Prevalence of ataxia in children: a systematic review

Abstract

Objective: To estimate the prevalence of childhood ataxia resulting from both genetic and acquired causes.

Methods: A systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement. Five databases were searched for articles reporting a frequency measure (e.g., prevalence, incidence) of ataxia in children. Included articles were first grouped according to the World Health Organization (WHO) regions and subsequently classified according to etiology (genetic, acquired, or mixed). Each article was assessed for its risk of bias on the domains of sampling, measurement, and analysis. Incidence values were converted to prevalence estimates whenever possible. European prevalence estimates for different etiologies of ataxia were summed to gauge the overall prevalence of childhood ataxia.

Results: One hundred fifteen articles were included in the review. More than 50% of the data originated from the Europe WHO region. Data from this region also showed the least susceptibility to bias. Little data were available for Africa and Southeast Asia. The prevalence of acquired ataxias was found to vary more greatly across regions than the genetic ataxias. Ataxic cerebral palsy was found to be a significant contributor to the overall prevalence of childhood ataxia across WHO regions. The prevalence of childhood ataxias in Europe was estimated to be ∼26/100,000 children and likely reflects a minimum prevalence worldwide.

Conclusions: The findings show that ataxia is a common childhood motor disorder with a higher prevalence than previously assumed. More research concerning the epidemiology, assessment, and treatment of childhood ataxia is warranted.

Figure 1. Flow diagram outlining the identification and screening of articles

Common reasons for exclusion of articles are listed in the bottom right box. HSP = hereditary spastic paraplegia

Figure 2. Dot distribution map made using ArcGIS (Ersi, Redlands, CA)

Each color represents a different World Health Organization region: Europe (light blue), Americas (red), Eastern Mediterranean (green), Western Pacific (brown), Africa (yellow), Southeast Asia (dark blue). Gray dots indicate the location of articles returned in the search. If an article reported data for an entire country, the dot is placed near the middle of the country. One article may be represented by more than one dot if the article reported data from more than one country.

Figure 3. Prevalence of genetic ataxias in children (rate/100,000 and 95% confidence interval)

Each symbol represents the prevalence estimate from a specific World Health Organization (WHO) region. Different symbols represent different WHO regions. Prevalence rates are plotted on a logarithmic scale because of the large range of rates reported. *Study of progressive ataxia in which authors stated the cause of ataxias was likely metabolic in origin. **Prevalence of profound biotinidase deficiency reported, partial biotinidase deficiency not included. For a complete list of the metabolic ataxias included in the results of Dionisi-Vici et al. (2002), see appendix e-2. ^◇Prevalence of 0/100,000 reported in this article. ^∇Mitochondrial disorder. For citations, see appendix e-2. ARSAC = autosomal recessive spastic ataxia of Charlevoix-Saguenay; EOCA with RTR = early-onset cerebellar ataxia with retained tendon reflexes; OTC = ornithine transcarbamylase.

Figure 4. Prevalence of acquired ataxias in children (rate/100,000 and 95% confidence interval)

Each symbol represents the prevalence estimate from a specific World Health Organization (WHO) region. Different symbols represent different WHO regions. Prevalence rates are plotted on a logarithmic scale because of the large range of rates reported. ^◇United States now routinely vaccinates against varicella. For citations, see appendix e-2. ACA = acute cerebellar ataxia; ADEM = acute disseminated encephalomyelitis.

Figure 5. Prevalence of ataxias of mixed etiology (i.e., genetic and environmental) in children (rate/100,000 and 95% confidence interval)

Each symbol represents the prevalence estimate from a specific World Health Organization (WHO) region. Different symbols represent different WHO regions. Prevalence rates are plotted on a logarithmic scale because of the large range of rates reported. **Two articles report on same dataset. For citations, see appendix e-2. MS = multiple sclerosis.