MIDTERMS: muscular Dystrophies

Question 1

What are the main clinical evaluations used in assessing myopathies?

Answer 1

Clinical evaluations include history (chief complaint, family, maternal history), physical examination (atrophy, pseudohypertrophy, reflexes, gait), and diagnostic studies (CK levels, EMG-NCV, genetic studies, muscle biopsy).

Question 2

What is the typical inheritance pattern for myopathies?

Answer 2

Myopathies can follow autosomal dominant (multigenerational) or autosomal recessive (single-generation) inheritance patterns.

Question 2

What laboratory findings are associated with myopathies?

Answer 2

: Elevated creatine kinase (CK) levels, ECG abnormalities in cases like Duchenne Muscular Dystrophy (DMD), and sometimes muscle biopsy findings showing fibrosis or absence of key proteins like dystrophin.

Question 2

: How does Becker’s Muscular Dystrophy differ from DMD?

Answer 2

Becker’s Muscular Dystrophy has a milder progression with onset typically around 10-15 years, patients maintain ambulation longer, and dystrophin is present but abnormal.

Question 3

What are the characteristic features of Duchenne Muscular Dystrophy (DMD)?

Answer 3

Onset before age 5, progressive proximal weakness, calf pseudohypertrophy, positive Gower’s sign, wide-based gait, intellectual impairment, absent or decreased MSRs.

Question 3

What are the progressive problems and typical cause of death in Duchenne Muscular Dystrophy?

Answer 3

Progressive issues include ventilatory insufficiency, contractures, scoliosis, obesity, and death often results from chronic respiratory failure.

Question 3

What is Gower’s sign and in which condition is it seen?

Answer 3

Gower’s sign is when a patient uses their hands to “climb up” their legs to stand, commonly seen in Duchenne Muscular Dystrophy.

Question 3

What diagnostic findings are commonly seen in Duchenne Muscular Dystrophy?

Answer 3

Elevated CK (300-400x normal), right precordial R waves on ECG, muscle biopsy shows fibrosis and absent dystrophin.

Question 4

Which myopathy is known for sparing deltoid and forearm muscles and affecting facial muscles?

Answer 4

Facioscapulohumeral Dystrophy (FSHD)

Question 4

What interventions help manage complications in DMD?

Answer 4

Interventions include ventilatory support, stretching for contractures, spinal fusion for scoliosis, and weight management to prevent obesity.

Question 4

What characterizes Limb-Girdle Muscular Dystrophy (LGMD)?What characterizes Limb-Girdle Muscular Dystrophy (LGMD)?

Answer 4

Autosomal inheritance, affects hip and shoulder girdle muscles, typically begins in the second or third decade, associated with cardiopulmonary complications.

Question 4

What associated features may be present in FSHD?

Answer 4

: Some patients may have congenital absence of biceps and brachioradialis, and in infantile-onset FSHD, nerve deafness may be observed

Question 4

What are the clinical signs of Facioscapulohumeral Dystrophy (FSHD)?

Answer 4

FSHD presents with facial weakness, shoulder girdle and anterior leg muscle weakness, often sparing the deltoid and forearm muscles.

Question 4

What is seen in muscle biopsy for Central Core Myopathy?

Answer 4

Central areas of muscle fibers lack mitochondria and oxidative enzymes.

Question 5

What are the common cardiopulmonary issues in myopathies?

Answer 5

Cardiomyopathy, conduction abnormalities (especially in Myotonic Dystrophy and Emery-Dreifuss), and respiratory insufficiency in advanced stages.

Question 5

What lifestyle modifications are beneficial for patients with myopathies?

Answer 5

Balanced physical activity, respiratory exercises, nutritional support to prevent obesity, and psychosocial support for quality of life.

Question 5

What is the triad of Emery-Dreifuss Muscular Dystrophy?

Answer 5

: Early contractures (elbows, Achilles tendons, neck), cardiac conduction defects, and progressive humeroperoneal muscle weakness.

Question 5

How is Duchenne Muscular Dystrophy (DMD) managed?

Answer 5

Treatments include corticosteroids, deflazacort, physical exercise, electrical stimulation, experimental gene therapy, psychosocial support, and orthoses for mobility.

Question 5

What are the characteristics of Central Core Myopathy?

Answer 5

Autosomal dominant; floppy at birth with congenital hip dislocations, clumsy, slender, and short stature in children; mild disease course with normal lifespan; CK usually normal.

Question 5

What are typical signs of muscle atrophy in myopathies?

Answer 5

Progressive weakness, abnormal gait, and focal muscle wasting are common signs.

Question 5

Describe the presentation and complications of Myotonic Dystrophy.

Answer 5

Features include progressive distal muscle weakness, myotonia (delayed relaxation), cataracts, cardiac abnormalities, endocrine issues, typically begins in late teens or early adulthood.

Question 5

q What genetic abnormality is associated with Duchenne and Becker Muscular Dystrophy?

Answer 5

Mutations in the dystrophin gene, where DMD involves absence of dystrophin and Becker involves abnormal dystrophin.

Question 5

What unique finding is seen in Nemaline Myopathy muscle biopsy?

Answer 5

Small, rod-like particles on trichrome stains.

Question 5

What defines Polymyositis and Dermatomyositis?

Answer 5

Acquired inflammatory myopathies with acute and subacute onset, muscle pain, and aches; DM has a bimodal distribution (childhood, middle age); DM in adults can be associated with neoplasms.

