Objectives: Intrathecal (IT) drug administration is an advanced technique in pain treatment algorithm for patients poorly responsive to systemic pharmacological treatment or less invasive techniques. The aim is to improve analgesia lowering side effects; despite this premise, many side effects of long-term IT therapy have been described, mainly related to opioid administration. We observed, in some of the patients regularly followed for pump refills in our Pain Unit, the appearance of excessive daytime sleepiness (EDS) interfering with daily life and work activity; this study aims to investigate the incidence of EDS in patients on IT analgesia with opioid or non-opioid drugs and its possible relationship with respiratory problems during sleep.
Materials and methods: 21 patients on IT therapy for chronic pain answered the Epworth Sleepiness Scale (ESS). The incidence of EDS in patients receiving IT opioids was compared to a control group not receiving opioids. In 10 patients, who performed polysomnography (PSG) and maintenance of wakefulness test (MWT) for sleep complaints, we studied the relationship between PSG data and ESS scores and we verified the concordance of ESS and MWT results.
Results: 38% of the patients reported EDS, according to ESS data; all the patients with EDS were receiving an IT opioid. Even if some patients presented sleep apneas, we failed to correlate this data with daytime sleepiness. Subjective sleepiness is confirmed by the results of MWT.
Conclusion: Our data demonstrate that EDS is a frequent and important side effect of IT analgesia and it seems related to opioids administration.