Affiliations: [a]
Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| [b]
Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| [c]
Department of Neurology, University Medical Centre Utrecht, The Netherlands
| [d]
Department of Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| [e]
Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, UK
| [f]
Institute de Myologie, Paris, France
Correspondence:
[*]
Correspondence to: N.C. Voermans MD PhD, Neurologist, Associate Professor, Radboud University Medical Centre, P.O. Box 9101, 6500 HB Nijmegen (910), The Netherlands. Tel.: +0031 24 3613396; E-mail: nicol.voermans@radboudumc.nl; http://www.radboudumc.nl
Abstract: Background:The slow channel syndrome is a rare hereditary disorder caused by a dominant gain-of-function variant in one of the subunits of the acetylcholine receptor at the neuromuscular junction. Patients typically experience axial, limb and particularly extensor finger muscle weakness. Objective:Age at diagnosis is variable and although the long-term prognosis is important for newly diagnosed patients, extensive follow-up studies are rare. We aim to provide answers and perspective for this patient group by presenting an elaborate description of the lifetime follow-up of two slow channel syndrome patients. Methods:We describe 40 years follow-up in two, genetically confirmed cases (CHRNA1; c.866G > T p.(Ser289Ile)(legacy Ser269Ile) and CHRNE; c.721C > T p.(Leu241Phe)(legacy Leu221Phe) variants). Results:We find that the disease course has a fluctuating pattern and is only mildly progressive. However, hormonal imbalances, (psychological) stress or excessive hot or cold environments are often aggravating factors. Quinidine and fluoxetine are helpful, but ephedrine and salbutamol may also improve symptoms. Conclusion:Slow channel syndrome is mildly progressive with a fluctuating pattern. The observations reported here provide a lifespan perspective and answers to the most pressing questions about prognosis and treatment options for newly diagnosed patients.
