Even though mortality decreased to 4-12% with appropriate antibiotics, delay in initiating appropriate therapy has been associated with increased mortality . It remains therefore important to be aware of this classic syndrome so that its clinical presentation can be recognize and appropriate therapy is initiated early.
The time interval between the onset of the initial oropharyngeal infection and the emergence of internal jugular vein thrombophlebitis and associated septicemia is generally less than a week, but may be up to 3 weeks . As the infection progresses and internal jugular vein thrombophlebitis develops, high spiking fevers, and toxicity appears.[5, 11] Patients may have trismus and swelling and tenderness along the sternocleidomastoid muscle at the angle of the jaw. These findings may be associated with [5, 16] Local findings may be minimal when the infection involves the posterior compartment of the lateral pharyngeal space. [17
The internal jugular vein thrombophlebitis generates septic emboli, that mimics endocarditis. Patients may present with pulmonary involvement that can include dyspnea, pleuritic chest pain, and occasionally hemoptysis.  Chest x-ray can show bilateral nodular infiltrates, pleural effusions and cavitary lesions. CT can demonstrate intravascular thrombus; but is less sensitive than high resolution ultrasonography for identifying small mural thrombi.12 Radionuclide gallium scans can localize the source of infection. However, inability to document a thrombus should not delay initiation of appropriate antibiotic therapy for anaerobic sepsis. Severe respiratory compromise requiring mechanical ventilation, and adult respiratory distress syndrome, empyema, and lung abscess have all been observed.[16,18]
Septic arthritis of the large joints, including the knee, hip, shoulder, ankle, and sternoclavicular joint, have decreased in frequency since the advent of antibiotics. Osteomyelitis, soft tissue abscesses, cutaneous pustular lesions are common, and meningitis, pyomyositis, renal involvement, and acute abdomen are rare. [5, 17, 20]
F. necrophorum is often isolated from the blood, parapharyngeal abscess, or metastatic infection site and its recovery is a valuable clue to the diagnosis. Diagnosis of Lemierre’s Syndrome, requires the presence of both metastatic infection and internal jugular vein thrombosis. The diagnosis of thrombophlebitis is often made presumptively, and only 25% of the reported cases were actually documented to have thrombophlebitis either surgically or radiographically.  The imaging method of choice is contrast-enhanced CT is because it is more sensitive than other methods and enables the discovery of additional pathologies such as pulmonary emboli, soft tissue abscesses, osteomyelitis, and septic arthritis.[8, 23, 24, 25] It can identify low attenuation intraluminal filling defects, distended veins with enhancing walls, and localized soft tissue edema.  High resolution computed tomography (HRCT) can complement helical CT in establishing the diagnosis of septic pulmonary emboli.