Erin* was lying in the floor on her stomach, reading to her two young daughters, when she suddenly began to feel weak, and her vision started to dim. She lay her head on the floor, and was unable to move. Her husband and daughters thought that she had passed out – but Erin was fully awake. Her entire body was paralyzed, but she was not unconscious. “I could hear them and kept thinking that I needed to let them know I was okay, but I couldn’t.” After a few minutes, Erin found that she was able to moan a bit, and about five minutes later she was able to open her eyes. Her strength slowly returned, and in time, she was back to normal. The entire episode lasted about fifteen minutes.
This was the first episode that Erin remembers, but there were others in the subsequent months. Her doctor diagnosed the episodes as petit mal seizures, and consequently put her on an anti-epileptic drug, even though all of Erin’s test came back negative for epilepsy. Even on the medication, Erin’s symptoms continued, and she went in search of a second opinion.
A muscular neurologist in Pittsburgh listened to Erin’s symptoms and concluded that she was not, in fact, suffering from epilepsy. Erin had a condition known as hypokalemic periodic paralysis, or HoKPP.
What is HoKPP?
According to www.hkpp.org, a website devoted to spreading information about HoKPP and other types of periodic paralysis, HoKPP is “a rare inherited muscle disorder that causes episodes of paralysis or weakness.” Symptoms usually appear in adolescence, but there are rare instances in which the first symptoms do not appear until much later in life. In Erin’s case, symptoms first appeared at the age of 30. Sometimes, a patient with HoKPP will experience localized weakness in one area of the body, and full-body paralysis is quite common (www.hkpp.org).
Episodes can vary in intensity from patient to patient, and one patient may experience varying degrees of paralysis from episode to episode. Patients with HoKPP experience paralytic episodes that can last anywhere from a few minutes to days at a time. In Erin’s case, her longest episode lasted about two hours, but most were around thirty minutes. When she regained full strength after an episode, she always felt extremely tired and thirsty.
What causes these episodes of paralysis?
During an attack, the patient’s muscle cells absorb the potassium from the bloodstream. The surplus of potassium in the muscle cells hinders the muscle’s ability to contract. This happens due to a flaw in the patient’s ion channel in the muscle membrane. “The ion channels control the movement of sodium, chloride, potassium and calcium across the cell membrane and from one cell compartment to another. This movement of ions produces the electrical ‘spark’ which allows our muscles to move. (www.hkpp.org)” The HoKPP patient is extremely sensitive to any fluctuation in blood potassium levels, more so than most people. What would be an unnoticeable drop in potassium levels in another person can cause an HoKPP patient to have a severe paralytic attack (www.hkpp.org).
HoKPP patients can often feel an episode coming on before it actually happens. Erin always knew when she was about to have an attack. “It was sort of like a drape coming over me. I would just lose movement over a period of several seconds to a couple of minutes.” These episodes can be extremely frightening, because patients are fully conscious but unable to move or react to their surroundings. “Once I was under I just couldn’t move. I couldn’t talk or open my eyes. Sometimes, with great effort, I would be able to moan or open my eyes a little.”
What treatment is available?
HoKPP can usually be managed with medication. Erin’s neurologist prescribed 30MEQ K-Dur, a potassium chloride supplement, to help manage her symptoms. Since beginning treatment, Erin has not experienced a single paralytic episode. “Once in a while I will get that weak feeling, like I had at the beginning of an episode, but as long as I rest for a couple of minutes, it never develops.”
Most patients with HoKPP can go on to lead normal lives with proper treatment. Unfortunately, many patients, especially elderly, are misdiagnosed and may not receive treatment. There have been cases in which a patient will have a prolonged period of paralysis, lasting weeks or months, and are simply diagnosed as having muscle weakness associated with old age. With proper treatment, these patients could return to full mobility, but because HoKPP is rare, it is often missed by doctors.
