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Grasp Reflex

Exams and Signs

Historical Overview

  • The first description of the grasp reflex is attributed to Janischewsky, who in 1909 coined the term “réflexe saississeur” (grabbing reflex) in a case of Parkinson’s disease with pseudobulbar symptoms.1

Description

  • The grasp reflex—or, more specifically, the palmar grasp reflex—is a primitive, cutaneo-muscular polysynaptic reflex displayed by infants that is frequently tested to evaluate newborns’ neurodevelopmental function.1,2

Pathophysiology

  • The palmar grasp reflex emerges at around 11 weeks in utero and is inhibited or suppressed at about 2-6 months after birth.2
  • The palmar grasp reflex results from an inborn coordination of movements that are ascribed to an instinctive motion that allows a baby to practice grasping and letting go of objects, which is important for grasping the mother’s hands, arms, and breast for nutrition; however, its anatomic basis is not completely understood. In general, primitive reflexes are considered involuntary motor responses that, in most cases, originate in the brainstem triggered by a specific sensory afferent input. Their inhibition is likely produced by higher cortical centers, often with the contribution of lower brainstem centers, and the absence of supratentorial brain structures in hydranencephalic infants does not preclude the elicitation of a strong grasp reflex.1,2
  • Ontogenetically, primitive reflexes are observed in newborn infants and disappear during infancy as a normal step in development, following the process of cortex maturation and white matter myelination. The later reemergence of a palmar grasp reflex in adult life has been linked to the presence of focal lesions or diffuse neurodegeneration involving the frontal lobes and/or their efferent connections.1

Instructions3

  1. Ensure that the infant is awake.
  2. Lay the infant on a flat surface in the symmetrical supine position.
  3. Insert one index finger into the infant’s palm from the ulnar side and apply light pressure to the palm.
  4. Tactile without pressure and nociceptive stimulation of the palm are both inadequate.
  5. Observe if and how the infant responds to the stimulus.

Related Signs and Tests4

  • Plantar grasp reflex
  • Moro reflex
  • Asymmetric tonic neck reflex
  • Galant reflex
  • Step reflex

Diagnostic Performance Characteristics

  • The palmar grasp reflex is regarded as abnormal when it is absent or diminished during the first 6 months of the baby’s life or lasts beyond this time period. An exaggerated reflex can also be abnormal.3
  • The response of the palmar grasp reflex may be less intense during the first and second days after birth. The absence of this reflex usually reflects peripheral (i.e., root, plexus, or nerve) or spinal cord involvement, especially regarding asymmetrical responses, but lesions of the upper brain structures also can affect the response.3
Definition of Positive Result
  • A positive result occurs when the infant flexes all fingers around the examiner’s finger, locking it tightly with the thumb, followed by the other fingers.
Definition of Negative Result
  • A negative result occurs when the infant does not flex the fingers to lock onto the examiner’s finger after the stimulus, or does so in an exaggerated manner.
Comments and Pearls
  • Both the palmar and plantar grasp reflexes are very primitive in the sense that they can be elicited in all normal preterm infants at as early as 25 weeks of postconceptional age During routine ultrasound examination, fetal palmar reflex grasping of the umbilical cord has been repeatedly observed, which first appears at 16 weeks’ gestation. These grasp reflexes are easy to elicit but have been proved to be of distinctive clinical significance for the early detection of infants with neurodevelopmental abnormalities.3
  • The disappearance of the palmar and plantar grasp reflexes is significantly related to the commencement of the voluntary use of hands or standing.3
  • One aspect that could contribute to the failure of accurately defining the anatomic basis of the grasp reflex is the lack of uniform nomenclature and methodology in eliciting the grasp reflex, as well as the different methods used for the diagnosis of concomitant brain lesions.1
References
  1. Mestre, T and Lang, AE. The grasp reflex: a symptom in need of treatment. Mov Disord 2010;25(15):2479-85. PMID: 20848621
  2. Tan, U and Tan, M. Incidences of asymmetries for the palmar grasp reflex in neonates and hand preference in adults. Neuroreport 1999;10(16):3253-6. PMID: 10599829
  3. Futagi, Y, Toribe, Y and Suzuki, Y. The grasp reflex and moro reflex in infants: hierarchy of primitive reflex responses. Int J Pediatr 2012;2012:191562. PMID: 22778756
  4. Futagi, Y and Suzuki, Y. Neural mechanism and clinical significance of the plantar grasp reflex in infants. Pediatr Neurol 2010;43(2):81-6. PMID: 20610116
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