Baseline characteristics of the included brainstem AVMs
| Characteristics | All patients (n=61) |
| Sex (male) | 33 (54.1) |
| Age (years) | 29.5±14.0 |
| Onset manifestation | |
| Haemorrhage | 49 (80.3) |
| Neurofunctional deficit | 4 (6.6) |
| Others | 8 (13.1) |
| Hydrocephalus | 5 (8.2) |
| Admission mRS | 1.2±1.4 |
| AVM grading (SM grade) | |
| I | 0 (0.0) |
| II | 30 (49.2) |
| III | 22 (36.1) |
| IV | 4 (6.6) |
| V | 3 (4.9) |
| VRAS | |
| 0 | 0 (0.0) |
| 1 | 3 (4.9) |
| 2 | 27 (44.3) |
| 3 | 15 (24.6) |
| 4 | 16 (26.2) |
| RBAS | |
| <1 | 19 (31.1) |
| 1–2 | 31 (50.8) |
| >2 | 11 (18.0) |
| Location | |
| Midbrain | 30 (49.2) |
| Midbrain-pons | 5 (8.2) |
| Pons | 10 (16.4) |
| Pons-medulla | 3 (4.9) |
| Medulla | 6 (9.8) |
| Middle cerebellar peduncle | 5 (8.2) |
| Others | 2 (3.3) |
| Size (cm) | 2.4±1.4 |
| Deep venous drainage | 26 (42.6) |
| Drainage varix | 15 (24.6) |
| Aneurysms (flow-related) | 10 (16.4) |
| Diffuse nidus | 10 (16.4) |
| Deep perforating arteries | 45 (73.8) |
| Treatment modalities | |
| Conservation | 13 (21.3) |
| Microsurgery | 6 (9.8) |
| Embolisation | 12 (19.7) |
| SRS | 21 (34.4) |
| Embolisation+SRS | 9 (14.8) |
| Follow-up duration (years) | 4.5±2.1 |
AVM RBAS score= (0.1)*(AVM volume)+(0.02)*(patient age)+(0.3)*(AVM location).
Values are expressed as number of cases (%) or mean±SD, unless otherwise indicated.
AVMs, arteriovenous malformations; SM grade, Spetzler-Martin grade; mRS, modified Rankin Scale; RBAS, Radiosurgery-based AVM Score; SRS, stereotactic radiosurgery; VRAS, Virginia Radiosurgery AVM Scale.