UNDERSTANDING ATNR AND RETAINED ATNR: CAUSES, DIAGNOSIS AND TREATMENT

Medically Reviewed by Dr. Rosmy Barrios

As newborns, our bodies have primitive reflexes that help us survive and develop. One of these reflexes is the Asymmetric Tonic Neck Reflex (ATNR), which is also called the "Fencing Reflex". This reflex is essential for a child’s neurological development and plays an integral role in the emergence of coordinated motor skills. However, when this reflex is retained or prolonged, it can significantly impact our physical and cognitive development.

In this article, we will explore what ATNR is, the effects of retained ATNR, and how it can be diagnosed and managed.

What is the ATNR Reflex?

The Asymmetric Tonic Neck Reflex is a primal reflex in newborns and typically disappears within the first 5-7 months of life. When the head is turned to one side, the reflex triggers, causing the arm and leg on that side to extend (like a fencer) while the opposite arm and leg flex, curling up towards the chest. This reflex is essential for developing hand-eye coordination, muscle tone, and motor skills.

The ATNR reflex emerges in the womb and is present at birth. It is a survival reflex that helps newborns navigate the birth canal and adapt to their new environment. As the baby grows and develops, the ATNR reflex becomes integrated into more complex movements, such as reaching and grasping, and eventually disappears.^[1]

What is Retained ATNR?

Retained ATNR, also known as Prolonged ATNR, is when the ATNR reflex persists beyond the typical age of disappearance. This ensues due to various factors, such as birth trauma, delayed development, or neurological conditions.

A persisting ATNR can substantially influence a person's physical and cognitive abilities. For example, it can make it difficult for a baby to bring their hands together to the midline, interfering with feeding, grasping, and other self-care skills. It can also lead to problems with balance, coordination, and posture.

Asymmetrical Tonic Neck Reflex in Adults

While the ATNR reflex is typically associated with newborns, it can also be present in adults with retained ATNR.

In adults, retained ATNR is not the cause of problems, but rather a sign that an underlying issue may be present.^[2].

It connects to many basic brain structures, including the brainstem and the sensory-motor cortex. A lack of development can promote the reflex in adults, which may affect other activities that rely on the same brain areas, impacting cross-pattern movements.

The reflex can manifest as difficulty with fine motor skills, poor balance, and coordination issues. It can also affect eye movements and visual tracking, making it challenging to focus, follow objects, or read^[3].

Several studies suggest that those with retained primitive reflexes, such as ATNR, are at a higher risk for acquiring neurological disorders later in life and developmental disorders during childhood.

Causes of Prolonged or Retained ATNR

The ATNR reflex tends to wane throughout the infant's development, integrating into other movements and reflexes as the child attempts to sit, crawl, and walk on a regular basis. Sensory integration is vital to this process, with movement and other tactile exposures stimulating the brain and paving the way for new growth and development.

In some cases, the infant battles to integrate this reflex. Causes may include physical deficits, a lack of sensory stimulation, or both.

Here are several potential causes of prolonged or retained ATNR that may require medical attention:

• Birth trauma or injury
• Premature birth
• Delayed development
• Neurological conditions such as cerebral palsy^[4] or autism^[5]
• Genetic factors

Risk factors that can interrupt development or promote a lack of stimulation include^[6]:

• Stress during pregnancy
• Substance abuse during pregnancy
• Cesarean section birth
• Brain damage during labor
• Premature and low birth weight babies
• Neonatal intensive care unit stays
• Lack of tummy time or time spent on the tummy, which encourages vital developmental movement
• Excessive time in baby containers like cribs, swings, bouncers, walkers, etc.

Signs of Retained ATNR

The signs of retained ATNR tend to vary in accordance with the individual and the severity of the reflex.

Some common signs include:

• Difficulty with fine motor skills
• Poor balance and coordination
• Difficulty with eye movements and visual tracking
• Developmental delays
• Poor hand-eye coordination
• Muscle weakness or tightness
• Difficulty with writing or other fine motor tasks
• Poor posture
• Difficulty with sports or physical activities

ATNR and ADHD

There is some evidence to suggest a link between retained ATNR and ADHD (Attention Deficit Hyperactivity Disorder). A study published in the Journal of Frontiers of Psychiatry found that children with ADHD were more likely to have retained primitive reflexes, including the ATNR. ATNR was more common among girls than boys, who were more likely to retain STNR (symmetric TNR).

