Stiff Person Syndrome: A Rare Neurological Disorder, Heterogeneous in Clinical Presentation and Not Easy to Treat

Association of type 1 stiff-person syndrome and insulinoma: a case report and narrative review

INTRODUCTION

Stiff-person syndrome (SPS) is a rare neurological disorder that causes progressive muscle rigidity, gait disturbances, and functional impairment; type 1 is autoimmune, with positive anti-GAD antibodies (Ab), while type 2 is paraneoplastic and associated with antiamphiphysin Ab.

CASE PRESENTATION

A 41-year-old man with a silent medical history presented with stiffness and functional impairment; after numerous rheumatological and neurological investigations, he was diagnosed with SPS, with evidence of high titer anti-GAD Ab. After treatment with benzodiazepines was started, the patient began to experience episodes of confusion, which persisted even after reducing the dosage. During one of these episodes, he was admitted to the emergency department and a glucose level of 26 mg/dL was found. Differential diagnosis led to detection of an insulin-secreting neuroendocrine tumor of the pancreas; thus, a paraneoplastic origin of SPS was hypothesized. However, antiamphiphysin Ab were negative, anti-GAD Ab were persistently elevated, and symptoms only transiently improved after removal of the tumor.

CONCLUSION

This is the first case, to our knowledge, demonstrating association between type 1 SPS and insulinoma, along with describing partial and transient improvement of neurological symptoms after resolution of the associated hypoglycemic syndrome.

Stiff Person Syndrome With Positive Anti-glutamic Acid Decarboxylase (GAD) Autoantibodies

Stiff person syndrome (SPS) is a progressive autoimmune disorder characterized by muscle rigidity, frequent falls, and spasms, affecting primarily women. Recent advances have linked SPS to specific antibodies, such as anti-glutamic acid decarboxylase (GAD)-65, but effective treatments remain elusive. We report the case of a 53-year-old female who developed chronic lower back pain, tingling paresthesias, and progressive rigidity in the lower limbs. Electromyographic examination revealed muscle spasms and co-contractions, along with severe rigidity and reactive spasms upon touch. Imaging studies showed a polymyomatous uterus and no hypermetabolic lesions. She was diagnosed with stiff person syndrome with positive anti-GAD65 autoantibodies. Patient was treated with methylprednisolone, oral corticosteroids, gabapentin, baclofen, alprazolam, immunoglobulins, and rituximab, leading to moderate improvement in her condition. This case report aims to highlight the association between SPS and anti-GAD65 autoantibodies, emphasizing the importance of early diagnosis and comprehensive management.

Stiff-person syndrome revealing an occult gray zone lymphoma: A diagnostic challenge

Key Clinical Message

Stiff-Person Syndrome (SPS) can be associated with various malignancies, including lymphomas. Therefore, clinicians should always remain vigilant for the presence of an underlying malignancy, especially in older patients presenting with SPS.

Abstract

Stiff-person syndrome (SPS) is a rare neurological disorder characterized by painful muscle spasms. It can occur as a paraneoplastic syndrome associated with various malignancies. We present a case of an older male adult with a history of recurrent fever episodes and elevated inflammatory markers for 1 year who subsequently developed neurological symptoms. The presence of positive amphiphysin antibodies led to the diagnosis of SPS, which prompted further investigations revealing an underlying Gray Zone lymphoma (GZL). This case highlights the challenges in diagnosing lymphoma and emphasizes the importance of considering SPS as a paraneoplastic syndrome in guiding toward the final diagnosis. The diagnostic challenge in our case is summarized in Chart 1.

