Many intelligent people seem not to be able to get their heads around that the attack triggers themselves may be very banal, but the consequence of ignoring them can be very significant, even fatal. It is entirely exhausting when ill in the hospital for whatever reason to constantly have to challenge and check things — drugs, meals, etc — to make sure they will not harm me. And because so very few people understand these rare PP disorders, I am rapidly assumed to just be fussy and anxious, which further disadvantages my medical care and adds to my adrenaline stress.
And finally, a footnote so to speak, a story of anatomic anomalies in ATS. My partner has teased me gently for years about my rather peculiar toes and little fingers. I thought they were rather distinguished! But one PP specialist I saw was so delighted by my — even subtle — syndactyly and clinodactyly, that his face lit up when I took my socks off (not a common reaction to my feet). I finally know why I have strange digits, but it did cheer me up that someone was actually interested at last in one of my clinical features.
This concludes Dr Baughan’s account of her personal experience with PP. She and Ms Cavel-Gréant jointly responded to the questions below.
Neurology Advisor: Based on your experience, what are your thoughts on the current state of treatment for PP?
Individual ideal prophylactic measures, treatment of acute attacks at home, and potassium treatment regimens are significantly hampered by the lack of an easy-to-use, insurance-funded, and accurate home-use finger prick blood potassium meter. There is a meter available for saliva testing, but it does not have US Food and Drug Administration approval. The ability to accurately measure one’s blood potassium level would help transform the lives of many patients with PP. One waits in hope for someone, somewhere to champion this and get it to market.
The need for potassium supplementation in hypokalemic PP appears to be highly individual. But it needs to be recognized that some patients require very high doses of prophylactic potassium, and doctors need to be reassured that high doses (even 200-300 MEq daily) are typically tolerated very well — just some overview and caution is needed in elderly patients and in anyone with abnormal renal function.
Available treatments for PP are at best only adequate. Very few patients are attack free, and even long-term treatment does not prevent disabling permanent muscle myopathy in all patients. However, without treatment, many patients would be completely disabled and run the risk of fatal attacks resulting from respiratory and cardiac failure and/or arrest.
The most important thing any physician needs to know when treating a patient with one of the periodic paralyses is that one size does not fit all, even between 2 members in the same family. Mother and child, or brother A and brother B, may need different medications and different doses. Therapies may need to be combined to achieve control over episodes — for example, for patients with hypokalemic PP, a potassium-sparing diuretic plus oral fast-acting potassium to take at the first symptom of an attack. Likewise, patients with hyperkalemic potassium paralysis and myotonia might begin with a potassium-sparing diuretic plus a low dose of a sodium channel blocking agent like paroxetine (20-40 mg once daily) or lacosamide (50 mg twice daily), which are used off label rather than using the cardiac drugs with their much greater side effects.
Undoubtedly, more clinical trials need to be carried out for PP. This is not easy because of the rarity, but it is doable. Many patients are disappointed that so much emphasis is given to molecular channel and genetic research in the PP disorders and so little to clinical trials and observational studies. Why are there so many publications about the minutiae of genetic mutations and muscle cell electrophysiology and so few about patients’ symptoms and their treatment?
Neurology Advisor: What are some of the misunderstandings that can cause problems for patients with PP, and what else should physicians know about these disorders?
The first and most common misunderstanding, and perhaps the most important one, is that potassium levels during attacks must be either lower or higher than laboratory norms — this is not true. Dr Ingrid Gamstorp, who described the hyperkalemic form of PP, campaigned vigorously for the rejection of the terms “hypokalemic” and “hyperkalemic,” as weakness in these disorders is not directly related to the serum potassium level but is actually related to the ratio between the intracellular and extracellular potassium. Many patients’ serum potassium levels never leave the laboratory normal range, especially those with hyperkalemic PP and patients who are past adolescence.
Attack triggers may be trivial — for example getting cold, missing a meal — but the consequences of ignoring them may be very serious. Healthcare staff must be repeatedly encouraged to understand this.
Publications classically say that respiratory muscles are not affected in PP. Many, many patients say otherwise. Hypoventilation, choking, even clinical respiratory distress, are well known, and respiratory failure is a well-recognized cause of death in a paralytic attack. There are also widespread sleep disturbances in PP, including a substantial number of patients who have been diagnosed with obstructive or central sleep apnea. This is rarely recognized by doctors. We would suggest that polysomnogram testing be carried out in every patient with a PP diagnosis.
Paralytic attacks can last from minutes to days. There is often something of a pattern in individual patients, and between the different PP disorders, but this is not set in stone and should never be used as a criterion to exclude a diagnosis. The speed of onset of paralysis attacks varies too. Some patients have even 30 minutes of warning, others, just seconds. This should be discussed with each patient to establish a system of safety for them. There is no typical distribution of the paralysis or paresis. It may be unilateral, or just an arm, for example. “Dense quadriplegia” is not a prerequisite for diagnosis.
The steady-state ECG among different patients with ATS is hugely variable, from literally thousands of ventricular ectopies daily, to a normal ECG. There is no definitive, diagnostic pattern. Some patients require internal defibrillators and/or pacemakers, while many others do not. Although all medications that prolong the QT interval are contraindicated in all patients with ATS, some patients do not have a prolonged QT interval, while in some it is intermittent, and in others it is a permanent feature.