Neuropathic Vs. Nociceptive Pain in Adolescent Sickle Cell Disease (SCD) Evaluated by a Computer-Based Self-Assessment Pain Tool.

Pain remains the most frustrating and debilitating symptom of sickle cell disease (SCD). Yet, because pain is a perception of a sensation, objective assessment of pain remains elusive. In order to achieve adequate pain control, it is imperative that the patient be able to effectively communicate with the physician regarding the extent, severity and quality of the pain, as well as the response of the pain to the therapeutic intervention. Moreover, SCD pain may have two components, nociceptive (due to organ/tissue injury) and neuropathic (due to somatosensory system lesion or disease), with differing pathophysiologies, and differing responses to pain medications. PAINReportIt® is a multi-dimensional computerized, self-assessment pain reporting tool based on the McGill Pain Questionnaire (MPQ). The MPQ has been validated for adolescents and adults. However, the PAINReportIt®, which was developed originally for the evaluation of cancer pain, has not previously been used in adolescents, nor in the study of adolescents' SCD pain. The purpose of this study was to examine the frequency with which pain experienced in various body areas by adolescents and young adults had characteristics consistent with nociceptive and neuropathic pain.

Inclusion criteria included an SCD diagnosis (SS, SC or S-beta thal) and age at least 14 years. Patients attending two pediatric/adolescent comprehensive sickle cell clinics were invited to participate. Consenting subjects were first instructed and then allowed to complete the PAINReportIt® tool, in which they marked their painful sites on a graphic body outline, selected pain quality descriptors from word lists provided by the computer, and for each site they matched each site to the pain quality descriptors that represented the site. The descriptors included sensory descriptors that are known to be characteristic of either neuropathic pain or nociceptive pain.

PAINReportIt® tools were completed by 49 SCD subjects, whose ages ranged from 14 to 27 years (mean, 18 +/− 2.6 years). For analysis, the body was divided into nine segments, and the computer analyzed the marked painful body outline sites and identified the body segments involved. Descriptive statistics were used to determine the frequency for which each body segment included a painful site, and the frequencies for which that site was characterized as having neuropathic or nociceptive pain qualities, or both. These results are summarized in the Table below.

As the Table shows, virtually all body segments were frequently involved with pain, the upper back and legs being the most frequently reported, and the lower back the least (Column 1). For body segments reported as painful, few were reported as having only nociceptive (Column 2) or neuropathic (Column 3) pain qualities. The majority of painful sites were described by subjects as having mixed pain qualities (Column 4). As Column 5 shows, from 76% to 100% of all painful sites were characterized as having a neuropathic pain component. When the number of descriptors associated with each site was reviewed (data not shown), the right leg was matched to the largest number of neuropathic descriptors (Aching, Burning, Cold, Drilling, Flickering, Numb, Penetrating, Radiating, Shooting, Spreading, Tight, Tingling). The upper back was matched to the largest number of nociceptive descriptors (Beating, Cramping, Crushing, Gnawing, Hurting, Piercing, Pounding, Pressing, Pulsing, Sharp, Sore, Splitting, Squeezing, Tender, Throbbing).

When utilizing a computer-based self-reporting pain tool, SCD patients overwhelmingly describe a neuropathic component to their pain as well as a nociceptive component. The high frequency of neuropathic pain has been underappreciated, and this may contribute to the difficulty in managing sickle cell pain, since this pain component is not well controlled by opioid analgesics.

No relevant conflicts of interest to declare.