An update on malignant tumor-related stiff person syndrome spectrum disorders: clinical mechanism, treatment, and outcomes

Stiff person syndrome (SPS) is a rare central nervous system disorder associated with malignancies. In this review, we retrieved information from PubMed, up until August 2023, using various search terms and their combinations, including SPS, stiff person syndrome spectrum disorders (SPSSDs), paraneoplastic, cancer, and malignant tumor. Data from peer-reviewed journals printed in English were organized to explain the possible relationships between different carcinomas and SPSSD subtypes, as well as related autoantigens. From literature searching, it was revealed that breast cancer was the most prevalent carcinoma linked to SPSSDs, followed by lung cancer and lymphoma. Furthermore, classic SPS was the most common SPSSD subtype, followed by stiff limb syndrome and progressive encephalomyelitis with rigidity and myoclonus. GAD65 was the most common autoantigen in patients with cancer and SPSSDs, followed by amphiphysin and GlyR. Patients with cancer subtypes might have multiple SPSSD subtypes, and conversely, patients with SPSSD subtypes might have multiple carcinoma subtypes. The first aim of this review was to highlight the complex nature of the relationships among cancers, autoantigens, and SPSSDs as new information in this field continues to be generated globally. The adoption of an open-minded approach to updating information on new cancer subtypes, autoantigens, and SPSSDs is recommended to renew our database. The second aim of this review was to discuss SPS animal models, which will help us to understand the mechanisms underlying the pathogenesis of SPS. In future, elucidating the relationship among cancers, autoantigens, and SPSSDs is critical for the early prediction of cancer and discovery of new therapeutic modalities.

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.

Stiff-Person Syndrome: A Treatment Update and New Directions

Stiff-person syndrome (SPS) is a rare and disabling central nervous system disorder with no satisfactory treatment. Muscle rigidity, sporadic muscle spasms, and chronic muscle pain characterize SPS. SPS is strongly correlated with autoimmune diseases, and it is usual to find high titers of antibodies against acid decarboxylase (GAD65). Due to its highly disabling nature and complicated treatment, we aim to create a treatment protocol through a narrative review of currently available treatments that show efficacy. We expect to facilitate management based on treatment responses ranging from first-line medication to refractory medication. We conducted a medical subject heading (MeSH) strategy. We used the term SPS with the subheading treatment: "Stiff-Person Syndrome/Therapy" [MeSH]. An initial data gathering of 270 papers came out with the initial research. After using the inclusion criteria, we had 159 articles. We excluded 31 papers for being either systematic reviews, literature reviews, or meta-analysis. From the 128 remaining articles, we excluded another 104 papers because the extraction of the data was not possible or the study outcome did not meet our demands. There are two main treatments for SPS: GABAergic (gamma-aminobutyric acid) therapy and immunotherapy. For treatment, we suggest starting with benzodiazepines as first-line treatment. We recommend adding levetiracetam or pregabalin if symptoms persist. As second-line therapy, we recommend oral baclofen over rituximab and tacrolimus. We also suggest rituximab over tacrolimus. For patients with refractory treatment, we can use intrathecal baclofen, intravenous immunoglobulin (IVIG), or plasmapheresis. We conclude that intrathecal baclofen and IVIG are more effective than plasmapheresis in patients with refractory symptoms. Propofol may be used as a bridge - temporary therapy before initiating a permanent treatment.

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.

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.

A case of stiff dog syndrome associated with anti-glutamic acid decarboxylase antibodies

BACKGROUND

The stiff person syndrome (SPS) is a rare and debilitating autoimmune disorder with an unknown pathogenesis and variable clinical presentation that can present a diagnostic challenge. Although entities that clinically mimic stiff-person spectrum disorders (SPSD) have manifested in horses, they have not been reported in dogs.

CASE PRESENTATION

We describe a 2-year-old beagle dog presented for progressive attacks of muscular rigidity and lordosis with superimposed spasms of the appendicular muscles triggered by tactile stimulation which resulted in marked gait impairment. Resting electromyography revealed continuous motor unit activity in the axial musculature. Compared to age-matched healthy beagle dogs, this patient had elevated glutamic acid decarboxylase antibody concentrations in serum and cerebrospinal fluid.

CONCLUSION

This dog presented with phenotypic, electrodiagnostic, and immunologic criterion consistent with an SPSD, including elevated anti-GAD antibody titers, which we have termed the "stiff dog syndrome (SDS)". Durable clinical improvement was achieved with symptomatic and immunosuppressive treatments including baclofen, gabapentin, prednisone, and intravenous immunoglobulin.