Motor Delays
Peter A. Blasco
I. Description of the problem. Delayed motor milestones are the highest-ranked concern of parents with children between ages 6-12 months. Related complaints include vague references to tone abnormalities (“too stiff” or “too weak”), perceived structural abnormalities (most commonly the legs or feet), or an awkward/clumsy gait in the ambulating child.
A. Epidemiology.
The prevalence of significant motor delays in the general pediatric population is not established. By statistical definition, 2%-3% of infants will fall outside the range of normal motor milestone attainment. A minority of these milestone-delayed children (15%-20%) will prove to have a significant neuromotor diagnosis, most commonly cerebral palsy or a birth defect, rarely some progressive nervous system or muscle disease.
Early motor delays in the remainder of children often represent a marker for subtle neurologic dysfunction, which manifests itself more definitively in later childhood as troublesome awkwardness (now referred to diagnostically as developmental coordination disorder), attention deficit syndromes, and/or specific learning disabilities.
II. Making the diagnosis.
A. Evaluation. The clinician should organize data gathered from the history, physical examination, and neurodevelopmental examination into three domains: motor developmental milestones, the classic neurologic examination, and markers of cerebral neuromotor maturation (primitive reflexes and postural reactions).
1. Motor milestones are extracted from the developmental history, as well as from observations during the neurodevelopmental examination (Tables 56-1 and 56-2). Milestone assessment is best summarized as a single (or narrow) motor age for the child. The motor age can be converted to a motor quotient (MQ) giving a simple expression of deviation from the norm: MQ = motor age/chronologic age × 100.
Table 56-1. Gross motor development timetable
Prone
Head up
1 mo
Chest up
2 mo
Up on elbows
3 mo
Up on hands
4 mo
Rolling
Front to back
3-5 mo
Back to front
4-5 mo
Sitting
Sit with support (“tripod” sitting)
5 mo
Sit without support
7 mo
Get up to sit (unassisted)
8 mo
Walking
Pull to stand
8-9 mo
Cruise
9-10 mo
Walk with 2 hands held
10 mo
Walk with 1 hand held
11 mo
Walk alone
12 mo
Run (stiff-legged)
15 mo
Walk up stairs (with rail)
21 mo
Jump in place
24 mo
Pedal tricycle
30 mo
Walk down stairs, alternating feet
3 yr
Table 56-2. Fine motor development timetable
Retain ring (rattle)
1 mo
Hands unfisted
3 mo
Reach
3-4 mo
Hands to midline
3-4 mo
Transfer
5 mo
Take 1-in. cube
5-6 mo
Take pellet (crude grasp)
6-7 mo
Immature pincer
7-8 mo
Mature pincer
10 mo
Release
12 mo
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