Neuromuscular Disorders in Children — MCQs

10 questions

Duchenne's muscular dystrophy follows which inheritance pattern?

A 5 year old boy suffering from Duchenne muscular dystrophy has to undergo tendon lengthening procedure. The most appropriate anaesthetic would be –

Give the most probable diagnosis of a 1 yr. old child of normal intelligence with features of hypotonia. On examination there are tongue fasciculations and he keeps his body in a frog like position ?

A 2-year- old boy presents with progressive clumsiness and difficulty walking. On physical examination, the child has large calves. He has difficulty walking on his toes and has a waddling gait as shown. Which of the following is the most likely diagnosis?

A 4-year-old male child presents with muscle weakness. His mother reports that her child has difficulty in climbing stairs and getting up from the floor. On muscle biopsy, small degenerated muscle fibers and absence of dystrophin were found. What is the diagnosis?

Deficiency of which vitamin during early pregnancy will result in neural tube defect?

Which of the following is a symptom of cerebral palsy?

A 25-year-old pregnant woman, at 18 weeks of gestation, undergoes a routine ultrasound scan. The ultrasound images provided show below. Based on the imaging findings, what is the most likely diagnosis?

Fracture of the femur in young children (2-5 years) is typically treated by:

Q10

A pole vaulter had a fall during pole vaulting and had paralysis of the arm . Which of the following investigations gives the best recovery prognosis -

Neuromuscular Disorders in Children Indian Medical PG Practice Questions and MCQs

Question 1: Duchenne's muscular dystrophy follows which inheritance pattern?

A. X-Linked dominant
B. X-Linked recessive (Correct Answer)
C. Autosomal dominant
D. Autosomal recessive

Explanation: ***X-Linked recessive*** - **Duchenne's muscular dystrophy (DMD)** is a classic example of an **X-linked recessive** genetic disorder, primarily affecting males. - The gene responsible for producing **dystrophin** is located on the X chromosome; males have only one X chromosome, so a single defective copy leads to the disease. *X-Linked dominant* - In **X-linked dominant** disorders, only one copy of the affected gene on the X chromosome is sufficient to cause the disorder, affecting both males and females, but often with more severe manifestations in males. - Examples include **Fragile X syndrome** and **Rett syndrome**, which do not fit the clinical presentation of DMD. *Autosomal dominant* - **Autosomal dominant** disorders are caused by a mutation in a single copy of a gene on one of the **non-sex chromosomes** (autosomes). - This inheritance pattern means that an affected individual has a 50% chance of passing the disorder to each child, regardless of sex, which is not characteristic of DMD. *Autosomal recessive* - **Autosomal recessive** disorders require an individual to inherit two copies of the mutated gene (one from each parent) to develop the condition. - While other muscular dystrophies like **limb-girdle muscular dystrophy** can be autosomal recessive, DMD specifically follows an X-linked recessive pattern.

Question 2: A 5 year old boy suffering from Duchenne muscular dystrophy has to undergo tendon lengthening procedure. The most appropriate anaesthetic would be –

A. Induction with inhalation sevoflurane; maintenance with isoflurane and vecuronium
B. Total intravenous anesthesia (TIVA) with propofol and remifentanil (Correct Answer)
C. Induction with intravenous propofol and N2O; TIVA maintenance with propofol
D. Induction with intravenous thiopentone; maintenance with sevoflurane and non-depolarizing muscle relaxants

Explanation: ***Total intravenous anesthesia (TIVA) with propofol and remifentanil*** - **Duchenne muscular dystrophy (DMD)** patients are highly susceptible to **malignant hyperthermia** and rhabdomyolysis when exposed to volatile anesthetics (e.g., sevoflurane, isoflurane) and succinylcholine. TIVA avoids these triggers. - **Propofol** and **remifentanil** are suitable anesthetic agents for TIVA in DMD patients, providing stable anesthesia without triggering adverse muscle reactions. *Induction with inhalation sevoflurane; maintenance with isoflurane and vecuronium* - **Sevoflurane** and **isoflurane** are volatile anesthetic agents that can trigger **malignant hyperthermia** and severe rhabdomyolysis in patients with DMD due to their muscle pathology. - While vecuronium is a non-depolarizing muscle relaxant that is generally safe in DMD, the use of volatile agents makes this regimen inappropriate. *Induction with intravenous propofol and N2O; TIVA maintenance with propofol* - **Nitrous oxide (N2O)**, while not a direct trigger for malignant hyperthermia itself, is often used in conjunction with volatile anesthetics and does not significantly mitigate the risks associated with them in DMD patients. - Although propofol for induction and TIVA maintenance is appropriate, the inclusion of N2O does not improve safety in the context of DMD, and concerns about potential interactions or masking early signs of complications might arise. *Induction with intravenous thiopentone; maintenance with sevoflurane and non-depolarizing muscle relaxants* - **Thiopentone** (thiopental) is an intravenous anesthetic that is generally safe for induction in DMD patients. - However, **sevoflurane** is a volatile anesthetic that is contraindicated in DMD due to the risk of triggering **malignant hyperthermia** and severe rhabdomyolysis.

