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.
On this page:
Pathology
Causes include 2:
- neuropathy
- autoimmune disorders
- viral infection
- prolonged nerve compression
- nerve infiltration by neoplasm
- penetrating injury
- Parsonage-Turner syndrome
Radiographic features
MRI
In the very early stage, muscle signal may be normal.
Acute denervation
- 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
Subacute and chronic denervation
- features are less specific
- muscle atrophy and fatty infiltration with an increase in T1 signal
- heterogeneous edema-like signal