Denervation changes in muscles

Last revised by Mohamed Saber on 26 Feb 2021

Denervation changes in muscles or denervation myopathy can be observed in a number of settings and results from partial or complete loss of innervation.

There is a wide spectrum of clinical manifestations:

  • temporary or permanent
  • symptomatic or asymptomatic.

Causes include 2:

  • neuropathy
  • autoimmune disorders
  • viral infection
  • prolonged nerve compression
  • nerve infiltration by neoplasm
  • penetrating injury
  • Parsonage-Turner syndrome

In the very early stage, muscle signal may be normal.

  • the earliest and most pathognomonic feature is increased T2 signal (best seen on a fat-saturated T2WI such as STIR) representing muscle edema
  • normal muscle contrast enhancement
  • muscle bulk is normal
  • causative lesions may be apparent such as:
    • tumor compressing or displacing the neurovascular bundle
    • nerve discontinuity due to penetrating trauma
  • features are less specific
  • muscle atrophy and fatty infiltration with an increase in T1 signal
  • heterogeneous edema-like signal

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