Amyotrophic lateral sclerosis: Analysis of ALS cases in a predominantly admixed population of Ecuador

Abstract

Recent studies suggest amyotrophic lateral sclerosis (ALS) prevalence, incidence, and age of onset are heterogeneous across populations. These include studies from South America (SA) where lower prevalence, earlier onset, and reduced survival time of ALS are reported. However, the scarcity of epidemiological and clinical data confounds effective comparison. To investigate ALS incidence in the predominantly admixed population of Ecuador, we analyzed patient data. We analyzed case data from two major hospitals. To confirm diagnosis, we evaluated clinical and EMG examinations in a cohort of patients. For 2000–2012, we found 116 patients with ALS diagnosis in the two hospitals. Crude incidence was 0.2–0.6 per 100,000. Median age of onset was 54.3 (+ 15.06 SD). Clinical re-evaluation found misdiagnosis in three cases in the cohort. In conclusion, ALS incidence in the Ecuadorian hospital population is in accord with rates reported in recent studies for other admixed populations, and lower than that in the United States and Europe. Our study found that appropriate EMG administration and interpretation for the purposes of supporting a diagnosis of ALS with current consensus guidelines prevent adequate use of this test as an essential tool in the evaluation and diagnosis of ALS. Training for required standardization in Ecuador is recommended.

Key words::

• ALS
• South America
• EMG
• Ecuador
• ALS diagnosis

Acknowledgements

Miriam Bucheli was supported by Program Prometheus, National Secretary of Higher Education, Science, Technology, and Innovation, Quito, Ecuador. We are thankful for the support of the neurologists: Fernando Alarcon (Chair) and Robert Salinas (Hospital Eugenio Espejo, site collaborators), Ramiro Montenegro (Hospital Metropolitano, site collaborator), Cristian Calero (Hospital Carlos Andrade Marin), Pilar Guerrero (National Police Hospital, site collaborator), and Hugo Zapata (Hospital de Los Valles, site collaborator). Additional thanks are expressed to Magdalena Sanchez (Director) and Daniel Galarraga - FUNDEM (Ecuadorian foundation for multiple sclerosis), Janet Montenegro for media relations, Ecuadorian Ministry of Public Health, the Ecuadorian Neurology Society, and University San Francisco of Quito.

Declaration of interest: Miriam Bucheli received research funding support from the program Prometheus-SENESCYT. Nazem Atassi has acted as a consultant to Biogen Idec, a paid speaker for Oakstone Publishing, and receives research funding from the Muscular Dystrophy Association, ALS Association, American Academy of Neurology, and ALS Therapy Alliance. James Berry has acted as a consultant to Biogen Idec, a paid speaker for Oakstone Publishing, and receives research funding from the Muscular Dystrophy Association, ALS Association, American Academy of Neurology, and ALS Therapy Alliance.

The authors alone are responsible for the content and writing of the paper.