Sub-study to Spinal Cord Stimulation to Restore Cough

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. In fact, pneumonia
is a major cause of death in this patient population.

In a recent clinical trial, we have shown that the expiratory muscles can be electrically
activated by spinal cord stimulation (SCS), a technique which involves the surgical placement
of disc electrodes on the surface of the spinal cord. This method is successful in achieving
an effective means of expiratory muscle activation, as demonstrated by the generation of
large airway pressures and peak airflow rates. Importantly, SCS facilitates secretion
removal, reduces the need for caregiver support, reduces the incidence of respiratory tract
infections and improves life quality. This method therefore has the potential to reduce
health care costs and improve survival in spinal cord injured subjects.

The purpose of this trial is to directly compare activation of the expiratory muscles using
wire electrodes, which can be inserted percutaneously through a needle, with the previously
employed disc electrodes.

In this trial, researchers will study 6 adults (18-70 years old) with spinal injuries (T5
level or higher), at least 12 months following the date of injury. After an evaluation
including medical history, a brief physical examination, and initial testing, each
participant will undergo a surgical procedure to implant small electrodes (metal discs) over
the surface of the spinal cord on the lower back to stimulate the expiratory muscles and
restore cough. Prior to permanent implantation of this system, wire and disc electrodes will
be compared by assessing the degree of expiratory muscle activation with each electrode type.
The disc electrodes will then be permanently implanted, allowing the participant to have use
of a fully functioning stimulation system to restore an effective cough.

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