3 MONTH OLD: NORMAL EXAM
Behavior
This baby is almost 3 months old. He is alert and attentive to the environment and the examiner. He visually tracks. He has a social smile and is able to frown. There is definite social awareness and interaction.
Cranial Nerves
The vestibulo-ocular reflex evokes a full range of conjugate eye movements. The baby should also be able to visually track 180 degrees in the horizontal plane. Facial expression is full and symmetric.
Motor - Upper Extremity Tone
In the newborn, flexor tone is predominate. After the first few weeks, the flexor tone is less. Passive range of motion is still met with resistance but with the appropriate amount. The hand pulled across the body to the opposite shoulder still does not extend beyond the shoulder.
Motor - Hand Movements
The hand is now held in a more open position. The infant will hold on to an object when placed in his hand but will not yet reach for the object. At this age, the infant may start to bat at objects. He also watches his hands.
Motor - Lower Extremity Tone
Tone in the lower extremities is present with the appropriate resistance to passive range of motion. The tight flexor tone of the newborn is no longer present.
Motor - Head and Trunk Control
When pulled to a sitting position, a baby this age should be able to have only slight head lag and, when sitting, the head should be upright but there may still be some wobbling of the head. The back is still rounded, so the baby slumps forward.
Positions - Supine
In the supine position, the baby’s extremities are held off the mat and there is spontaneous movement of all extremities. During the first 3 months of life, babies will often lie with their head turned to one side or the other. This may be associated with extension of the arm that the head is turned towards. This is part of the asymmetric tonic neck reflex, which is most prominent during this time but diminishes by 3 to 4 months of age and is gone by 6 months of age.
Positions - Prone
In the prone position, the baby is now able to bring his head up and look forward with the head being 45 to 90 degrees off the mat. Weight is borne on the forearms. When the head and chest are well off the mat, the baby is ready to start to roll from the prone to the supine position. Rolling front to back usually occurs at 3 to 5 months of age. Rolling over too early can be due to excessive extensor tone.
Positions - Ventral Suspension
In ventral suspension, the baby’s posture is very similar to the prone position. The trunk and legs are in the same plane and the back is kept straight. The head is above the body looking forward. The baby is able to maintain a forward-looking position.
Positions - Vertical Suspension
In vertical suspension with the feet touching the mat, the baby should start to support some weight with his legs. Bearing weight on the legs is the earliest postural reflex to appear and usually is present at 3 to 4 months of age. The baby’s shoulder girdle is strong and there is no slipping through the examiner’s hands.
Reflexes - Deep Tendon Reflexes
One of the main obstacles to obtaining deep tendon reflexes at this age is catching the extremity at rest. Positioning the extremity is also important. As demonstrated in this baby, a crossed adductor can be seen at this age and still be normal but should not persist beyond 7 months of age. A few beats of ankle clonus can be normal in the first few weeks of life but sustained ankle clonus at any age is abnormal.
Reflexes - Plantar Reflex
Stroking the lateral aspect of the plantar surface of the foot still elicits a strong “Babinski sign” which is an up-going great toe and fanning of the other toes.
Primitive Reflexes - Root
The baby still has a root reflex and turns the mouth towards the stimulus. The rooting reflex disappears at about 4 months of age.
Primitive Reflexes - Moro
The baby no longer has a Moro reflex. Usually the Moro reflex is absent by 4 to 5 months of age. Persistence of the Moro reflex beyond this time can be seen with upper motor neuron disorders.
Primitive Reflexes - Galant
The Galant reflex is still present but should diminish and be gone by 4 months of age.
Primitive Reflexes - Grasp
The palmer grasp reflex is still present for this baby. The grasp reflex is usually gone by 4 to 6 months of age for the hands and 6 to 12 months for the toes. The reflex palmer grasp is gradually replaced by the voluntary activity of reaching and grasping with the hand.
Primitive Reflexes - Asymmetric Tonic Neck
The asymmetric tonic neck reflex is present in the first 3 to 4 months of life. When the head is turned to one side, the ipsilateral arm and leg will extend while the contralateral extremities will be in flexion. The baby should be able to overcome this reflex and move out of this posture. If the asymmetric reflex is obligate (the infant can not move out of or overcome the reflex) or if the reflex persists beyond 6 months of age, then it is abnormal and can be seen in upper motor neuron disorders.