Pediatric Myopathies Flashcards
Why do we perform developmental screens?
The sooner we identify developmental delays, the sooner we can intervene
[Note: Remember that a failed screen in simply an indication for a more thorough evaluation]
Name the 4 general domains of pediatric development
Gross motor
Fine motor
Language
Cognitive/Social-Emotional and Behavioral
If developmental delays are identified, early intervention is key. It is important to note that not hitting developmental milestones can be serious, but hitting milestones and then ______ is even more ominous
Regressing
Gross motor developmental milestones for 6 months, 9 months, and 1 year screening
6 months — Sits momentarily
9 months — pulls up, cruises, sits well without support
1 year — stands momentarily
Gross motor developmental milestones for 2 years and 3 years screening
2 years — walks up stairs, kicks ball forward
3 years — tricycle
Gross motor developmental milestones for 4 years and 6 years screening
4 years — balance on one foot (1-3 seconds), hop on one foot
6 years — skips
At which of the following ages should a child be able to skip?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
G. 6 years
At which of the following ages should a child be able to walk up stairs and kick a ball forward?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
D. 2 years
At which of the following ages should a child be able to pull themselves up, cruise around, and sit well without support?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
B. 9 months
At which of the following ages should a child be able to stand momentarily?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
C. 1 year
At which of the following ages should a child be able to balance on one foot for 1-3 seconds and hop on one foot?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
F. 4 years
At which of the following ages should a child be able to sit momentarily?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
A. 6 months
At which of the following ages should a child be able to ride a tricycle?
A. 6 months B. 9 months C. 1 year D. 2 years E. 3 years F. 4 years G. 6 years
E. 3 years
Thorough, standardized, and validated developmental screening tool often performed at 9, 18, and 24 or 30 months of age
DDST-II (Denver Developmental Screening Test II)
_____ = Muscle disease unrelated to any disorder of innervation or neuromuscular junction
Myopathy
Inheritance of DMD
X-linked recessive
[Carrier mom, sons have a 50% chance of having DMD, daughters have 50% chance of being carriers]
Note that 33% of cases are due to spontaneous mutations
Frameshift mutations disrupt reading frame —> absence of muscle dystrophin —> severe muscle weakness
If mom is a carrier of DMD, and has a daughter that is a carrier, what are some clinical features that may appear in the daughter?
May have CK elevation
May develop cardiomyopathy, muscle weakness, or muscle cramps
Clinical features of DMD
Weak neck flexors
Delayed walking, difficulty running, can’t “keep up”
Broad-based, waddling, lordotic gait
Gowers sign (due to proximal mm. weakness)
Calf and thigh muscle hypertrophy (early on)
Toe-walking by age 6
Limited hip flexion due to IT band contractures
Progressive scoliosis, loss of independent ambulation by age 9-10
Compromised respiratory status
Cardiomyopathy
Gastric hypomotility
Intellectual impairment in some — ADD, learning disability
What is Gowers sign?
Sequence of postures used in attaining the upright position in pts with DMD
First legs are pulled up under the body and weight is shifted to hands and feet, hips are then thrust in the air as knees are straightened and hands are brought close to legs, trunk is slowly extended by the hands walking up the thighs until erect position is attained
Inheritance and genetics of BMD
X-linked recessive
Caused by in-frame mutation in dystrophin gene —> production of abnormal or semi-functional dystrophin [less severe mm. weakness than DMD]
Clinical features of BMD
Proximal mm. weakness after age 5 (older presentation than DMD)
Maintenance of independent walking until after age 16
Preserve anti-gravity strength of neck flexors
Age of death varies between 4th and 6th decades of life
Describe presentation of congenital muscular dystrophies
Present at birth or early infancy
Hypotonia
Severe muscle weakness (proximal > distal)
Joint contractures
May present with: malformations of eyes, malformations of brain, cardiomyopathy, and/or rigid spine
Role of dystrophin in muscular dystrophies
Dystrophin is required for muscle membrane stability (anchoring) — occurs in skeletal mm., cardiac mm., smooth mm., and brain
Without dystrophin, the membrane tears, and muscle necrosis and fibrosis occurs
Chronic muscle damage outpaces the body’s ability to repair
What is the importance of GGT in differentiating between muscle disease and liver disease?
GGT (gamma-glutamyl transferase) level can help determine if the liver is involved
If elevated — think liver
If normal — think muscle
Describe statin induced myopathy
Necrotizing and inflammatory myopathy
Symptoms include muscle weakness, pain, and tenderness
Elevation of CK to more than 10x normal
[occurs in 0.5% of pts who use a statin]
What is the most common idiopathic inflammatory myopathy in children?
Juvenile dermatomyositis
Major clinical findings of juvenile dermatomyositis
Mean age of onset 7 y/o
Generalized muscle weakness (proximal > distal)
Red or purplish heliotrope rash over eyelids
Raised erythematous papules over extensor joint surfaces (Gottren papules)
Thrombi or hemorrhage in peri-ungual capillary beds
Glycogen storage disorder type 2 (Pompe disease) is due to autosomal recessive acid alpha-glucosidase gene mutations, resulting in buildup of glycogen in lysosomes of cells, especially muscle.
What are clinical features?
Presents in early infancy
Generalized weakness and hypotonia Hypertrophic cardiomyopathy Respiratory failure Feeding difficulty Hearing loss
Important serum measurement to get in genetic or acquired muscle diseases
Serum creatine kinase
Course and prognosis of mitochondrial myopathies
Most often affect multiple organs (can be limited to one organ); organs dependent on aerobic metabolism are most affected — heart, skeletal mm., brain
Present at any age
May be “syndromic” (e.g., mitochondrial encephalomyopathy with lactic acidosis and stroke-like symptoms aka MELAS) or “non-syndromic”
SYMPTOMS AND PROGNOSIS VARY GREATLY
