Concern about prescribing controlled substances underlies, in part, the undertreatment of pain, even in palliative care settings. That the same is true for human immunodeficiency virus (HIV) patients is therefore not surprising, particularly given injection drug use as a risk factor.
Breitbart and DiBiase wisely frame their review of pain and acquired immunodeficiency syndrome (AIDS) with these issues. They begin with a discussion of the high prevalence of pain in HIV patients and make the important point that the problem has not been well studied in women and children. They conclude with practical suggestions for adapting general pain management guidelines to individuals with prior or active substance abuse or addiction.
The Role of Accurate Diagnosis
Pain is a symptom of diverse disease processes, including acute or ongoing visceral or somatic tissue injury, disordered peripheral or central neural activity, and even depression. Because treatment varies widely by specific etiology, the importance of understanding what is causing pain, while seemingly obvious, cannot be overstated.
The prevalence of distal symmetric polyneuropathy (DSP)due to HIV or caused by the nucleoside antiretrovirals didanosine(Drug information on didanosine) (ddI, Videx), zalcitabine(Drug information on zalcitabine) (ddC, Hivid), or stavudine(Drug information on stavudine) (d4t, Zerit) and potentiated by hydroxyureadepends on how the disorder is defined. The condition is nearly ubiquitous in pathologic series and was clinically evident in about one-third of a series of AIDS patients admitted to San Francisco General Hospital. Studies utilizing electrodiagnostic testing, which is more sensitive than clinical evaluation but less so than histologic examination, demonstrate a similarly intermediate prevalence of neuropathy. Hence, not all DSP is painful, and it seems likely that most is minimally symptomatic.
Conversely, not all pain is DSP. While neuropathic pain and headache were each evident in about half of ambulatory patients studied by Hewitt et al, muscle, joint, abdominal, and bone pain each affected over 15% of patients. Thus, it is not appropriate to simply diagnose any and all limb pain as DSP.
A classic "dying back" axonal neuropathy, DSP shares pathogenesis, and hence, clinical features, with the most common types of diabetic and alcoholic polyneuropathy. Symptoms begin symmetrically in the feet, and examination usually reveals depressed or absent ankle jerks and mild distal sensory loss, particularly to vibration. The hands are typically not involved until symptoms, signs, or both ascend to above the midcalf. Weakness is uncommon unless DSP is quite advanced, and bowel and bladder function are spared.