A randomized, double blind, double-dummy placebo controlled, 3-way cross-over study to determine the test-retest reliability of, and the effect of oral retigabine and riluzole on, peripheral motor nerve excitability measurements in patients with ALS.

1. Ability to understand the purpose and risks of the study and provide signed and dated informed consent.
2. Aged 18 to 80 years old, inclusive, at the time of informed consent.
3. Women of childbearing potential must practice effective contraception for the duration of the study.
4. Willing to limit the intake of alcohol to no more than 2 units per day from the screening visit to the the last scheduled visit and to refrain from alcohol intake 48 hours prior to each study visit until their stay in the clinical research unit. One unit of alcohol is defined as 1 pint of beer (350 mL), 1 glass of wine (150 mL) or 1 shot of liquor (30 mL).
5. Willing to refrain from marijuana use throughout the study.
6. Willing to refrain from vigorous exercise within 48 hours prior to each study visit.
7. Must have a diagnosis of *definite*, *probable*, or *probable laboratory-supported*, ALS according to the World Federation of Neurology El Escorial criteria (revised according to the Airlie House Conference 1998 [Brooks 1999]).
8. Fasciculations in the arms observed by the treating neurologist

1. History of diabetes or neuropathy.
2. History of neuromuscular disorders (other than ALS) including but not limited to ALS mimic syndromes, myopathy, myasthenia gravis, and other motor neuron diseases.
3. Median nerve CMAP less than 1 mV.
4. Unstable cardiac, pulmonary, renal, hepatic disease or active malignancy.
5. Clinically significant abnormalities in laboratory test results as judged by the investigator. In the case of uncertain or questionable results, laboratory tests performed during the screening visit may be repeated 1 time before participation in the study to confirm eligibility or may be judged to be clinically irrelevant.
6. History or symptoms of any clinically significant cardiac, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal, and ophthalmologic or other major disease, as determined by the investigator (with the exception of the neurological syndrome listed in the inclusion criteria section).
7. 12-lead ECG demonstrating QTcB >450 msec at Screening.
8. Concomitant disease or condition that can interfere with the conduct of the study, or that in the opinion of the investigator, would pose an unacceptable risk to the subject in this study.
9. History of trauma to the upper extremities or other orthopaedic conditions that, in the opinion of the investigator, could affect the electrophysiological measurements.
10. Use of medications including but not limited to anticholinergics and muscle relaxants that, in the opinion of the investigator, could affect the electrophysiological measurements within 2 weeks prior to first dosing or within 6 times the elimination half-life of the medication prior to first dosing (whichever is longer).
11. Current enrolment in any interventional clinical study in which treatment with an investigational drug or approved therapy for investigational use is administered within 30 days prior to the screening or participation in an interventional study for an investigational drug or device within 3 months prior to Screening.
12. Pregnant, breastfeeding, or a positive pregnancy test result at Screening.
13. A positive urine test for drugs of abuse at Screening.
14. Unwillingness or inability to comply with study requirements.
15. Unspecified reasons that, in the opinion of the Investigator, make the subject unsuitable for enrollment.