Lower Thoracic Spinal Cord Stimulation to Restore Cough in Patients with Spinal Cord Injury: Results of a National Institutes of Health-Sponsored Clinical Trial Part I: Methodology and Effectiveness of Expiratory Muscle Activation

Arch Phys Med Rehabil, 2009 · DOI: 10.1016/j.apmr.2008.11.013 · Published: May 1, 2009

Spinal Cord Injury Pulmonology Neurology

Simple Explanation

This study explores using electrical stimulation of the lower spinal cord to improve coughing in people with tetraplegia (paralysis of all four limbs). Tetraplegia often weakens the muscles needed for coughing, making it hard to clear the airways. The researchers implanted electrodes near the spinal cords of participants and then applied stimulation to activate the expiratory muscles, which are crucial for generating a strong cough. The goal was to see if this stimulation could produce strong enough airway pressures and airflow rates to mimic a normal, effective cough.

Study Duration

28 weeks with follow up at 3 and 6 month intervals

Participants

9 subjects (8 men, 1 woman) with cervical spinal cord injury and weak cough

Evidence Level

Clinical trial

Key Findings

1
Lower thoracic spinal cord stimulation (SCS) can effectively activate expiratory muscles in individuals with tetraplegia.
2
The stimulation resulted in high positive airway pressures and peak airflow rates, approaching those seen in normal cough efforts.
3
Combined stimulation at two different spinal levels (T9, T11, and L1) produced the best results, without significant added benefit from stimulating all three levels.

Research Summary

This study evaluated the use of lower thoracic spinal cord stimulation (SCS) to restore cough function in patients with tetraplegia. The researchers hypothesized that SCS would activate expiratory muscles and generate sufficient airway pressures and airflow rates for effective coughing. Nine participants with cervical spinal cord injuries received surgically implanted stimulation systems. The system stimulated the T9, T11, and L1 spinal levels. The study found that SCS effectively activated expiratory muscles, resulting in significant airway pressure and peak airflow generation. Combined stimulation at two spinal levels was most effective. These findings suggest SCS has the potential to improve cough function, reduce respiratory complications, and enhance the quality of life for individuals with SCI.

Practical Implications

Improved Airway Clearance

SCS can potentially help SCI patients clear airway secretions more effectively, reducing reliance on manual suctioning and assisted coughing.

Reduced Respiratory Complications

By improving cough effectiveness, SCS may lower the risk of atelectasis and recurrent respiratory infections, which are major causes of morbidity and mortality in SCI patients.

Enhanced Patient Independence

Restoring cough function through SCS could increase patient mobility and independence by reducing the need for caregiver assistance with airway management.

Study Limitations

1
Accurate measurement of airway pressure and airflow was highly dependent upon operator technique and subject cooperation.
2
Procedurally related complications included mild edema at the receiver site in 5 subjects which generally resolved over several weeks.
3
In two other subjects, 1 of the 3 leads was not functional.

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