childhood spinal muscular atrophy

Childhood Spinal Muscular Atrophy (SMA) Description

Spinal muscular atrophy (SMA) in children is a rare genetic condition that affects the motor nerve cells in the spinal cord, leading to progressive muscle wasting and weakness. The symptoms of SMA may appear between ages 2 and 17 years [3].

Common Symptoms:

• Clumsiness
• Trouble walking
• Mild muscle weakness
• Floppiness or little movement in infancy
• Poor head control
• Weak suck or inability to feed

As the condition progresses, children with SMA may experience severe muscle weakness and trouble breathing, coughing, and swallowing [5]. The affected child's muscles closest to the center of the body, including the shoulders, hips, thighs, and upper back, are weakened, leading to a curve in the spine [7].

Key Facts:

• SMA is a genetic disease that affects the spinal cord and nerves.
• There are five subtypes of SMA.
• Symptoms may appear between ages 2 and 17 years.
• Children with SMA experience progressive muscle wasting and weakness.

References:

[3] - Context result 3 [5] - Context result 5 [7] - Context result 7

Early Signs and Symptoms

Children who have noticeable SMA symptoms at or shortly after birth usually exhibit significant weakness, difficulty breathing, sucking, and swallowing [1]. This can be a critical indicator of the condition.

Muscle Weakness and Movement Problems

SMA can affect a child's ability to crawl, walk, sit up, and control head movements. Severe SMA can damage the muscles used for breathing and swallowing [2]. The symptoms may vary in severity, but they often involve a weakness of the muscles that control movement.

Specific Symptoms

Some common signs and symptoms of childhood spinal muscular atrophy include:

• Floppiness or little movement in infancy
• Poor head control
• Weak suck or inability to feed
• Muscle weakness – such as floppy or weak arms and legs
• Movement problems – such as difficulty sitting up, crawling, walking, standing up, or climbing [3][4][5]
• Trouble breathing, coughing, and swallowing (in severe cases) [6]

Age of Onset

Symptoms may appear in children between ages 2 and 17 years. These children show signs of clumsiness, trouble walking, and mild muscle weakness [7]. In some cases, measurable muscle weakness and difficulty with physical activities like climbing or standing up may be observed early on, followed by progression to more severe symptoms [8].

It's essential for parents and caregivers to recognize these signs and symptoms promptly, as early diagnosis and treatment can significantly improve the child's quality of life.

References: [1] - Context result 1 [2] - Context result 2 [3] - Context result 5 [4] - Context result 7 [5] - Context result 9 [6] - Context result 6 [7] - Context result 8 [8] - Context result 9

Diagnosing Childhood Spinal Muscular Atrophy (SMA)

Spinal muscular atrophy (SMA) is a genetic disorder that affects the nerve cells responsible for controlling voluntary muscle movement. Diagnosing SMA in children requires a combination of medical history, physical examination, and laboratory tests.

• Physical Examination: A thorough physical exam by a doctor can help identify symptoms of SMA, such as weakness or wasting of muscles, particularly in the arms and legs [4].
• Genetic Testing: Genetic testing is the standard tool for diagnosing SMA. This test can confirm 95% of SMA cases by identifying problems with the SMN1 gene [5]. Each state in the US now routinely screens newborns for SMA.
• Blood Tests: A simple blood test can diagnose SMA, and it's usually done after noticing symptoms of SMA through newborn screening or a physical exam [2][6].
• Electromyography (EMG) and Nerve Conduction Study (NCS): These tests can help rule out other conditions that may cause similar symptoms. They measure the electrical activity of muscles and nerves [3].

Confirming Diagnosis

To confirm SMA, doctors will obtain a thorough medical history, perform a physical exam, and conduct a neurological exam to assess muscle strength and reflexes [4]. If genetic testing isn't able to confirm SMA, other tests like EMG or NCS may be performed.

References:

[1] Context result 1 [2] Context result 2 [3] Context result 3 [4] Context result 4 [5] Context result 5 [6] Context result 6

Spinal Muscular Atrophy (SMA) is a genetic disorder that affects nerve cells and muscle strength in children. While there is no cure for SMA, several drug treatments have been approved to manage the condition.

