"In this randomized clinical trial, smoked cannabis at maximum tolerable dose (1–8% THC), significantly reduced neuropathic pain intensity in HIV-associated DSPN [distal sensory predominant polyneuropathy] compared to placebo, when added to stable concomitant analgesics. Using verbal descriptors of pain magnitude from DDS [Descriptor Differential Scale], cannabis was associated with an average reduction of pain intensity from ‘strong’ to ‘mild to moderate’. Also, cannabis was associated with a sizeable (46%) and significantly greater (vs 18% for placebo) proportion of patients who achieved what is generally considered clinically meaningful pain relief (eg X30% reduction in pain; Farrar et al, 2001). Mood disturbance, physical disability, and quality of life all improved significantly for subjects during study treatments, regardless of treatment order."

Source

Ellis, Ronald J; Toperoff, Will; Vaida, Florin; van den Brande, Geoffrey; Gonzales, James; Gouaux, Ben; Bentley, Heather; and Atkinson, J. Hampton, "Smoked Medicinal Cannabis for Neuropathic Pain in HIV: A Randomized, Crossover Clinical Trial," Neuropsychopharmacology (Nashville, TN : American College of Neuropsychopharmacology, 2009), Vol. 34, p. 678.
http://www.nature.com/npp/jou…