Which physical findings suggest motor complications of herpes zoster (shingles)?

Updated: Feb 11, 2021
  • Author: Camila K Janniger, MD; Chief Editor: Dirk M Elston, MD  more...
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Although VZV typically invades only sensory nerves (for unknown reasons), viral particles occasionally cross over to the anterior horn of the involved ganglion and cause motor symptoms. These symptoms range from weakness to total paralysis, depending on how many roots of the involved nerve plexus are affected. Whereas most motor involvement (like most sensory involvement) is self-limited, partial or complete paresis can persist indefinitely, particularly when cranial (CN V or VII), phrenic, and extremity nerves are affected.

Paresis may be seen in extraocular muscles, any area of facial innervation, and anywhere along the spinal cord, including the phrenic nerve. Paresis most commonly is observed when muscles of an arm or leg are involved; however, this may be because it is detected most easily at those locations.

Fabian et al reported a patient who had a left upper arm monoplegia after zoster multiplex involving C4, C5, and C6 nerves. [65] The authors believed that the brachial plexus inflammation was an extension of a dorsal ganglionitis. They found that the motor neuropathy was an inflammatory demyelinating process.

Truncal motor involvement may be more common than generally is believed, because both physician and patient easily may overlook a small area of muscle weakness of the central trunk. Paralysis of abdominal musculature can cause a hernial bulge.

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