The following symptoms and complaints may indicate spinal muscular dystrophy (SMA):
In the spontaneous course, i.e., without therapy, SMA is characterized by proximal and leg-emphasized, usually symmetrical muscle weakness and atrophy.
The following is a presentation of the symptomatology of 5q-associated spinal muscular atrophy:
| SMA type | Synonyms | Start | Motor skills | Clinical findings |
| 0 | neonatal form | congenital | reduced fetal (infantile) movements | respiratory disturbances at birth |
| 1 | Acute infantile SMA; Werdnig-Hoffmann type. | Within the first 6 months of life | Unable to sit, stand, or walk freely; frog leg posture (bending of legs, angling of knees outward, and angling of feet inward) | Severe muscular hypotonia (“floppy infant”), powerless crying, weak/reduced coughing, dysphagia (dysphagia of swallowing) with pseudohypersalivation (in this case, there is no increased salivation due to increased saliva production, but an inability to swallow saliva effectively to the required degree) |
| 2 | Chronic infantile SMA; intermediate SMA. | 7-18 months of age | Sitting freely is possible, but dependent on walking aids;standing and walking not possible |
Delayed motor development, poor thriving, fine-beat hand tremor (hand tremor), weak/reduced cough thrust, respiratory insufficiency (respiratory weakness) as it progresses; Scoliosis (lateral curvature of the spine) and joint contractures (joint stiffness). |
| 3 | Kugelberg catfish (juvenile SMA) | > 18 months of age | Free standing and walking is learned | Variable expression of muscle weakness and atrophy; fine-beat hand tremor, loss of walking ability is possible over time/falls |
| 3a | < 3 years | |||
| 3b | > 3 years | |||
| 4 | adult SMA | <30 years of age | Free standing and walking is learned | Mild course with ability to walk usually preserved; falls |