Progressive Encephalomyelitis with Rigidity and Myoclonus with Glycine Receptor Antibodies
Mar Guasp1, Albert Saiz2, Marina Ruiz-Vives2, Míriam Almendrote3, Jordi Bruna4, Jordi González-Menacho5, Juntaro Kaneko6, Lorena Martín-Aguilar7, Francisco Antonio Martínez-García8, Kazuyuki Noda9, Angel Ruiz Molina10, Sara Sequeiros11, Mateus Simabukuro12, Megumi Takenaka13, Martín Zurdo14, Josep Dalmau15, Takahiro Iizuka16, Francesc Graus15
1Hospital Clínic Barcelona - IDIBAPS, 2Hospital Clinico De Barcelona, 3Department of Neuroscience, Hospital Universitari Germans Trias i Pujol, Universitat Autonoma de Barcelona, Spain, 4Hospital Universitari De Bellvitge - ICO Duran I Reynals, 5Neurology Unit, Hospital Universitari de Sant Joan, Institut d’Investigacio Sanitaria Pere Virgili, Universitat Rovira i Virgili, Reus, Spain, 6Department of Neurology, Kitasato University School of Medicine, Sagamihara, Japan, 7Department of Neurology, Hospital de la Santa Creu i Sant Pau, Universitat Autonoma de Barcelona, Spain, 8Department of Neurology, Hospital Clinico Universitario Virgen de la Arrixaca, Murcia, Spain, 9Department of Neurology, Juntendo University Shizuoka Hospital, Izunokuni, Japan, 10Service of Neurology, Hospital Universitario Puerta de Hierro Majadahonda, Madrid, Spain, 11Service of Neurology, Hospital Alvaro Cunqueiro, Vigo, Spain, 12Hospital Das Clinicas, Sao Paulo U Scho of Med, 13Department of Neurology, Chugoku Rosai Hospital, Kure, Hiroshima, Japan, 14Department of Neurology, Hospital Virgen del Puerto, Plasencia, Spain, 15Neuroimmunology Program, Institut d’Investigacio Biomedica August Pi i Sunyer (IDIBAPS), Barcelona, Spain, 16Department of Neurology, Kitasato University School of Medicine
Objective:
The aim of this study was to describe the clinical features and long-term outcome of patients with glycine receptor (GlyR) antibody–mediated progressive encephalomyelitis with rigidity and myoclonus (PERM).
Background:
PERM is a disease commonly included under the term of stiff-person spectrum disorders (SPSDs).
Design/Methods:
Retrospective analysis of patients with PERM and GlyR antibodies diagnosed in our laboratory and a systematic literature review of previously reported patients with ≥12 months of follow-up.
Results:
Forty-one patients were identified, 22 from our database and 19 from the literature. The median age was 58 years (IQR: 43–66 years), and 36 (88%) were male. Median time from symptom onset to admission was 2 weeks (IQR 1–4 weeks). Predominant presentations included brainstem symptoms, mainly dysphagia and trismus, in 23 patients (56%); muscle stiffness and myoclonus in 9 (22%); dysesthesias or pruritus in 7 (17%); and cacosmia with dysgeusia in 2 (5%). Five patients (12%) never developed muscle stiffness. The median (range) mRS score at nadir was 5 (3–5). All patients received immunotherapy. Eleven patients died, 8 from complications of PERM. There were 12 relapses in 10/36 (28%) patients who lived >6 months; all responded to immunotherapy. The functional status at the last visit, median time 24 months (IQR: 18–72 months), was good (mRS<3) in 23 (70%) of the 33 patients who did not die from PERM. Age (HR: 1.06; 95% CI 1.01–1.11; p = 0.019) and admission to the intensive care unit (HR: 5.26; 95% CI 1.41–19.57, p = 0.013) were independent predictors of bad outcome (mRS≥3).
Conclusions:
GlyR antibody–mediated PERM is a rapidly progressive and severe disease that predominantly affects men and frequently presents with brainstem involvement. Its distinct demographic and clinical features suggest that it should be considered separately from SPSDs, which typically follows a chronic course and is more commonly associated with glutamic acid decarboxylase antibodies.
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