Long-term follow-up of spinal cord stimulation to restore cough in subjects with spinal cord injury

Abstract

Objective: To determine the long-term effects of the cough stimulation system.

Design: Nonrandomized clinical trial of subjects using the study device well beyond the period of close follow-up.

Setting: Use of the study device in the home setting.

Participants: Subjects (N = 10) implanted with the device for a minimum of 2 years (mean 4.6 ± 0.6 years).

Interventions: Application of daily stimulation.

Outcome measures: Airway pressure generation and other clinical assessments including ease in raising secretions, life quality, caregiver support, and incidence of respiratory tract infections were measured at 1 year and mean 4.6 years after implantation.

Results: Each subject continued to use the device on a regular basis. During SCS, mean maximum airway pressures were 103.1 ± 20.4 and 107.7 ± 23.0 cm H₂O at the 1-year and mean 4.6-year follow-up points, respectively (P < 0.05 compared with pre-implant and not significantly different (NS) compared with 1-year follow-up). Benchmarks related to ease in raising secretions and improvements in life quality related to respiratory care were maintained at the mean 4.6 year follow-up. The need for trained caregivers to provide other means of secretion management remained significantly below the pre-implant values (P < 0.05). The incidence of acute respiratory tract infections remained low at 0.2 ± 0.1 events/year, which is significantly below the pre-implant value of 1.4 ± 0.3 events/year (P < 0.05).

Conclusion: Subjects continued to use the system on a long-term basis beyond the period of close follow-up and to continued derive significant clinical benefits.

Keywords: Cough; Expiratory muscles; Spinal cord stimulation.

Figure 1

Airway pressure generation during spontaneous efforts pre-implant (left panel) and during SCS after 1 year (middle panel) and mean 4.6 years (right panel) of follow-up. See text for further explanation.

Figure 2

Subject responses to frequency of need for conventional means of secretion clearance, severity of such episodes, difficulty in raising secretions and change in ease in raising secretions using the cough stimulation system compared with previous methods. Compared to pre-implant, there were significant improvements in all parameters of secretion management at 1-year follow-up (P < 0.05). This improvement was maintained at the mean 4.6-year follow-up assessment (P < 0.05 compared with pre-implant; NS compared with 1-year follow-up).

Figure 3

Subject responses to life quality assessment related to secretion management. There was improvement in most parameters at 1-year follow-up. These were maintained at the mean 4.6-year follow-up.

Figure 3

Subject responses to life quality assessment related to secretion management. There was improvement in most parameters at 1-year follow-up. These were maintained at the mean 4.6-year follow-up.

Figure 4

Compared with pre-implant, there were significant reductions in the need for caregiver support to manage secretion clearance at 1-year follow-up (P < 0.05). This reduction was maintained at the mean 4.6-year follow-up (P < 0.05 compared with pre-implant; NS compared to 1-year follow-up).

Figure 5

There was a significant reduction in the incidence of acute respiratory tract infections after 1 year of use of the cough stimulation system from 1.4 ± 0.3 to 0.3 ± 0.2 events/year (P < 0.05). The incidence of respiratory tract infection was further reduced at the mean 4.6-year follow-up point to 0.2 ± 0.1 events/year (P < 0.05 compared with pre-implant; NS compared with 1-year follow-up).