What happens during an attack of Periodic Paralysis?
People with Periodic Paralysis (PP) have episodes in which their muscles become weak or paralyzed in response to variations in the amount of potassium in their blood. These variations occur during sleep, they may result from food the person has eaten, from a sudden change in a person’s activity level, from rest after activity, emotional stress, from becoming chilled, or a number of other factors. Potassium levels vary all the time.
A study of 68 healthy individuals1 showed that, on average, their serum potassium level varied by 1.4 mmol/l during a week of normal activity. The body is designed to handle such variations without the slightest problem but people with periodic Paralysis have genetic flaws which make them abnormally sensitive to normal variations in serum potassium. Anyone will become weak in response to a drastic change in serum potassium levels, but PP patients may respond to small changes in potassium levels as if they were major shifts. Recovery from weakness occurs after a few hours to a few days, but permanent weakness can develop after many years of such attacks.
I don’t know what triggers my episodes!
Periodic paralysis can be easy to diagnose if you have frequent episodes of flaccid paralysis that leave you unable to move for 12-24 hours. It can be less easy to recognize when the signs are more subtle, which they are in many cases. People often come to us after a diagnosis of periodic paralysis has been suggested to them without any idea of where to go from there. In such cases it may only be by carefully observing patterns of weakness in relation to known triggers that the decision can be made to pursue further testing. This method can also help newly diagnosed patients learn what their triggers are and how to avoid them.
How to keep a triggers diary
Get a spiral notebook and set up a simple chart. For each hour of the day reserve several lines on which to record everything you’ve eaten in that hour – including juice, pop, alcohol – everything except water. Record the amount, and the time you ate/drank it. Also leave space to record your activities during that hour. (For example: walked three blocks. cleaned out the barn and groomed 40 horses. laid on the sofa and watched TV.)
For the same hour, on a scale of 1-10 record your general strength level. Be objective. One means you couldn’t get out bed if it were on fire, 10 means you could leap a tall building in a single bound. If you are experiencing localized weakness record where (arms, legs, trunk, hands etc.) and grade it separately 1-10.
If you had an episode of weakness or fatigue within the last hour record how long it lasted, what areas of your body were affected and grade it 1 – 10. If you hurt say where and grade it on a scale of 1-10. One is a mosquito bite and 10 is akin to having your leg amputated with a rusty crosscut saw.
Record any other significant symptoms like nausea, chest pain or heart palpitations, pins and needles, shortness of breath, headache, etc. In some forms of periodic paralysis, muscle stiffness or rigidity is a particularly significant symptom. This stiffness may cause a sense of “tightness” or hesitation when moving, an inability to fully open the eyes on awakening, or a problem ‘letting go’ of grasped objects. Stiffness may come and go or be a more or less constant companion, but watch for increased stiffness following exercise or the ingestion of certain foods. If you have muscle stiffness, notice if it improves or grows worse as you ‘warm up’ or use your muscles. This may change from episode to episode with the HyperKPP/PMC combination (explained below), so close observation is necessary.
Example of what a diary entry might look like:
Monday 6th Jan 4:00 PM
|Able to walk around house
|Able to walk around house
|couldn’t use can opener
|pins/needles, aching muscles
You may have to keep this record every day for two-four weeks. Yes, it takes time and it’s really annoying, but it is vital for several reasons. One, it can establish whether you actually have a pattern of episodic weakness and two, if you do it will reveal your triggers and allow you to begin the establishment of an effective management program.
What do I do with all this information?
At the end of each week sit down with a piece of graph paper and make a chart for each day. Begin at the bottom line and number each line on the graph from 10 to 1 as it goes up the side of the paper. Across the bottom mark down the hours of the day, beginning each morning when you got up and ending when you took the last ‘reading’ of the day.
Transfer the information about your hourly strength levels from your notebook to the graph paper. Then connect the dots. Look at it very carefully. Does your strength fluctuate from hour to hour? Do you have times where all of a sudden your strength dips like crazy (from say – three – down to seven) and then in a few hours it’s back up to three again? Or does it do this over a period of days? Say on Monday you were feeling great at two and on Wednesday you woke up at a nine and stayed there for six hours? If you find this is so – look at the times when you have the dips in strength and look at; 1. What you ate and 2. your activity in the 24 hour period before the dip (some people have to go back up to 72 hours before to find the trigger).
Search for common triggers
Look at the list of common triggers. Compare them with what you did or ate during the 24 hours prior to your episode of weakness. Did you eat a plate of mashed potatoes, a Big Mac or a pizza, an entire apple pie? A cantaloupe or a bag of dried apricots? Maybe you played 18 holes of golf or went dancing? Make a note of your diet and activities in relationship to your episodes of weakness. Is there always a dip in strength an hour after meals or ten minutes after your jog around the park? Does the dip in strength happen 48 hours later?
Look for what makes you stronger
Is there anything you eat that consistently makes you stronger? Maybe drinking soda pop or eating candy makes you stronger, perhaps a high carbohydrate meal makes you feel better. If you are experiencing continual weakness the variations may be very subtle.
Some patients, especially patients in their 50s or 60s, may be in what is called an abortive attack. This form of episode can literally last for weeks, even months, at a time, leaving them feeling weak/greatly fatigued almost continually, yet never completely paralyzed.
Or one area of the body (legs, arms) may be much weaker than the rest of the body. In these cases it is important to watch for fluctuations in strength that may follow a pattern. There may be a consistent pattern of morning weakness with greater strength in the evening, or a slightly greater period of strength at one particular time of the time.
The triggers for episodes vary, depending on the type of periodic paralysis. There are two basic types, one in which patients are sensitive to potassium, and eating potassium-rich foods may cause weakness, and a type in which weakness is triggered by drops in blood potassium. Those who have Hyperkalemic Periodic Paralysis may find that high-potassium foods like cantaloupe, bananas, dried fruit, nuts etc. may trigger weakness. Those with Hypokalemic Periodic Paralysis are more apt to be bothered by sweets, starchy foods like baked goods, pasta, rice and salty foods.
There are also forms, HyperKPP with Paramyotonia Congenita, and some Andersen-Tawil Syndrome patients in which episodes can be triggered by potassium fluctuations in either direction. All types may find episodes of weakness are triggered by sleep, rest after exercise, eating a big meal, or getting too hungry. Becoming chilled will provoke an episode in many people. Becoming overheated provokes episodes in many patients as well. Once you’ve correlated a trigger with an episode look at ALL your episodes and see if they have a common trigger. They may not have.
It may take a combination of several triggers to initiate an episode, and they may not all be the same triggers every time. Some people have observed these patterns already, but many times the triggers and the episodes are spaced just far enough apart so that the cause and effect are not readily apparent. But if you see a distinct pattern of episodic weakness triggered by factors which are ‘known’ to alter blood-serum levels of potassium then it’s time to gather evidence to take to your doctor and ask for further testing.
1. Harris EK, Kanofsky P, Shakarji G, and Cotlove E; Long-Term Studies of Serum Constituents in Normal Subjects. Clinical Chemistry, Vol. 16, No. 12, pp 1022-27, 1970