Presentation
Right hip pain and limb weakness
Patient Data
There is compression of the right L5 and S1 nerve roots by herniated disc material
These findings are better seen on the axial section where the right S1 root is not seen seperately (yellow) as compared to normal left root (blue).Note the resulting denervation edema in the right gluteus minimus muscle. it also shows atrophy with fatty infiltration suggesting that these are chronic changes.
Case Discussion
Subacute muscle denervation causes edema uniformly throughout an involved muscle, it does not become evident on MR images until approximately 2–4 weeks after denervation
Pathogenesis is poorly understood.
If normal innervation is restored, the MR imaging findings eventually return to normal .
Atrophy with fatty infiltration suggests irreversible muscle changes.