPS) is a rare neurologic disorder characterized by muscle rigidity. It is a disorder of reduced GABA activity leading to increased muscle tone and often painful spasms. It generally presents in the axial musculature but rarely can involve only one limb, typically a lower extremity. In rare cases it can be paraneoplastic which generally resolves on treatment of the underlying neoplasm.

Case Report

A 46-year-old male with a history of Hodgkin's Lymphoma in remission presented with left upper extremity pain secondary to a diagnosis of Stiff Person Syndrome limited to his left upper extremity. He had previously benefitted from plasmapheresis and was on diazepam and baclofen at home with relatively good control of his symptoms. SPS had previously been diagnosed with EMG and anti-GAD-65 antibody titers and was confirmed by an elevated anti-GAD-65 antibody titer. He was treated with plasmapheresis and maximum doses of medical treatment including botulinum toxin with only transient mild improvement in his symptoms.

Conclusion

This case represents a case of a rare disease that was refractory to all known therapies. It outlines the need for further understanding of this disorder in order to provide better symptomatic treatment or potentially more definitive care.

The Stiff People: Two Rare Cases of Stiff-person Syndrome

Stiff-person syndrome (SPS) is a rare disorder that affects the central nervous system and is characterized by progressive muscle stiffness, rigidity, and spasm of axial and limb muscles. The syndrome is caused by a lack of gamma aminobutyric acid (GABA), which occurs because of antibodies against glutamic acid decarboxylase (GAD), an essential enzyme for GABA synthesis. Hence, the patients present with increased muscular activity. In this article, we will discuss two case studies of stiff-person syndrome.

Anti-glutamic acid decarboxylase antibody positive neurological syndromes

A rare kind of antibody, known as anti-glutamic acid decarboxylase (GAD) autoantibody, is found in some patients. The antibody works against the GAD enzyme, which is essential in the formation of gamma aminobutyric acid (GABA), an inhibitory neurotransmitter found in the brain. Patients found with this antibody present with motor and cognitive problems due to low levels or lack of GABA, because in the absence or low levels of GABA patients exhibit motor and cognitive symptoms. The anti-GAD antibody is found in some neurological syndromes, including stiff-person syndrome, paraneoplastic stiff-person syndrome, Miller Fisher syndrome (MFS), limbic encephalopathy, cerebellar ataxia, eye movement disorders, and epilepsy. Previously, excluding MFS, these conditions were calledhyperexcitability disorders. However, collectively, these syndromes should be known as "anti-GAD positive neurological syndromes." An important limitation of this study is that the literature is lacking on the subject, and why patients with the above mentioned neurological problems present with different symptoms has not been studied in detail. Therefore, it is recommended that more research is conducted on this subject to obtain a better and deeper understanding of these anti-GAD antibody induced neurological syndromes.

Clinical and Immunologic Investigations in Patients With Stiff-Person Spectrum Disorder

IMPORTANCE

Symptoms of stiff-person syndrome (SPS), stiff-limb syndrome (SLS), or progressive encephalomyelitis with rigidity, myoclonus, or other symptoms (SPS-plus) can occur with several autoantibodies, but the relative frequency of each antibody, syndrome specificity, and prognostic implications are unclear.

OBJECTIVE

To report the clinical and immunologic findings of a large cohort of patients with stiff-person spectrum disorder (SPSD), including SPS, SLS, and SPS-plus.

DESIGN, SETTING, AND PATIENTS

This study retrospectively examined a case series (January 1, 1998, through December 31, 2014) of immunologic investigations performed in a neuroimmunology referral center. The study included 121 patients with clinical features of SPSD. Data analysis was performed from July 1, 2015, through November 1, 2015.

MAIN OUTCOMES AND MEASURES

Analysis of clinical-immunologic associations, including autoantibodies to 8 proteins expressed in inhibitory synapses.

RESULTS

The median age of the patients was 51 years (interquartile range, 40-61 years), and 75 (62.0%) were female. Fifty (41.3%) had SPS, 37 (30.6%) had SPS-plus, 24 (19.8%) had SLS, and 10 (8.3%) had SPS or SLS overlapping with ataxia, epilepsy, or encephalitis. Fifty-two patients (43.0%) had glutamic acid decarboxylase (GAD65) antibodies (2 with γ-aminobutyric acid-A [GABA-A] receptor antibodies), 24 (19.8%) had α1-subunit of the glycine receptor (GlyR) antibodies (2 with GAD65 antibodies), 5 (4.1%) had other antibodies, and 40 (33.1%) tested negative for antibodies. None had gephyrin or glycine transporter antibodies. Among the main immunologic groups (GAD65 antibodies, GlyR antibodies, and antibody negative), those with GAD65 antibodies were more likely to be female (45 [86.5%] of 52, 8 [36.4%] of 22, and 18 [45.0%] of 40, respectively; P < .001), have systemic autoimmunity (34 [65.4%] of 52, 7 [31.8%] of 22, and 13 [32.5%] of 40, respectively; P = .004), and have longer delays in being tested for antibodies (median, 3 vs 0.5 and 1 year; P < .001). Patients with GAD65 antibodies were more likely to develop SPS (27 [51.9%] of 52) or overlapping syndromes (8 [15.4%] of 52) than patients with GlyR antibodies (5 [22.7%] and 0 [0%] of 22, respectively), who more often developed SPS-plus (12 [54.5%] of 22 vs 7 [13.5%] in those with GAD65 antibodies); antibody-negative patients had an intermediate syndrome distribution. In multivariable analysis, symptom severity (P = .001) and immunologic group (P = .01) were independently associated with outcome. Compared with patients with GlyR antibodies, those with GAD65 antibodies (odds ratio, 11.1, 95% CI, 2.3-53.7; P = .003) had worse outcome. Patients without antibodies had similar outcome than patients with GlyR antibodies (odds ratio, 4.2, 95% CI, 0.9-20.0; P = .07).

CONCLUSIONS AND RELEVANCE

In SPSD, symptom severity and presence and type of antibodies are predictors of outcome.