Why It Is Not Always Anxiety: A Tough Diagnosis of Stiff Person Syndrome

Abstract

Anxiety disorder is a commonly used diagnosis that may mask underlying conditions. Stiff person syndrome (SPS) is a rare neuroimmunological disorder characterized by progressive rigidity and painful muscle spasms affecting axial and lower extremity musculature. These episodes can be triggered by sudden movement, noise, or emotional stress, which may present as a psychiatric condition. We report the case of a 30-year-old female who presented with recurrent panic attacks with multiple prior hospital admissions for anxiety, rigidity, and difficulty in walking. Previous electroencephalogram (EEG) and brain and cervical spine magnetic resonance imaging (MRI) were unremarkable. She was empirically treated with diazepam and beta-blockers for SPS, which was confirmed by positive glutamic acid decarboxylase (GAD) antibodies. The patient's symptoms became refractory to benzodiazepines and required steroids with intravenous immunoglobulin (IVIG). Her rigidity subsequently responded to plasmapheresis. In SPS, antibodies in the cerebrospinal fluid (CSF) most commonly target the GAD antigen on gamma-aminobutyric acid (GABA) neurons. The goal of treatment is to ameliorate symptoms and improve quality of life. Our case of SPS was masked as generalized anxiety disorder for at least six years since onset of symptoms. The criteria for both diagnoses may overlap as seen in this patient.

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

“…In this rare autoimmune disorder with variant clinical expressions (e.g., stiff limb syndrome, paraneoplastic), fluctuating muscle rigidity and spasms are due to continuous activation of muscle motor units [ 58 – 60 ]. Up to half of affected persons have psychological symptoms (data limited) [ 61 , 62 ], and individuals may be misdiagnosed initially as having a primary anxiety disorder [ 63 , 64 ]. In stiff person syndrome, BZs are considered to be first-line therapy for muscular spasms and rigidity with good efficacy [ 58 ], though treatment-resistance and tachyphylaxis [ 59 , 65 ] may require other approaches such as other GABAergic drugs, intravenous immunoglobulin administration, and plasmapheresis [ 58 , 65 ].…”

Expanding clinical profiles and prognostic markers in stiff person syndrome spectrum disorders

“…There is some literature suggesting high incidence of and potentially an increased risk of psychiatric comorbidities in SPS [ 21 , 23 , 24 ]. Recognizing the frequent confounding factors of psychiatric co-morbidities is important as to not mis-attribute such symptoms to psychiatric or psychogenic processes [ 23 , 25 , 26 ] and also to improve the identification of these co-morbid conditions which need treatment.…”

“…There is some literature suggesting high incidence of and potentially an increased risk of psychiatric comorbidities in SPS [21,23,24]. Recognizing the frequent confounding factors of psychiatric co-morbidities is important as to not mis-attribute such symptoms to psychiatric or psychogenic processes [23,25,26] and also to improve the identification of these co-morbid conditions which need treatment. There are frequent mis-diagnoses as well as delay in diagnosis of SPSD, thus recognizing the salient features of the history and examination are important for timely and accurate diagnosis [14,23].…”

Exogenous Insulin Injection-Induced Stiff-Person Syndrome in a Patient With Latent Autoimmune Diabetes: A Case Report and Literature Review

“…These symptoms can be induced by external stimuli, such as sounds, stress, and emotional upheaval ( 5 ). Low levels of GABA also lead to other neurological abnormalities, such as depression, panic disorders, and agoraphobia ( 5 , 16 , 22 ). The diagnostic approach and Dalakas' diagnostic criteria are summarized in Table 4 ( 1 ).…”