Hypertonia is characterized by rigidity of the muscles and difficulty with flexion and movement of the limbs. Infants with hypertonia typically develop this condition due to injury to the central nervous system while they are in the mother’s womb (in utero) or during birth or shortly following birth. The injury disrupts the communication channels between the muscles and the brain. Hypertonia can be a frustrating condition to deal with because it requires long-term care and therapy.
Hypertonia is classified into two main types – spastic hypertonia and dystonic hypertonia. Spastic hypertonia is usually the result of a spinal cord injury or brain injury such as that seen with cerebral palsy. The spastic type of hypertonia is associated with uncontrolled movements, contractions, spasms of the muscles, and exaggerated reflexes.
Dystonic hypertonia is characterized by reduced flexibility and an abnormally fixed posture which is resistant to stretching. The increased muscle tone in dystonic hypertonia results in rigid and stiff muscles. Stiff muscles and joints affect balance and make the affected person prone to falling. Severe hypertonia can result in frozen joints known as joint contractures.
Some of the injuries and medical conditions that can lead to hypertonia include:
- Traumatic head injuries
- Central nervous system infections
- Hypoxic or anoxic brain injuries (paucity or lack of oxygen)
- Stroke (lack of blood supply to a part of the brain)
- Heavy metals or other toxins
- Brain tumors
- Neurodegenerative conditions (Parkinson’s, multiple sclerosis)
Physical therapy and exercise are the cornerstones of hypertonia treatment. They help preserve muscle movement. Some of the medications used to treat the spasticity associated with hypertonia include:
- Muscle relaxants (dantrolene, diazepam, baclofen)
- Botulinum toxin (Botox) for localized hypertonia
- Levodopa/carbidopa (rigidity of Parkinson’s disease)
High Muscle Tone in Infants
Hypertonia (high muscle tone) in infants must be differentiated from hypotonia (low muscle tone). Hypertonic muscles feel rigid, tight, and stiff. Hypotonic muscles feel mushy, floppy, and flexible. Hypotonia is often found in children with a diagnosis of Down’s syndrome. Hypertonia can also be caused by brain injury during birth. Both conditions benefit from physical and occupational therapy.
Can Hypertonia Be Cured?
The prognosis depends on the cause and severity of hypertonia. If the hypertonia is associated with cerebral palsy, it may persist for the person’s lifetime. If hypertonia is caused by a disease of the central nervous system, it may worsen when the underlying disease worsens.
Mild hypertonia may have minimal to no effect on an individual’s lifestyle. Moderate to severe hypertonia can result in joint contractures and immobility. Immobility, in turn, can lead to further complications such as bone fragility, pneumonia, bed sores, and infections.