The etiology of every fourth ischemic stroke remains unclear after the initial work-up. Recent studies predominantly focused on covert atrial fibrillation, non-stenosing aggressive artery plaques and cancer-associated hypercoagulability as undetected causes of stroke in such patients.1 Haertl et al. now cast the light on bone or cartilage anomalies affecting the brain supplying arteries as rare structural cause of ischemic stroke.2
From a pathophysiological perspective, such anomalies could directly damage the arterial vessel wall leading to dissections or compress brain-supplying arteries with consecutive hemodynamic alterations both causing ischemic stroke. Although these so-called bony strokes are not new (e.g., bow hunter’s syndrome), the presented manuscript gives a nice overview of possible bone/cartilage-associated etiologies in acute ischemic stroke patients. However, due to the retrospective study design the reported incidence of 0.14% (6 bony strokes in 4200 ischemic stroke patients) must be interpreted cautiously and might underestimate the true rate of bony strokes.2
Bone/cartilage-associated strokes can easily be overlooked as the diagnosis is relatively complex warranting a combination of different imaging modalities including computed tomography, magnetic resonance imaging and ultrasound. Ultrasound imaging of the brain-supplying vessels offers the easiest method to identify dynamic changes of cerebral blood flow and can therefore be used to screen for significant vessel compression in different head positions.
To summarize, the combination of recurrent ischemic strokes of unknown source affecting a single vascular territory should raise awareness of an underlying bony stroke. Although rare, such patients should be screened with dynamic examinations of the brain-supplying vessels.
Key Points:
- Bone or cartilage anomalies with affection of brain-supplying vessels are a rare etiology of ischemic stroke.
- Recurrent ischemic stroke in a single vascular territory should raise awareness of a bony stroke.
- Dynamic imaging of the intra- and extracranial vessels (e.g., ultrasound imaging) is crucial to identify bone/cartilage-associated strokes.
References:
- Diener HC, Easton JD, Hart RG, Kasner S, Kamel H, Ntaios G. Review and update of the concept of embolic stroke of undetermined source. Nat Rev Neurol. 2022;18(8):455-465. doi: 10.1038/s41582-022-00663-4.
- Haertl J, Renz M, Wunderlich S, Hemmer B, Hofauer B, Gempt J, et al. Bony Stroke: Ischemic Stroke Caused by Mechanical Stress on Brain Supplying Arteries From Anatomical Bone or Cartilage Anomalies. Stroke. 2023;54(5):1246-1256. doi: 10.1161/STROKEAHA.122.041946.
Co-author(s):
Vlad Tiu, Department of Neurology, Elias Emergency University Hospital Bucharest, UMFCD, Romania
Elsa Azevedo, Department of Neurology, Centro Hospitalar Universitário de São João, Porto, Portugal
Publish on behalf of the Scientific Panel on Neurosonology