Paediatrics Marrow Pg 191-200 (CNS )
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Questions and Answers

Which gene is primarily affected in Spinal Muscular Atrophy (SMA)?

  • SMN 1 gene (correct)
  • SMN 3 gene
  • SMN 2 gene
  • SMN 4 gene

    • Hypotonia in SMA is characterized by normal muscle tone.

    False

    What is the primary consequence of increased apoptosis of motor neurons in SMA?

    Hypotonia and flaccidity of muscles

    The _____ type of weakness is characteristic of Spinal Muscular Atrophy.

    <p>LMN</p> Signup and view all the answers

    Match the clinical features of SMA with their descriptions:

    <p>Hypotonia = Weakness with absent reflexes Frog leg posture = Characteristic limb positioning Tongue fasciculations = Muscle twitching in the tongue Disuse atrophy = Muscle wasting due to lack of use</p> Signup and view all the answers

    What is the primary cause of neurocysticercosis?

    <p>Larval stage of the pork tapeworm <em>Taenia solium</em></p> Signup and view all the answers

    Neurocysticercosis can be diagnosed using a blood test.

    <p>False</p> Signup and view all the answers

    What is a common clinical presentation of neurocysticercosis involving the brain?

    <p>Seizures</p> Signup and view all the answers

    Treatment for single cysts in neurocysticercosis includes the medication __________ for 10-14 days.

    <p>Albendazole</p> Signup and view all the answers

    Match the treatment methods with their respective purposes:

    <p>Dexamethasone = Reducing inflammation Oxcarbazepine = Treatment for focal epilepsy Sodium valproate = Treatment for generalized epilepsy Praziquantel = Cysticidal therapy for multiple cysts</p> Signup and view all the answers

    What is the most common worldwide cause of Japanese Encephalitis?

    <p>Japanese Encephalitis virus</p> Signup and view all the answers

    The primary vector for Japanese Encephalitis is the Culex tritaeniorhynchus mosquito.

    <p>True</p> Signup and view all the answers

    What is the first-line treatment for Herpes Simplex Encephalitis?

    <p>IV Acyclovir</p> Signup and view all the answers

    Japanese Encephalitis primarily affects ______ children.

    <p>school-going</p> Signup and view all the answers

    Match the following features with their associated conditions:

    <p>Increased lymphocytes = Japanese Encephalitis PLED = Herpes Simplex Encephalitis Taenia solium = Neurocysticercosis Supportive treatment = Japanese Encephalitis</p> Signup and view all the answers

    What is the most common cause of congenital hypothyroidism?

    <p>Thyroid dysgenesis</p> Signup and view all the answers

    Goitre is commonly present in cases of thyroid dysgenesis.

    <p>False</p> Signup and view all the answers

    Name one feature of congenital hypothyroidism that can be observed after the first week of life.

    <p>Decreased activity of the child</p> Signup and view all the answers

    In cases of thyroid dyshormonogenesis, one common defect is __________ deficiency.

    <p>peroxidase</p> Signup and view all the answers

    Match the following investigations with their results in congenital hypothyroidism:

    <p>Decreased T3 = Thyroid Function Test Increased TSH = Thyroid Function Test Heel prick testing = Screening for infants Decreased free T4 = Thyroid Function Test</p> Signup and view all the answers

    What is the primary consequence of decreased gonadotropins in children with hypopituitarism?

    <p>Delayed puberty</p> Signup and view all the answers

    Prolonged jaundice is a common symptom associated with Growth Hormone Deficiency.

    <p>False</p> Signup and view all the answers

    What is the recommended treatment for Growth Hormone Deficiency?

    <p>Recombinant Growth Hormone (rGH)</p> Signup and view all the answers

    The most common preventable cause of intellectual disability is __________.

    <p>Congenital Hypothyroidism</p> Signup and view all the answers

    Match the conditions with their respective treatments or management:

    <p>Turner syndrome = Recombinant GH injection Small for gestational age = Recombinant GH injection Hypothyroidism = Thyroid hormone replacement Prader Willi syndrome = Recombinant GH injection</p> Signup and view all the answers

    What is the most common cause of Growth Hormone Deficiency?

    <p>Idiopathic</p> Signup and view all the answers

    Laron's Dwarfism is caused by an overproduction of GH receptors.

