To the Editor, The Moro reflex is one of the most frequently used primitive reflexes in the general pediatric practice all over the world. It is best elicited by a sudden dropping of the baby’s head in relation to its trunk [1–3]; Moro himself elicited this reflex by hitting the infant’s pillow with both hands [4]. Moro reflex may show variable reaction patterns. According to Towen [2] and Prechtl and Beintema [3] the patterns of Moro reflex can be classified into distinct responses ranging from light extension of the arms and spreading of the fingers only, till evident abduction/extension and subsequent adduction/flexion of the arms occasionally with cloni.
The normal response consists of extension and abduction of the upper extremities with subsequent adduction and flexion, but many authorities consider a positive response only an extension/abduction of the arms, even without a flexor phase (maturity effect usually seen beyond the 3rd month of life) [5]. It appears at 28–32 weeks of gestation and disappears before 6 months of age [1–3].
Absence, asymmetry or diminution of the reflex in the first months of life, or persistence beyond the 6th month, indicates neurological dysfunction [1–4]. As part of a prospective study regarding the prognostic significance of primitive reflexes [6], postural reactions [7] and other neurological signs (i.e. ankle clonus) [8], we had the chance to examine the Moro reflex longitudinally in a series of 204 high-risk infants at 1, 3, 5, 7, 9 and 11 months of life. At follow-up at 3 years of age, 58 children developed cerebral palsy (CP) (13 spastic tetraplegia, 24 spastic diplegia, 12 spastic hemiplegia, seven athetoid CP and two ataxic CP), 22 children had developmental retardation without motor disturbance (DR) and 124 children had a normal development.
Moro reflex was elicited in the same way as described in most standard textbooks and was considered only present or absent regardless of the intensity of the response. Our primary goal was to determine whether the total absence of the Moro reflex in the first months of life, or its presence after the 6th month of life could be of prognostic importance in high-risk infants. Moro reflex was also considered as absent in cases of a pure unilateral response; an asymettrical response was not considered as pathological, as already pointed out by Dubowitz [9]. For premature infants the age at the time of each examination was expressed as the corrected age according to the expected birth date. The results are summarised in Table 1.
Moro reflex disappeared at the 5th month of life in 86.3{f607f86846ba214ecc118a24d8f221d0f6091e2f284aa65c23a2cf36879dc8e8} of children with a normal development; in the 7th month the reflex was retained in only one child. In the first 3–5 months of life, statistically fewer CP children demonstrated a positive Moro reflex compared to normal children ( P , 0.001).
The above results were reversed at the 5th month in patients with spastic diplegia and at the 7th month in patients with spastic tetraplegia and hemiplegia ( P , 0.001); this reflex positivity was further retained till the 11th month of life (P , 0.001). In the vast majority of athetoid patients (88.9{f607f86846ba214ecc118a24d8f221d0f6091e2f284aa65c23a2cf36879dc8e8}), Moro reflex was consistently present from birth till the 11th month ( P , 0.001 from the 5th month). Patients with ataxic CP demonstrated no difference in Moro reflex profile compared to normal children; however, the number of patients was too small to allow any definite conclusions. Finally, in children with DR, the Moro reflex persisted from 5th till 9th month of life ( P , 0.001 and P , 0.05 compared to normal children), disappearing completely afterwards. The above results suggest that Moro reflex remains a Brain & Development 21 (1999) 216–217
