Fencing response
Encyclopedia
The fencing response is a peculiar position of the arms following a concussion. Immediately after moderate forces have been applied to the brainstem, the forearms are held flexed or extended (typically into the air) for a period lasting up to several seconds after the impact. The fencing response is often observed during athletic competition involving contact, such as football
, hockey
, rugby
and martial arts
. It is used as an overt indicator of injury force magnitude and midbrain localization to aid in injury identification and classification for events including, but not limited to, on-field and/or bystander observations of sports-related head injuries.
” position that initiates a fencing bout, with the extension of one arm and the flexion of the other.
Tonic posturing (see abnormal posturing
) preceding convulsion
has been observed in sports injuries at the moment of impact where extension and flexion of opposite arms occur despite body position or gravity. The fencing response emerges from the separation of tonic posturing from convulsion and refines the tonic posturing phase as an immediate forearm motor response to indicate injury force magnitude and location.
in human infants, such as the asymmetric tonic neck reflex, Moro reflex
, and parachute reflexes, which are likely mediated by vestibular nuclei in the brainstem. The lateral vestibular nucleus
(LVN; Deiter’s nucleus) has descending efferent fibers in the vestibulocochlear nerve distributed to the motor nuclei of the anterior column and exerts an excitatory influence on ipsilateral limb extensor motoneurons while suppressing flexor motoneurons. The anatomical location of the LVN, adjacent to the cerebellar peduncles (see cerebellum
), suggests that mechanical forces to the head may stretch the cerebellar peduncles and activate the LVN. LVN activity would manifest as limb extensor activation and flexor inhibition, defined as a fencing response, while flexion of the contralateral limb is likely mediated by crossed inhibition necessary for pattern generation.
The most challenging aspect to managing sport-related concussion (mild traumatic brain injury
, TBI) is recognizing the injury. Consensus conferences have worked toward objective criteria to identify mild TBI in the context of severe TBI. However, few tools are available for distinguishing mild TBI from moderate TBI. As a result, greater emphasis has regularly been placed on the management of concussions in athletes than on the immediate identification and treatment of such an injury. On-field predictors of injury severity can define return-to-play guidelines and urgency of care, but past criteria have either lacked sufficient incidence for effective utility, did not directly address the severity of the injury, or have become cumbersome and fraught with interrater reliability issues. By providing a clear, discernable physiological event immediately upon injury, the fencing response can discern moderate brain injury forces from milder forces, providing an additional criterion by which the identification and classification of concussions can be improved, with immediate application to sport-related on-field diagnoses and decisions affecting return-to-play status for athletes, thereby facilitating the transition from diagnosis to the treatment of any post-concussion symptoms (PCS).
and subsequent shell shock
. There are currently no studies or data to determine the utility of the fencing response in such an arena.
Football
Football may refer to one of a number of team sports which all involve, to varying degrees, kicking a ball with the foot to score a goal. The most popular of these sports worldwide is association football, more commonly known as just "football" or "soccer"...
, hockey
Hockey
Hockey is a family of sports in which two teams play against each other by trying to maneuver a ball or a puck into the opponent's goal using a hockey stick.-Etymology:...
, rugby
Rugby football
Rugby football is a style of football named after Rugby School in the United Kingdom. It is seen most prominently in two current sports, rugby league and rugby union.-History:...
and martial arts
Martial arts
Martial arts are extensive systems of codified practices and traditions of combat, practiced for a variety of reasons, including self-defense, competition, physical health and fitness, as well as mental and spiritual development....
. It is used as an overt indicator of injury force magnitude and midbrain localization to aid in injury identification and classification for events including, but not limited to, on-field and/or bystander observations of sports-related head injuries.
Relationship to fencing reflex and posturing
The fencing response designation arises from the similarity to the asymmetric tonic neck reflex in infants (commonly known as the fencing reflex). Like the reflex, a positive fencing response resembles the “en gardeEn garde
En Garde can refer to* A French warning, "On [your] guard"** A term in fencing adopted from the French warning* EnGarde Secure Linux* En Garde by the band Criteria* En Garde!, a role-playing game*En Garde a 2004 film...
” position that initiates a fencing bout, with the extension of one arm and the flexion of the other.
Tonic posturing (see abnormal posturing
Abnormal posturing
Abnormal posturing is an involuntary flexion or extension of the arms and legs, indicating severe brain injury. It occurs when one set of muscles becomes incapacitated while the opposing set is not, and an external stimulus such as pain causes the working set of muscles to contract. The posturing...