    <p>False</p> Signup and view all the answers

    What is a characteristic feature of Isolated Growth Hormone Deficiency?

    <p>Doll-like appearance</p> Signup and view all the answers

    The pathology of Laron's Dwarfism primarily involves defective _____ receptors.

    <p>GH</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Idiopathic = Most common cause of GH deficiency Craniopharyngioma = Type of tumor associated with acquired GH deficiency GH = Hormone mediating growth effects through IGF-1 IGF-1 = Insulin-like growth factor with a role in growth promotion</p> Signup and view all the answers

    What is the mode of inheritance for Myotonic Dystrophy Type 1?

    <p>Autosomal dominant</p> Signup and view all the answers

    Myotonic Dystrophy Type 1 is caused by a defect in the DMPK gene located on chromosome 19.

    <p>True</p> Signup and view all the answers

    Name one clinical feature of Myotonic Dystrophy Type 1 related to facial appearance.

    <p>Ptosis</p> Signup and view all the answers

    Individuals with Myotonic Dystrophy Type 1 commonly experience _____ in their limb muscles.

    <p>weakness</p> Signup and view all the answers

    Match the following clinical features with their corresponding descriptions:

    <p>Myotonia = Delayed relaxation of muscles HATCHET facies = Characteristic facial appearance Posterior capsular cataract = Eye issue associated with the condition Endocrinopathies = Hormonal imbalances linked to the disorder</p> Signup and view all the answers

    What is the characteristic gait associated with proximal muscle weakness in neuromuscular disorders?

    <p>Waddling gait</p> Signup and view all the answers

    Calf muscle pseudo hypertrophy is a typical feature in the early stages of neuromuscular disorders.

    <p>False</p> Signup and view all the answers

    At what age does proximal muscle weakness typically occur in children with neuromuscular disorders?

    <p>3-4 years</p> Signup and view all the answers

    The major cause of death in individuals with neuromuscular disorders is due to cardiac and __________ muscle insufficiency.

    <p>respiratory</p> Signup and view all the answers

    Match each investigation with its description:

    <p>Serum creatinine kinase = Elevated to 10 times the normal value Gene testing = Utilizes multiplex PCR and MLPA Muscle biopsy = Used for diagnostic confirmation Exon skipping therapy = Eteplisren treatment</p> Signup and view all the answers

    What is the most common cause of morbidity/mortality in Spinal Muscular Atrophy (SMA)?

    <p>Aspiration pneumonitis</p> Signup and view all the answers

    Duchenne Muscular Dystrophy (DMD) is an autosomal dominant condition.

    <p>False</p> Signup and view all the answers

    What is the primary mechanism of action for Zolgensma in treating SMA?

    <p>Gene therapy incorporating the SMN gene with a vector.</p> Signup and view all the answers

    The _____ type of muscular dystrophy is caused by a mutation in the dystrophin gene.

    <p>Duchenne</p> Signup and view all the answers

    Match the clinical types of SMA with their lifespan:

    <p>Type 0 = Few weeks Type 1 = &lt; 2 years Type 2 = 2nd - 3rd decade Type 3 = Normal</p> Signup and view all the answers

    Which type of muscular dystrophy is characterized by late onset muscle weakness around the age of 5 years?

    <p>Becker Muscular Dystrophy</p> Signup and view all the answers

    Facioscapulohumeral Dystrophy is inherited in an autosomal recessive manner.

    <p>False</p> Signup and view all the answers

    What are the defective proteins associated with Limb Girdle Muscular Dystrophy?

    <p>Caveolin 3 and calpain 3</p> Signup and view all the answers

    In Becker Muscular Dystrophy, individuals may have a longer lifespan until the age of ___ years.

