ETIOLOGY OF ISCHEMIC STROKE

Bone and cartilage disorders and stroke

David Goldemund M.D.
Updated on 19/06/2024, published on 14/06/2024

bone or cartilage anomalies may affect cerebral arteries and cause ischemic stroke (“bony stroke“); however, the association of bone disorders with cerebrovascular diseases is often indirect and accidental
mainly, single case reports or small case series have been reported
more common in the relatively young patients
the following pathomechanisms may contribute:
- direct affection of the vessel wall resulting in dissection (Eagle syndrome)
- chronic irritation of a vessel leading to the formation of pseudoaneurysms, which can be a source of arterial embolism
- hypoperfusion due to arterial stenosis/occlusion/compression (osteopetrosis, Bow-hunter syndrome)
each of these mechanisms may be permanent or transient, depending on the specific head position
bony strokes are a possible cause of recurrent ischemia of unknown cause in a single vascular territory and may also cause fracture of previously implanted stents
the diagnosis of a bony stroke is based on a combination of medical history and imaging modalities (CT/MR angiography, ultrasound of brain-supplying vessels)
- dynamic imaging modalities (ultrasound, CTA, or even DSA) with the patient’s head in a fixed rotation or reclination can help detect transient compressive disorders
- competing etiologies of ischemic stroke should be sufficiently excluded, and contact between a bone or cartilage anomaly and the affected vessel should be demonstrated
treatment options require a multidisciplinary approach and include:
- conservative treatment
- endovascular stenting
- occlusion of the affected vessel
- surgical bypass
- bone/cartilage removal
correct diagnosis and timely treatment may eliminate the risk of stroke recurrence and significantly impact the patient’s long-term outcome; prospective trials are needed to optimize care

Fibrocartilaginous emboli

embolization (spinal or intracranial) can very rarely result from a ruptured nucleus pulposus

Skull disorders

osteopetrosis (OP) is a rare, inherited metabolic disorder of unknown etiology, characterized by abnormal accumulation of bone mass, probably due to reduced bone resorption
- cerebrovascular involvement is quite rare; strokes can occur due to arterial compression caused by the mechanical constriction of the basal foramina from the osteopetrotic bone
cerebrovascular disorders in patients with Paget´s disease are mainly of mechanical origin
spondyloepiphyseal dysplasia – an autosomal recessive disorder where cerebral ischemia, associated with the moyamoya phenomenon, has been reported

Vascular Eagle syndrome

a condition associated with the contact of the ICA with the elongated styloid process or a calcified stylohyoid ligament
clinically characterized by throat and neck pain that radiates to the ear; rarely, it may cause carotid dissection (Ogura, 2015) (Saccomanno, 2018)
in cases where dissections are treated with stenting, an unrecognized elongated styloid process may cause subsequent stent fracture (Haertl, 2023)

Spine and neck anomalies

Bow-Hunter syndrome

Bow Hunter’s syndrome (also known as Rotational vertebral artery occlusion syndrome) is a condition characterized by symptomatic vertebrobasilar insufficiency, typically transient, resulting from the mechanical compression of the vertebral artery at the atlanto-axial joint during head rotation within the normal physiological range
in DDx exclude compression by the thyroid cartilage (see below)

Vertebral artery affection by a bony spur

bony spur is a rare cause of recurrent posterior circulation strokes
it usually can be detected on a CT scan
in some cases (recurrent stroke despite best medical treatment), endovascular occlusion of the vessel may be performed

Vertebral artery compression from the thyroid cartilage

VA compression in the V2 segment due to thyroid cartilage may cause recurrent posterior circulation ischemic strokes
in some cases, the lesion may not become apparent until the stent is deployed and its compression by the thyroid cartilage is documented
close anatomic relationship to the thyroid cartilage may become more pronounced during swallowing and/or head rotation (dynamic imaging)
surgical treatment options:
- surgical removal of the thyroid cartilage
- surgical bypass to the V3 segment with occlusion of the V2 segment

Periodontal disorders

periodontal disease is highly prevalent
- gingivitis, the mildest form of periodontal disease, is caused by the bacterial biofilm (dental plaque) that accumulates on the teeth adjacent to the gingiva
- periodontitis results in loss of connective tissue and bone support and is a significant cause of tooth loss in adults
periodontitis appears to be an independent risk factor for cardiovascular disease and ischemic stroke (Leng, 2023) (Karnoutsos, 2008)
the association has several possible pathophysiologic links:
- increased risk of thrombosis induced by periodontal pathogens
- accelerated atherosclerosis (periodontal bacteria have been found in the atheromatous plaques and can influence cardiovascular risk factors, such as lipids, fibrinogen, and C-reactive protein)