Hypotonia Is A State Of Low Muscle Tone

Hypotonia is a state of low muscle tone, the condition can affect children or adults. Hypotonia is usually detected at birth or during infancy. If your infant has hypotonia, he or she may appear limp at birth and not be able to keep his or her knees and elbows slightly bent. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases and disorders that affect motor nerve control by the brain or muscle strength.

Hypotonia is not the same as muscle weakness, although it can be difficult to use the affected muscles. Muscle weakness sometimes develops in association with hypotonia, however, depending on the cause.

Causes

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 or encephalopathy, 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
Rare genetic disorders, in which the body cannot properly turn food into energy
Infections

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

Down syndrome
Prader-Willi syndrome
Tay-Sachs disease
Trisomy 13

Other disorders that can lead to the condition include:

Achondroplasia
Congenital hypothyroidism
Congenital cerebellar ataxia
Marfan syndrome
Poisons or toxins
Spinal cord injuries that occur around the time of birth

Symptoms

Hypotonia present at birth is often noticeable by the time a child is six months old, if not before. Newborn babies and young children with severe hypotonia are often described as being “floppy” or like a “rag doll”.

Specific signs of hypotonia in a child can include:

having little or no control of their neck muscles, so their head tends to flop
feeling limp when held, as though they could easily slip through your hands
being unable to place any weight on their leg or shoulder muscles
their arms and legs hang straight down from their sides, rather than bending at their elbows, hips and knees
finding sucking and swallowing difficult, and they may have a weak cry

A child with hypotonia may also take longer to reach developmental milestones, such as sitting up, crawling, walking, talking and feeding themselves.

An adult with hypotonia may have the following problems:

becoming clumsy and falling frequently
difficulty getting up from a lying or sitting position
an unusually high degree of flexibility in the hips, elbows and knees
difficulty reaching for or lifting objects

Diagnosis

The approach to diagnosing the etiology of hypotonia (as with all syndromes in neurology) is first localization. The physician must first determine if the hypotonia is due to muscle, nmj, nerve, or central etiology. This will narrow the etiological possibilities. If the cause of the hypotonia is found to lie in the brain, then it can be classified as a cerebral palsy. If the cause is localized to the muscles, it can be classified as a muscular dystrophy. If the cause is thought to be in the nerves, it is call hypotonia due to polyneuropathy. Many cases cannot be definitively diagnosed.

Diagnosing a patient includes obtaining family medical history and a physical examination, and may include such additional tests as computerized tomography (CT) scans, magnetic resonance imaging (MRI) scans, electroencephalogram (EEG), blood tests, genetic testing (such as chromosome karyotyping and tests for specific gene abnormalities), spinal taps, electromyography muscle tests, or muscle and nerve biopsy.

Mild or benign hypotonia is often diagnosed by physical and occupational therapists through a series of exercises designed to assess developmental progress, or observation of physical interactions. Since a hypotonic child has difficulty deciphering his spatial location, he may have some recognizable coping mechanisms, such as locking the knees while attempting to walk. A common sign of low-tone infants is a tendency to observe the physical activity of those around them for a long time before attempting to imitate, due to frustration over early failures. Developmental delay can indicate hypotonia.

Treatment

Treatment varies depending upon how your child is affected. Your child’s general health and ability to participate in therapies will help shape a treatment plan. Some children work frequently with physical therapists. Depending upon your child’s abilities, he or she may work toward specific goals such as sitting upright, walking, or taking part in sports. In some cases, your child may need help with his or her coordination and other fine motor skills.

Children with severe conditions may need wheelchairs for mobility. Hypotonia can cause complications such as frequent joint dislocations and a need for casts or braces to correct and prevent injuries.

Types of therapy for hypotonia
There are several types of therapy for hypotonia, these include:

Physiotherapy
Regular physiotherapy is important to improve muscle tone and prevent contractures.

Physiotherapy aims to improve posture, and co-ordination and strengthen the muscles around the joints of the limbs to provide more stability and support.

Regular exercises are prescribed for this purpose.

Occupational therapy
Occupational therapy helps patients in the activities of daily living.

For example, fine finger skills are focussed upon to improve feeding and dressing etc.

Speech and language therapy
Speech and language therapy is recommended for patients who have speech and swallowing problems due to hypotonia.

This therapy helps develop better control of the jaw and mouth muscles.

Assisted breathing
Patients with hypotonia often suffer from difficulty in breathing at night due to further loss of muscle tone.

These patients need assisted artificial breathing and ventilation through machines.

They are also at risk of repeated respiratory infections that need to be treated. Annual flu vaccination is necessary.

Orthopaedic review
Orthopaedic review is important annually to check for spinal deformities, hip dislocation and joint weakness and slipping (subluxation).

Some patients may need braces and surgical procedures to improve movement and support of the limbs.

Feeding interventions
In babies and children with severe hypotonia and difficulty in feeding, interventions like tube feeding may be needed.

Ideal weight maintenance and adequate nutrition is important part of management.

Specific medication
Babies with myasthenia gravis need specific medication. These are drugs like Neostigmine, Physostigmine etc.

The treatment may often last a life time.

In myasthenia gravis the body’s immune system attacks certain receptors at the neuromuscular junction. Sometimes drugs that suppress the immunity like corticosteroids may be added to regular myasthenia gravis therapy to relieve symptoms of muscle weakness.

Antibiotics
Hypotonia may be caused due to an infection, meningitis or encephalitis.

If antibiotics are administered to fight these infections, symptoms may be reduced.

Therapy for genetic disorders causing hypotonia
Genetic disorders like Down’s syndrome, Prader Willi syndrome, Marfan’s syndrome, Ehler-Danlos syndrome etc. do not always have specific therapy.

These conditions with hypotonia may be treated symptomatically with physical and occupational therapy.

Genetic counselling may be offered to parents regarding future pregnancies.

Therapies are not always needed
Premature babies who are born with hypotonia often recover by themselves as they grow. They may need vigilance against infections, sepsis and feeding difficulties.

Babies with no specific cause of hypotonia called Benign congenital hypotonia often need no therapy apart from physical and occupational therapy.

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