    <p>40</p> Signup and view all the answers

    Match the types of muscular dystrophy with their characteristics:

    <p>Becker Muscular Dystrophy = Mild allelic variant of DMD Facioscapulohumeral Dystrophy = Autosomal dominant inheritance Limb Girdle Muscular Dystrophy = Autosomal recessive and dominant forms Duchenne Muscular Dystrophy = More severe muscle weakness onset</p> Signup and view all the answers

    Study Notes

    Spinal Muscular Atrophy (SMA)

    • Autosomal recessive disorder caused by a mutation in the SMN1 gene on chromosome 5q.
    • The SMN1 gene codes for the SMN protein, which protects motor neurons from apoptosis.
    • A defective SMN1 gene leads to increased motor neuron apoptosis, resulting in muscle weakness and hypotonia.
    • Two types of SMN genes: SMN1 and SMN2.
    • SMN1 produces a fully functional protein, while SMN2 produces a dysfunctional protein due to the absence of exon 7.
    • SMN1 is the primary gene affected in SMA; SMN2 is a backup gene.
    • Hypotonia is a hallmark of SMA, especially Type 1, characterized by:
      • Frog leg posture
      • Decreased or absent spontaneous limb movements
      • No resistance to passive flexion
      • Ragged doll appearance
    • Lower motor neuron (LMN) type of weakness with:
      • Decreased or absent deep tendon reflexes (DTR)
      • Disuse atrophy of muscles
    • Extraocular muscles are not involved in SMA, but are affected in myasthenia gravis.
    • Other classic signs of SMA include:
      • Tongue fasciculations
      • Normal mentation
      • A characteristic frog-like posture in infants with flexed thighs and extended legs.

    Neurocysticercosis

    • A neurological infection caused by the larval stage of the pork tapeworm Taenia solium.
    • Transmitted via ingestion of undercooked pork or contaminated food.
    • Presents acutely with encephalitis:
      • Fever
      • Altered sensorium
      • Seizures (focal or generalized epilepsy, recent onset)
    • Cysts in the brain can be visualized through brain imaging (CT or MRI):
      • Single cyst with surrounding edema: Often presents as epilepsy
      • Multiple cysts plus perilesional edema: Exhibits a "starry sky" appearance
    • Treatment:
      • Steroids: Dexamethasone (within 148 hours of diagnosis) to reduce inflammation
      • Anti-epileptics:
        • Oxcarbazepine (focal epilepsy) for 6 months
        • Sodium valproate (general epilepsy) for 6 months
      • Cysticidal therapy:
        • Albendazole (10-14 days) for single cysts
        • Praziquantel (for multiple cysts)

    Japanese Encephalitis (JE)

    • Caused by Japanese Encephalitis virus, the most common cause of encephalitis worldwide.
    • Herpes Simplex virus (HSV) is the most common cause of sporadic encephalitis.
    • Vector: Culex tritaeniorhynchus (Culex mosquito)
    • Host: Ticks (amplifier host), birds
    • Most commonly affects school-going children.
    • Diagnosis:
      • Polymerase Chain Reaction (PCR)
      • Cerebrospinal Fluid (CSF) analysis:
        • Increased lymphocytes
        • Normal sugar
        • Slightly elevated protein
      • Imaging:
        • Target areas: Basal ganglia > Thalamus
    • Management:
      • Supportive treatment
    • Prevention:
      • JE vaccine

    Herpes Simplex Encephalitis

    • Characterized by:
      • Fever
      • Focal seizures
      • Focal neurological deficits (e.g., aphasia, speech defects)
      • Behavioral disturbances
      • Movement disorders
    • Investigations:
      • CSF analysis:
        • Increased lymphocytes
        • Normal sugar
        • Slightly elevated protein
      • PCR
      • Imaging
      • EEG
      • Target areas: Temporal lobe
      • Characteristic finding: Periodic Lateralizing Epileptiform Discharges (PLED)
    • Treatment:
      • Intravenous Acyclovir (DOC): 14-21 days

    Endocrine System - Hypothyroidism

    • Classified based on the pathology:
      • Primary: Thyroid gland pathology
      • Central: CNS pathology
        • Hypothalamus
        • Pituitary
    • Etiology:
      • Anomaly: Thyroid dysgenesis
        • Most common cause
        • Sporadic
      • Thyroid dyshormonogenesis: Defects in organification
        • Most common type
        • Peroxidase deficiency
        • Autosomal recessive inheritance
      • Severe Iodine deficiency: Endemic goitre/cretinism
        • Seen in underdeveloped countries
      • Maternal causes:
        • Transplacental transfer of maternal antibodies: TSH
        • Receptor blocking antibody
        • Antithyroid drugs
    • Difficult to identify in newborns (first week) due to maternal hormone masking.
    • Features after one week include:
      • Decreased activity
      • Wide open posterior fontanelle (>5 mm)
      • Cold, dry skin
      • Constipation/delay in passing meconium
      • Macroglossia
      • Umbilical hernia
      • Hoarse cry
      • Prolonged jaundice
      • Goitre (usually absent in thyroid dysgenesis, present in dyshormonogenesis and maternal antithyroid drug usage)
    • Investigations:
      • Thyroid Function Test (TFT):
        • Decreased T3
        • Decreased free T4
        • Increased TSH
      • Screening: Heel prick dried blood spot testing for all infants

