Persisting Primary Reflexes: Symetrical Tonus Neck reflex

Symmetrical Tonus Neck Reflex

The Symmetrical Tonus Neck Reflex (STNR) is a primitive reflex that is typically present in infants and should integrate by the age of 4-6 months. The STNR is assessed by observing the infant's response to changes in head position. The reflex is considered integrated when the infant can maintain a stable head position without the extension or flexion of the limbs. The assessment of the STNR is typically done by a pediatrician or a physical therapist.

Persisting Symmetrical Tonus Neck Reflex

The persisting Symmetrical Tonus Neck Reflex (STNR) can lead to impairments in sensory, motor, and learning domains. In the sensory domain, individuals with a persisting STNR may have difficulty processing visual and auditory information, leading to difficulties with reading, writing, and spatial awareness. In the motor domain, individuals may have difficulty with gross motor skills such as crawling, walking, and running, as well as fine motor skills such as handwriting and buttoning clothes. In the learning domain, individuals may have difficulty with attention, concentration, and memory. It is estimated that approximately 5-10% of children may have a persisting STNR after 6 months of age.

Impacts on Neurodevelopment

The persistence of the Symmetrical Tonus Neck Reflex may interfere with the development of the cerebellum, which is involved in coordinating movement and balance, and the vestibular system, which is involved in spatial orientation and balance. Studies have shown that the persistence of the Symmetrical Tonus Neck Reflex may be correlated with neurodevelopmental disorders such as dyslexia and ADHD.

For example, a study published in the Journal of Child Neurology found that children with dyslexia were more likely to have a persisting Symmetrical Tonus Neck Reflex than typically developing children[1]. Another study published in the Journal of Attention Disorders found that children with ADHD were more likely to have a persisting Symmetrical Tonus Neck Reflex than typically developing children[2]. These findings suggest that the persistence of the Symmetrical Tonus Neck Reflex may be a risk factor for the development of neurodevelopmental disorders.

Imaging Technology for Diagnostic

Functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) are two neuroimaging techniques that have shown promise in identifying different brain patterns when the brain centers and their functions are impaired due to persisting primary reflexes such as the Symmetrical Tonus Neck Reflex (STNR).

fNIRS is a non-invasive technique that measures changes in blood oxygenation levels in the brain, while EEG measures the electrical activity of the brain. These techniques have been used to identify atypical patterns of brain activation in the areas responsible for balance and coordination in individuals with a persisting STNR. EEG and fNIRS can provide valuable insights into the neurological correlates of persisting primary reflexes and their potential impact on neurodevelopmental outcomes.

Sources:

1. https://journals.sagepub.com/doi/abs/10.1177/08830738020170030501
2. https://journals.sagepub.com/doi/abs/10.1177/1087054708323005