About werdnig-hoffman paralysis

What is werdnig-hoffman paralysis?

The spinal muscular atrophies (SMAs), are characterized by degeneration of nerve cells (motor nuclei) within the lowest region of the brain (lower brainstem) and certain motor neurons in the spinal cord (anterior horn cells) leading to muscle weakness of the truncal, and extremity muscles initially, followed by chewing, swallowing and breathing difficulties. Motor neurons are nerve cells that transmit nerve impulses from the spinal cord or brain (central nervous system) to muscle or glandular tissue.

Approximately 80 percent of individuals with SMA fall into the severe category (Werdnig-Hoffman disease or SMA1). Infants with SMA1 experience severe weakness before 6 months of age, and the patient never achieves the ability to sit independently when placed. Muscle weakness, lack of motor development and poor muscle tone are the major clinical manifestations of SMA1. Infants with the gravest prognosis have problems sucking or swallowing. Some show abdominal breathing in the first few months of life. Abdominal breathing is noted when the abdomen protrudes during inspiration. Normally, the chest expands during inspiration as the intercostal muscles (the muscles between the ribs) expand during inspiration. Abdominal breathing occurs when the intercostal muscles are weak and the diaphragm muscle is responsible for inspiration. Movement of the diaphragm (the muscle between the chest and abdomen) expands causing the abdomen to move during the inspiration cycle. Twitching of the tongue is often seen (fasciculations). Cognitive development is normal. Most affected children die before 2 years of age but survival may be dependent on the degree of respiratory function and respiratory support.

The different subtypes, SMA 0-4 are based on the age of onset of symptoms and the course and progression of the disease. SMA represents a continuum or spectrum of disease with a mild end and a severe end. SMA0 patients are extremely weak at birth, require immediate artificial ventilation and will never breathe independently. Werdnig-Hoffman disease, which is also known as spinal muscular atrophy type 1 (SMA1) or acute spinal muscular atrophy, refers to individuals who have symptom onset prior to 6 months of age. SMA 2 patients will show symptoms prior to age 1 year, will sit but never walk. SMA 3 patients (Kugelberg-Welander disease) will show symptoms after age 1, and will walk for a period of time prior to loss of motor abilities. SMA 4 patients will not develop symptoms much before age 10 years.

All the SMAs are inherited as an autosomal recessive trait. Molecular genetic testing has revealed that all types of autosomal recessive SMA are caused by disruptions or errors (mutations) in the SMN1 (survival motor neuron 1) gene on chromosome 5.

What are the symptoms for werdnig-hoffman paralysis?

People with SMA might not be able to walk or stand on their own, or they might lose their ability to do so later on in life.

Children with type 2 SMA will have to use a wheelchair to get around. Children with type 3 SMA may be able to walk well into adulthood.

There are many devices to help young children with Muscle Weakness stand and get around, such as powered or manual wheelchairs and braces. Some families even design custom wheelchairs for their child.

What are the causes for werdnig-hoffman paralysis?

Mutations in the UBA1 gene cause X-linked infantile spinal muscular atrophy. The UBA1 gene provides instructions for making the ubiquitin-activating enzyme E1. This enzyme is necessary for a process that targets damaged or unneeded proteins to be broken down (degraded) within cells. Protein degradation helps to maintain the proper balance of protein production and breakdown (protein homeostasis) that cells need to function and survive.

UBA1 gene mutations lead to a decrease in enzyme production or the production of an enzyme with reduced or abnormal function. As a result, damaged or unneeded proteins build up inside cells instead of being degraded, which may damage cells and contribute to cell death. This buildup also disrupts protein homeostasis. Old proteins must be removed before cells can make new proteins. If these damaged or unneeded proteins are not degraded, they can impair normal cell functions by stopping the production of new proteins. An imbalance in protein production and breakdown can ultimately lead to cell death. Specialized nerve cells that control muscle movement (motor neurons) are particularly susceptible to disruptions in cell function, likely due to their large size. Loss of these cells causes many of the signs and symptoms of X-linked infantile spinal muscular atrophy.

What are the treatments for werdnig-hoffman paralysis?

There are two pharmaceutical treatments now available for people with SMA.

Nusinersen (Spinraza) is approved by the Food and Drug Administration (FDA) for use in children and adults. The medication is injected into the fluid surrounding the spinal cord. It improves head control and the ability to crawl or walk, among other mobility milestones in infants and others with certain types of SMA.

The other FDA-approved treatment is onasemnogene abeparvovec (Zolgensma). It’s intended for children under 2 years old with the most common types of SMA.

An intravenous medication, it works by delivering a functional copy of an SMN1 gene into the child’s target motor neuron cells. This leads to better muscle function and mobility.

The first four doses of Spinraza are administered over a period of 72 days. Afterward, maintenance doses of the medication are administered every four months. Children on Zolgensma receive a one-time dose of the medication.

Talk with your child’s doctor to determine whether either medication is right for them. Other treatments and therapies that may bring relief from SMA include muscle relaxers and mechanical, or assisted, ventilation.

Is there a cure/medications for werdnig-hoffman paralysis?

The life expectancy in childhood-onset SMA varies.

Most children with type 1 SMA will only live a few years. However, people who’ve been treated with new SMA drugs have seen promising improvements in their quality of life — and life expectancy.

Children with other types of SMA can survive long into adulthood and live healthy, fulfilling lives.

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