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Chapter Objectives

Upon completion of this chapter, the learner should be able to:

  1. Describe the differences in clinical presentation between hypotonia and flaccidity.

  2. Predict possible musculoskeletal problems that may be associated with hypotonia and flaccidity.

  3. Describe predictors of optimal functional outcomes for individuals with hypotonia or flaccidity.

  4. Explain developmental and age-related changes that may affect functional outcomes in persons with hypotonia or flaccidity.

  5. Propose and plan for appropriate safety considerations in the management of hypotonia and flaccidity.

  6. Choose appropriate tests and measures for a patient who displays hypotonia or flaccidity.

  7. Choose appropriate supportive and protective devices for a patient who displays hypotonia or flaccidity.

  8. Plan appropriate functional interventions for patients with hypotonia and flaccidity.

  9. Justify appropriate use of facilitation techniques or other interventions for patients with hypotonia and flaccidity.


The patient is a 10 year-old with spinal muscular atrophy. This patient was born full term and weighed 6 pounds 11 ounces. At 3 months, the mother felt this child seemed “loose.” What does this mean? The child was diagnosed with spinal muscular atrophy at 9 months of age. At present, she has literally no muscle tone except enough to adduct her thumb to mobilize a power wheelchair. Upon evaluation, you note the heavy, loose, floppy feeling in this child’s extremities, trunk, neck, and head. This child has no functional strength in which to assist in any aspect of her mobility. Where do you begin?

Hypotonia and flaccidity, considered variants of muscle tone, are impairments seen as a component of many different conditions of neuromuscular, genetic, metabolic, connective tissue, mitochondrial, or central nervous system (CNS) causes. In children, hypotonia may also be of unknown origin, termed idiopathic hypotonia or benign congenital hypotonia (BCH) (Strubhar, 2007). Muscle tone is clinically defined as the amount of tension or stiffness in a resting muscle or the amount of resistance present in a resting muscle during passive stretch (Kandel, 2013, p. 809; Hiengkaew, 2003). During passive range of motion, the limb of an individual with normal tone should feel light and move easily without resistance. With active movement, an individual with normal tone should be able to move freely and smoothly through gravity. Changes in tone, either decreased or increased from “normal,” are considered atypical and are usually the result of neurological deficit. Looking beyond muscle tone within one muscle or limb, postural tone clinically refers to the state of muscular tension in axial musculature necessary to maintain antigravity support (Kandel, 2013, p. 936).

The terms hypotonicity and flaccidity are general with no truly objective measures available (Hunt, 2002; Leonard, 2001). Generally, hypotonia is considered to be an abnormal decrease in skeletal muscle tone, while flaccidity is considered to be the absence of muscle tone. This chapter will address hypotonia and flaccidity, from pathophysiology to examination, and present a variety of possible interventions.

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