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Lemierre syndrome is a septic thrombophlebitis of the internal jugular vein (IJV), typically following an oropharyngeal infection (e.g., pharyngitis or tonsillitis), and often complicated by septic emboli, particularly to the lungs.

It is a clinical-radiologic emergency requiring early diagnosis and aggressive treatment.

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Etiology

Pathogenesis

1. Initial oropharyngeal infection invades peritonsillar/parapharyngeal space.
2. Spreads to carotid sheath → infects and thromboses the internal jugular vein (IJV).
3. Septic emboli dislodge from the thrombus → most commonly to the lungs, but also joints, liver, skin.

![Course of events leading to Lemierre’s syndrome: 1. Colonization of the tonsils by F. necrophorum leading to tonsillitis. 2. Invasion into the parapharyngeal space. 3. Invasion of the internal jugular vein, haematogenously via the tonsillar veins, by septic lymph or through the tissue, leading to intense inflammation and thrombosis. 4. Detachment of clot material containing bacteria leading to septic pulmonary emboli. 5. Systemic haematogenous dissemination and distant manifestations from joints, skin, skeleton, muscles, liver and meninges. 6. In rare cases, retrograde progression of the internal jugular vein thrombosis may resulting in intracranial sinus thrombosis. (Image Mattias Karlén)

“A syndrome so characteristic” Molecular and clinical studies of Fusobacterium necrophorum and Lemierre’s syndrome | Lund University. https://www.lunduniversity.lu.se/lup/publication/38f81245-d376-49cd-88f5-79f7a148e54d](attachment:16ce80e2-bdc8-49f8-8446-8aefd91ed461:image.png)

Course of events leading to Lemierre’s syndrome: 1. Colonization of the tonsils by F. necrophorum leading to tonsillitis. 2. Invasion into the parapharyngeal space. 3. Invasion of the internal jugular vein, haematogenously via the tonsillar veins, by septic lymph or through the tissue, leading to intense inflammation and thrombosis. 4. Detachment of clot material containing bacteria leading to septic pulmonary emboli. 5. Systemic haematogenous dissemination and distant manifestations from joints, skin, skeleton, muscles, liver and meninges. 6. In rare cases, retrograde progression of the internal jugular vein thrombosis may resulting in intracranial sinus thrombosis. (Image Mattias Karlén)

“A syndrome so characteristic” Molecular and clinical studies of Fusobacterium necrophorum and Lemierre’s syndrome | Lund University. https://www.lunduniversity.lu.se/lup/publication/38f81245-d376-49cd-88f5-79f7a148e54d

Epidemiology

• Most common in adolescents and young adults (15–30 years)
• Often missed initially due to non-specific symptoms
• Increasing incidence due to reduced antibiotic use for sore throat

Clinical Features

Complications