| Characteristics | Groups | p* | ||
| CN4 | CN6 | |||
| N (%) | 103 (51.5) | 73 (36.5) | ||
| Mean Age (±SD) (years) | 22.5±19.1 | 35.1±21.4 | 0.001 | |
| Gender No.(%) | Male | 64 (62.1) | 46 (63.0) | 0.911 |
| Female | 39 (37.9) | 27 (37.0) | 0.911 | |
| Laterality No.(%) | Unilateral | 100 (97.1) | 68 (93.2) | 0.133 |
| Bilateral | 3 (2.9) | 5 (6.8) | 0.133 | |