What is Werdnig Hoffmann Disease?

Werdnig-Hoffmann disease is a motor neuron disease. It belongs to a group of neurological disorders of the brain, spinal cord, and nerves that get progressively worse over time.

Werdnig Hoffman disease is a type of spinal muscular atrophy (SMA). It is a genetic disease that is inherited from one’s parents. The condition is a slowly progressive muscle disease characterized by severe weakness, wasting of skeletal muscles, and loss of voluntary muscle control.

Other motor neuron diseases include amyotrophic lateral sclerosis, commonly called Lou Gehrig’s disease.

Please continue reading to learn more about Werdnig Hoffmann disease, including what causes it, how it affects motor abilities, whether there’s a cure and the life expectancy of spinal muscular atrophy patients.

What is spinal muscular atrophy type 1?

Spinal muscular atrophy type I is also called Werdnig-Hoffmann disease. It affects approximately 1 in 10,000 people worldwide. Men and women are equally affected by this progressive muscular disorder.

Werdnig Hoffman disease is the most common and severe form of spinal muscular atrophy, which is a motor neurone disease. It accounts for 50-80% of all cases. Babies born with Werdnig-Hoffmann disease show symptoms at birth or within the first few months of life (always before 6 months of age).

What are the different types of spinal muscular atrophy?

The different types of spinal muscular atrophy (motor neuron disorder) are listed below:

SMA type 1 (Werdnig-Hoffmann disease)
SMA type 2 (Dubowitz disease, intermediate SMA, or chronic infantile SMA)
SMA type 3 (Kugelberg-Welander disease)
SMA type 4

What causes Werdnig Hoffmann syndrome?

Werdnig Hoffmann syndrome is a genetic disease inherited from one’s parents. It occurs due to defective genes that result in a loss of motor neurons which are a special type of nerve cells that control motor development and muscle movement.

How is spinal muscular atrophy (SMA) inherited?

Spinal muscular atrophy is a common autosomal recessive disorder. This means both parents carry one copy of the defective gene that causes SMA. Because the parents carry only one copy of the mutated gene, they don’t have any symptoms. However, their child inherits one copy of the mutated gene from each parent and therefore has symptoms.

Rarely, a person with spinal muscular atrophy can inherit one copy of the defective gene from one parent and have a spontaneous new mutation in the other copy of the gene during early embryonic development.

Molecular genetic testing can confirm the condition. Prenatal diagnosis of spinal muscular atrophy is also possible.

What are SMA disease symptoms?

In general, the weakness associated with spinal muscular atrophy is in the proximal muscles (closer to the center of the body) and less so in the distal muscles (away from the center of the body). The muscle weakness tends to get progressively worse with time as motor regression occurs. Symptoms vary according to the type of SMA.

SMA type 0

Rare but severest form of the disease.
Usually evident before birth.
Babies with this type of SMA move less during the pregnancy and are frequently born with deformities like joint contractures.
Symptoms after birth include hypotonia (extremely poor muscle tone), failure to achieve normal motor milestones, and weak swallowing and respiratory muscles.
Congenital heart defects and cardiac muscle involvement may be present.

SMA type I (Werdnig-Hoffmann Disease)

Most common type of acute spinal muscular atrophy with severe symptoms.
Symptom onset is within 6 months of birth.
Poor head control and inability to sit unassisted.
Swallowing problems, feeding difficulties, and failure to thrive.
Abnormally shaped chest such that the lungs cannot expand fully, leading to respiratory difficulties.

SMA type II (Dubowitz Disease)

Symptoms of muscle weakness develop between the age of 6 and 12 months.
Affected children may be able to sit without aids initially, but with increasing disease severity and severe motor weakness, they may require support later on. Individuals with this type of SMA are unable to stand or walk without aids.
Respiratory symptoms.
Tremors (involuntary trembling) of the fingers.
Scoliosis (spinal curvature).
Weakness of the respiratory muscles

SMA type III (Kugelberg-Welander Disease)

Muscle weakness develops later in childhood.
Affected people can stand and walk without aids, but with the passage of time, this can become difficult due to progressive muscular atrophy.
Many affected individuals develop poor balance and severe muscle weakness and often need a wheelchair once the disease progresses.

SMA type IV

Rare form of the condition with minimal symptoms compared to the other forms.
Presenting symptoms are usually seen in young adults and are less severe symptoms.
Affected individuals have mild to moderate muscle weakness, mild breathing difficulties, and tremors.

Can SMA disease be cured?

There is no cure for spinal muscular atrophy. Doctors can offer supportive treatment with medications to control symptoms and help with breathing, feeding, and muscle weakness. However, medications do not stop the progression of the disease.

A drug called Nusinersen is an FDA-approved treatment for spinal muscular atrophy in adult and pediatric patients. This drug helps to improve the survival of the motor neuron protein.

Children with spinal muscular atrophy may require a feeding tube (percutaneous endoscopic gastrostomy (PEG) tube) for nutritional supplementation and tracheostomy and ventilator support as symptoms worsen. Physical and occupational therapy can help with muscle strengthening and stretching to minimize contractures. Braces or surgical procedures may be offered for scoliosis.

What is the life expectancy of someone with spinal muscular atrophy?

The life expectancy of a person with spinal muscular atrophy depends on the type.

Type 0: Babies often do not survive past infancy due to respiratory failure.
Type 1: Most children do not survive past early childhood due to respiratory failure.
Type 2: Many people live into their 20s or 30s.
Type 3: Affected individuals usually have a normal life expectancy.
Type 4: Minimal symptoms and normal life expectancy.

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