Short and Long Term Treatment With 4-AP in Ambulatory SMA Patients

The primary outcome measure will be distance walked in the 6MWT. This measure is an objective evaluation of functional capacity which measures the distance a person can walk quickly in six minutes and is most representative of a person's ability because the test intensity is self-selected. The 6MWT can be safely performed in ambulatory SMA patients and correlates with standard SMA outcome measures including timed walking tests. In SMA, the 6MWT may be more sensitive to clinically meaningful changes in patients with type 3 SMA as it is a direct measure of their functional mobility.

The primary outcome measure will be distance walked in the 6MWT. This measure is an objective evaluation of functional capacity which measures the distance a person can walk quickly in six minutes and is most representative of a person's ability because the test intensity is self-selected. The 6MWT can be safely performed in ambulatory SMA patients and correlates with standard SMA outcome measures including timed walking tests. In SMA, the 6MWT may be more sensitive to clinically meaningful changes in patients with type 3 SMA as it is a direct measure of their functional mobility.

Assessments of motor function are clinically relevant and are a good adjunct to tests of walking ability. The HFMSE, a 33-item scale designed for SMA type 2 and 3 patients, and is associated with minimal patient burden requiring only standard equipment and is completed on average in less than 15 minutes. The HFMSE showed good test-retest reliability and is correlated with other clinical and physiological measures in SMA. The score range is 0 (all items failed) to 66 (all items achieved unaided), with higher score indicating higher level of motor function.

Assessments of motor function are clinically relevant and are a good adjunct to tests of walking ability. The HFMSE, a 33-item scale designed for SMA type 2 and 3 patients, and is associated with minimal patient burden requiring only standard equipment and is completed on average in less than 15 minutes. The HFMSE showed good test-retest reliability and is correlated with other clinical and physiological measures in SMA. The score range is 0 (all items failed) to 66 (all items achieved unaided), with higher score indicating higher level of motor function.

MMT will involve pushing and pulling against the evaluators hand (MMT). The purpose of this test is to measure the strength in different muscles. MMT was performed on 28 muscle groups (8 muscle groups on each leg and 6 muscle groups on each arm), including proximal and distal musculature. The score range for each muscle group is 0 to 10, with a higher score indicating better muscle strength. The total score range is 0 to 280.

MMT will involve pushing and pulling against the evaluators hand (MMT). The purpose of this test is to measure the strength in different muscles. MMT was performed on 28 muscle groups (8 muscle groups on each leg and 6 muscle groups on each arm), including proximal and distal musculature. The score range for each muscle group is 0 to 10, with a higher score indicating better muscle strength. The total score range is 0 to 280.

Motor Unit Number Estimation (MUNE) is a noninvasive test that identifies the number of motor units (motor nerve cells and the territory of muscle fibers they control) using electrical muscle stimulation and recording the response. The nerve conduction study involves the administration of modest electrical stimulations (pulsations or throbbing sensations from low level electricity) to a total of 4 nerves in the right arm and leg while recording the response over a muscle innervated by each nerve. MUNE is calculated by determining the compound motor action potential (CMAP) amplitude or area under the curve of a distal muscle in response to supramaximal stimulation, and then dividing the result by the amplitude or area under the curve of a single motor unit action potential.