Bony Stroke May Be Cause for Recurrent Ischemic Stroke of Unknown Cause

Bony strokes may be considered in patients with recurrent ischemic stroke of unknown cause.

Patients who are experiencing recurrent ischemic stroke of unknown cause may be having symptoms due to bony stroke. These are the findings of a study published in the journal Stroke.

Anterior and posterior circulation ischemic strokes may be caused by structural bone and cartilage anomalies. Proper diagnosis of bony strokes through computed tomography (CT)- and magnetic resonance imaging (MRI)-angiography and treatment may reduce or eliminate risk for recurrence of such strokes.

This retrospective diagnostic workup was designed to describe bony strokes to raise awareness of the condition. Researchers reviewed the medical records from patients (N=4,200) who presented with stroke at the Technical University of Munich in Germany between 2017 and 2022. A total of 6 patients who had bony stroke were identified and discussed in this case report.

Patient 1 was a man of 20-30 years of age. He presented with occlusion of the left middle cerebral artery. He experienced a recurrence 9 months later. At a 6-month follow-up, an asymptomatic, partially thrombosed pseudoaneurysm was observed by CT- and MRI-angiography. Reevaluation of imaging data revealed a close anatomical relationship between the affected artery and an elongation of the styloid process and vascular eagle syndrome was diagnosed. The patient underwent surgical removal of the styloid process and was clinically stable at a 6-month follow-up.

“Due to the possibly high risk of stroke recurrence and potentially causative treatment options, bony strokes seem to be highly relevant for clinical practice.”

Patients 2 and 3 were found to have bow hunter syndrome. Patient 2 was a 70–to-80-year-old man who presented with an acute posterior circulation wake-up stroke. The patient had had 4 ischemic strokes and one transient ischemic attack and had a history of 4 events in the previous year. All events had occurred in the morning and began after use of a new pillow.

Reclination and slight rotation of the head was found by CT-angiography to cause occlusion of the left vertebral artery (VA) which was ultimately related with an osteophytic alteration in the fifth cervical vertebrae. The patient was offered surgical intervention but declined.

Patient 4 was a man aged 50 to 60 years old who presented for a consultation after 3 recurrent ischemic strokes within 5 months. Upon reevaluation of CT scans, a bony spur that made immediate contact with the left VA was observed. The left VA was confirmed to have high-grade stenosis and the patient underwent coil occlusion of the vessel. The patient was stable at a 9-month follow-up.

Patients 5 and 6 were found to have compression caused by thyroid cartilage. Patient 5 was a man aged 50-to-60 years old who presented with a total of 6 ischemic strokes in the posterior cerebral circulation within 23 months. High-grade atherosclerotic stenosis was thought to be the cause; however, an emergency CT-angiography revealed the compression was caused by thyroid cartilage. The patient underwent emergency surgical bypass from the anterior occipitalis to the V3 segment of the right VA. No recurrences occurred during a 24-month follow-up.

The researchers concluded, “Due to the possibly high risk of stroke recurrence and potentially causative treatment options, bony strokes seem to be highly relevant for clinical practice. In patients with recurrent strokes in one vascular territory, the presence of a symptomatic anatomic bone or cartilage anomaly may be considered as a differential diagnosis after sufficient exclusion of competing etiologies of an ischemic stroke.”

References:

Haertl J, Renz M, Wunderlich S, et al. Bony stroke: ischemic stroke caused by mechanical stress on brain supplying arteries from anatomical bone or cartilage anomalies. Stroke. Published online April 13, 2023. doi:10.1161/STROKEAHA.122.041946