Question 3: Give the most probable diagnosis of a 1 yr. old child of normal intelligence with features of hypotonia. On examination there are tongue fasciculations and he keeps his body in a frog like position ?

A. Guillain-Barré Syndrome
B. Limb girdle atrophy
C. Spinal muscular atrophy (Correct Answer)
D. Down's syndrome

Explanation: ***Spinal muscular atrophy*** - The combination of **hypotonia**, **normal intelligence**, **tongue fasciculations**, and a **frog-leg position** in an infant is highly characteristic of **Spinal Muscular Atrophy (SMA)**, particularly Type 1 (Werdnig-Hoffmann disease). - **Tongue fasciculations** are a key diagnostic sign resulting from denervation of the tongue muscles, and the **frog-leg position** is a compensatory posture due to proximal muscle weakness. *Guillain-Barré Syndrome* - **Guillain-Barré Syndrome (GBS)** is an acute, post-infectious demyelinating polyneuropathy that typically presents with **rapidly progressive ascending paralysis** and areflexia. - While GBS can cause hypotonia, it is rare in infants under 1 year of age and usually presents with an acute onset, unlike the more chronic presentation implied by the frog-leg position often seen in SMA. *Limb girdle atrophy* - **Limb-girdle muscular dystrophies** typically manifest later in childhood or adolescence, not usually in a 1-year-old infant. - These conditions primarily affect the **proximal muscles** of the shoulders and hips, causing weakness, but **tongue fasciculations** are not a typical feature. *Down's syndrome* - **Down syndrome** is characterized by distinctive **facial features**, intellectual disability, and often congenital heart defects, which are not mentioned here. - While **hypotonia** is common in Down syndrome, **tongue fasciculations** are not a feature, and intelligence is not normal.

Question 4: A 2-year- old boy presents with progressive clumsiness and difficulty walking. On physical examination, the child has large calves. He has difficulty walking on his toes and has a waddling gait as shown. Which of the following is the most likely diagnosis?

A. Myotonic dystrophy
B. Facioscapulo humeral dystrophy
C. Becker muscular dystrophy
D. Duchenne muscular dystrophy (Correct Answer)
E. Limb-girdle muscular dystrophy

Explanation: ***Duchenne muscular dystrophy*** - This X-linked recessive disorder is characterized by **progressive muscle weakness** and **atrophy**, typically presenting in early childhood with symptoms like **clumsiness, difficulty walking, and a waddling gait**. - **Pseudohypertrophy of the calves**, due to fat and connective tissue infiltration, and walking on toes are classic signs, along with a **Gowers' sign** (using hands to push off the floor to stand). *Myotonic dystrophy* - This autosomal dominant disorder is frequently characterized by **myotonia** (delayed muscle relaxation), which is not described. - Clinical features usually include **distal muscle weakness**, **facial weakness**, **cataracts**, and **cardiac conduction abnormalities**, and symptoms typically begin in adolescence or adulthood, though congenital forms exist with more severe weakness. *Facioscapulohumeral dystrophy* - This genetic disorder has a primary presentation involving weakness of the **facial muscles**, **shoulder girdle**, and **upper arm**, which is not the predominant symptom set. - Onset is typically in adolescence or adulthood, with initial symptoms rarely affecting lower limb ambulation as severely in early childhood. *Becker muscular dystrophy* - While also an X-linked recessive disorder caused by a dystrophin gene mutation, **Becker muscular dystrophy** typically has a **later onset** and a **milder, slower progression** compared to Duchenne muscular dystrophy. - Symptoms usually appear in adolescence or early adulthood, and patients often retain the ability to walk into adulthood, unlike the rapid progression seen in this 2-year-old. *Limb-girdle muscular dystrophy* - This heterogeneous group of disorders primarily affects **proximal muscles** of the pelvic and shoulder girdles. - While it can present with proximal weakness, onset is typically **later in childhood or adolescence**, and **calf pseudohypertrophy** is less prominent than in Duchenne muscular dystrophy. - The age of presentation (2 years) and classic features make Duchenne more likely.

