Prechtl's assessment of general movements: a diagnostic tool for the functional assessment of the young nervous system.

General movements (GMs) are part of the spontaneous movement repertoire and are present from early fetal life onwards until the end of the first half a year of life. GMs are complex, occur frequently, and last long enough to be observed properly. They involve the whole body in a variable sequence of arm, leg, neck, and trunk movements. They wax and wane in intensity, force and speed, and they have a gradual beginning and end. Rotations along the axis of the limbs and slight changes in the direction of movements make them fluent and elegant and create the impression of complexity and variability. If the nervous system is impaired, GMs loose their complex and variable character and become monotonous and poor. Two specific abnormal GM patterns reliably predict later cerebral palsy: 1) a persistent pattern of cramped-synchronized GMs. The movements appear rigid and lack the normal smooth and fluent character. Limb and trunk muscles contract and relax almost simultaneously. 2) The absence of GMs of fidgety character. So-called fidgety movements are small movements of moderate speed with variable acceleration of neck, trunk, and limbs in all directions. Normally, they are the predominant movement pattern in an awake infant at 3 to 5 months. Beside a sensitivity and specificity of 95% each, the assessment of GMs is quick, noninvasive, even nonintrusive, and cost-effective compared with other techniques, e.g., magnetic resonance imaging, brain ultrasound, and traditional neurological examination.