Signs of loss of function include:
True weakness is a lack of physical or muscle strength and the feeling that extra effort is required to move your arms, legs, or other muscles. If your muscle weakness is caused by pain, you may be able to make your muscles work, but it will hurt.
Weakness in one area of your body and loss of function, even for only a few minutes, may occur with a decrease in blood flow to the brain. This type of weakness may occur with a stroke or a transient ischemic attack (TIA). Early symptoms of a stroke and TIA can be the same and usually start with signs of loss of function.
Other medical problems that can cause temporary weakness or weakness that comes and goes include multiple sclerosis, electrolyte imbalances, herniated disc, myasthenia gravis, or a seizure disorder.
Prompt medical attention is required if someone has signs of loss of function, even if it is brief and temporary.
WebMD Medical Reference from Healthwise