Table 2.
Study cohort final diagnosis and histopathological patterns
| Patients | Histopathology | |||
|---|---|---|---|---|
| Pathological MND | Pathological MN | Not diagnostic | ||
| ALS | 71 (69.6%) | 56 (78.9%) | 0 | 15 (21.1%) |
| Revised El Escorial Criteria at time of biopsy | ||||
| Negative | 63 (88.8%) | 50 (79.4%) | 0 | 13 (20.6%) |
| Possible ALS | 3 (4.2%) | 3 (100%) | 0 | 0 |
| Probable laboratory-supported ALS | 5 (7.0%) | 3 (60.0%) | 0 | 2 (40.0%) |
| Non-ALS | 31 (30.4%) | 5 (16.1%) | 16 (51.6%) | 10 (32.3%) |
| Final diagnosis: | ||||
| Inflammatory neuropathya | 11 (35.5%) | 0 | 10 (90.1%) | 1 (9.9%) |
| Idiopathic neuropathyb | 11 (35.5%) | 2 (18.2%) | 6 (54.5%) | 3 (27.3%) |
| Myopathyc | 3 (9.7%) | 0 | 0 | 3 (100%) |
| Amyloid neuropathy | 2 (6.5%) | 1 (50.0%) | 0 | 1 (50.0%) |
| Spondylotic myelopathy | 2 (6.5%) | 1 (50.0%) | 0 | 1 (50.0%) |
| HU-PSMN | 1 (3.2%) | 1 (100%) | 0 | 0 |
| Femoral nerve entrapment | 1 (3.2%) | 0 | 0 | 1 (100%) |
Histopathological data are expressed as n (% of the total row). HU-PSMN = anti-Hu paraneoplastic sensory-motor neuronopathy. Pathological features consistent with MND were detected in almost 80% of ALS; while none satisfied criteria for pathological motor neuropathy (MN). In the ALS group, not diagnostic samples were either normal (n= 11) or not conclusive (n= 4). Among non-ALS mimics, biopsy highlighted pathological features diagnostic for motor neuropathy in 16 of 26 motor neuropathies of different aetiologies, while in five cases the pathological features suggested an MND.
Three multifocal motor neuropathy (n= 3), CIPD (n= 1), chronic motor axonal neuropathy (n= 1), Lewis–Sumner syndrome (n= 1), systemic lupus erythematosus-associated inflammatory motor neuropathy (n= 1), inflammatory neuropathy, not otherwise specified (n= 4).
Idiopathic sensory-motor neuropathy (n= 7) and four idiopathic motor neuropathy (n= 4).
Including two inclusion body myositis;.