Table 1.
Comparisons between MuSK MG, double seronegative generalized MG (dSNMG) and motor neuron disease (MND) groups
| MuSK MG (n = 27) | dSNMG (n = 62) | MND (n = 30) | P values | ||
|---|---|---|---|---|---|
| MuSK MG vs. dSNMG | MuSK MG vs. MND | ||||
| Onset age, mean (years) [range] | 48.2 [21–71] | 48.0 [20–82] | 62.4 [34–78] | > 0.1 | < 0.001 |
| Female, % (n) | 85.2 (23/27) | 43.5 (27/62) | 46.7 (14/30) | < 0.001 | 0.005 |
| Ocular form at onset, % (n) | 25.9 (7/27) | 12.9 (8/62) | 0.0 (0/30) | > 0.1 | 0.004 |
| MuSK Ab positive | |||||
| ELISA, % (n) | 81.5 (22/27) | 0.0 (0/62) | 6.7 (2/30) | < 0.001 | < 0.001 |
| CBA, % (n) | 92.6 (25/27) | 0.0 (0/62) | NA | < 0.001 | NA |
| RIPA, % (n) | 82.4 (14/17) | 0.0 (0/34) | NA | < 0.001 | NA |
| RNST (abnormal decrements), % (n) | 77.8 (21/27) | 66.1 (39/59) | 41.4 (12/29) | > 0.1 | 0.007 |
| Pharmacological response, % (n) | 66.7 (4/6) | 75.0 (15/20) | 23.5 (4/17) | > 0.1 | > 0.1 |
| Thymic hyperplasia or thymoma, % (n) | 12.0 (3/25) | 15.7 (8/51) | 0.0 (0/23) | > 0.1 | > 0.1 |
| MGFA classification at presentation | |||||
| ≥ 3, % (n) | 22.2 (6/27) | 19.4 (12/62) | 28.6 (8/28) | > 0.1 | > 0.1 |
| B classification, % (n) | 70.4 (19/27) | 40.3 (25/62) | 78.6 (22/28) | 0.012 | > 0.1 |
| Current MGFA classification | |||||
| ≥ 3, % (n) | 14.8 (4/27) | 16.1 (10/62) | NA | > 0.1 | NA |
| B classification, % (n) | 66.7 (18/27) | 30.6 (19/62) | NA | 0.002 | NA |
| Myasthenic crisis or mimics, % (n) | 40.7 (11/27) | 11.3 (7/62) | 3.8 (1/26) | 0.003 | 0.002 |
| MGCS, mean [range] | 9.8 [0–33] | 6.1 [0–24] | 10.1 [0–26] | 0.046 | > 0.1 |
Ab Ab, CBA cell-based assay, dSNMG double seronegative generalized myasthenia gravis, ELISA enzyme-linked immunosorbent assay, MGCS myasthenia gravis composite scale, MGFA myasthenia gravis foundation of America, MND motor neuron disease, MuSK muscle specific tyrosine kinase, NA not available, RIPA radioimmunoprecipitation assay, RNST repetitive nerve stimulation test