Question 30.1

Created on Tue, 06/06/2017 - 05:12
Last updated on Thu, 08/31/2017 - 06:04
Pass rate: 40%
Highest mark: 8.3

Other SAQs in this paper

Other SAQs on this topic

List six clinical features associated with myotonic dystrophy.        (30% marks)

[Click here to toggle visibility of the answers]

College answer

• Frontal baldness
• Myotonic facies
• Wasting of facial muscles, sternocleidomastoids, muscles of distal extremities
• Myotonic spasms (e.g. delay in opening fingers after making a fist)
• Percussion myotonia
• Cardiomyopathy
• Cataracts
• Testicular atrophy
• Slurred speech (pharyngeal myotonia)
• Intellectual impairment
• Absent reflexes

Discussion

What a weird thing to ask about. Myotonic dystrophy is a  congenital disorder which results in an abnormal skeletal muscle myosin kinase protein. The college answer lists 11 features, but in fact there may be many more. An excellent review by Turner et al (2010) adds a few extra features.  Remixed with the college answer, the full list looks like this:

Neuromuscular phenomena
  • Myotonic facies
  • Wasting of facial muscles, sternocleidomastoids, muscles of distal extremities
  • Ptosis
  • Myotonic spasms (e.g. delay in opening fingers after making a fist)
  • "Warm up phenomenon" - grip strength increases with repeated contractions
  • Slurred speech (pharyngeal myotonia)
  • Percussion myotonia
  • Absent reflexes

Other features

  • Frontal baldness
  • Cardiomyopathy
  • Cardiac conduction defects
  • Cataracts / lenticular opacities
  • Testicular atrophy
  • Intellectual impairment
  • Insulin insensitivity

References

Mudge, Barbara J., Peter B. Taylor, and Abraham FL Vanderspek. "Perioperative hazards in myotonic dystrophy." Anaesthesia 35.5 (1980): 492-495.

Turner, Chris, and David Hilton-Jones. "The myotonic dystrophies: diagnosis and management." Journal of Neurology, Neurosurgery & Psychiatry 81.4 (2010): 358-367.