Massive knee-jerk reaction. Literally!

August 15, 2013 4:15 PM

What does it mean when the doctor hits your knee with the rubber mallet and you kick like a Rockette?

Startled the doctor today at my physical because my leg shot up so strongly it came back with a loud bang against the table. The other leg was only slightly less dramatic. My doc chuckled but didn't say it was a problem. Out of curiosity I googled it and read somewhere thats its bad for the leg to kick too little or too big, but I couldn't find out why (and don't have time to do the research). So can anyone give me the short answer? I had rode my bike to the appointment, so maybe my legs were just extra tense?

posted by hellameangirl to Health & Fitness (9 answers total)

My nurse practitioner said it was a function of my thyroid. I'm not sure if that's true or not but the reflexes did calm down after I had my thyroid removed. I bet there are many explanations though.
posted by dawkins_7 at 4:24 PM on August 15, 2013

Google "hyperreflexia".

Sure, you could have tetanus or eclampsia, but 99% chance, especially with no other symptoms, you just happen to have more active reflexes than some other people and it indicates nothing else. I have unusually active reflexes myself.
posted by latkes at 4:28 PM on August 15, 2013 [1 favorite]

I now have a nearly absent patellar reflex.

Beyond saying 'huh' doctors have had nothing to say about it. (it does test to specific nervous system stuff, disorders, nerve damage, brain lesions. But I don't know why they do it if they don't follow up on the finding/explain why they're not following up...)
posted by bilabial at 4:41 PM on August 15, 2013

Hyperreflexia (or hyporeflexia) is only concerning in certain clinical contexts. It's quite variable from person to person and from situation to situation, for example a normally reflexive person can be made hyporeflexive if they are mentally focusing on their patellar reflex - the way around this is to distract them by having them do something else with their hands while you're doing the reflex testing. It might pique your doctor's interest if only ONE leg was hyperreflexic and the other was not, but if you're otherwise fine, this is probably not a big deal at all.
posted by treehorn+bunny at 5:03 PM on August 15, 2013 [1 favorite]

I noticed that my reflexes were a little screwey when I was on Zoloft. In my case, they were delayed. I once turned on a light, saw the bulb flash, realized that the bulb had burnt out, THEN got startled. Weirdest thing.

Anyway, are you on any medications that might affect neurotransmitters?
posted by gjc at 5:06 PM on August 15, 2013

Response by poster: Nope, not on any medications. I am a pretty jumpy person in general for no known reason. Friends tease me about it actually. Its good though when I need to 'spring into action', like I saved a dog once from running into a busy street while everyone else around me stared slack-jawed.
posted by hellameangirl at 5:22 PM on August 15, 2013 [3 favorites]

When I was tested for MS, I had the same thing. Initially, my neurologist was very concerned by it -- then she asked about the cup I'd brought in, which contained a double latte. She said caffeine can exaggerate your reflexes a lot. When she checked me the next time (no coffee), there was much less kicking and jerking. Back to normal.
posted by sweltering at 5:35 PM on August 15, 2013 [1 favorite]

How active are you? At the height of my athleticism (2-3 hours a day minimum of very high intense activity every day) i had minimal kickitude. I was told that was because i was an athlete. I believed her because she was very attractive.
posted by hiddenknives at 6:21 PM on August 15, 2013 [1 favorite]

It sounds like you have very ready reflexes.

As a kid, I used to kick when my knee was hit with a mallet because I knew I was supposed to. I didn't know it was supposed to kick by itself. By itself? Isn't my knee useless without me? Silly grownups.
posted by tel3path at 5:44 AM on August 16, 2013 [2 favorites]