Postural Reflexes

Postural reflexes are automatic movements that control the equilibration we require once upright and moving and having to combat the effects of gravity.

• Origin: Controlled by higher centers (Midbrain, Basal Ganglia, Cortex).
• Pattern: unlike Primitive reflexes (which are present at birth and disappear), Postural reflexes appear during infancy and generally persist throughout life.
• Function: They provide the basis for voluntary movement, posture, and balance.

CLASSIFICATION AND TIMELINE

They are broadly classified into three groups based on their function.

1. RIGHTING REFLEXES (Midbrain Level)

These reflexes are responsible for maintaining the head in the vertical position and aligning the body segments.

A. Labyrinthine & Optical Righting

• Test: Blindfold child (Labyrinthine) or open eyes (Optical), suspend vertically and tilt. Head orients to vertical.
• Significance: * Head Control: Their emergence (2-4 months) correlates directly with the acquisition of head control.
  • Delay: Indicates general developmental delay or hypotonia.

B. Landau Reflex

• Test: Suspend infant horizontally in prone position.
• Response: Extension of head, trunk, and hips ("Airplane posture").
• Timeline: Appears 3 months, peaks 6-8 months, disappears 12-24 months.
• Clinical Significance:
  • Hypotonia: The infant collapses into an inverted "U" shape (Floppy infant).
  • Hypertonia/Spasticity: Excessive extension or scissoring may be seen.
  • Absence: Strong indicator of motor dysfunction (e.g., Cerebral Palsy).

C. Body-on-Body (BOB) & Neck-on-Body (NOB)

• Test: Rotate the head to one side (NOB) or rotate the hips (BOB).
• Response:
  • Immature (0-4 mo): Log rolling (body turns as a solid block).
  • Mature (6+ mo): Segmental rolling (shoulders rotate, then pelvis follows).
• Significance: Segmental rolling indicates cortical maturation and the ability to dissociate body parts, essential for crawling and walking.

2. PROTECTIVE / PARACHUTE REACTIONS (Cortical Level)

Also known as Propping reactions. These occur when the body is displaced such that the center of gravity moves outside the base of support.

A. Anterior Parachute

• Test: Suddenly thrust the infant downwards towards the surface while holding the waist.
• Response: Extension of arms and opening of hands to break the fall.
• Timeline: Appears 6 months; Persists.
• Clinical Significance:
  • Asymmetry: The most sensitive sign for mild Hemiplegia. The arm on the affected side will not extend or will extend slowly with a fisted hand.
  • Absence: Seen in severe quadriparesis or severe cognitive delay.

B. Lateral and Posterior Propping

• Timeline: Lateral (7 months), Posterior (9 months).
• Significance:
  • Determines the readiness for Independent Sitting. A child cannot sit safely alone until lateral propping is established (Tripod sitting).
  • Posterior propping allows the child to pivot while sitting.

3. EQUILIBRIUM REACTIONS (Cortical Level)

These are subtle adjustments of trunk tone to maintain balance when the supporting surface is tilted.

• Test: Tilt the child on a rocker board or bed.
• Response: Curving of the trunk against the tilt and extension of extremities on the uphill side (to shift center of gravity back).
• Significance:
  • Prerequisite for Standing and Walking.
  • If a child has righting and protective reflexes but lacks equilibrium reactions, they may stand but will fall frequently.

SUMMARY OF CLINICAL UTILITY

1. Early Diagnosis of Cerebral Palsy (CP)

The "Motor Quotient" for CP diagnosis relies on the interplay of reflexes:

• Classic CP Pattern: Retention of Primitive Reflexes (e.g., ATNR, Moro) + Delayed/Absent Postural Reflexes.
• Example: A 9-month-old with a persistent Moro and absent Parachute reflex has a high probability of CP.

2. Localization of Lesions

• Asymmetry: In Parachute or Placing reactions suggests hemiparesis.
• Level of Injury:
  • Absent Righting = Midbrain damage.
  • Absent Equilibrium = Cortical/Basal Ganglia damage.

3. Prognostication

• The timely appearance of postural reflexes is a better predictor of eventual ambulation than the mere disappearance of primitive reflexes.
• The presence of the Landau reflex is a good prognostic sign for eventual standing.