Fentanyl-Induced Neurotoxicity and Paradoxic Pain Tomasz R. Okon, MD, Mathews Lal George, MD  Journal of Pain and Symptom Management  Volume 35, Issue 3, Pages 327-333 (March 2008) DOI: 10.1016/j.jpainsymman.2007.04.023 Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

Fig. 1 Pain scores (shaded bars) and micrograms of fentanyl/hour (light bars) captured at 12 hour intervals. The graph temporally follows the patient's progress in three settings: (1) Pl-4=preadmission, (2) Al-11=days of hospitalization at the referring hospital prior to the transfer, and (3) Tl-5=days after the transfer. Arrow 1 depicts occurrence of severe sedation and objective respiratory depression recorded on day A6 prior to transfer; naloxone (0.4 mg) was administered. Arrow 2 (day T2) indicates the period of documented neurotoxicity and paradoxical pain (see text for detail). Bracket A shows time in which the “severe” descriptors of pain scores are represented as 8.5/10, since no numeric pain intensity scores (scale=1-10) were documented (records state: “intractable” and “severe”). Bracket B shows the time frame in which numeric pain scores (scale=1-10) were systematically recorded every 4 hours. Conversions of opioids made the following potency assumptions: intravenous morphine: intravenous fentanyl=1:100, oral tramadol: oral morphine=1:4. No distinction is made between transdermal and intravenous fentanyl. Medication dose reflects total amount given over 12 hour periods, all represented or converted to μg/hour of fentanyl. Journal of Pain and Symptom Management 2008 35, 327-333DOI: (10.1016/j.jpainsymman.2007.04.023) Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions