Natural history of neuronopathic form of Hunter syndrome in children: observational cohort study

Introduction. Mucopolysaccharidosis type II (MPS II, Hunter syndrome)  (mucopolysaccharidosis type II, MPS II) is a progressive multisystem disorder. Neurodegenerative course characterizes the severe (neuronopathic) form of MPS II. Pathogenetic therapy for the severe form of the disease is under development, and symptomatic neurological treatment is to be improved. Natural history data are required for rationalization of symptomatic care and assessment of emergent treatment effectiveness.

The aim of the study. To describe the course of neurodegenerative disease in children with neuronopathic form of MPS II.

Materials and methods. Fifty eight boys with established diagnosis of MPS II were included in the study. The course of  the disease  in 42 patients was classified as neuronopathic. Data on complaints, anamnesis and neurological examination obtained from medical documentation and within the framework of this study, as well as descriptions of video-EEG monitorings, performed in  National Medical Research Center of Children’s Health, were used.

Results. The spectrum and chronology of neurological symptoms in children with severe Hunter syndrome were described. 64% of patients were found to achieve the level of phrasal speech at any time of the development. Laughter or crying paroxysms in children with neuronopathiс MPS II were judged to be a manifestation of pseudobulbar affect. Burden of sleep disorder was demonstrated to increase through the course of the disease. Absence of epileptic seizure was significantly more frequent than epilepsy manifestation during the first two years after epiactivity appears on EEG (75 vs 25%; p = 0.046).

Conclusion. Obtained natural history descriptions of severe MPS II cases are intended to be used in optimization of neurological care for patients and in assessment of emergent treatments’ effectiveness in real clinical practice.

Contribution: 
Osipova L.A. — concept; complaints and anamnesis data collection; neurological examination; data processing and analysis; text writing; text editing;
Kuzenkova L.M. — concept; text editing; 
Podkletnova T.V. — concept; complaints and anamnesis data collection; text editing.
All co-authors — are responsible for the integrity of all parts of the manuscript and approval of its final version.

Acknowledgements. The study had no sponsorship.

Conflict of interest. The authors declare participation in educational activities with the support of Takeda Pharmaceutical Company.

Received: May 4, 2023
Accepted:  May 23, 2023
Published: June 30, 2023

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