Table 3 Some Historical, Physical Exam, and Laboratory Diagnostic Considerations for Ion Channelopathies [9,16]

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