Purpose: To evaluate the change in signal intensity of skeletal muscles after denervation and to determine the clinical usefulness of magnetic resonance (MR) imaging in diagnosis of denervation.
Materials and methods: Denervated skeletal muscles associated with various forms of peripheral neuropathy and spinal radiculopathy were studied with MR imaging in 17 patients.
Results: On T1-weighted images, signal intensity of denervated muscles was normal in 14 patients and high in three. On T2-weighted images, all denervated muscles showed high signal intensity on at least one MR image. High signal intensity in the denervated muscles on T2-weighted images was observed 15 or more days after onset of paralysis. In two patients, signal intensity of denervated muscles returned to normal after relief of paralysis.
Conclusion: MR imaging is a noninvasive and accurate method for use in diagnosis of denervation and may ultimately eliminate the need for electromyography.