Module 19 Flashcards
What are the two most common forms of muscular dystrophy?
Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD).
What is the role of dystrophin in muscular dystrophy?
Dystrophin stabilizes muscle cell membranes; mutations lead to muscle degeneration.
What chromosomal abnormality causes DMD and BMD?
X-linked recessive mutations on the short arm of the X chromosome.
What are key clinical signs of DMD in children aged 2–3 years?
Frequent falls, pseudohypertrophy of calves, abnormal postures, joint contractures.
What is the expected disease progression of DMD?
Wheelchair use by age 7–12; preserved hand function; eventual respiratory/cardiac failure.
How is DMD diagnosed?
Elevated creatine kinase, genetic testing, muscle biopsy.
What is the pathophysiology of myasthenia gravis?
Autoimmune destruction of acetylcholine receptors at the neuromuscular junction.
What are early clinical manifestations of MG?
Ptosis, diplopia, muscle weakness starting proximally and worsening with activity.
When are MG symptoms typically worse—morning or evening?
Evening (fatigue worsens throughout the day).
How is MG diagnosed?
Edrophonium (Tensilon) test, electrophysiology, and antibody testing.
What distinguishes myasthenic crisis from cholinergic crisis?
Myasthenic crisis involves respiratory failure due to under-medication; cholinergic crisis involves excessive muscarinic effects due to overdose (e.g., bradycardia, diarrhea, salivation).
What causes carpal tunnel syndrome?
Compression of the median nerve by the transverse carpal ligament, often due to repetitive wrist use.
What tests are used for carpal tunnel diagnosis?
Positive Tinel’s sign and Phalen’s maneuver.
What is Guillain-Barré syndrome (GBS)?
Acute immune-mediated polyneuropathy causing ascending flaccid paralysis.
What usually precedes the onset of GBS?
Viral or flu-like illness; occasionally vaccination.
What is the prognosis for GBS?
Recovery is possible with supportive care; severity varies.
What causes a herniated intervertebral disc?
Trauma, aging, and degenerative changes leading to nerve compression.
What is sciatica?
Radiating pain along the sciatic nerve due to lumbar disc herniation.
What test is used to diagnose a herniated disc?
Straight-leg test.
What neurons are damaged in ALS?
Both upper and lower motor neurons.
What are early symptoms of ALS?
Muscle cramps and weakness in one limb; progresses to multiple areas.
Why do ALS patients retain normal cognition and sensation?
ALS affects motor neurons only; sensory and cognitive pathways are preserved.
What is the pathogenesis of MS?
Autoimmune destruction of CNS myelin; leads to sclerotic plaques and impaired nerve conduction.
What are hallmark MS symptoms?
Optic neuritis, paresthesias, abnormal gait, bladder issues, fatigue, and Lhermitte’s sign.
