Table 3.
Comparison of clinical features between myotonia congenita and paramyotonia congenita.
| MC(n = 17) | PMC(n = 3) | ||
|---|---|---|---|
| Gender (M:F) | 13:4 | 2:1 | |
| Family history (+) | 8/17 | 0/3 | |
| Age of onset (y) | 11.6 ± 12.3 | 2.7 ± 1.7 | |
| Myotonia | Limbs | 17 | 3 |
| Face | 2 | 3 | |
| Muscle hypertrophy | 13 | 3 | |
| Myalgia | 3 | 0 | |
| Percussion myotonia | 14 | 3 | |
| Grip myotonia | 16 | 3 | |
| Cold sensitivity | 9 | 3 | |
| Warm-up | 17 | 3 | |
| Permanent weakness | 0 | 1 | |
| Joint contracture | 5 | 3 | |
| Cardiac involvement | 9 | 2 | |
| EMG | Myotonic runs | 17 | 3 |
| Myopathic potentials | 7 | 0 |
MC, myotonia congenita; DMC, autosomal dominant Thomsen's myotonia congenita; RMC, autosomal recessive Becker's myotonia congenita; PMC, paramyotonia congenita; M, male; F, female; y, year(s); EMG, electromyography.