Neuro-Development

The foundation of neurologic teaching is "localization of the lesion". A diagnosis is made when a patient's age, developmental level, and neurologic signs are compared to known diseases that effect the Central Nervous System to produce developmental disruption or pathologic signs or symptoms.

Neuro-Development proceeds in an age-dependent, programmed order.

Developmental systems:
  1. Language Development
  2. Social Development
  3. Gross Motor Development
  4. Fine Motor Development
Signs of neuro-developmental pathology
  1. Failure of developmental progress at an age appropriate time (Developmental Plateau)
  2. Asymmetrical development or movement or reflexes
  3. Loss of previously acquired developmental skills
Basic Neurobiologic Correlates

Language development has the highest correlation with future cognitive development.
Language and cognitive skills are dependent on the Gray matter, neurons. Hypertonia & Hyper-reflexia:
  • Upper motor neuron (motor cortex, corticospinal tracts)
  • Hypotonia & Hypo-reflexia:
    • Lower motor neuron, (nerve or muscle),
    • central brainstem, metabolic-toxic (global)
Areflexia (no reflexes): Lower motor neuron (anterior horncell or nerve fiber pathology)

Primitive Reflexes

Primitive Reflexes are nervous system mediated responses to stimulation that vary with age, developmental level and pathologic conditions.
  • Moro
    • Appears: 28-32 weeks
    • Disappears: 5-6 months
  • Stepping reflexes
    • Disappears: 4-5 months
  • Tonic Neck Reflexes
    • Disappears: 6 months
  • Palmar Grasp
    • Appears: 28 weeks
    • Disappears: 4-5 months
  • Plantar Grasp
    • Appears: 40 weeks
    • Disappears: 9-12 months
  • Parachute Reaction
    • Appears: 4-9 (avg. 6) months
Head Size

Head Circumference is a way to estimate brain growth. The HC is one of the few objective areas of the neurologic exam. The HC is a number with known normal values and typical pattern of change over time in the healthy child. Therefore, a deviation of the HC from normal is a marker for possible neurologic pathology. There are 2 commonly used HC charts. The preferred is the Nellhaus Chart (Nellhaus G, Composite International and Interracial Graphs, Pediatrics, 41:106, 1968.) This chart goes from birth to age 18 years and contains full 2 standard deviation (SD) boundries for 2% to 98%.

All HCs should be plotted on a standard HC chart. As a rule of thumb, the mean HC at 40 weeks gestation is 34 cm. The range of two standard deviations is 36 cm to 32 cm. The head grows 2 cm/month in the first 3 months, 1 cm/month for the next 3 months and then 0.5 cm/month for the next 6 months.

Macrocephaly

enlarged head, greater than 2 SD above expected for age and sex Causes of Macrocephaly
  • Familial (measure and plot the parents HCs)
  • subdural fluid collections
  • hydrocephalus
  • space occupying lesion
  • metabolic diseases (Tay-Sachs, Canavan's, Alexanders)
  • syndromes (NF-1, Sotos')
Microcephaly

small head, less than 2 SD below expected for age and sex

Causes of Microcephaly
  • CNS insult with brain loss
  • IUGR
  • cerebral dysgenesis
  • Fetal EtOH syndrome
  • Rett's Syndrome (acquired microcephaly)
Developmental Milestones
  • 8 weeks (2 months): Head held bobbing erect sitting, Head held in mid-position prone
  • 16 weeks (4 months):Head held mid-line while supine, Engages hands while spine
  • 28 weeks (6-7 Months):Lifts head while supine, Sits erect momentarily, Supports most of weight while standing and bounces, Grasp, hold 1 object and grasp for a second, transfers hand to hand
  • 52 weeks (12 Months):Walks with 1 hand held, 3 word vocabulary (Moma, Dada,...), Tries to stack blocks after demonstration (but fails), Releases cube unto a cup after demonstration, Tries to copy inserting pellet in a bottle, Looks at a round shape
  • 24 Months: Runs without falling, Walks up and down stairs, Kicks large ball, Builds a 6-7 cube tower, Aligns 2 cubes to form a train, Inserts square block into a square hole, Copies vertical and attempts circular drawing
  • 3 Years: Builds a 10 cube tower, Strings beads, Cuts with scissors, Copies a circle and draws a person's head, Copies a bridge with cubes, Matches forms, Repeats 3 digits, and recites Nursery rhymes
  • 4 Years: Walks down stairs by alternating feet, Tandem walks forward, Balances on one foot for 5 seconds, Throws ball over hand and broad jumps, Copies a square and draws a person's head and body, Knows basic colors, Understands 4 prepositions
  • 5 Years: Copies a triangle, Draws a person including arms and legs, Repeats 4 digits, Copies steps with cubes, skips