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Some Historical, Physical Exam, and Laboratory Diagnostic Considerations for Ion Channelopathies [9,16] |
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| Question |
If positive, suggests: |
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| Family history |
hyperPP, hypoPP, ATS, PMC, MC, PAM |
| Carbohydrates induce attacks |
TPP, hypoPP, +/- PMC, ATS |
| Carbohydrates ameliorate attacks |
hyperPP, ATS, PMC, PAM |
| Stiffness after exercise |
PMC, MC |
| Tongue stiffens when eating ice cream |
PMC |
| Less stiffness decreases with repeated exercise of a given muscle (warm-up phenomenon) |
MC |
| Myotonia increases with continued exercise |
PMC |
| Serum potassium elevated during attack |
PAM, hyperPP, ATS, PMC |
| Serum potassium normal during attack |
all diagnoses are possible |
| Serum potassium low during attack |
hypoPP, TPP, ATS, PMC, diuretic abuse, hyperaldosterone states, RTA |
| Difficult to open eyes in the cold |
PMC |
| Attacks of muscle stiffness |
MC, ATS, PMC, PAM |
| Attacks of muscle weakness |
MC, TPP, hyperPP, hypoPP, ATS, PMC |
| Duration of attacks are hours |
hypoPP, TPP, ATS, PMC |
| Duration of attacks are minutes to hours |
hyperPP, PAM, MC, ATS |
| EMG with myotonia |
hyperPP, PAM, MC |
| EMG silent during attack of weakness |
hypoPP, TPP, ATS, PMC, MC |
| Palpitations |
ATS, hypoPP, hyperPP, TPP, PMC |
| EKG – tachycardia |
TPP |
| EKG – long QTc and/or ventricular arrhythmia |
ATS |
| EKG – u waves |
ATS, hypoPP, TPP |
| Hyporeflexia during attack of weakness |
hypoPP, TPP, ATS, hyperPP |
| Percussion myotonia |
MC, PMC, PAM |
| Physical exam with some of: fifth digit clinodactyly, ocular hypertelorism, low-set ears, webbed fingers/toes, broad nasal root, small mandible, short stature, brachydactyly, microcephaly, short palpebral fissures, thin upper lip, small hands/feet, residual primary dentition, delayed bone age [16] |
ATS |
| McManis nerve conduction protocol (i.e., changes in compound muscle action potential after exercise) |
ATS, hyperPP, hypoPP, TPP |
| Muscle biopsy with tubular aggregates |
ATS, hyperPP, hypoPP, TPP, PMC, PAM, MC |
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hyperPP = hyperkalemic periodic paralysis; hypoPP = hypokalemic periodic paralysis; ATS = Andersen-Tawil syndrome; PMC = paramyotonia congenita; MC = myotonia congenita; PAM = potassium-aggravated myotonia; TPP = thyrotoxic periodic paralysis; RTA = renal tubular acidosis | |
Levitt Journal of Translational Medicine 2008 6:18 doi:10.1186/1479-5876-6-18 |
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