ETIOLOGY OF ISCHEMIC STROKE
Bone and cartilage disorders and stroke
Updated on 23/09/2024, 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)