Approved Treatments

According to recent studies [1], three orphan drugs have been approved for the treatment of SMA: nusinersen, onasemnogene abeparvovec, and risdiplam. These medications work by enhancing the production of a protein called survival motor neuron (SMN), which is essential for muscle function.

• Nusinersen [7] was the first drug approved to treat children (including newborns) and adults with SMA in 2016.
• Onasemnogene abeparvovec, also known as Zolgensma, is a gene therapy that has been FDA-approved for use in children under two years old [6].
• Risdiplam was approved by the FDA in 2020 for use in children two months and older [3].

Treatment Goals

The primary goal of treatment for SMA is to prevent complications related to muscle weakness. This may involve a combination of medications, physical therapy, and other supportive care measures [8]. While these treatments can improve quality of life and prolong survival, they do not cure the condition.

References:

[1] Crisafulli S (2023) - To date, three orphan drugs have been approved for the treatment of SMA: nusinersen, onasemnogene abeparvovec, a gene therapy, and risdiplam. [2] Wadman RI (2019) - Drugs that have been tested in open and uncontrolled studies of children with SMA type I are riluzole (Abbara 2011; ASIRI 2008), valproate (CARNIVAL Type I ... [3] Risdiplam is the third treatment for SMA and was FDA approved in 2020 for use in children 2 months and older. [4] Aug 7, 2020 — The U.S. Food and Drug Administration today approved Evrysdi (risdiplam) to treat patients two months of age and older with spinal muscular atrophy. [5] Available Treatments. Currently, three SMN-enhancing (SMA) spinal muscular atrophy treatments are approved by the U.S. Food and Drug Administration (FDA). [6] Children's Hospital of Philadelphia currently offers the one and only FDA-approved gene therapy for SMA: onasemnogene abeparvovec-xioi (brand name Zolgensma®). [7] May 31, 2022 — In December 2016, the FDA approved nusinersen (Spinraza), the first drug approved to treat children (including newborns) and adults with SMA ... [8] SMA has no cure. Treatment is supportive. It focuses on preventing complications of weakness. The severity of muscle weakness determines likelihood of survival.

Differential Diagnosis of Childhood Spinal Muscular Atrophy (SMA)

Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder that can be challenging to diagnose, especially in children. A differential diagnosis is essential to rule out other conditions that may present with similar symptoms.

Conditions to Consider:

• Cerebral Palsy: Hypotonic diplegia, a form of cerebral palsy, can mimic the symptoms of SMA, particularly in young children [8].
• Congenital Muscular Dystrophy: This condition can cause muscle weakness and wasting, similar to SMA [9].
• Transverse Myelitis: An inflammatory condition that affects the spinal cord, leading to muscle weakness and paralysis.
• Juvenile Myasthenia Gravis: A rare autoimmune disorder that causes muscle weakness and fatigue.

Other Conditions:

• Guillain-Barré Syndrome: A rare autoimmune disorder that can cause muscle weakness and paralysis [2].
• Multiple Sclerosis: A chronic autoimmune disease that affects the central nervous system, leading to muscle weakness and other symptoms [2].

Key Points to Consider:

• Age of Onset: SMA typically presents in infancy or early childhood, while some conditions may present later in childhood.
• Muscle Weakness Pattern: The pattern of muscle weakness can help differentiate between SMA and other conditions.
• Family History: A family history of neuromuscular disorders can increase the likelihood of SMA.

References:

[1] TW Prior · 2020 - Establishes the diagnosis of SMA in a proband with a history of motor difficulties or regression, proximal muscle weakness, reduced/absent reflexes. [2] Jul 1, 2021 - Suggests considering Guillain-Barré syndrome and multiple sclerosis in the differential diagnosis for SMA. [3] May 31, 2022 - Describes the spinal muscular atrophies (SMAs) as a group of autosomal-recessive disorders characterized by progressive weakness of the lower limbs. [4] Differential diagnosis of SMA​​ - Explains that SMA primarily results from homozygous deletions or mutations involving the SMN1 gene at locus 5q13 of chromosome 5.

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