| Condition | Pain? | Weakness Location | CK Level | Key USMLE Feature |
|---|---|---|---|---|
| Polymyositis/DM | +/- | Proximal (Symm) | ↑↑↑ | CD8+ (PM) / CD4+ (DM), Rash (DM) |
| PMR | Yes | Pain > Weakness | Normal | ↑ ESR, >50y, Temporal Arteritis |
| Hypothyroidism | +/- | Proximal | ↑ | Delayed DTRs, ↑ TSH |
| Steroid Myopathy | No | Proximal | Normal | Hx of steroid use, Cushingoid |
| Myasthenia Gravis | No | Ptosis/Bulbar | Normal | Worsens with use, thymoma |
| Lambert-Eaton | No | Proximal | Normal | Improves with use, SCLC |
| ALS | No | Asymmetric | Normal/Mild | UMN + LMN signs, no sensory loss |