What Is the Fencing Response?

A Sign of Serious Brain Injury

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A fencing response is an involuntary physical position that occurs as a result of severe brain injury. This type of posture resembles an athletic fencing position—one arm is bent towards the body, and the other arm is outstretched.

A person can experience a fencing response immediately after head trauma. It can last for several seconds. Often, a fencing response is followed by a seizure. Any person who has a fencing response should get immediate medical attention.

This article describes the symptoms, causes, and prognosis of fencing response. 

An illustration with information about fencing response

Illustration by Zoe Hansen for Verywell Health

Fencing Response: Effect on Posture 

A fencing response is usually noticeable by observers, while the person experiencing it is usually unaware of the situation. A person usually falls on their back or on their side, and they will have one arm flexed, and the other extended—and there can be some variation in the positioning,

A fencing position develops as a result of widespread changes in the brain, which include:

  • Rapid changes in vascular permeability (the blood vessels become leaky)
  • Sudden alterations in sodium and potassium concentration
  • Extensive damage to neurons (nerve cells)

These changes may occur rapidly due to biomechanical forces that can happen during a severe blow to the head, such as when a boxer is knocked out.

Neurological Posturing

A fencing response is a type of neurological posturing. Neurological posturing refers to involuntary physical positions the body takes due to severe brain damage.

Swelling in the brain, bleeding, and bruising in the brain can develop within hours after a fencing response.

Other types of posturing that can occur along with the fencing response are:

  • Decorticate posture: This is abnormal posturing in which a person is stiff with bent arms, clenched fists, and legs held out straight. The arms are bent in toward the body, and the wrists and fingers are bent and held on the chest. This type of posturing usually signals damage to the midbrain, which is part of the brain stem. Decorticate posture can occur due to direct midbrain damage from a condition like a massive stroke or a tumor, or it can occur when severe brain swelling causes the brain to push down on the brain stem, a dangerous situation described as brain herniation. 
  • Decerebrate posture: This is an abnormal body posture that involves the arms and legs being held straight out, the toes being pointed downward, and the head and neck being arched backward. The muscles are tightened and held rigidly. This type of posturing usually indicates severe damage to the cerebral cortex on both sides of the brain.

Fencing Posture vs. Fencing Reflex

A fencing reflex is not the same as a fencing posture. The fencing reflex is present in healthy newborn babies. It fades away by the time a baby is 6 months old, as the baby’s brain develops and matures. In a fencing reflex, the baby's head is turned to one side, one arm becomes flexed, and the other arm extends.

This is one of the primitive reflexes, which are reflexes that are normally present at birth and go away as a baby matures in early childhood. Primitive reflexes that persist after they are expected to go away may be a sign of brain damage.

Signs of Head Trauma From the Fencing Response 

A fencing response generally occurs along with other signs and symptoms of head trauma or brain damage. When it occurs due to head trauma, it is often noticeable after a fall.

Other symptoms that can occur are:

  • Vomiting
  • Loss of consciousness 
  • Severe dizziness
  • Head pain 
  • Vision changes 
  • Weakness and sensory changes on one or both sides of the body 
  • Difficulty communicating 
  • Confusion 

A fencing response may not be obvious if there are accompanying symptoms. 

When a fencing response occurs due to a neurological condition, it can come on abruptly after a serious and sudden event (such as a ruptured brain aneurysm), or it may occur as the condition worsens (such as a stroke). 

Fencing Response Complications

A person who has exhibited a fencing response after head trauma or other type of brain damage is likely to have neurological complications or other traumatic injuries associated with the condition that caused the fencing response. The fencing response itself does not cause these complications.

Complications may include:

  • Persistent pain
  • Diminished mobility
  • Problems with coordination and balance
  • Depression or anxiety
  • Post-traumatic stress disorder (PTSD) associated with the injury
  • Emotional dysregulation (poor ability to control emotional responses) caused by the brain damage
  • Difficulty sleeping
  • Dizziness

A recognized condition called post-concussion syndrome can involve headaches, brain fog, depression, and sleeping problems. Many people recover after a concussion, but some may have persistent symptoms for years.

Fencing Response Recovery 

The fencing response is a symptom of an underlying disease, and recovery depends on the disease and how that is treated. Some people may experience a full recovery, especially if there was no damage to the brain.

However, people who have sustained a severe concussion, hemorrhage (bleeding) in the brain, a skull fracture, or a significant stroke may have at least some long-term effects associated with the condition.

Rehabilitation includes a combination of physical therapy, occupational therapy, cognitive therapy, psychological counseling, and getting enough rest. Not everyone who has a fencing response will need all of these types of therapies. The determination will be based on the effects of the brain damage.

Recovery can take months or longer and requires patience. Sometimes improvement is slow or appears to plateau before recovery resumes.

Considerations include things like returning to play sports, driving, and working. Safety is essential during the recovery process.


A fencing response is a sign of serious brain injury, but not all major brain injuries involve a fencing response. In this posture, the arm position is held in a way that resembles the arm of a person performing the sport of fencing: one arm is flexed toward the body and the other arm is extended. This is an involuntary posture that occurs without awareness or the ability to control it.

Anyone who exhibits a fencing posture needs immediate medical care and may have sustained serious neck trauma in addition to head trauma. Often a fencing posture is followed by a convulsion (a sudden, violent, irregular movement of a limb or body).

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.