Abstract Bensmail D, Marquer A, Roche N, Godard A-L, Lofaso F, Quera-Salva M-A. Pilot study assessing the impact of intrathecal baclofen administration mode on sleep-related respiratory parameters. Objective To assess the impact of intrathecal baclofen (ITB) mode of administration on sleep and sleep-related breathing events in severely disabled patients with severe spasticity. Design Open prospective trial. Setting Physical medicine and rehabilitation department. Participants Patients (N=11) treated with ITB pump for severe spasticity. Intervention Assessment of patients' sleep before and after ITB pump implantation, and comparison of polysomnography results after continuous or bolus mode of administration of ITB. Main Outcome Measures Polysomnography and sleep-related breathing events. Results ITB reduced periodic limb movements and increased the respiratory disturbance index (RDI) and central apneas in our population of patients. This study showed that ITB mode of administration may affect sleep-disordered breathing. Indeed, we observed a significant increase of respiratory events in the bolus condition (RDI and central apneas). In contrast, continuous infusion did not induce a significant modification of sleep-disordered breathing. When a sleep apnea syndrome was preexisting, it was generally severely worsened by the bolus mode of administration. Conclusions These results indicate that sleep function and sleep-related respiratory events should be assessed before ITB pump implantation. It is probably better to use a continuous mode of infusion if patients have preexisting sleep-disordered breathing.