While more research is needed to understand this connection fully, it highlights the importance of addressing retained ATNR in children with ADHD.

When to Seek Professional Help

If you or your child are experiencing any signs or symptoms of retained ATNR, it is essential to seek professional help. A doctor or occupational therapist can diagnose properly and recommend appropriate treatment and management strategies.

Diagnosis of Retained ATNR

The diagnostic process can involve a series of tests to assess the presence and severity of the reflex and may include^[7]:

• Observation of movements and posture
• Assessment of fine motor skills
• Evaluation of eye movements and visual tracking
• Reflex testing
• Medical history review

The "head turn" test is commonly used to assess whether a child's ATNR has been integrated. The child is asked to turn their head to one side while standing or on all fours. The therapist will observe their arms for any changes in movement. This test can help assess the presence and severity of the ATNR reflex.

Treatment and Management of Retained ATNR

Some adults with retained ATNR can learn to integrate the reflex, while others require integration at younger ages.

While there is no cure for retained ATNR, various treatment and management strategies can help improve symptoms and promote development. These are typically formulated and prescribed only after a comprehensive examination to rule out neurological pathologies.

Facilitating Optimal Development

If ATNR retention is observed early, simply facilitating the infant with enough stimulation in a safe environment may swiftly integrate the reflex and correct the issue. Infants must be placed on their stomachs, which encourages them to grapple with moving their head, arms, and legs. They also need space and time to crawl outside a crib or any other limiting factor, such as a walking ring.

Occupational Therapy

Occupational therapy is an effective way to integrate a retained ATNR. An occupational therapist can work with the individual to improve muscle strength, coordination, and balance. They may also recommend targeted exercises to help integrate the ATNR reflex and promote the development of more complex movements.

Targeted Exercises for Retained ATNR

There are several exercises that can help integrate the ATNR reflex and improve symptoms of retained ATNR. These may include:

• Cross crawling: Crawling helps to integrate the ATNR reflex and promotes the development of more complex movements. The child can emulate crawling by trying to crawl on all fours or by tapping an elbow on the opposite knee and vice versa.^[8]
• Tummy time exercises: Laying on the stomach and shifting the head and arms in different positions can help to complete any lacking developmental milestones and integrate the reflex.
• Practicing Midline Movements: Keeping the arms straight while looking ahead can help to strengthen midline movement coordination. The palms should face down, and the child should run on the spot, lifting their knees while looking to the left. After 10 seconds, this can be repeated while they look to the right.

An occupational therapist can offer more exercises to enhance hand-eye and head-arm coordination.

Treating Comorbid Conditions

In some with a retained ATNR, the cause relates to brain injuries, congenital disorders, or other problems that may require medical attention. It is essential to get a more comprehensive diagnosis from a skilled medical professional if exercises are ineffective in aiding the integration of the reflex. 

What Activities are Good for ATNR?

Many activities can help promote the integration of the ATNR reflex and improve symptoms of retained ATNR. All of them help to strengthen cross movements of the head and the arms in a way similar to the above exercises. These can include:

• Playing catch: Playing catch can help improve hand-eye coordination and promote the development of more complex movements.
• Dancing: Dancing can help improve balance, coordination, and muscle tone.
• Swimming: Swimming can help improve muscle strength and coordination while providing a low-impact exercise form.
• Yoga: Yoga can help improve balance, coordination, and muscle tone while promoting relaxation and mindfulness.
• Various sports: Tennis, cricket, golf, hockey, and many other sports help to strengthen head-arm coordination, making use of equipment that encourages turning the head to the side while using the arms to achieve an action.

Conclusion

Retained ATNR is a condition that can significantly impact an individual's physical and cognitive abilities. By understanding this condition's causes, signs, and symptoms, individuals can seek proper diagnosis and treatment to improve their quality of life. With appropriate management strategies, individuals with retained ATNR can integrate the reflex and avoid the potential consequences.

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