Question 5: A 4-year-old male child presents with muscle weakness. His mother reports that her child has difficulty in climbing stairs and getting up from the floor. On muscle biopsy, small degenerated muscle fibers and absence of dystrophin were found. What is the diagnosis?

A. Myotonic dystrophy
B. Becker's muscle dystrophy
C. Limb-girdle muscular dystrophy
D. Duchenne muscular dystrophy (Correct Answer)

Explanation: ***Duchenne muscular dystrophy*** - The classic presentation of a young boy with **progressive muscle weakness**, difficulty climbing stairs (**Gowers' sign**), and **absent dystrophin** on muscle biopsy is characteristic of Duchenne muscular dystrophy. - It is an **X-linked recessive disorder** that leads to severe muscle degeneration and weakness due to a complete lack of functional dystrophin protein. *Myotonic dystrophy* - This condition is characterized by **myotonia** (delayed relaxation of muscles after contraction) and typically affects adults, although congenital forms exist. - While it causes muscle weakness, the primary differentiating feature of **myotonia** and its later onset are not present in this case. *Becker's muscle dystrophy* - Becker's muscular dystrophy (BMD) is also an X-linked recessive disorder and a milder form of muscular dystrophy, caused by a **reduced but still functional dystrophin** protein. - Patients with BMD typically present later in childhood or adolescence with slower progression and **some dystrophin** presence, unlike the absent dystrophin and early onset here. *Limb-girdle muscular dystrophy* - This is a group of muscular dystrophies that primarily affect the **pelvic and shoulder girdle muscles**. - It can present with similar weakness, but the **complete absence of dystrophin** found on biopsy points specifically to Duchenne muscular dystrophy, not typical limb-girdle dystrophy, which involves other genetic defects.

Question 6: Deficiency of which vitamin during early pregnancy will result in neural tube defect?

A. Folic acid (Correct Answer)
B. Iron
C. Cyanocobalamine
D. Vitamin E

Explanation: ***Folic acid*** - **Folic acid** (vitamin B9) is crucial for **neural tube closure** during the first 28 days of embryonic development. - Deficiency leads to conditions like **spina bifida** and **anencephaly**. - **Periconceptional supplementation** with 400-800 mcg daily is recommended to prevent neural tube defects. *Iron* - **Iron** is essential for **hemoglobin synthesis** and fetal growth, but its deficiency does not directly cause neural tube defects. - Iron deficiency in pregnancy can lead to **maternal anemia** and premature birth. *Cyanocobalamine* - **Cyanocobalamine** (vitamin B12) is involved in DNA synthesis and neurological function, but its direct link to neural tube defects is not as strong as folic acid. - Severe B12 deficiency can cause **megaloblastic anemia** and neurological issues. *Vitamin E* - **Vitamin E** is a fat-soluble antioxidant that protects cell membranes from oxidative damage. - While important for overall health during pregnancy, it does not play a specific role in neural tube closure. - Deficiency is rare and does not cause neural tube defects.

Question 7: Which of the following is a symptom of cerebral palsy?

A. Microcephaly
B. Ataxia (Correct Answer)
C. Hypotonia
D. Flaccid paralysis

Explanation: ***Ataxia*** - **Ataxia** (lack of voluntary coordination of muscle movements) is one of the primary **motor symptoms of cerebral palsy**, specifically seen in **ataxic cerebral palsy** which accounts for 5-10% of CP cases. - Ataxic CP presents with **poor coordination, tremors, and balance difficulties**, representing a distinct motor presentation pattern. - It is a direct neurological symptom resulting from **cerebellar or basal ganglia involvement**. *Hypotonia* - **Hypotonia** (decreased muscle tone) can occur in cerebral palsy, particularly as an **early finding in infants**. - However, hypotonia often **evolves into other motor patterns** (spasticity, dyskinesia) as the child develops, making it less specific as a defining symptom. - While present in some forms, it's more transitional than a consistent motor symptom across CP types. *Microcephaly* - **Microcephaly** (abnormally small head) is not a symptom of cerebral palsy itself, but rather a potential **associated condition or underlying cause**. - It suggests **abnormal brain development** which *could* lead to cerebral palsy, rather than being a neurological motor symptom *of* CP. *Flaccid paralysis* - **Flaccid paralysis** involves complete **loss of muscle tone and voluntary movement**, characteristic of **lower motor neuron lesions**, **spinal cord injury**, or certain **neuromuscular diseases**. - Cerebral palsy is an **upper motor neuron disorder** typically presenting with **spasticity, dyskinesia, or ataxia**, rather than pure flaccid paralysis.

Question 8: A 25-year-old pregnant woman, at 18 weeks of gestation, undergoes a routine ultrasound scan. The ultrasound images provided show below. Based on the imaging findings, what is the most likely diagnosis?

