# Why do people who suffer head trauma get stiff limbs immediately afterward?

**URL:** <https://boards.straightdope.com/t/why-do-people-who-suffer-head-trauma-get-stiff-limbs-immediately-afterward/711729>\
**Category:** Factual Questions\
**Created:** [February 3, 2015, 5:06pm UTC](https://boards.straightdope.com/t/why-do-people-who-suffer-head-trauma-get-stiff-limbs-immediately-afterward/711729 "2015-02-03T17:06:42Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![MichaelEmouse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/michaelemouse/32/101_2.png) [@MichaelEmouse](https://boards.straightdope.com/u/MichaelEmouse)\
**Post date:** [February 3, 2015, 5:06pm UTC](https://boards.straightdope.com/t/why-do-people-who-suffer-head-trauma-get-stiff-limbs-immediately-afterward/711729/1 "2015-02-03T17:06:42Z")

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I’ve noticed that people who get hit in the head badly tends to stiffen up.

What is the mechanism of action?  
Does stiffening up indicate something in terms of the consequences of the head trauma?

Examples:  
ACHTUNG! Safe for work but, you know, people getting badly hurt:

[![](https://img.youtube.com/vi/HxQlKgXSLTw/maxresdefault.jpg "BMX Crash Seizure ALWAYS WEAR YOUR HELMET") ](https://www.youtube.com/watch?v=HxQlKgXSLTw)

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**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\
**Post date:** [February 3, 2015, 5:22pm UTC](https://boards.straightdope.com/t/why-do-people-who-suffer-head-trauma-get-stiff-limbs-immediately-afterward/711729/2 "2015-02-03T17:22:06Z")

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I didn’t watch the videos here at work but one mentions seizures in the title. The head trauma can cause a seizure - which involves involuntary muscle contractions. Is that what you’re asking about?

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**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\
**Post date:** [February 3, 2015, 5:27pm UTC](https://boards.straightdope.com/t/why-do-people-who-suffer-head-trauma-get-stiff-limbs-immediately-afterward/711729/3 "2015-02-03T17:27:15Z")

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With spinal cord injuries, the [Schiff-Sherington phenomenon](http://medical-dictionary.thefreedictionary.com/Schiff-Sherrington+phenomenon) is caused by release of inhibitory influences.

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**Author:** ![cardinal\_fang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal_fang/32/15316_2.png) [@cardinal\_fang](https://boards.straightdope.com/u/cardinal_fang)\
**Post date:** [February 3, 2015, 9:34pm UTC](https://boards.straightdope.com/t/why-do-people-who-suffer-head-trauma-get-stiff-limbs-immediately-afterward/711729/4 "2015-02-03T21:34:22Z")

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Both of your videos appear to be examples of the [Fencing Response](https://en.wikipedia.org/wiki/Fencing_response), an involuntary reflex typically associated with concussions. Google produces many more videos (if you have the stomach for it).