) preceding convulsion
Convulsion
A convulsion is a medical condition where body muscles contract and relax rapidly and repeatedly, resulting in an uncontrolled shaking of the body. Because a convulsion is often a symptom of an epileptic seizure, the term convulsion is sometimes used as a synonym for seizure...
has been observed in sports injuries at the moment of impact where extension and flexion of opposite arms occur despite body position or gravity. The fencing response emerges from the separation of tonic posturing from convulsion and refines the tonic posturing phase as an immediate forearm motor response to indicate injury force magnitude and location.
Pathophysiology
The neuromotor manifestation of the fencing response resembles reflexes initiated by vestibular stimuli. Vestibular stimuli activate primitive reflexesPrimitive reflexes
Primitive reflexes are reflex actions originating in the central nervous system that are exhibited by normal infants but not neurologically intact adults, in response to particular stimuli. These reflexes disappear or are inhibited by the frontal lobes as a child moves through normal child...
in human infants, such as the asymmetric tonic neck reflex, Moro reflex
Moro reflex
The Moro reflex, which is distinct from the startle reflex, is one of the infantile reflexes.It may be observed in incomplete form in premature birth after the 28th week of gestation, and is usually present in complete form by week 34...
, and parachute reflexes, which are likely mediated by vestibular nuclei in the brainstem. The lateral vestibular nucleus
Lateral vestibular nucleus
The lateral vestibular nucleus is the continuation upward and lateralward of the principal nucleus, and in it terminate many of the ascending branches of the vestibular nerve.-Anatomy:...
(LVN; Deiter’s nucleus) has descending efferent fibers in the vestibulocochlear nerve distributed to the motor nuclei of the anterior column and exerts an excitatory influence on ipsilateral limb extensor motoneurons while suppressing flexor motoneurons. The anatomical location of the LVN, adjacent to the cerebellar peduncles (see cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
), suggests that mechanical forces to the head may stretch the cerebellar peduncles and activate the LVN. LVN activity would manifest as limb extensor activation and flexor inhibition, defined as a fencing response, while flexion of the contralateral limb is likely mediated by crossed inhibition necessary for pattern generation.
Injury severity and sports applications
In a survey of documented head injuries followed by unconsciousness, most of which involved sporting activities, two thirds of head impacts demonstrated a fencing response, indicating a high incidence of fencing in head injuries leading to unconsciousness, and those pertaining to athletic behavior. Likewise, animal models of diffuse brain injury have illustrated a fencing response upon injury at moderate but not mild levels of severity as well as a correlation between fencing, blood brain barrier disruption, and nuclear shrinkage within the LVN, all of which indicates diagnostic utility of the response.The most challenging aspect to managing sport-related concussion (mild traumatic brain injury
Traumatic brain injury
Traumatic brain injury , also known as intracranial injury, occurs when an external force traumatically injures the brain. TBI can be classified based on severity, mechanism , or other features...
, TBI) is recognizing the injury. Consensus conferences have worked toward objective criteria to identify mild TBI in the context of severe TBI. However, few tools are available for distinguishing mild TBI from moderate TBI. As a result, greater emphasis has regularly been placed on the management of concussions in athletes than on the immediate identification and treatment of such an injury. On-field predictors of injury severity can define return-to-play guidelines and urgency of care, but past criteria have either lacked sufficient incidence for effective utility, did not directly address the severity of the injury, or have become cumbersome and fraught with interrater reliability issues. By providing a clear, discernable physiological event immediately upon injury, the fencing response can discern moderate brain injury forces from milder forces, providing an additional criterion by which the identification and classification of concussions can be improved, with immediate application to sport-related on-field diagnoses and decisions affecting return-to-play status for athletes, thereby facilitating the transition from diagnosis to the treatment of any post-concussion symptoms (PCS).
Further application
The fencing response may also have the potential to indicate traumatic brain injury for soldiers in military settings, specifically with regard to blast injuryBlast injury
A blast injury is a complex type of physical trauma resulting from direct or indirect exposure to an explosion. Blast injuries occur with the detonation of high-order explosives as well as the deflagration of low order explosives...
and subsequent shell shock
Shell Shock
Shell Shock, also known as 82nd Marines Attack was a 1964 film by B-movie director John Hayes. The film takes place in Italy during World War II, and tells the story of a sergeant with his group of soldiers....
. There are currently no studies or data to determine the utility of the fencing response in such an arena.