A. Spina bifida (Correct Answer)
B. Anencephaly
C. Encephalocele
D. Holoprosencephaly
E. Iniencephaly

Explanation: ***Spina bifida*** - The ultrasound image shows a **defect in the posterior elements of the fetal spine**, with characteristic splaying or widening of the vertebral arches. - This is a **neural tube defect** resulting from incomplete closure of the spinal column during embryonic development. - Associated findings on prenatal ultrasound may include the **"lemon sign"** (scalloping of frontal bones) and **"banana sign"** (abnormal cerebellar shape). - Spina bifida is typically detected on **second-trimester anatomy scan** (18-20 weeks). *Anencephaly* - This condition involves the **absence of a major portion of the brain, skull, and scalp** due to failure of anterior neural tube closure. - On ultrasound, anencephaly presents with **absent calvarium above the orbits** and absent cerebral hemispheres, which is distinctly different from a spinal defect. - This would be a **cranial abnormality**, not a spinal column defect. *Encephalocele* - An **encephalocele** is a protrusion of brain tissue and meninges through a defect in the skull, most commonly at the **occipital region**. - On ultrasound, this appears as a **cranial mass** extending beyond the skull contour, not a spinal defect. *Holoprosencephaly* - This condition results from **failure of forebrain (prosencephalon) to divide properly** into two hemispheres. - Ultrasound findings include **single ventricle**, fused thalami, and absent midline structures, often with associated **facial anomalies**. - The imaging would show **brain abnormalities**, not spinal column defects. *Iniencephaly* - This is a rare **neural tube defect** characterized by extreme retroflexion of the head with severe spinal defects in the cervical and thoracic regions. - On ultrasound, iniencephaly shows the fetal head in extreme **hyperextension** with the face looking upward, creating a characteristic "stargazing" appearance. - This differs from the typical spinal defect pattern seen in spina bifida.

Question 9: Fracture of the femur in young children (2-5 years) is typically treated by:

A. Gallow's splint
B. Open reduction (surgical intervention)
C. Closed reduction & splintage (Correct Answer)
D. Intramedullary nailing (surgical fixation)

Explanation: ***Closed reduction & splintage*** - In young children (2-5 years), **femur fractures** are often treated non-operatively with **closed reduction** and immediate application of a **hip spica cast** or other splintage. - This approach takes advantage of the excellent **bone remodeling potential** in young children, allowing for good functional outcomes. *Open reduction (surgical intervention)* - **Open reduction** is generally reserved for open fractures, - It is also indicated for fractures with associated neurovascular injury, compartment syndrome, or in older children where non-operative management has failed. *Gallow's splint* - The **Gallow's splint** (also known as Bryant's traction) involves suspending both legs vertically, and is typically used for **femur fractures in infants younger than 1 year** due to the risk of vascular compromise or compartment syndrome in older or heavier children. - It is not the primary treatment for children aged 2-5 years. *Intramedullary nailing (surgical fixation)* - **Intramedullary nailing** is a surgical option, usually considered for **femur fractures in older children** (typically 6 years and above) or adolescents. - It provides stable fixation but is generally avoided in very young children due to potential damage to the **growth plates** or complications related to implant size.

Question 10: A pole vaulter had a fall during pole vaulting and had paralysis of the arm . Which of the following investigations gives the best recovery prognosis -

A. Electromyography (Correct Answer)
B. Strength Duration Curve
C. Creatine phosphokinase levels
D. Muscle biopsy

Explanation: Electromyography - **Electromyography (EMG)** can help assess the extent of nerve damage and reinnervation, providing insights into the potential for recovery [1]. - The presence of **spontaneous activity** (fibrillations, positive sharp waves) indicates denervation, while the appearance of **motor unit action potentials (MUAPs)** suggests reinnervation [1]. *Creatine phosphokinase levels* - **Creatine phosphokinase (CPK)** levels primarily indicate **muscle damage**, not the extent of nerve injury or recovery potential. - While muscle damage can occur with nerve injury, CPK does not provide specific prognostic information for nerve regeneration. *Strength Duration Curve* - The **strength duration curve** assesses the excitability of a nerve or muscle to electrical stimulation. - While it can differentiate between **nerve and muscle damage**, it provides less comprehensive prognostic information compared to EMG regarding the status of nerve regeneration. *Muscle biopsy* - A **muscle biopsy** would directly evaluate muscle pathology, such as atrophy or regeneration. - However, it is an **invasive procedure** and provides less direct information about nerve recovery compared to EMG, which directly assesses nerve and muscle electrical activity.

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