Health-related Quality of Life in Chiari Malformation Type 1 - A National Cross-Sectional Patient Survey

The goal of this observational survey study is to investigate factors that may affect the health-related quality of life (HRQoL) in adults with Chiari malformation type 1 (CM1). The main questions it aims to answer are: How do CM1 patients rate their HRQoL compared to the general population? Are there any factors that lead to better or worse HRQoL in CM1 patients? Is there a difference in HRQoL in operated versus non-operated CM1 patients? Participants will be identified via the Swedish National Board of Health and Welfare's Patient register. They will be asked to participate in a survey of HRQoL containing standardized questionnaires, and their answers will be analyzed together with data from the Patient register. Their questionnaire answers will also be compared to normative Swedish data.

Inclusion Criteria: * diagnosis of Arnold Chiari Malformation (ICD-code Q07.0) * for operated patients: record of posterior fossa decompression (procedure code ABE50) * for non-operated patients: the diagnosis Q07.0 recorded during an outpatient visit to a neurosurgical unit Exclusion Criteria: * record of spina bifida diagnosis (Q05.X) * for non-operated patients: record of the procedures duraplasty (procedure code AAK10) or another operation on the cranium or dura (procedure code AAK99)