Hypotonia is a condition where there is decreased resting muscle tone. It is a symptom of an underlying condition that may be congenital (present since birth) or acquired (manifested later in life).
General symptoms of congenital hypotonia
Congenital hypotonia usually manifests as (1-4):
- Muscle weakness that is noticeable by the time the baby is six months old
- Initial symptom is a weak cry and inability to suck or swallow
- Little or no control of neck muscles leading to a floppy head and lack of head-holding
- Feeling of a limp body when held
- Inability to place any weight on legs or shoulders
- The baby’s arms and legs hang straight down from sides, rather than bending at the elbows, hips and knees.
- Delayed achievement of motor growth developmental milestones like sitting up, crawling, walking, talking or feeding themselves
- Frequent falls and slipping off the high chair
- If there are severe congenital myopathies there may be accompanying skeletal or bone and joint abnormalities. These include propensity for hip dislocation, deformities of the spine and foot.
- On examination of a hypotonic child there is weakness of the muscles of the face, trunk or foot and ankle muscles.
There may be ptosis or drooping eyelids, wing like outward protrusion of the scapula bones of the back and a thin body.
There may be a protrusion of the abdomen due to weak abdominal muscles that are unable to hold in the contents of the abdomen.
- Most patients with hypotonia may develop insufficiency of breathing and 50% of patients between ages 3 and 55 years need some form of artificial method to help them breathe at night.
Symptoms of congenital hypotonia that relate underlying conditions
Symptoms of acquired hypotonia
In case of acquired hypotonia or adults with hypotonia the usual manifestations include (3-4):
- Clumsy behavior that progressively worsens
- Frequent falls
- Inability or difficulty getting up from a lying or sitting position
- Difficulty in reaching for or lifting an object
- High flexibility of joints called joint laxity. This may occur at hips, elbows and knees
Specific symptoms of hypotonia
Specific symptoms and signs of hypotonia include (2) –
- Central hypotonia – This is seen in 60-80% cases. There may be additional problems like seizures, inability to track a visual object, failure to imitate facial gestures, lethargy etc.
- Peripheral Hypotonia – Seen in 15-30% of cases. These patients manifest with feeding difficulties, generalized weakness and absence of muscle reflexes on testing.
Edited by April Cashin-Garbutt, BA Hons (Cantab)
What is hypotonia?