Moro reflex

File:Moro reflex in four-day-old infant.ogv

The Moro reflex in a four-day-old infant: 1) the reflex is initiated by pulling the infant up from the floor and then releasing him; 2) he spreads his arms; 3) he pulls his arms in; 4) he cries (10 seconds)

File:Moro reflex while sleeping.ogv

Moro reflex while sleeping

The Moro reflex is an infantile reflex that develops between 25–30 weeks of gestation and disappears between 3–6 months of age. It is a response to a sudden loss of support and involves three distinct components:<ref name="Edwards 2019"> </ref>

1. spreading out the arms (abduction)
2. pulling the arms in (adduction)
3. crying (usually)

It is distinct from the startle reflex.<ref>Mary Ann,

 Physical Diagnosis in Neonatology. online version, 
  
 Philadelphia:Lippincott-Raven, 
 1998, 
  
  
 ISBN 978-0397513864,</ref> Unlike the startle reflex, the Moro reflex does not decrease with repeated stimulation.<ref name=":0">Suzuki, Yasuhiro, 
 The Grasp Reflex and Moro Reflex in Infants: Hierarchy of Primitive Reflex Responses, 
 International Journal of Pediatrics, 
 
 Vol. 2012,
 pp. 1–10,
 DOI: 10.1155/2012/191562,
 PMID: 22778756,
 PMC: 3384944,</ref>

The primary significance of the Moro reflex is in evaluating integration of the central nervous system.<ref> </ref><ref>Suzuki, Yasuhiro,

 The Grasp Reflex and Moro Reflex in Infants: Hierarchy of Primitive Reflex Responses, 
 International Journal of Pediatrics, 
 
 Vol. 2012,
 pp. 1–10,
 DOI: 10.1155/2012/191562,
 PMID: 22778756,
 PMC: 3384944,</ref>

Eliciting the Moro Reflex

Ernst Moro elicited the Moro reflex by slapping the pillow on both sides of the infant's head. Other methods have been used since then, including rapidly lowering the infant (while supported) to a sudden stop and pinching the skin of the abdomen. Today, the most common method is the head drop, where the infant is supported in both hands and tilted suddenly so the head is a few centimeters lower than the level of the body.<ref name=":0" />

Clinical Significance

The Moro reflex may be observed in incomplete form in premature birth after the 25th week of gestation, and is usually present in complete form by week 30 (third trimester).<ref name="Edwards 2019"/> Absence or asymmetry of either abduction or adduction by 2 to 3 months age can be regarded as abnormal, as can persistence of the reflex in infants older than 6 months.<ref name=":0" /> Furthermore, absence during the neonatal period may warrant assessment for the possibility of developmental complications such as birth injury or interference with brain formation.<ref name=":0" /> Asymmetry of the Moro reflex is especially useful to note, as it is almost always a feature of root, plexus, or nerve disease.<ref>Joseph J.,

 Neurology of the newborn, 
  
 Saunders/Elsevier, 
  
  
  
 ISBN 9781416039952,</ref>

The Moro reflex is impaired or absent in infants with kernicterus.<ref>

Kernicterus(link). NORD (National Organization for Rare Disorders).

Accessed 2019-08-06.

</ref>

An exaggerated Moro reflex can be seen in infants with several brain damage that occurred in-utero, including microcephaly and hydrancephaly.<ref> Multiple authors. Moro Reflex - an overview(link). ScienceDirect Topics.

Accessed 2019-08-01.

</ref> Exaggeration of the Moro reflex, either due to low threshold or excessive clutching, often occurs in newborns with moderate hypoxic-ischemic encephalopathy.<ref> </ref> The Moro reflex is also exaggerated in infants withdrawing from narcotics.<ref>Chasnoff, Ira J.,

 The Moro Reaction: A Scoring System for Neonatal Narcotic Withdrawal, 
 Developmental Medicine & Child Neurology, 
 
 Vol. 26(Issue: 4),
 pp. 484–489,
 DOI: 10.1111/j.1469-8749.1984.tb04475.x,</ref>

Persistence of the Moro reflex beyond 6 months of age is noted only in infants with severe neurological defects, including cerebral palsy.<ref>,

 Adams and Victor's Principles of Neurology, 
 9th edition, 
 New York:McGraw-Hill Medical, 
 2009, 
  
  
 ISBN 9780071499927,</ref><ref>Agarwal, Anil, 
 Cerebral palsy in children: An overview, 
 Journal of Clinical Orthopaedics and Trauma, 
 
 Vol. 3(Issue: 2),
 pp. 77–81,
 DOI: 10.1016/j.jcot.2012.09.001,
 PMID: 26403442,
 PMC: 3872805,</ref>

History

The Moro reflex was first described in western medicine by Austrian pediatrician Ernst Moro (1874–1951) in 1918. Moro referred to it as the Umklammerungsreflex (embracing reflex).<ref name=":1" /> In this publication, he stated: "When a young infant is placed on the examination table and one taps with hands on both sides of the pillow, there follows a rapid symmetrical extending abduction of both extremities, which approach each other in adduction immediately thereafter". According to him, this reflex should disappear after the infant's first 3–6 months of life. Since then, the moro reflex has been used to detect early neurological problems in infants.<ref name=":1">Weirich, Angela,

 Ernst Moro (1874–1951)—A great pediatric career started at the rise of university-based pediatric research but was curtailed in the shadows of Nazi laws, 
 European Journal of Pediatrics, 
 
 Vol. 164(Issue: 10),
 pp. 599–606,
 DOI: 10.1007/s00431-005-1703-2,</ref> Absence or prolonged retention of Moro reflex can be signs that the infants need neurological attention.<ref>

</ref>

Function

The Moro reflex may be a survival instinct to help the infant cling to its mother. If the infant lost its balance, the reflex caused the infant to embrace its mother and regain its hold on the mother’s body.<ref name=berk>Laura E.,

 Child Development. online version, 
 8th edition, 
 Boston:Pearson, 
 2009, 
  
  
 ISBN 978-0-205-61559-9,</ref>

External links

• Medline Plus: Moro reflex
• Video of the Moro Reflex from the University of Utah (Google Video)
• Pathologic Moro Reflex in an adult following acute demyelinating lesion of unknown origin in the medulla oblongata (Neurology)