Clinical History
A 30-year-old woman has an ultrasound performed in the 18th week of pregnancy. The ultrasound reveals no anomalies of major organs, but fetal movement is decreased. The baby is born at term. The umbilical cord is short. The baby is noted to be weak and floppy. Muscle stretch reflexes are absent. However, the baby is alert and responds to stimuli. The baby's weakness rapidly worsens. Death occurs at 8 months of age from respiratory failure with pneumonia.
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- What histopathologic finding is most likely to be seen in skeletal muscle?
- A. Marked variation in fiber size along with marked fibrosis between muscle fibers
- B. Acute inflammation with necrosis and abscess formation
- C. Grouped atrophy of muscle fibers without inflammation or fibrosis
- D. Extensive lymphocytic infiltrates between muscle fibers
- E. Marked glycogen deposition within muscle fibers
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Answer: C The findings are most suggestive of an infantile form of spinal muscular atrophy known as Werdnig-Hoffman disease. There is extensive loss of large motor neurons leading to a neurogenic form of muscle atrophy.
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- What is the most appropriate statement to make to the mother regarding this condition?
- A. You should have supplemented your diet with folate during pregnancy
- B. A vaccination for poliovirus should prevent this from happening again
- C. This is a sporadic condition not likely to occur again
- D. In subsequent pregnancies, there is a 25% recurrence risk
- E. A karyotype on fetal cells can help identify this condition
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Answer: D Werdnig-Hoffman disease is an autosomal recessive condition. There are other forms of spinal muscular atrophy which have an onset later in childhood and a longer course.
- What disease process with similar symmetrical and progressive muscular weakness has an onset in adults?
- A. Amyotrophic lateral sclerosis
- B. McArdle's disease
- C. Becker muscular dystrophy
- D. Myasthenia gravis
- E. Pompe's disease
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Answer: A Amyotrophic lateral sclerosis (ALS) is not an inherited condition, but has loss of motor neurons, similar to spinal muscular atrophy, leading to neurogenic muscular atrophy.
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