Postherpetic neuralgia (PHN) is a chronic pain syndrome that can be resistant to treatment, leading to physical and social disability, psychological disturbances, and potentially persisting for years . The varicella-zoster virus remains latent in the sensory neurons of individuals who have previously contracted varicella (chickenpox). Reactivation of the latent virus results in herpes zoster (HZ). In most patients, HZ initially presents with dermatomal pain, and within a few days, characteristic dermatomal vesicular eruptions typically develop. These skin lesions usually heal within 2-4 weeks; however, pain may persist even after the resolution of the rash .

The pathogenesis of PHN involves increased sensitization of central neurons, decreased function of inhibitory neuronal pathways, inflammation and nerve injury within the peripheral nervous system, and abnormal signal transmission following such damage. PHN represents the most common complication of HZ. It occurs in approximately 9-19% of all patients with HZ. The incidence of PHN increases with advancing age: it affects approximately 2% of individuals younger than 50 years, about 20% of those older than 50 years, and nearly 35% of those older than 80 years . Various treatment modalities, including pharmacologic agents and interventional procedures, are available for the management of PHN-related pain. This study primarily aims to evaluate the change in pain in PHN patients who underwent SPSIPB using the NRS-11. The secondary aim was to evaluate the effect of SPSIPB on neuropathic pain characteristics using the DN-4 scale and to investigate its effects on patients' quality of life using SF-12 scale.

After obtaining approval from the relevant ethics committee (University of Health Sciences, Istanbul Kanuni Sultan Suleyman Training and Research Hospital, KAEK/2025.05.139), patients over 18 years of age who underwent a single-session ultrasound (US)-guided serratus posterior superior intercostal plane block (SPSIPB) in the thoracic region (T1-T10 dermatomes) due to PHN between June 2023 and February 2025 were retrospectively evaluated. SPSIPB was performed in patients whose complaints persisted despite existing medical treatments. The study was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all patients enrolled in the study, which was carried out at the pain clinic of a tertiary care hospital. This retrospective, single-center cohort study was designed.

A total of 34 patients who met the inclusion criteria were included in the study .

Patients were excluded if they had cervical disc herniation; a history of trauma or surgery involving the neck, shoulder, or back; malignancy; kyphoscoliosis; a history of inflammatory diseases (e.g., rheumatoid arthritis, ankylosing spondylitis); congenital spinal anomalies; neck pain accompanied by neurological deficits; pregnancy; mental or psychotic disorders; hematologic diseases causing bleeding or coagulation disorders; use of antiplatelet or anticoagulant drugs or medications predisposing to bleeding; severe systemic infections such as sepsis; local infections at the planned intervention site; known allergies to any of the drugs to be used; or a history of invasive procedures for PHN in the thoracic region within the past 3 months.

Data Collection and Assessment Scales The following data were collected: Age, gender, body mass index (BMI), affected side in PHN, duration of PHN and affected dermatome, history of HZ vaccination (live/recombinant), data regarding immunosuppression (Human Immunodeficiency Virus, active cancer, high-dose steroids), PHN family history, level of procedure performed, complications, Numeric Rating Scale-11 (NRS-11), Neuropathic Pain Questionnaire (DN4), Short Form-12 (SF-12) quality of life index subscores and average daily tramadol (mg/day) consumption before and 1 and 3 months after the procedure were recorded.

Medication Management Patients' gabapentinoids and antidepressants (amiltriptyline, duloxetine, etc.) used for PHN were continued. Tramadol doses were either increased or decreased for pain control after SPSIPB. Total daily average tramadol consumption was recorded before, at the end of the first and third months after the procedure.

Inclusion Criteria:

Patients over 18 years of age

- who underwent a single-session ultrasound (US)-guided serratus posterior superior intercostal plane block (SPSIPB) in the thoracic region (T1-T10 dermatomes) for PHN between June 2023 and February 2025 were evaluated. -SPSIPB was performed in patients whose complaints persisted despite existing medical treatments.

Exclusion Criteria:Patients were excluded if they had cervical disc herniation -a history of trauma or surgery involving the neck, shoulder, or back; -malignancy- kyphoscoliosis; a history of inflammatory diseases (e.g., rheumatoid arthritis, ankylosing spondylitis)

• congenital anomalies of the spine; neck pain accompanied by neurological deficits
• pregnancy
• mental or psychotic disorders
• hematologic diseases causing bleeding or coagulation disorders
• use of antiplatelet or anticoagulant drugs or other medications predisposing to bleeding
• severe systemic infections such as sepsis
• local infection at the planned intervention site
• known allergy to any of the drugs to be used; or a history of invasive procedures for PHN in the thoracic region within the past three months.

Patients over 18 years of age who underwent a single-session ultrasound (US )guided serratus posterior superior intercostal plane block (SPSIPB) in the thoracic region (T1-T10 dermatomes) for PHN between June 2023 and February 2025 were evaluated. SPSIPB was performed in patients whose complaints persisted despite existing medical treatments.