    Myotonic Dystrophy Type 1

    • Mode of inheritance: Autosomal dominant
    • Trinucleotide repeats: CTG > 80 (Normal < 35)
    • Defective gene: DMPK gene on chromosome 19
    • Clinical features:
      • HATCHET Facies:
        • Early manifestations:
          • Ptosis
          • Inverted V appearance of the upper lip
        • Late manifestations:
          • Temporal hollowing
          • Thinning of cheek area
      • Myotonia:
        • Delayed relaxation of muscles
        • Inferred by:
          • Shaking hands
          • Difficulty in letting go of hand
          • Percussion at the base of the thumb
      • Limb weakness:
        • Distal muscles affected:
          • Retarded purposeful movements with hands
          • Flattened thenar and hypothenar eminences
          • Weak foot muscles: Foot drop, abnormal gait
      • Other features:
        • Posterior capsular cataract
        • Endocrinopathies:
          • Hyperinsulinism
          • Testicular atrophy
          • Adrenal gland atrophy

    Growth Hormone Deficiency

    • Most common cause: Idiopathic
    • Types:
      • Isolated
      • Congenital:
        • Developmental:
          • Ectopic pituitary
          • Septo-optic dysplasia
        • Genetic mutations:
          • GH gene
          • GHRH receptor gene
      • Acquired:
        • Trauma
        • Tumor:
          • Craniopharyngioma
          • Germinoma
          • Histiocytosis
          • Sarcoidosis
        • Infiltration
        • Irradiation
    • Laron's Dwarfism:
      • Due to hypopituitarism
      • Pathogenesis: Defective GH receptor (resistance to the effect of GH)
        • Defective GH receptors on the liver
        • Reduced release of IGF-1
      • Characteristic feature: Low levels of IGF-1
    • Features of Isolated GH Deficiency:
      • Normal at birth (no role of GH during fetal life)
      • Proportionate short stature during infancy
      • Decreased growth velocity (<4 cm/yr)
      • Doll-like appearance
      • Delayed bone age
      • Mid-parental height (MPH) < -2 SD from MPH
      • Decreased GH → decreased lipolysis → Fat deposition
      • Prominent cheeks
      • Overweight/obese

    Hypothyroidism

    • Thyroid gland is essential for brain development, so early detection (within the first two years) is crucial.
    • Undected and untreated hypothyroidism can lead to intellectual disability.
    • Congenital Hypothyroidism: Most preventable cause of intellectual disability.
    • Growth Hormone Deficiency & Hypothyroidism - Note:
      • If associated with hypopituitarism:
        • Decreased gonadotropins → Decreased testosterone and other sex hormones → Micropenis and small testes → Delayed puberty
        • Decreased ACTH → Decreased cortisol → Hypoglycemia
        • Prolonged jaundice

    Investigations for Growth Hormone Deficiency

    • Screening:
      • IGF-I levels (Malnutrition can alter IGF levels)
    • Confirmatory:
      • GH estimation: Stimulative/provocative GH testing (Random estimation is unreliable as GH is released in a pulsatile manner)
      • Provocative substances: Insulin, clonidine, arginine
      • GH < 10 ng/ml after test: Diagnostic

    Treatment for Growth Hormone Deficiency

    • Recombinant GH (rGH) given via subcutaneous injection, usually at night, until epiphyseal closure.
    • Other uses of rGH:
      • GTCS in Prader-Willi syndrome
      • GH deficiency
      • Turner syndrome
      • Chronic Kidney Disease (CKD)
      • Small for gestational age (SGA) > 2 years, SHOX gene mutation
      • Idiopathic
      • Noonan syndrome
      • Prader-Willi syndrome

    Becker Muscular Dystrophy

    • Mild allelic (less severe) variant of Duchenne Muscular Dystrophy (DMD).
    • Affected gene: Dystrophin gene.
    • Late onset muscle weakness (~5 years).
    • Slow progression of symptoms → Longer lifespan: Till 40 years.
    • Early onset cardiomyopathy (compared to DMD).

