Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Myoclonic and other spasms in iguanas and other reptiles

©2000 Melissa Kaplan


spasm [spa'zm] noun: A sudden, uncontrollable tightening of a muscle, or sudden burst of energy or activity.[1] A sudden, involuntary contraction of a muscle or group of muscles.[2] A sudden, violent, involuntary contraction of a muscle or a group of muscles, attended by pain and interference with function, producing involuntary movement and distortion.[3] A sudden but transitory constriction of a passage, canal or orifice.[4]

myoclonus [my oc' lo nus] noun: A sudden twitching of muscles or parts of muscles, without any rhythm or pattern, occurring in various brain disorders.[2]

Spasms, myoclonic or otherwise are generally not a good thing. Specifically, spasms that occur in clusters - several of them, one right after the other - are a sign that something is wrong. Health conditions that may cause spasms include:

The liver can sustain damage, causing impaired or reduced function, due the overdose, misuse, or hypersensitivity to one or more drugs; viral or bacterial infections; ingestion of toxic plants or other substances; exposure to environmental toxins, including many of the oft recommended forms of ridding enclosures and reptiles of mites by use of organophosphate products; chronic mild or acute dehydration, especially in conjunction with prolonged use of antibiotics. Liver dysfunction may be a prodrome to kidney failure, as if the liver isn't able to adequately detox the system, the toxins are passed along to the kidneys. When the liver isn't able to detox the system, toxins build up and are circulated through the blood stream. Some are able to cross the blood-brain barrier, which may then result in neurological signs, such as spasms, loss of motor control, coordination, ability to turn the body into its proper position, etc.

If you see repeated tremors or twitching in the toes or leg muscles, especially in conjunction with overall loss in muscle tone, suspect MBD. If you see repeated overall body spasms, suspect kidney problems.

Myoclonus (Myoclonic) Jerks
Myoclonus sounds bad - and it is if caused by any of the reasons discussed above - but there is a type of abrupt, single spasm you don't need to worry about. It occurs in humans, dogs, cats, iguanas and other animals. It often happens to humans just as they are falling asleep. When it happens when we are awake, some say, referring to some folkloric connection, "Someone's walking across my grave."

While no one really knows why this spasm occurs, when you or your iguana experience this spasm as just a single, isolated jerk, with no tremors, other spasms, twitches, loss of motor control, or mental disorientation, it is completely harmless and is not a sign of any underlying health problem.

Sidebar for humans:
If you regularly experience one or more myoclonic spasms when asleep, especially strong ones which cause you to injure yourself or your bed partner, you need to see a physician for this. There are drugs that can reduce or eliminate these spasms, though unfortunately, some doctors are reticent to prescribe them. Spasms may be caused by a calcium and/or magnesium deficiency, encroaching peripheral neuropathy due to dysregulation of insulin processing, nerve or arterial compression, or the "we don't know what's causing your spasms so we just call it Restless Legs Syndrome", to name a few of the reasons why muscles may regularly spasm.

Definition Sources:
1. Cambridge Dictionary of American Language
3 & 4. OnLine Dictionary


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