Spinal Cord Stimulation to Restore Cough

The purpose of this trial is to determine the efficacy of spinal cord stimulation to produce an effective cough in patients with spinal cord injuries.

Patients with cervical and thoracic spinal cord injuries often have paralysis of a major portion of their expiratory muscles - the muscles responsible for coughing - and therefore, lack a normal cough mechanism. Consequently, most of these patients suffer from a markedly reduced ability to clear airway secretions, a factor which contributes to the development of recurrent respiratory tract infections such as pneumonia and bronchitis. Expiratory muscles can be activated by electrical stimulation of the spinal roots to produce a functionally effective cough. The purpose of this trial is to determine if electrical stimulation of the expiratory muscles is capable of producing an effective cough on demand. According to the trial researchers, if successful, this technique will prevent the need for frequent patient suctioning - which often requires the constant presence of trained personnel. It will also allow spinal cord injured patients to clear their secretions more readily, thereby reducing the incidence of respiratory complications and associated illness and death. In the trial, researchers will study 18 adults (18-70 years old) with spinal injuries (T5 level or higher), at least 12 months following the date of injury. After an evaluation of medical history, a brief physical examination, and initial testing, participants will have small electrodes (metal discs) placed - by a routine surgical procedure - over the surface of their spinal cords on the lower back to stimulate the expiratory muscles and restore cough.

Spinal Cord Injuries, Spinal Cord Diseases, Paralysis, Central Nervous System Diseases, Cough, Trauma, Nervous System, Wounds and Injuries

Participants will have small electrodes (metal discs) placed - by a routine surgical procedure - over the surface of their spinal cords on the lower back to stimulate the expiratory muscles and restore cough. These electrodes are then activated at subsequent study visits using the external control unit.

The expiratory muscle stimulator consists of three small electrodes (metal discs) implanted over the surface of their spinal cords on the lower back to stimulate the expiratory muscles and restore cough. These electrodes are connected to an implanted receiver in the abdomen or chest wall. The device is activated through an external antenna connected to an external control box.

Effectiveness of Expiratory Muscle Activation to Generate Large Airway Pressures Characteristic of Normal Cough.

Airway pressure generation achieved with SCS cough system at the baseline (pre-implant) and 1 year follow up (post-implant).

Effectiveness of Expiratory Muscle Activation to Generate High Peak Airflows Characteristic of Normal Cough.

Peak airflow achieved with SCS cough system at the baseline (pre-implant) and 1 year follow up (post-implant).

The incidence of acute respiratory tract infections, defined by a change in the character, color, or amount of respiratory secretions and requiring antibiotic administration was tracked over the 2-year period prior to implantation of the cough system. The occurrence of respiratory tract infections was determined by subject history and corroborated by review of medical records, when available. After implantation of the cough system, the incidence of acute respiratory tract infections was tracked continually.

The degree of caregiver support was determined as the number of times it was necessary for a caregiver to provide the subject with any form of assistive means of secretion clearance including suctioning, manually assisted cough or use of the insufflation-exsufflation device. Caregiver support was evaluated over a 2-week period prior to implantation of the cough stimulation system and continuously over the course of the initial year and again at the 1-year follow-up.

Inclusion Criteria: Stable spinal cord injury T5 level or higher Expiratory muscle weakness Exclusion Criteria: Significant cardiovascular disease Active lung disease Brain disease Scoliosis, chest wall deformity, or marked obesity

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DiMarco AF, Kowalski KE, Hromyak DR, Geertman RT. Long-term follow-up of spinal cord stimulation to restore cough in subjects with spinal cord injury. J Spinal Cord Med. 2014 Jul;37(4):380-8. doi: 10.1179/2045772313Y.0000000152. Epub 2013 Nov 26.

DiMarco AF, Geertman RT, Nemunaitis GA, Kowalski KE. Comparison of disc and wire electrodes to restore cough via lower thoracic spinal cord stimulation. J Spinal Cord Med. 2022 May;45(3):354-363. doi: 10.1080/10790268.2021.1936388. Epub 2021 Jul 7.