| Prevalence | Very rare, estimated 1-2% of all ALS cases |
| Age | Typically presents in middle-aged adults (40-60 years) |
| Sex | Male predominance (approximately 2:1) |
| Course | Generally slower progression than classic ALS |
| Survival | Often decades-long disease course; many patients retain ambulation [@hu1998] |
| Proximal muscles | Deltoid, biceps, brachioradialis |
| Shoulder girdle | Rotator cuff muscles, scapular stabilizers |
| Distal involvement | May progress to hand intrinsic muscles (later stage) |
| SOD1 mutations | Associated with some familial cases |
| Rare variants in ALS-associated genes | May predispose to the flail arm phenotype |
| Anterior horn cell loss | Especially in cervical regions |
| Neuronal atrophy | Without prominent inclusion bodies |
| Databases | OMIMOrphanetClinicalTrialsPubMed |
No AI portrait yet
No comments yet. Be the first to comment!