Nationwide Epidemiology of Motor Neuron Diseases in Latvia (2020-2024): Incidence, Prevalence, and Clinical...

Motor neuron diseases (MNDs), including amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), and spinal and bulbar muscular atrophy (SBMA), are rare, progressive neurodegenerative conditions. Although well-studied in Western Europe, no nationwide epidemiological data have been published from Latvia. This study aimed to assess the incidence, prevalence, and clinical characteristics of MNDs in the Latvian population.

A retrospective, hospital-based analysis was performed using records from Pauls Stradiņš Clinical University Hospital, Riga East University Hospital, and the Children's Clinical University Hospital between January 2020 and December 2024. Patients were identified through relevant ICD-10 codes. Incidence and prevalence rates were calculated per 100,000 population and age-standardized to the 2013 European Standard Population.

A total of 181 prevalent MND cases were identified: 131 with ALS or related phenotypes, 10 with adult-onset SMA, 33 with pediatric SMA, and 7 with SBMA. The age-standardized incidence of ALS was 1.22 per 100,000 person-years, and the prevalence was 4.69 per 100,000. Limb weakness or paresis was the most common initial symptom (48.1%). The mean diagnostic delay was 13.4 months for ALS, 43.8 months for PLS, 206.8 months for SBMA and 17.3 months for pediatric SMA. The prevalence of pediatric SMA was 9.91 per 100,000, with type II being the most frequent subtype. All SMA and SBMA cases were genetically confirmed.

This first nationwide study of MNDs in Latvia highlights diagnostic delays and possible under-recognition of adult SMA and SBMA. Genetic testing, a national registry, and equitable therapy access should be prioritized.