Rationale: Segmental zoster paresis (SZP) is a relatively rare neurologic complication of herpes zoster (HZ), and is characterized by focal asymmetric motor weakness in the myotome that corresponds to skin lesions of the dermatome. The upper extremities are the second most commonly involved regions after the face, and predominantly involve proximal muscles. The pathogenesis of SZP remains unclear; however, most of the reports indicate that it is the inflammation because of the spread of the herpes virus.
Patient concerns: A 72-year-old man without trauma history of the left shoulder joint developed weakness of the left proximal upper extremity 10 days after vesicular eruption of HZ.
Diagnoses: His left shoulder girdle paresis was diagnosed with the upper truncus of the brachial plexus as a HZ complication according to a series of tests, including cervical magnetic resonance imaging (MRI), cerebral fluid analysis, sonography, and electrophysiological studies.
Interventions: Acyclovir and prednisolone were administered during hospitalization to treat SZP. Meanwhile, analgesics and gabapentin were administered to control the patient's neuralgic pain. He also received inpatient (daily) and outpatient (3 times per week) physical therapy along with range of motion and strengthening exercises.
Outcomes: Partial improvement of the strength of the left shoulder girdle, and no improvement of the left deltoid muscle was observed 2 months after the interventions.
Lessons: This case emphasizes that HZ infections may be complicated by segmental paresis and they should be considered in the differential diagnosis of acute paresis in the upper limb. Awareness of this disorder is important because it avoids unnecessary invasive investigations and interventions, leading to suitable treatments with favorable prognosis.