Carotidynia

• Eccentric thickening of perivascular tissues around the distal common carotid artery, carotid bulb, or proximal internal carotid artery with preserved or only mildly narrowed vessel lumen (the 'King Kong carotid' sign)
• Enhancement of the carotid wall and surrounding tissues on contrast-enhanced CT or MRI
• Fat stranding in the soft tissues surrounding the affected carotid segment
• Absence of true arterial dissection (no intimal flap, normal flow dynamics) and normal imaging appearance of other vessels to exclude vasculitis or thrombosis

• Eccentric, smooth thickening of the carotid adventitia and perivascular tissues centered at the level of the distal common carotid artery through proximal internal carotid artery, creating the characteristic 'King Kong carotid' appearance where the vessel is partially encircled by edematous tissue without significant luminal narrowing.
• Mild narrowing of the carotid lumen secondary to wall edema and inflammation, typically without high-grade stenosis or flow-limiting disease.
• Robust enhancement of the thickened carotid wall and perivascular soft tissues on contrast-enhanced CT or MRI (more pronounced on MRI), reflecting the inflammatory process involving the arterial adventitia.
• Fat stranding in the cervical soft tissues immediately surrounding the affected carotid segment, indicating perivascular inflammation and edema.
• Transient fatty plaque may be visualized during the healing phase, representing organization of inflammatory material within or adjacent to the carotid wall.
• Normal flow signal within the carotid lumen on MRI (no arterial dissection flap, no high-velocity jets, no flow interruption), and the absence of true intimal pathology distinguishes this from arterial dissection.
• Imaging findings are typically unilateral and localized to the region of the carotid bifurcation without evidence of systemic vascular disease or involvement of other major cervical vessels.
• All imaging features (wall thickening, enhancement, fat stranding) typically resolve spontaneously within 1-2 weeks, reflecting the transient and self-limiting nature of the inflammatory process.

• Carotid artery dissection: distinguished by presence of intimal flap, intramural hematoma with characteristic crescent-shaped wall thickening, and potential flow abnormalities or pseudoaneurysm; carotidynia shows smooth eccentric wall enhancement without intimal disruption.
• Giant cell arteritis (GCA): presents with concentric carotid wall thickening and enhancement typically in patients over 70 years with systemic symptoms; carotidynia affects younger patients (30-50 years) with eccentric thickening and rapidly resolves.
• Takayasu arteritis: involves larger segments of the carotid and subclavian arteries with long-segment narrowing and wall thickening in younger patients, often with systemic symptoms; carotidynia is localized to the carotid bifurcation and self-limited.
• Cervical lymphadenitis: presents with enlarged lymph nodes in the neck; carotidynia shows perivascular inflammation specifically involving the carotid artery wall rather than discrete lymph node enlargement.
• Jugular vein thrombosis: distinguished by thrombus within the vein lumen on imaging; carotidynia affects the carotid artery wall and perivascular tissues without involving the venous system.
• Submandibular gland disease or head and neck tumors: localized to glandular or soft tissue structures rather than the carotid wall; carotidynia demonstrates specific involvement of the carotid vessel wall with enhancement and perivascular inflammation.

Describe carotidynia as 'eccentric thickening and enhancement of the perivascular tissues surrounding the distal common carotid artery and carotid bulb with mildly narrowed or preserved vessel lumen, fat stranding in the surrounding soft tissues, and no evidence of arterial dissection, high-grade stenosis, or thrombosis—findings consistent with transient perivascular inflammation of the carotid artery (TIPIC syndrome), which is expected to resolve spontaneously.' Emphasizing the preserved flow dynamics and absence of dissection features is crucial for confident diagnosis.

• Misdiagnosis as arterial dissection: ensure careful assessment of the carotid wall to exclude intimal flap and intramural hematoma; dissection typically shows crescentic wall thickening with flow abnormalities, whereas carotidynia shows smooth eccentric perivascular inflammation without dissection flap.
• Over-interpreting mild luminal narrowing as hemodynamically significant stenosis: carotidynia causes only mild narrowing from wall edema; assess peak systolic velocity on ultrasound or flow dynamics on MR/CT to confirm absence of high-grade stenosis.
• Overlooking alternative diagnoses such as large vessel vasculitis: always compare appearance to other cervical vessels and review systemic symptoms; vasculitis typically involves longer arterial segments and affects older patients or those with constitutional symptoms.
• Confusing imaging features of the healing phase with progression: transient fatty plaque and mild enhancement may persist into early recovery; follow-up imaging or clinical correlation confirming symptom resolution helps differentiate carotidynia from other inflammatory or neoplastic processes.