Segmental Zoster Paresis: A Literature Review

Abstract

Background: Herpes zoster is an acute infectious skin disease that is induced by the re-activation of the virus incubated in nerve ganglions following initial infection with varicella-zoster virus in childhood. Herpes zoster mainly affects sensory nerves, resulting in severe acute pain, which is also the most common reason for medical intervention in this patient group. The concurrent involvement of motor nerves could induce the symptoms of segmental zoster paresis, which is manifested by localized asymmetric myasthenia, whose range generally follows the distribution of myomere with skin rashes. Due to the low incidence and unspecific clinical manifestations, segmental zoster paresis has not been sufficiently recognized by clinicians, and can easily be misdiagnosed. Objective: To summarize the previous studies on segmental zoster paresis and analyze the pathogeneses, diagnosis, and treatment of this disease, as well as stress the challenges in current treatment, which could provide useful evidence for the clinical diagnosis and better the treatment of patients with segmental zoster paresis in the future. Study Design: We conducted a narrative review. Setting: Hospitals, neurology departments, pain departments, and private practices. Methods: We searched PubMed and Chinese CNKI libraries using the terms “herpes zoster,” “muscle paresis,” “segmental zoster paresis,” and “motor nerve.” Clinical trials, reviews, and case reports were collected and reviewed. Results: As a rare complication following varicella-zoster virus infection, segmental zoster paresis has not been sufficiently recognized by clinicians, and there are still no guidelines available to guide the clinical treatments. The exact mechanism of segmental zoster paresis is still unclear. Electromyographic and magnetic resonance imaging examinations could be used as auxiliary diagnostic methods for segmental zoster paresis. Early regular anti-viral therapy could substantially decrease the risk of herpes zoster related complications. Combined application of glucocorticoids and some other physical therapy may also be useful in certain patients. The general prognosis of segmental zoster paresis is relatively good, with 67% patients achieving complete or almost complete recovery of the muscle function. Limitations: More clinical trials are needed to clarify the exact mechanisms and best treating methods. Conclusion: As the symptom in most segmental zoster paresis patients is self-limited, and the patients’ prognosis is generally good, early diagnosis of the disease is especially important, due to the avoidance of unnecessary diagnostic procedures and incorrect treatments. Standard treatment guidelines regarding the functional rehabilitation are still needed for patients with refractory segmental zoster paresis. Key words: Herpes zoster, postherpetic neuralgia, segmental zoster paresis, muscle strength, motor nerve, spinal dorsal ganglion, zoster infection, muscle paresis