What causes motor delays?

Understanding Motor Delays

The Impact of Hypotonia on Daily Life: Challenges in Everyday Tasks

Hypotonia, characterized by low muscle tone, can significantly affect a child's ability to perform everyday tasks. This condition can impact various aspects of a child's life, from simple activities to more complex functions.

Basic Motor Skills

Sitting and Standing:
   - Difficulty maintaining upright posture

 - Tendency to slump or lean forward, slouching
   - Struggling to sit up straight or stand straight

Fine Motor Skills

Hand Function:
   - Weak grip strength
   - Difficulty grasping objects, messy handwriting
   - Trouble with fine motor tasks like buttoning clothes or using utensils

Daily Activities

1. Dressing
   - Difficulty zipping/zapping clothes
   - Trouble tying shoelaces
   - Challenges with fastening buttons or snaps

2. Play and Recreation:
   - Limited ability to participate in physical activities
   - Difficulty climbing stairs or playground equipment
   - Reduced participation in sports or games requiring coordination

How does motor contol work?

In the Brain

1. Excitatory and Inhibitory Neurons: Excitatory neurons (like glutamatergic neurons) stimulate muscle contractions and then being released by Inhibitory neurons (like GABAergic neurons) modulate and fine-tune movements.

This excitatory/inhibitory balance explains activity of at the level of the muscle fibers and spindles. However, the excitatory /inhibitory balance is also part of muscle regulation at the level of the brain and involved in planning and regulating motor control. The brain cells in the motor areas of the brain also need to be in balance. 

2. Synaptic Plasticity: Changes in synaptic strength based on activity and crucial for learning and adapting motor skills. Since brain areas develop at different stages of development there could have been less efficient brain connections made at certain stages maybe due to illness or nutrient deficiency or other. 

3. Neurotransmitter Systems: dopamine, glutamate, serotonin, acetylcholine and more imbalances in these neurotransmitter systems can lead to motor delays. If there are insufficient ingridients or precursors to produce these compounds then insufficient levels of these neurotransmitters can disrput synaptic plasticity in motor areas regulated motor plans. 

At the muscle level, motor delays can manifest as:

1. Hypotonia: Low muscle tone resulting from reduced excitability of muscle spindles, which can lead to floppy muscles and poor posture

2. Muscle Fiber Composition: Type I (slow-twitch) vs. Type II (fast-twitch) fiber ratios and these alterations can affect endurance and speed capabilities

3. Neuromuscular Junctions: Sites where neurons connect to muscles, which impaired neurotransmission can lead to weakness or paralysis

Biological Basis of Motor Delays

Several factors can contribute to motor delays which essentially effect neuronal function. 

1. Excitation-Inhibition Imbalance: Excitatory neurons (like glutamatergic neurons) stimulate muscle contractions, Inhibitory neurons (like GABAergic neurons) modulate and fine-tune movements. Too much inhibition may endanger fine motor skills like holding a pencil. Too much excitation may sensory processing issues causing altered proprioception (awareness of body position and impacting motor planning and execution.

2. Mitochondrial Dysfunction: Insufficient ATP production, the fuel for energy in neurons means that all cellular processes can be completed due to lack of energy. Lack of energy at a cellular levels has implications for the whole body. If the body cannot make enzymes or break down proteins from foods into amino acids or create new proteins and more. 

3. Branched Chain Amino Acid (BCAA) Imbalance: BCAAs are amino acids that include Leucine, Isoleucine and Valine. The are derived from foods we eat and play crucial roles in protein synthesis, metabolism, and muscle maintenance. Alterations in BCAA levels have been associated with motor skill delays.

Future Directions

In addition to traditional occupational therapies, nutrient-based approaches can synergystically help build muscle tone and get rid of imbalances. The use of gut microbiome also is an emerging trend, which may effect absorption of key amino acids or reduce inflammation, increase mitochondrial output and reduce oxidative stress.

The field of nutrient-based interventions for developmental delays is continually evolving and ANeustart is part of that ongoing research. Many children may have the same symptoms but the biological basis may be different. Targeted supplementation and treatment must be personalized by the child's biology and symptoms. 

Citations:

[1] https://nba.uth.tmc.edu/neuroscience/m/s3/chapter01.html

[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC5033663/

[3] https://nba.uth.tmc.edu/neuroscience/m/s3/chapter06.html

[4] https://academic.oup.com/icb/article/47/1/16/634351

[5] https://pmc.ncbi.nlm.nih.gov/articles/PMC4818644/

[6] https://journals.physiology.org/doi/full/10.1152/japplphysiol.00135.2018

[7] https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2021.616820/full

[8] https://www.sciencedirect.com/topics/neuroscience/motor-evoked-potential

[9] https://kaw.wallenberg.org/en/research/new-discoveries-how-muscle-brain-sensory-feedback-controls-body-movements

[10] https://www.aafp.org/pubs/afp/issues/2015/0101/p38.html

[11] https://www.rch.org.au/kidsinfo/fact_sheets/Low_muscle_tone/
[12] https://www.physio-pedia.com/Hypotonia
[13] https://www.aacpdm.org/publications/care-pathways/central-hypotonia
[14] https://childdevelopment.com.au/areas-of-concern/diagnoses/low-muscle-tone/
[15] https://pmc.ncbi.nlm.nih.gov/articles/PMC10766446/
[16] https://lermagazine.com/special-section/surestep/understanding-hypotonia
[17] https://surestep.net/blog/severe-hypotonia-day-in-life/
[18] https://napacenter.org/hypotonia-exercises-at-home/
[19] https://pmc.ncbi.nlm.nih.gov/articles/PMC10887882/
[20] https://www.physio.co.uk/what-we-treat/paediatric/problems/neurological-problems/abnormal-muscle-tone/hypotonia.php