Question 5

: What are the main features of Nemaline Myopathy?

Answer 5

Autosomal dominant; weak facial muscles with a dysmorphic appearance, clubfeet, scoliosis; diagnosed before age 1; CK is normal to mildly elevated.

Question 6

What are the two forms of Myotubular (Centronuclear) Myopathy?

Answer 6

MTM I (autosomal recessive): delayed milestones, hypotonia, ptosis, ophthalmoplegia, generalized weakness, and possible seizures; MTM II (X-linked recessive): early respiratory failure, ptosis not severe.

Question 6

What are common skin manifestations of Dermatomyositis?

Answer 6

Violet rash on eyelids and cheeks with periorbital edema, erythematous rash on exposed areas, and calcinosis in children.

Question 6

: What is the mortality rate for Polymyositis/Dermatomyositis?

Answer 6

15-30%, with severe cases leading to respiratory failure.

Question 6

Which associated findings are seen with Polymyositis/Dermatomyositis?

Answer 6

Vasculitis, Raynaud’s phenomenon, myocardium and GI involvement, dysphagia, and neoplasms (breast, lung, ovary, stomach).

Question 6

A 1-year-old patient presents with weak facial muscles, a dysmorphic appearance, clubfeet, and mild scoliosis. CK levels are normal to mildly elevated. Muscle biopsy shows small rod-like particles on trichrome stain. What is the likely diagnosis?

Answer 6

Nemaline Myopathy.

Question 6

What is the typical physical examination finding in Polymyositis/Dermatomyositis?

Answer 6

Proximal weakness (hips → shoulders → anterior neck muscles), normal reflexes, mild atrophy, and minimal tenderness.

Question 6

What lab and diagnostic findings are typical in Polymyositis/Dermatomyositis?

Answer 6

Elevated CK in 90% of cases, increased myoglobin and ESR, EMG-NCV changes, muscle biopsy shows necrosis, phagocytosis, inflammatory cells, and degeneration.

Question 6

What is Sarcoidosis and which systems does it affect?

Answer 6

Multisystem granulomatous disorder affecting the lungs, eyes, skin, with hilar lymphadenopathy; muscle involvement in 50-80% of cases, often causing chronic proximal weakness and atrophy.

Question 6

What factors predict a poorer prognosis in Dermatomyositis?

Answer 6

Underlying malignancy, prior collagen-vascular disease, advanced age, delayed corticosteroid treatment, and chronic DM-PM form.

Question 6

What are common treatments for muscle involvement in Sarcoidosis?

Answer 6

What are common treatments for muscle involvement in Sarcoidosis?

Question 6

How is Sarcoidosis diagnosed in relation to muscle involvement?

Answer 6

CK is normal to mildly elevated, EMG shows myopathic changes, CXR shows bilateral hilar lymphadenopathy, and Kveim-Siltzbach skin reaction may be positive.

Question 7

What pharmacologic treatments are used for Polymyositis/Dermatomyositis?

Answer 7

Corticosteroids (oral prednisone), immunosuppressants (methotrexate, cyclophosphamide, cyclosporine, azathioprine, chlorambucil), immunoglobulins, and low-dose irradiation for resistant cases.

Question 8

A 5-month-old infant has delayed milestones, generalized hypotonia, ptosis, and ophthalmoplegia. Muscle biopsy reveals central nuclei in muscle fibers. The child’s parents are concerned as a sibling had early respiratory issues. Which congenital myopathy could this child have?

Answer 8

Myotubular (Centronuclear) Myopathy, specifically MTM I (autosomal recessive).

Question 9

A 50-year-old patient reports muscle weakness, especially in the proximal muscles, and develops Raynaud’s phenomenon and dysphagia. EMG shows myopathic changes, and muscle biopsy reveals inflammatory cell infiltration. What condition is suspected, and which additional assessment should be considered?

Answer 9

Polymyositis; additional cancer screening should be considered due to the potential association with malignancies.

Question 10

A patient with chronic sarcoidosis reports muscle pain and weakness primarily in the proximal muscles, with mild elevation in CK levels. Chest X-ray shows bilateral hilar lymphadenopathy. What is the likely cause of the muscle symptoms, and how should they be managed?

Answer 10

Sarcoid myopathy; management includes corticosteroids or adrenocorticotropic hormones.

Question 11

A 4-year-old boy presents with difficulty running and climbing stairs. On exam, he exhibits Gower’s sign, calf pseudohypertrophy, and progressive proximal muscle weakness. CK levels are extremely elevated. What is the likely diagnosis, and what gene mutation is associated?

Answer 11

Duchenne Muscular Dystrophy (DMD); associated with mutations in the dystrophin gene.

Question 12

A 12-year-old boy presents with mild muscle weakness that started in his teens. His parents report he has delayed motor milestones but is still able to walk independently. CK levels are elevated but less so than in other muscular dystrophies. What is the likely diagnosis?

Answer 12

Becker Muscular Dystrophy, a milder form of dystrophinopathy with a later onset compared to Duchenne Muscular Dystrophy.

Question 13

An 8-year-old girl presents with proximal muscle weakness and difficulty swallowing. Her skin shows a characteristic violet-colored rash on the eyelids and cheeks. She also has erythematous patches on her knuckles and other joints. What is the most likely diagnosis, and what treatment is indicated?

Answer 13

: Juvenile Dermatomyositis; treatment includes corticosteroids and immunosuppressive therapy.