This research indicated that innocuous and noxious thermal as well as mechanical perception was shown to be diminished in lesions of HS patients, suggesting peripheral neuropathy.
Several different pain mechanisms are likely contributors to the pain experienced by patients with hidradenitis suppurativa (HS), according to recent findings, which could imply the necessity for multimodal therapeutic strategies.1
Lesions from HS were found to be insensitive to noxious heat, innocuous thermal stimuli, and light touches, though both lesions and control sites on the back of patients’ hands were found to be hypersensitive to noxious pinprick and deep pressure pain.
The aim of this new research was to define somatosensory profiles in individuals with the skin disease at both affected and unaffected areas in comparison to pain-free reference data, and the research was led by Ali Alsouhibani, PT, PhD, from the Department of Anesthesiology at Emory University’s School of Medicine in Atlanta, Georgia.
“In other chronic painful conditions, effective therapy depends on the underlying pain mechanisms,” Alsouhibani and colleagues wrote. “Assessment of pain mechanisms in patients with HS could aid in identifying effective pain management strategies in HS and individualizing treatments.”2
The investigators recruited individuals with HS diagnoses from Emory University’s Dermatology Clinic in the time period between September 2020 and November 2021.
The rules for eligibility required the existence of at least a single tender HS lesion at the time of a patient’s testing, with exclusion criteria being conditions unrelated to HS leading to chronic pain or neuropathy and recent analgesic medication use within 24 hours of quantitative sensory testing (QST).
The design of the team’s research was cross-sectional. Prior to the QST, the investigators had a comprehensive skin exam conducted by an experienced dermatologist who ended up examining scarring tunnels through the Hurley stage.
Additionally, the dermatologist evaluated severity of HS through the use of the International Hidradenitis Suppurativa Severity Score System (IHS4), and they utilized the Hidradenitis Suppurativa Area and Severity Index–Revised for the rest of the assessment. Study participants self-reported their racial and ethnic data for the study.
The investigators used surveys in order for the research team to gauge patients’ neuropathy, pain, descriptors of pain, itch severity, HS-specific quality of life, depression, quality of life associated with skin disorders, and anxiety.
The research team used several different QST parameters, spanning both innocuous and noxious sensory perceptions of participants. These parameters included the thresholds for detecting warmth, cold, and light touch, as well as thresholds for perceiving heat, cold, pinprick, and deep pressure pain, along with suprathreshold pinprick sensitivity.
Additionally, the study examined temporal summation of pinprick sensations, paradoxical thermal sensations, and dynamic mechanical allodynia, characterized by pain triggered by light stroking of the patient’s skin.
The cross-sectional study ended up using 20 total participants, with 75% being women and a median age of 35.5 years. Additionally, the investigators noted that racial and ethnic backgrounds varied, with 55% being identified as Black, 30% as White, and smaller numbers as Asian or other.
Compared to the results of the healthy controls, lesions from HS were shown to have diminished sensitivity to innocuous cold as well as warmth, light touch, and noxious heat (all P < 0.001). Conversely, lesions were shown to have substantial hypersensitivity to deep pressure types of pain (P < 0.001) and cutaneous pinprick (P = 0.046).
The investigators also noted that hypersensitivity to deep pressure pain, notably, was also seen in the control site (P < 0.001).
Some participants with HS were found to have altered pain processing qualities commonly linked to neuropathic as well as nociplastic pain issues. Such changes were shown to have included hypersensitivity to repetitive pinpricks for 26%, paradoxical thermal sensations for 15%, and pain upon light stroking of the skin with 50%.
“Additional studies that evaluate the association between QST findings and other measures of small nerve fiber function across a broader population of patients with HS are needed to further elucidate cutaneous sensory changes that may contribute to pain and itch in HS,” they wrote.