Condition 101 About Hypotonia

What is the definition of Hypotonia?

Hypotonia means decreased muscle tone.

What are the alternative names for Hypotonia?

Decreased muscle tone; Floppy infant


Hypotonia is often a sign of a worrisome problem. The condition can affect children or adults.

Infants with this problem seem floppy and feel like a "rag doll" when held. They rest with their elbows and knees loosely extended. Infants with normal tone tend to have flexed elbows and knees. They may have poor head control. The head may fall to the side, backward, or forward.

Infants with normal tone can be lifted with the adult's hands placed under the armpits. Hypotonic infants tend to slip between the hands.

What are the causes for Hypotonia?

Muscle tone and movement involve the brain, spinal cord, nerves, and muscles. Hypotonia may be a sign of a problem anywhere along the pathway that controls muscle movement. Causes may include:

  • Brain damage, due to lack of oxygen before or right after birth, or problems with brain formation
  • Disorders of the muscles, such as muscular dystrophy
  • Disorders that affect the nerves that supply muscles
  • Disorders that affect the ability of nerves to send messages to the muscles
  • Infections

Genetic or chromosomal disorders, or defects that may cause brain and nerve damage include:

  • Down syndrome
  • Spinal muscular atrophy
  • Prader-Willi syndrome
  • Tay-Sachs disease
  • Trisomy 13

Other disorders that can lead to the condition include:

  • Achondroplasia
  • Being born with hypothyroidism
  • Poisons or toxins
  • Spinal cord injuries that occur around the time of birth


Take extra care when lifting and carrying a person with hypotonia to avoid causing an injury.


The physical exam will include a detailed examination of the nervous system and muscle function.

In most cases, a neurologist (specialist in brain and nerve disorders) will help evaluate the problem. Geneticists may help diagnose certain disorders. If there are also other medical problems, a number of different specialists will help care for the child.

Which diagnostic tests are done depends on the suspected cause of the hypotonia. Most of the conditions associated with hypotonia also cause other symptoms that can help in the diagnosis.

Many of these disorders require ongoing care and support. Physical therapy may be recommended to help children improve their development.



Burnette WB. Hypotonic (floppy) infant. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 29.

Johnston MV. Encephalopathies. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 616.

Marcdante KJ, Kliegman RM. Weakness and hypotonia. In: Marcdante KJ, Kliegman RM, eds. Nelson Essentials of Pediatrics. 8th ed. Elsevier; 2019:chap 182.

Sarnat HB. Evaluation and investigation of neuromuscular disorders. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 625.

Latest Advances On Hypotonia

  • Condition: Postoperative Hyptonia after Surgery for Spasticity
  • Journal: Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery
  • Treatment Used: Selective Posterior Rhizotomy (SPR)
  • Number of Patients: 0
  • Published —
This article provides insights into postoperative hypotonia after selective posterior rhizotomy (SPR) in patients with spasticity.
  • Condition: Hypotonia Diagnosis
  • Journal: Annals of clinical and translational neurology
  • Treatment Used: Metabolic Screening
  • Number of Patients: 164
  • Published —
This study investigated the use of metabolic screening to detect developmental delays in infants, likely as a result of hypotonia.

Clinical Trials For Hypotonia

Clinical Trial
  • Status: Not yet recruiting
  • Phase: Phase 2
  • Intervention Type: Other, Dietary Supplement
  • Participants: 14
  • Start Date: March 15, 2021
Mitochondrial Complex I Dysfunction in Prader Willi Syndrome: A New Therapeutic Target
Clinical Trial
  • Status: Recruiting
  • Intervention Type: Other
  • Participants: 60
  • Start Date: November 6, 2020
Validity Reliability of The Dubousset Functional Test in Stroke Patients