Herpes zoster (HZ), also known as shingles, is caused by the varicella-zoster virus
(VZV). Approximately 1/4 of the global population is affected by HZ, with statistics
showing that about 90% of shingles patients experience acute neuralgia, and about 1/3
develop postherpetic neuralgia (PHN) after shingles. In PHN patients, about 30%-50% of
the pain can persist for more than one year, and some cases can last for more than 10
years. PHN is a common complication of HZ characterized by intense pain in the area where
the rash has healed, often described as burning, electric shock-like, or stabbing pain,
severely affecting patients' sleep, emotions, work, and daily life. Additionally,
approximately 43% of PHN patients exhibit symptoms of toxic anxiety or depression,
significantly impacting their quality of life and increasing the societal burden. Due to
the global aging population, the incidence of HZ and PHN is expected to significantly
increase in the next 10 years, making effective prevention and treatment of PHN an urgent
health issue. Although various treatments are available for PHN, a small number of
patients remain unresponsive to multiple therapies, resulting in treatment-resistant
chronic pain. The lack of a clear understanding of the underlying mechanisms contributes
to the suboptimal treatment outcomes for PHN. Elastography, a technique that quantifies
the mechanical properties of tissues by measuring their natural elasticity, trauma,
degeneration, and healing processes, has shown promise as an innovative approach. Shear
wave elastography (SWE) has been used to study the biomechanical characteristics of
skeletal muscles by measuring the propagation speed of shear waves induced by ultrasound
to quantify the shear elastic modulus, which characterizes the stiffness of soft tissues.
In this study, the investigators intend to use elastography to observe the elasticity of
muscle tissue in the lesions of PHN patients, with the unaffected side serving as a
control. Elastography offers non-invasive, convenient, and straightforward advantages,
further contributing to providing new directions for treatment and revealing the role of
muscle tissue in PHN by offering new evidence. It also offers new treatment options and
targets for PHN patients. While treatment of PHN is primarily focused on neural
mechanisms due to HZ's neurotropism nature, recent evidence suggests that muscle tissues
within the affected regions may also experience pathological changes, that contribute to
the pain. These changes could reveal novel therapeutic targets and enhance patient
prognosis. This study aims to investigate these muscular changes and explore myogenic
pain mechanisms in PHN patients. It employs ultrasound elastography to compare muscle
elasticity between the affected and unaffected sides and conduct muscle biopsies for
pathophysiological analysis to uncover the underlying mechanisms.