Heterogeneous sensory processing in persistent postherniotomy pain

Eske Kvanner Aasvang, Birgitte Brandsborg, Troels Staehelin Jensen, Henrik Kehlet

    58 Citations (Scopus)

    Abstract

    Previous studies on sensory function in persistent postherniotomy pain (PPP) have only identified pressure pain threshold to be significantly different from pain-free patients despite several patients reporting cutaneous pain and wind-up phenomena. However the limited number of patients studied hinders evaluation of potential subgroups for further investigation and/or treatment allocation. Thus we used a standardized QST protocol to evaluate sensory functions in PPP and pain-free control patients, to allow individual sensory characterization of pain patients from calculated Z-values. Seventy PPP patients with pain related impairment of everyday activities were compared with normative data from 40 pain-free postherniotomy patients operated >1 year previously. Z-values showed a large variation in sensory disturbances ranging from pronounced detection hypoesthesia (Z = 6, cold) to pain hyperalgesia (Z = -8, pressure). Hyperalgesia for various modalities were found in 80% of patients, with pressure hyperalgesia in ∼65%, and cutaneous (mechanical or thermal) hyperalgesia in ∼35% of patients. The paradoxical combination of tactile hypoesthesia and hyperalgesia was seen in ∼25% of patients. Increased pain from repetitive tactile and/or brush stimulation was found in 51%, suggesting a role of altered central nociceptive function in this subpopulation. A high incidence (26%) of pressure hyperalgesia was found in the contralateral groin, with a significant correlation (rho = 0.58, p = 0.002) to the hyperalgesic level on the painful side, again suggesting central nervous mechanisms in PPP. In conclusion, this study shows that a standardized trauma results in heterogeneous combinations of hypo- and hyperalgesia. Z-score evaluation of sensory function identifies subpopulations in PPP, which may be used in selecting surgical and/or pharmacological treatment strategies.

    Original languageEnglish
    JournalPain
    Volume150
    Issue number2
    Pages (from-to)237-42
    Number of pages6
    ISSN0304-3959
    DOIs
    Publication statusPublished - 1 Aug 2010

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