Objective:

To report a case of transient focal neurological episodes (TFNEs) associated with convexity subarachnoid hemorrhage (cSAH) in a young patient with severe ipsilateral extracranial internal carotid artery stenosis, highlighting the clinical significance of these findings.

Key Findings:

• The patient exhibited transient focal neurological episodes linked to multiple ipsilateral cSAHs, indicating a potential correlation.
• Severe atherosclerosis with subtotal occlusion of the ipsilateral extracranial ICA was identified as the underlying cause, emphasizing the need for awareness of this condition.
• No evidence of common cSAH etiologies such as RCVS or CAA was found, suggesting a unique case.

Interpretation:

The case suggests that severe extracranial ICA stenosis can lead to cSAH and TFNEs, highlighting the need for thorough diagnostic evaluation in similar presentations to prevent misdiagnosis.

Limitations:

• The case is singular and may not represent broader population trends, indicating the need for further studies.
• Lack of long-term follow-up data on the patient's neurological status post-treatment limits the understanding of outcomes.

Conclusion:

This case underscores the importance of considering severe carotid artery stenosis as a potential cause of cSAH and associated neurological symptoms in younger patients, advocating for early diagnosis and intervention.