Yong Liu,1 Hui Liu,2 Queqiao Bian,1 Shuhuan Zhang,1 Yanmin Guan3 

1Department of Dermatology & STD, the Third Central Hospital of Tianjin; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases; Artificial Cell Engineering Technology Research Center, Tianjin Institute of Hepatobiliary Disease, Tianjin, People’s Republic of China; 2Tianjin Institute of Hepatobiliary Disease, Tianjin, People’s Republic of China; 3Department of Tuberculosis, Tianjin Haihe Hospital, Tianjin, People’s Republic of China

Correspondence: Yong Liu, Department of Dermatology & STD, the Third Central Hospital of Tianjin, No. 83, Jintang Road, Hedong District, Tianjin, 300170, People’s Republic of China, Tel +8602284112488, Email liuyongtj@163.com

Background: Herpes zoster (HZ) typically manifests in the acute phase with distinct blisters and severe neuropathic pain. Remarkably, a subset of patients initially presents with only a mild skin rash and moderate pain that gradually intensifies, following a parabolic pattern. Despite being frequently observed in clinical settings, the underlying causes of this trajectory and its potential connection with post-herpetic neuralgia (PHN) remain unclear.
Methods: To investigate this phenomenon in-depth, we conducted a meticulous retrospective study involving 529 eligible HZ patients. All these patients sought medical care at the Third Central Hospital of Tianjin, China, between January 2020 and December 2023.
Results: The research identified that 14.6% of the sample (77 patients) experienced pain scores aligning with a parabolic curve. This trend was significantly more prevalent in patients aged 60 and above, accounting for 90.9% of this group, and demonstrated a positive correlation with age. Moreover, 87.0% of these patients had pre-existing medical conditions, highlighting the potential role of comorbidities in influencing the pain trajectory. A concerning 45.5% of patients sought medical attention more than seven days after the onset of symptoms, a delay that could exacerbate neurological damage. Notably, among those following a parabolic pain pattern, 66.2% eventually developed PHN, a considerably higher rate compared to the broader patient population.
Conclusion: We emphasize that healthcare practitioners meticulously assess patients who initially report lower pain scores for high-risk factors potentially leading to parabolic pain increases, including being over 60 years old, having comorbid conditions, and delaying medical consultation beyond seven days from symptom onset. Early implementation of supplementary pain management therapies may mitigate the risk of PHN development and enhance the quality of life for patients. This study furnishes clinicians with a deeper understanding of the variations in HZ-related pain trajectories, promising to improve treatment approaches and prognoses for HZ patients while paving the way for enriched clinical practice in the future.

Keywords: parabolic pain trajectory, herpes zoster, post-herpetic neuralgia, delayed-onset pain, adjunctive analgesics, early intervention strategies