Range of motion, or ROM, refers to the degree of movement in a person's joints. Passive ROM is often used to assess muscle tone and maintain joint mobility in infants and people with mobility disorders. In passive ROM, the subject does not use his muscles to move his arms, legs and other extremities. Another person, such as a nurse or occupational therapist, moves the parts of the body and tests reflexes.
Disorders
A baby who exhibits too little resistance in passive ROM exercises may have hypotonia. For example, in the heel-to-ear tone test, a baby whose foot reaches her ear with no resistance has hypotonia. There are many possible causes of hypotonia, including muscular dystrophy, brain damage and Down syndrome. A baby exhibiting too much resistance may have hypertonia. Hypertonia may indicate cerebral palsy.
Arms
Most passive ROM arm exercises are done while the baby is in the supine position, lying flat on his back. When a baby's right hand is pulled across the neck toward the left shoulder, the elbow should not pass the midpoint of the chest and the right hand should not pass the left shoulder. When the forearms are held close to the chest, then extended and released, the arms should return to the flexed position in a motion called "recoil." Asymmetrical or absent recoil may indicate a disorder.
Hands
Newborns typically hold their hands curled into a fist, with the thumb on the inside. When the hand is stimulated by touching the back of the hand or base of the palm, the fingers should extend. Placing a finger in the center of the baby's palm should trigger a grasping motion. Babies who maintain the closed fist consistently after age 2 months may have a neurological disorder.
Legs
Infants typically keep their limbs tucked close to their bodies at rest. When a baby's leg is lifted at the ankle, the knee should remain slightly flexed. When the legs are held in the flexed position with the knees near the ribcage, then rapidly extended and released, the legs should return to the flexed position. When lifting the leg back toward the head, the foot should reach to about chest level.
Feet
A baby's toes should fan out when the bottom of the foot is stroked from heel to center. The toes point upward in a motion known as the Babinski reflex when the ball of the foot is stimulated. The Babinski reflex lasts until about 12 months of age.
Caution
Do not attempt to perform passive range of motion exercises on an infant without medical advice and supervision. Performed incorrectly, ROM exercises can result in serious injury to the baby.
