Inclusion Criteria:

1. Age 21 years or older.
2. Sporadic or familial ALS diagnosed as definite, probable or possible ALS as defined by revised El Escorial criteria.
3. Evidence of hypoventilation at Screening with at least one of the following:
   1. Maximal static inspiratory pressure (MIP) <60 cm H20.
   2. Upright or supine forced vital capacity (FVC) <50% predicted for gender, age, and height.
4. Both hemi-diaphragms must be able to be stimulated with a recordable compound muscle action potential (CMAP ≥ 0.1milivolts amplitude and distal latency ≤ 11 milliseconds) with standard phrenic nerve conduction studies.
5. Subjects must not have taken riluzole for at least 30 days, or be on a stable dose of riluzole for at least 30 days, prior to randomization (riluzole-naïve subjects are permitted in the study).
6. Capable of providing informed consent and following trial procedures.
7. Geographically accessible to the site.
8. Negative urine pregnancy test at Screening in women of child bearing potential (WOCBP). (Women who are post-menopausal or who have had a hysterectomy are deemed not of child bearing potential).
9. Women of child bearing potential must use an adequate form of contraception: abstinence, hormonal contraception (oral contraception, implanted contraception, injected contraception or other hormonal (patch or contraceptive ring, for example) contraception), intrauterine device (IUD) in place for ≥ 3 months, barrier method in conjunction with spermicide, or another adequate method.

Exclusion Criteria:

1. Upright forced vital capacity (FVC) ≤ 45% of predicted for gender, age, and height.
2. Any prior use of non-invasive ventilation (NIV) outside of sleep (nighttime or naps).
3. Any pulmonary or cardiac disorder or other medical disorder that would be a contraindication for general anesthesia or DPS hardware implantation in the chest.
4. Implanted electrical device such as a pacemaker or cardiac defibrillator.
5. Known diaphragm abnormality such as hiatal hernia or para-esophageal hernia of abdominal contents into the thoracic cavity.
6. Participation in another treatment research study for people with ALS.
7. Exposure to any other agent currently under investigation for the treatment of people with ALS (off-label use or investigational) within 30 days of the Screening Visit.
8. Clinically significant history of unstable or severe cardiac, oncologic, hepatic, psychiatric, renal disease, or other medically significant illness.
9. Pregnant women or women currently breastfeeding.