Table 5. Electrophysiologic assessment of SMA type 2 and 3 patients.
| SMA type 2 | SMA type 3 | Overall (n = 63) | ||||
|---|---|---|---|---|---|---|
| Non-Sitter (n = 12) | Sitter (n = 24) | Non-Ambulant (n = 8) | Ambulant (n = 16) | |||
| Ulnar-ADM | ||||||
| Exploitable results (%) | 87 | 92 | 100 | 100 | 97 | |
| 1st CMAP Amplitude (mV) ** | 0.9 a (0.6–2.0) | 1.1 a (0.7–1.7) | 7.0 b (5.7–9.0) | 6.8 b (4.9–10.2) | 2.0 (0.8–6.6) | |
| Amplitude Decrement (%) 1 | -4.1 (-5.0–0.0) | -8.0 (-12.4–0.9) | -4.2 (-7.7- -2.1) | -2.2 (-7.3–0.7) | -4.1 (-8.0–0.3) | |
| Pathologic Amplitude Decrement (n) | 2 a | 9 a | 0 a | 2 a | 13 | |
| Area Decrement (%) | -6.0 (-14.7–0.3) | -9.2 (-18.2- -2.4) | -7.6 (-9.5- -1.2) | -8.0 (-11.7- -3.5) | -8.0 (-14.2- -2.0) | |
| Accessory-trapezius | ||||||
| Exploitable results (%) | 87 | 92 | 88 | 100 | 92 | |
| 1st CMAP Amplitude (mV) ** | 0.4 a (0.2–1.2) | 0.7 a (0.5–1.4) | 4.0 b (3.1–6.4) | 5.2 b (3.5–8.2) | 1.5 (0.5–4.2) | |
| Amplitude Decrement (%) | -12.2 (-26.7- -9.0)) | -18.0 (-36.0- -5.0) | -4.3 (-19.3–2.0) | -6.5 (-8.8- -2.4) | -11.3 (-22.5- -3.4) | |
| Pathologic Amplitude Decrement (n)* | 9 a | 16 a | 3 a, b | 3 b | 31 | |
| Area Decrement (%) | -16.1 (-38.5- -9.2) | -22.0 (-43.0- -5.3) | -11.2 (- 29.0- -4.0) | -8.4 (-19.0- -3.6) | -12.8 (-29.3- -5.0) | |
| Radial-anconeus | ||||||
| Exploitable results (%) | 73 | 62 | 88 | 94 | 73 | |
| 1st CMAP Amplitude (mV) ** | 0.5 a (0.4–1.2) | 0.8 a (0.4–1.2) | 3.1 b (1.5–7.4) | 2.9 b (2.3–4.4) | 1.5 (0.7–3.1) | |
| Amplitude Decrement (%) | -0.1 (-17.2–4.2) | -6.0 (-28.6- -3.0) | -9.0 (-14.7–4.6) | -6.0 (-8.6- -3.0) | -6.0 (-16.0–0.0) | |
| Pathologic Amplitude Decrement (n) | 3 a | 7 a | 3 a | 2 a | 15 | |
| Area Decrement (%) | -10.0 (-18.0–2.5) | -18.0 (-30.8- -4.5) | -12.5 (-21.7- -1.0) | -7.5 (-12.0- -1.0) | -11.0 (-20.4- -1.0) | |
| Peroneal-tibialis anterior | ||||||
| Exploitable results (%) | 40 | 77 | 100 | 94 | 73 | |
| 1st CMAP Amplitude (mV) ** | 0.5 a (0.3–1.0) | 0.8 a, b (0.5–1.2) | 2.4 b, c (1.7–3.9) | 4.5 c (2.4–5.9) | 1.5 (0.6–3.9) | |
| Amplitude Decrement (%) * | 1.0 (-11.5–15.0) | -7.0 (-25.0- -2.3) | -6.5 (-9.5- -1.5) | -4.0 (-6.0- -2.0) | -5.5 (-10.0- -1.8) | |
| Pathologic Amplitude Decrement (n) | 1 a | 9 a | 2 a | 1 a | 13 | |
| Area Decrement (%) * | 2.4 a (-13.0–14.5) | -21.4 b (-31.7- -6.2) | -7.8 a, b (-13.7- -3.8) | -6.0 a, b (-11.0- -5.0) | -8.7 (-20.2- -4.4) | |
Abbreviations: ADM: Abductor Digiti Minimi; CMAP: Compound Muscle Action Potentials
Values are median (IQR) and overall population size is n = 63 unless otherwise indicated
1 The decrement is considered as pathologic when higher than 10%
* p ≤ 0.05
** p ≤ 0.001
a, b, c Subscript letters represent Post-hoc tests results. In a row, a same subscript letter indicates a subset of categories (SMA type 2, non-ambulant SMA type 3 and ambulant SMA type 3) which do not differ significantly from each other at level 0.05.