Hypotonia: Is It a Clear Term and an Objective Diagnosis? An Exploratory Systematic Review

BACKGROUND

Hypotonia is considered a determinant factor in multiple developmental disorders and is associated with various characteristics and morbidities. It is necessary to perform a systematic review to know which characteristics are described as associated with hypotonia in children and which methods are used for its diagnosis.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used to develop the systematic review protocol. A search of databases (Pubmed, Cochrane, Web of Knowledge, among others) was performed in May 2021 to identify relevant studies. Those describing characteristics or tests of hypotonia assessment were included, excluding those that exclusively addressed peripheral hypotonia. Two reviewers evaluated the articles and collected the data in a table, noting the authors, date of publication, type of study, and characteristics or tests described in relation to hypotonia. The quality of the studies was also assessed, and data were extracted.

RESULTS

A total of 8778 studies were identified and analyzed, of which 45 met the inclusion criteria. Fifty-three characteristics associated with hypotonia and tests used for its evaluation were located, with pull to sit and vertical suspension being the most frequently referenced.

CONCLUSIONS

The characteristics associated with hypotonia, more highly debated by authors are muscle strength, hypermobility, or the maintenance of antigravity postures. The most used test in the diagnosis of hypotonia is observation, followed by the pull-to-sit test, and adoption of frog posture. A unanimous understanding of the term hypotonia would favor further research.