Cervical Root Enlargement in Segmental Zoster Paresis: A Study with Magnetic Resonance Imaging and Nerve Ultrasound

A 72-year-old woman presented with acute-progressive muscle weakness after a rash in the left upper limb. Muscle weakness was restricted to the left C5 innervated muscles. Short inversion time inversion recovery magnetic resonance imaging (MRI) showed a high-intensity signal in the left C5 nerve root, and nerve ultrasound showed its enlargement. She was diagnosed with segmental zoster paralysis (SZP) and treated with acyclovir and methylprednisolone. Her muscle strength gradually recovered, and the abnormal signal and enlargement in the left C5 nerve root improved. This is the first SZP case of confirmed improvement of abnormal findings on MRI and nerve ultrasound in association with muscle power recovery.