Myopathies - Myotonic Dystrophy

 

Thank you for asking to examine Harry who presented with upper arm weakness.

 

The most salient findings were symmetrical weakness with the arms, particularly the forearm muscles, associated with myotonia, atrophy of the sternocleidomastoid muscles, and characteristic facial features, which are consistent with myotonic dystrophy.

 

In further detail...

 

On general inspection, the patient was comfortable will nil apparent gait aids. There was/was not frontal baldness. There was/was not characteristic myotonic facies (triangular ‘Hatchet’ facies) with temporalis, masseter and sternomastoid atrophy and/without bilateral partial ptosis. There was/was not evidence of cataracts.

 

In the upper limbs, there was muscle wasting, especially in the forearms, and fasciculations.

 

There was grip myotonia. There was percussion myotonia (tap over the thenar eminence, which causes contraction then slow relaxation of the abductor pollicis brevis).

 

Tone was reduced/increased/normal.

 

There was symmetrical distal weakness in the arms with __/5 power in ____ (mainly in forearm muscles for DM1, but can involve proximal muscles over time. DM2 is neck flexors and finger flexors to begin with, however can often involve more proximal muscles such as the hip girdle early on).

 

Reflexes were reduced in the triceps, biceps, brachioradialis and fingers. However, in general, reflexes preserved in myopathy until late.

 

Coordination was normal.

 

Sensation was normal or.... reduced asymmetrical/symmetrically in a dermatomal/stocking distribution, with reduced sensation to pinprick to ____. There was normal/reduced vibrations sensation to ___. Proprioception as intact/impaired to the ___. (Usually neuropathy is very mild). (Usually sensation is normal, or very mild)

 

In the neck, there was/was not sternocleidomastoid atrophy, associated with weakness of neck flexion. Neck extension was preserved.

 

In the chest, there was gynaecomastia (uncommon).

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​In the legs, there was distal wasting and weakness with foot drop. There was a high steppage gait.

 

On further examination:

• There was/was not evidence of diabetes

• There was/was not evidence of cardiomyopathy or valvular heart disease (MVP), or AF.

• I would like to do a cognitive screen (may have mild cognitive impairment)

 

In summary, Harry presented with upper arm weakness. My findings are a symmetrical weakness with characteristic features suggestive of myotonic dystrophy, without evidence of complicating diabetes and cardiomyopathy.

 

Differential diagnoses:

• Hereditary inclusion body myopathy

• Limb girdle muscular dystrophy

 

I would like to confirm my diagnosis with:

• CK and EMG

• Genetic testing - DM1 is autosomal dominant (CTG repeat in DMPK gene)