Introduction: Understanding Autonomic Dysregulation (4) - Yin (Dorsal) Vagus and Mixed Patterns

 Parasympathetic Dominance: The Dorsal Vagal Freeze Response

The dorsal vagal freeze response represents an extreme parasympathetic state, where the body enters a shutdown mode due to overwhelming stress. Unlike typical parasympathetic activation, which restores balance, the freeze state represents pathological yin—a state of hypoactivity and stagnation. In this state, the body cannot access the vagus nerve, blocking the usual parasympathetic calming response. This leads to a complete collapse of normal autonomic regulation and function. The system enters a hibernation-like state, and the body cannot respond to external stimuli, including stressors.

Dorsal vagal freeze states are challenging to diagnose for TCM and other providers due to conflicting symptoms. Patients often feel cold but show signs such as an elevated pulse, rapid breathing, insomnia, night sweats, and high blood pressure. Their emotional state can also appear extreme. These elevated markers, which many practitioners confuse with heat, arise from the body working harder to move through the parasympathetic freeze state. In TCM, this pattern is often described as true cold, false heat. However, it is much harder to recognize in practice because it combines opposing signs. Without access to the vagus nerve, normal regulation cannot occur. This imbalance represents the severe separation of yin and yang, as the body cannot integrate both systems properly.

The yin presentation can be an acute state that can indicate end of life if not addressed. It is commonly seen in end-stage MS and early stroke patients, where immediate intervention is essential to prevent further deterioration. Rescuing devastated yang must be combined with harmonizing the ANS to restore balance.

In some cases, yang tonics such as Rhodiola or aconite are used to stimulate the kidneys, but this may create more problems because it does not address the autonomic imbalance. In addition, the inflammatory process extends beyond the sinew channels and gut, to affect neurotransmitter function. Dysregulation of key neurotransmitters—such as serotonin, dopamine, and GABA—contributes to emotional instability, heightened anxiety or agitation. In states of high arousal, stress hormones influence gene expression, particularly in the hypothalamus, where oxytocin is produced. When oxytocin methylates, it renders oxytocin inactive, impairing its neuroregulatory role in emotional bonding and empathy. This methylation reduces the body's ability to regulate emotions and decreases the capacity for social connection. 

 

Mechanisms of Freeze States

  Sensory Pathways: Thalamic overload redirects sensory input from the amygdala to the ACC and PCC, bypassing cortical processing. Once in a dorsal state, sensory processing is limited to only that which is needed for survival.

  Respiratory Suppression: Delayed or shallow breathing reduces oxygen exchange, leading to hypoxia. Poor carbon dioxide exchange exacerbates systemic inflammation, diminished cellular respiration and spasticity in the tissues.

  Oxidative Stress and DNA Damage: Oxygen is life-giving when attached to a heme group. In pathological yin states, the Krebs cycle becomes impaired, leading to reactive oxygen species (ROS). When this occurs in brain regions that produce dopamine, serotonin, and GABA, it can damage the nerves, DNA, shorten telomeres, and disrupt gene expression. In Parkinson's disease, this process affects the substantia nigra, where dopamine is produced. In Alzheimer's disease, it impacts the hippocampus and vestibular system. The plaques seen in neurodegenerative diseases are incomplete breakdown products from an impaired immune system. In multiple sclerosis, lesions can form anywhere in the brain or spinal cord.

  Neurochemical Dysregulation: Oxytocin methylation defects impair emotional bonding and recovery processes.

• Symptoms of Freeze States

• Respiratory: Shallow breathing, diaphragmatic disengagement.
• Gastrointestinal: Gastroparesis, chronic constipation, slow transit time.
• Neurological: Impaired sensory processing, temperature dysregulation, learing disorder, ADD.
• Emotional: Dissociation, fear, or anger linked to limbic dysregulation. Mood disorders, personality disorder, dysthymia.  Poor regulation, poor social interactions.

 

Mixed Presentations: Complex Dysregulation

Most patients present with a complex mixture of sympathetic overactivation (yang) and parasympathetic suppression (yin). These patterns are the most common in individuals with a history of early developmental trauma, early-stage neurogenic diseases like MS, Parkinson’s, Alzheimer’s, stroke patients, immigrants and refugees, first responders and those with PTSD. 

Perinatal events such as birth complications (e.g., forceps delivery, prolonged labor, or intubation), early separation from caregivers (as seen in adoption or neonatal ICU stays), or chronic childhood illness or surgery can disrupt the normal integration of primitive reflexes and cranial nerve function. These disruptions anchor the body into maladaptive autonomic patterns, and combine elements of sympathetic overactivation (e.g., tachycardia and shallow breathing) with parasympathetic suppression (e.g., infertility, gastrointestinal stasis and emotional dissociation).

This causes persistent autonomic fragmentation, where the nervous system shifts between overactivation and withdrawal without finding balance. Emotional overwhelm can trigger shifts between sympathetic (ventral vagus) and extreme parasympathetic (dorsal vagus) states, increasing  the separation between yin and yang. 

Like the pathological yin states, the mixed pattern is difficult to diagnose, as the physiological stress response includes symptoms like elevated pulse, rapid breathing, Harmonizing the yin (PANS) and yang (SANS) is essential in these cases.

 

Clinical Data

• Neuroplasticity: Mixed autonomic patterns impair the nervous system’s adaptability and recovery, common in PTSD and neurogenic conditions.

• Sleep: Imbalance disrupts sleep cycles, causing insomnia and poor rest.

• Emotional Regulation: Dysregulation triggers anxiety, irritability, and mood instability.

• Gastrointestinal Function: Impairment causes gastroparesis, constipation, and slow transit.

• Reproductive Health: Conditions like ED, PCOS, and menstrual irregularities are common.

• Cardiovascular Disease: Increases risk for hypertension, arrhythmias, and heart disease.

• Immune System: Affects immune responses, linked to autoimmune disorders and chronic inflammation.

• Endocrine System: Disrupts thyroid function, adrenal health, and insulin resistance.

• Musculoskeletal System: Fibromyalgia, muscle stiffness, and chronic pain result from this imbalance.

• Respiratory System: Issues like shortness of breath and respiratory suppression arise. COPD

 These imbalances are additive, and affect multiple systems. As such, they become more difficult to manage. Mindfulness practices, qi cultivation, diet and lifestyle changes are the most effective at this stage. Unfortunately, many of our patients only seek help after a catastrophic diagnosis. 

Bibliography

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