Recurrent posterior circulation infarction caused by anomalous occipital bony process in a young patient

Abstract

Background: Structural anomaly of the cervical spine or craniocervical junction has been reported as one of the rare causes of ischemic stroke. We report a case of a young patient with recurrent posterior circulation infarction that may have been associated with an anomalous occipital bony process compressing the vertebral artery.

Case presentation: A 23-year-old man experienced recurrent posterior circulation infarction 5 times over a period of 5 years. He had no conventional vascular risk factors. Young age stroke work-up including thorough cardiac, intra- and extracranial vascular evaluation and laboratory tests for the hypercoagulable state or connective tissue disease yielded unremarkable results. An anomalous bony process from the occipital base compressing the left vertebral artery was observed on brain CT. All the recurrent strokes were explainable by the arterial thromboembolism originating from the compressed left vertebral artery. Therefore, the left vertebral artery compressed by the anomalous occipital bony process may have been the culprit behind the recurrent thromboembolic strokes in our patient. Intractable recurrent strokes even under optimal medical treatment led us to make a decision for the intervention. Instead of surgical removal of the anomalous occipital bony process, the left vertebral artery was occluded permanently by endovascular coiling after confirming that this would cause no neurological deficits or flow disturbance in the posterior circulation. There was no recurrence of stroke for 2 years after permanent occlusion of the left vertebral artery.

Conclusion: Arterial thromboembolism originating from the left vertebral artery compressed by the anomalous occipital bony process is a rare but not to be overlooked cause of posterior circulation infarction. When intractable to medical treatment, endovascular occlusion of the vertebral artery without flow disturbance to the posterior circulation may be a useful treatment option when surgical removal is not feasible.

Figure 1

Medication history and findings of diffusion-weighted MRI and angiography of five recurrent strokes. (A: first stroke; B: second stroke; C: third stroke; D: fourth stroke; E: fifth stroke). Recurrent thromboemboli were observed in the distal basilar artery (arrows). Finally, the left vertebral artery was permanently occluded with detachable coils after the fifth stroke.

Figure 2

Anomalous occipital bony process compressing the vertebral artery. CT angiography showed the left vertebral artery (arrowheads) compressed by the anomalous occipital bony process (arrows).

Figure 3

Dynamic time-of-flight MR angiography showed that left vertebral artery stenosis (arrows) was slightly aggravated when the head was turned to the right side (A: right head rotation, B: neutral position, C: left head rotation).

Figure 4

Procedure of endovascular occlusion of the left vertebral artery. A. Left vertebral artery angiography showed stenosis (arrow). B. The first detachable coil (arrowhead) was placed across the stenotic segment with proximal flow control with microballoon catheter. C. The left vertebral artery was completely occluded after the coil embolization. D. The right vertebral artery sufficiently took over the entire posterior circulation territory perfusion. The left vertebral artery is opacified retrogradely.