Spurts of activity can refer to both ADOS and SPASMS. ADOS stands for Attention Deficit/Hyperactivity Disorder Symptoms, which is a mental disorder characterized by difficulty focusing, impulsivity, and hyperactivity. SPASMS stands for Spontaneous Periodic Activity Syndrome, which is a neurological disorder that causes sudden, involuntary muscle contractions. Both ADOS and SPASMS involve sudden, unexpected bursts of activity.