    Facioscapulohumeral Dystrophy

    • Mode of inheritance: Autosomal dominant.
    • Defective gene: FSHD1 (Facioscapulohumeral dystrophy).
    • Clinical features: Muscle weakness
      • Facial:
        • Defective eye closure
        • Rounded mouth
        • Puckering of lips
      • Humeral:
        • Weakness of arm muscles
      • Scapular:
        • Forearm muscles normal: Popeye appearance

    Limb Girdle Muscular Dystrophy

    • Mode of inheritance: Autosomal recessive (most common in children) and autosomal dominant (most common in adults).
    • Defective proteins: Caveolin 3, Calpain 3 (Cytoskeletal proteins)
    • Clinical features:
      • Affected areas: Shoulder girdle and hip girdle
      • Neck and bulbar muscles are not affected
      • Cardiac muscle involvement is rare
      • Normal IQ

    Neuromuscular Disorders

    • Early features: Delay in attaining motor milestones
    • Borderline low IQ (intellectual disability)
    • Proximal muscle weakness:
      • Occurs between 3-4 years of age.
      • Hip: Waddling gait, Gower's sign (characteristic but not diagnostic)
      • Shoulder and hip muscles affected
      • Distal muscles (hands, feet) are not affected
      • Calf muscle pseudo hypertrophy
    • Plateauing of illness: Between 4–6 years of age.
    • Progression:
      • Dangerous manifestation:
        • Spine muscles: Scoliosis and lordosis
        • Bulbar muscles: Dysfunction of pharyngeal/laryngeal muscles
        • Cardiac and respiratory muscle insufficiency: Leading cause of death (usually between 20-25 years of age)
    • Investigations:
      • Serum Creatinine kinase: 10 times the normal value.
      • Gene testing: Diagnostic
        • Multiple PCR
        • Multiplex Ligand-dependent Probe Amplification (MLPA)
      • Muscle biopsy
    • Management:
      • Incurable
      • Steroids: Reduce the apoptosis rate
        • Deflazacort
        • Prednisolone
      • Nerve treatment:
        • Exon skipping therapy (AON): Eteplisren
        • Ataluren: Suppress nonsense mutation

    Duchenne Muscular Dystrophy (DMD)

    • Most common type of neuromuscular disorder (NMD)
    • Mode of inheritance: X-linked recessive (Xp)
    • Mutated gene: Dystrophin gene (most common: nonsense mutation)
    • Dystrophin protein:
      • Cytoskeletal protein in muscle
      • Promotes stabilization of muscle fibers
      • Coordinates muscle contraction
    • Mechanism of absence of dystrophin protein:
      • Muscle instability
      • Muscle weakness
      • Premature apoptosis of muscle fibers
      • Repair process
      • Fibrous fatty deposition

    Clinical Types of SMA (Based on Severity)

    Type Age of Onset Motor Milestones Lifespan
    0 (Fatal) Antenatal (< 6 months) - Few weeks
    1 (Werdnig-Hoffman disease) < 6 months Up to head control < 2 years
    2 (Dubowitz disease) < 18 months Up to sitting independently (Cannot stand/walk) 2nd - 3rd decade
    3 (Kugelberg-Welander disease) > 18 months Stand, walk (Partially ambulant) Normal
    4 Adolescence/adult Fully ambulant Normal

    Management of SMA

    • Not a curable condition.
    • Recent advances:
    • Drug | Therapy | Mechanism of action | |---|---|---| | Zolgensma | Gene therapy: SMN gene incorporated with vector (Adenovirus) | SMN gene incorporates with an RNA vector.| | Nusinersen (Antisense oligonucleotide: AON) | Exon skipping therapy | Binds to the defective exon 7 area, producing a partially functioning protein.| | Risdiplam | | Includes exon 7 into a defective area of the gene.|

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    Description

    This quiz covers the fundamental aspects of Spinal Muscular Atrophy (SMA), an autosomal recessive disorder linked to mutations in the SMN1 gene. Learn about the role of SMN1 and SMN2 genes, the clinical features of SMA, and its implications for muscle function. Test your understanding of this critical neuromuscular condition.

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