Notable fencing displays
Increased awareness of clinical significance on behalf of the bystander is critical to the utility of the fencing response designation. Therefore, notable fencing displays are listed below in order to aid the bystander in identifying the various physical manifestations of the fencing response as well as demonstrating the prevalence of such a response in popular sporting and social events.- Videos of various sports-related fencing responses and news reports
- Austin CollieAustin CollieAustin Kirk Collie is a Canadian-American football wide receiver for the Indianapolis Colts of the National Football League . He was drafted by the Colts in the fourth round in the 2009 NFL Draft...
, professional American football wide receiver for the Indianapolis Colts - Indianapolis vs. Philadelphia, November 8, 2010 - Denarius Moore, NCAA college football wide receiver for the Tennessee Volunteers - Tennessee vs. Alabama, October 23, 2010
- James RodgersJames Rodgers (football)James Rodgers is an American football wide receiver for the Oregon State Beavers. He is the older brother of former Oregon State and Atlanta Falcons running back Jacquizz Rodgers.-High school career:...
, NCAA college football wide receiver for the Oregon State Beavers - Oregon State vs. Boise State, September 25, 2010 - Kenny Shaw, NCAA college football wide receiver for Florida State - Oklahoma vs. Florida State, September 17, 2011
- Jahvid BestJahvid BestJahvid Andre Best is a running back for the Detroit Lions of the National Football League. He was selected by the Lions with the 30th pick in the 2010 NFL Draft. In college, he played for the California Golden Bears, setting several records, including most all-purpose yards in a single season and...
, collegiate American football running back, California Golden Bears - following a dive into the endzone against Oregon State. November 7, 2009 - Justin McBrideJustin McBrideJustin Travis McBride is a former professional bull rider on the PBR's Built Ford Tough Series Tour. He is a two-time PBR World Champion , has a record 32 career wins, and was the first professional bull rider to earn more than $5 million in the course of his career.He is a country music singer...
, professional bull rider - 2007 Glendale PBR. - Willis McGaheeWillis McGaheeWillis Andrew McGahee III is an American football running back for the Denver Broncos of the National Football League. He was drafted by the Buffalo Bills in the first round of the 2003 NFL Draft...
, professional American football running back - 2009 AFC Championship Game. - Paris Rosen, professional motocross athlete - failed front flip attempt at X Games 16, July 30, 2010.
- Tim TebowTim TebowTimothy Richard "Tim" Tebow is an American football player who is currently the starting quarterback for the Denver Broncos of the National Football League . He was drafted by the Broncos as the 25th overall pick in the 2010 NFL Draft...
, collegiate American football quarterback - Florida vs. Kentucky, September 27, 2009 - John TerryJohn TerryJohn George Terry is an English professional footballer. Terry plays in a centre back position and is the captain of Chelsea in the Premier League...
, professional soccer player - 2007 Football League Cup Final. - Jermain TaylorJermain TaylorJermain Taylor is an American professional boxer and former undisputed middleweight champion. He made his professional boxing debut in 2001 and won his first 25 bouts, which included victories over former champions Raúl Márquez and William Joppy...
, professional boxer - following a brutal 12th round knockout at the hands of Arthur AbrahamArthur AbrahamArthur Abraham is an Armenian-German professional boxer HyeFighter residing in Berlin, Germany. He was IBF world middleweight champion from 2005 to 2009, making ten successful defences of his title...
. - Ulf SamuelssonUlf SamuelssonUlf Samuelsson is a retired Swedish professional ice hockey player and currently the head coach of Modo Hockey of the Elitserien . He played for the Hartford Whalers, Pittsburgh Penguins, New York Rangers, Detroit Red Wings, and Philadelphia Flyers.- Biography :He specialized in heavy body checks...
, professional hockey player - following a punch to the head by Tie DomiTie DomiTahir "Tie" Domi is a retired Canadian professional ice hockey player. During a sixteen-year NHL career when he was known for his role as an enforcer, he played for the Toronto Maple Leafs, New York Rangers and Winnipeg Jets....
. - Nathan HortonNathan HortonNathan Horton is a Canadian professional ice hockey winger who currently plays for the Boston Bruins of the National Hockey League...
, professional hockey player - following a late hit from Aaron RomeAaron RomeAaron Rome is a Canadian professional ice hockey defenceman currently playing for the Vancouver Canucks of the National Hockey League . He was originally selected out of the Western Hockey League 104th overall in the 2002 NHL Entry Draft by the Los Angeles Kings...
. - James MayJames MayJames Daniel May is an English television presenter, journalist and writer. He is best known for his role as co-presenter of the award-winning motoring programme Top Gear alongside Jeremy Clarkson and Richard Hammond....
, a television presenter - after being thrown to the ground by a taught line.