Primary periodic paralysis (PP) is a group of autosomal dominant channelopathies that cause episodes of paralysis or muscle weakness that have many triggers including medication, exercise, certain foods, or stress. There is wide variation in the age of symptom onset, ranging from just after birth to late adulthood, although patients typically begin to experience attacks before age 20 years. PP affects individuals of both sexes and all races.1
The types of PP are defined by shifts in blood potassium levels during acute episodes: hypokalemic PP, the most common form of PP, involves a downward shift in serum potassium levels, whereas hyperkalemic PP is characterized by an upward shift. However, in many patients, the blood potassium levels do not fall outside the normal laboratory reference range. In Andersen-Tawil syndrome (ATS), potassium levels are inconsistent during attacks.2
“Diagnosis of PP requires a history of transient episodes of weakness, determination of ictal and steady-state serum potassium levels, [electromyogram,] and exclusion of secondary causes,” according to authors of a paper published in Brain.2 However, doctors often attribute the symptoms to other diseases or to psychological distress, and patients may not receive a diagnosis until many years after onset.
That was certainly the case for Annabelle Baughan, a retired hematologist-oncologist in France who ultimately had to investigate and determine her own diagnosis. She spoke in depth with Neurology Advisor about her disease history and frustrating encounters in the healthcare system in pursuit of a diagnosis and appropriate treatment, as well as her current status, with important advice for physicians who may encounter patients with PP.
Dr Baughan’s story is below, ending just after she was finally diagnosed.
Dr Baughan: I have ATS with hypokalemic/normokalemic PP (ATS PP).3 I consider myself lucky — my cardiac rhythm abnormalities are milder than some people with ATS,4 and my paralyses have so far never put my life at risk. I am also a physician, which brings the huge advantage of usually being able to refer myself to a doctor of my choice, but it also brings the disadvantage of being “on duty” all the time, as I usually have enough medical knowledge to challenge other doctors’ misconceptions. This is very helpful but can be very exhausting.
I am British, and I have been living in France for the last decade. I was finally diagnosed at age 64 years, having had symptoms for nearly 50 years. Very significant delays in diagnosis are sadly not at all unusual in the genetic PP disorders. I have no known family history of PP, but my family is very small, and there is no one to ask now. But since my diagnosis was confirmed, I feel sure that my mother also had ATS PP. She had very similar muscle symptoms and 2 cardiac arrests, for which no cause was given, in the absence of structural heart disease. She died from an unrelated illness in the 1980s and was never investigated for a muscular disorder. She was told those symptoms were “neurosis.”
My muscles became noticeably symptomatic at age 15 years. I went to the family doctor with my parents and described that my arms and, particularly, legs were sometimes very weak, even paralyzed, and my muscles were often sore and painful and sometimes stiff. I also had frequent, severe muscle cramps including in rather unusual sites such as the ankles, fingers, and shins. I had very strong muscle power for brief action but almost no muscle endurance; repeated squats, for example, were impossible, no matter how much I exercised.
I had very frequent episodes of paresis, from minutes to hours of very unstable gait resembling a drunk penguin, and paralytic episodes (mostly legs, but sometimes the whole body) lasting up to 90 minutes, maybe 15 times a year, typically waking during the night and realizing I could not turn over in bed, or indeed move at all. In between paretic events I was fit and active.
The doctor told us that my symptoms were “hypochondria caused by academic stress” and that I should be referred to a psychiatrist. My splendid parents disagreed with that diagnosis and refused the referral. I think they might have felt that any sign at all of me taking my studies seriously enough to be stressed by them was not believable! The family doctor refused to refer me to a specialist physician, nor were any investigations ordered.
However, the weakness and paralysis always recovered promptly, I was otherwise well, and the muscle pain and cramps were just “one of those things.” So, my parents and I ignored it all, and I continued as a fit and active youngster. But my parents did notice that I very rarely tolerated medication of any sort: those drugs I wasn’t actually allergic to seemed to give me other strange adverse effects, and often at very low doses.
During the next decade or so, a few doctors I consulted for minor illnesses told me that my muscle symptoms were a result of being overweight (then just 7 pounds over ideal weight at 5 feet 10 inches tall) and “lazy.” At the time I was playing many sports at a high level and seldom sat still for more than a few minutes. I told the doctors this, but they presumably thought I was lying. I rapidly learned that if you want your odd, unexplained symptoms diagnosed and treated properly, you should never, ever, be even an ounce overweight; it’s such an easy target for ignorant healthcare professionals to aim for, I think, particularly if the patient is female. I remained large, so I thought it prudent not to mention my muscles again to any doctor.
In my 20s, I had to give up all serious sports, as I frequently had very weak limbs in the rest period after exercise, and it was becoming a nuisance for work. This weakness also resulted in many trips and falls, multiple sprains and bruising, and 3 minor fractures. But I was not otherwise physically clumsy. The worst attack as a young adult was after playing tennis in the morning and then having intravenous diazepam for dental surgery in the afternoon. An hour later, my legs became very weak and I could not stand for the next 3 days. When one is refused a diagnostic process, especially when told symptoms all psychogenic or laziness, one inevitably starts developing strange rationalizations. Mine included: “I must be hypersensitive to the sedative effects of diazepam, and to antihistamines,” and, “I have intermittent vertebral disc prolapse,” and “this must be an atypical fibromyalgia,” and so on. Some of my thoughts were rather silly, especially as I am a physician. My fallback rationalization for everything, even daily, was, “silly me, I’ve overdone the exercise yet again.”