Primary Periodic Paralysis: Advice for Clinicians & Future Directions

muscle tissue
muscle tissue
Neurology Advisor speaks with Annabelle Baughan, a retired hematologist-oncologist, and discusses her personal experience with Andersen-Tawil syndrome.

In part 1 of this 2-part series, retired hematologist-oncologist Annabelle Baughan described her difficult personal experience as a patient with a periodic paralysis (PP) disorder. This article, part 2, resumes just after she was finally diagnosed and, later in the article, includes input from Deborah Cavel-Gréant, the president of Periodic Paralysis International.

Dr Baughan: I have so-called “gene negative,” Andersen-Tawil Syndrome (ATS), Type 2; that is, no mutation has yet been found in the commonly examined areas of my KCNJ2 gene. This does not currently impinge on the quality of care I receive, but it significantly delayed my diagnosis and appropriate management. It does however mean that I cannot participate in any clinical trials in ATS, as the very few that exist require that patients have a defined KCNJ2 mutation. Up to 30% to 40% of patients with a PP disorder are so-called gene negative; that is, their mutation has not yet been characterized. But these patients, with identical phenotypes to “gene-positive” patients can and should have the diagnosis clinically confirmed and, in the state of current knowledge, should be treated in the same way.

Why is it so difficult to obtain treatment and advice before genetic results are available? The president of Periodic Paralysis International, Deborah Cavel-Gréant, sums it up perfectly: “It has frequently been our experience that physicians are unwilling to treat until a patient has a genetic identification. Since identification of genetic variants remains an ongoing process, this can leave patients without treatment for years. Before 1994, physicians relied on their clinical skills to diagnose patients, and a good clinical diagnosis is and should be entirely viable as a treatment platform.”

My routine care is with annual review now, or as needed, with a local neurologist and cardiologist — and both are wise and supportive. My general practitioner continues to be superb — this is so crucial with rare life-long diseases — and does everything possible to facilitate my own medical overview of my increasingly complex set of disorders and medications. I made the decision not to risk taking a carbonic anhydrase inhibitor, as I had a severe allergic response to a sulfa drug as a child. I take eplerenone, prescribed to help reduce muscle edema and raise serum potassium level. I am careful with my diet, but I am lucky compared to most people with hypokalemic PP in that I do tolerate a reasonable level of carbohydrates and sodium — this tolerance can be seen in hypokalemic PP when part of ATS. But I am very sensitive to fasting — delayed or missing meals are marked triggers for palpitations and muscle weakness.

I take prophylactic potassium supplements, at least 100 MEq a day and often 200 MEq, in a mixture of both immediate-release and slow-release potassium. The dose is highly empiric, and depends on the frequency of severe palpitations and supraventricular tachycardia episodes. I frequently manage these episodes myself without going to the emergency department using high-dose immediate-release oral potassium, a beta-blocker, relaxation exercises, and Valsalva maneuvers. I also self-check my serum potassium levels, thanks to an open-ended request form from my family doctor and a very convenient system of walk-in commercial laboratories here in France, with results available on the internet within a few hours. As can be seen in patients with ATS, potassium supplementation is very helpful for my cardiac depolarization defect, but too much potassium can make my muscles weaker. It’s clinical decision-making, several times a day, but now completely routine for me.

I keep emergency supplies of effervescent potassium everywhere — in the car and in all handbags. I never leave the house without it nor without my little hand-held electrocardiogram (ECG) recorder. I can usually cope with supraventricular tachycardias myself but polymorphic ventricular ectopy on the trace would mean that I should hightail it to the emergency department. None of this is fun, but I can cope with it, particularly with the immense support and loving tolerance I am lucky enough to have from my partner. Loving friends remain very supportive, but not all of them — one loses friends when one has a chronic severe disorder. Most are unable to understand the concept of my completely unpredictable “good days” and “bad days,” which can be awkward socially. I need to cancel events at short notice too often. It is trying for one’s friends — and for me.

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My physical, muscular, capacity is now about 25% of what it was 10 years ago. I do not tolerate any formal exercise now, as it routinely shifts so much potassium intracellularly that I run too high a risk for an acute dysrhythmia, but I try to walk at least 100 yards most days. I usually need a walking stick. Long days wandering around cities and shops and museums are now out of the question, but I can still enjoy trips out if I pace myself. Carrying anything heavy is difficult and  worsens my muscle pain for a day or two. But rail and air travel have been transformed for the better by always using their services for people with disabilities — lovely young porters taking all the luggage, being seated on the train before anyone else, being sped in a wheelchair past passport control lines — it’s bliss!

It took me a couple of years to properly define the triggers for my attacks. Some triggers affect my muscles more than the heart, and vice versa. They are triggers common to many other patients with PP. Many drugs — including, from my experience, magnesium, benzodiazepines, corticosteroids, antihistamines, adrenaline in local anesthetics, and opiates. And with ATS, all drugs that prolong the QT interval are contraindicated. Being cold and damp, adrenergic stress, fasting, prolonged muscular tension, a large carbohydrate load, prolonged immobilization, and very low barometric pressure are additional triggers that I recognize and attempt to avoid. I also avoid fluorescent lighting whenever possible, wearing dark sunglasses when I can’t avoid it. I can also be triggered by red and yellow food colorings and monosodium glutamate. From a cardiac rhythm point of view, I also need to avoid caffeine in any form.

Living with ATS is finally pretty stable for me now, but things can still go wrong sometimes, either because I “overdo it” or because many healthcare staff will not listen to me or my partner. They often will not read a medical summary and the ATS management guidelines I carry with me always. I consider hospitals, particularly as an inpatient, to be very dangerous places for people with PP. Most of us with a PP disorder need to take so much care in our daily lives to optimize our health — take the right medication at the right dose and at the right time, avoid triggers, eat the right sort of food at the right time of day, exercise when needed, rest when needed, and so on. Once one is an inpatient, all that careful management is usually thrown out the window by the staff. My worst paralysis — and it was bad — in the last year was iatrogenic: during an elective admission for an unrelated disorder. The nursing and medical staff ignored all recommendations about keeping me warm, avoiding prolonged fasting, switching off fluorescent lighting, avoiding prolonged muscle immobilization, and other requirements. It was a sort of PP attack trigger cascade nightmare — unforgivable.