SEPTIC CAVERNOUS SINUS THROMBOSIS; A RARE CAUSE OF UNILATERAL EXOPHTHALMOS.

Editor,

We wish to present an interesting case of Septic Cavernous sinus thrombosis (CST), which is fatal yet infrequent condition associated with high mortality and debilitating morbidity.1 A 28-year-old man presented with cold like symptoms for 7 days which progressed into worsening headache, fever and nausea. His past medical history was unremarkable with no recent travel history. His examination revealed temperature of 38.1 0C and facial puffiness with no other systemic findings. His investigations only showed raised C-reactive protein 288 mg/L and white cell count 15.0 x 109/L. In light of headache and visual symptoms he had Computerized tomography scan (CT) Head done without contrast which only revealed sphenoid & posterior ethmoid sinusitis. He remained febrile for four days despite being on broad spectrum antibiotics, and on day 5 he developed double vision, Cranial nerve VI palsy and unilateral exophthalmos, confirmed by formal ophthalmological/orthoptic assessment with no papilledema or any retinal disease. Repeat CT imaging of head/orbits failed to identify any cause of unilateral exophthalmos. Both initial blood cultures from the admission of day grew Proteus mirabilis sensitive to pipercillin/tazobactam while subsequent multiple blood cultures did not grew any organisms. A CT Head venogram was performed which confirmed a filling defect consistent with CST and inflammatory changes in sphenoid & ethmoid sinuses (figure 1 and 2). Other investigations such as chest X-ray, viral serology, abdominal ultrasound, echocardiogram, lumbar puncture, urine and stool cultures were all negativefor any alternate source of infection.

Figure 1

CT Venogram with arrow showing the cavernous sinus thrombosis on the right

Figure 2

CT Venogram showing exophthalmos on the right (short arrow) and sphenoid sinusitis (long arrow)

He was initially treated with ceftriaxone/amoxicillin for 3 days for possible meningitis which was later switched to piperacillin/tazobactam as per sensitivity on the blood cultures. After no response clinically and confirmation of septic CST, he was started on therapeutic dose of low molecular weight heparin alongside intravenous Meropenem and Metronidazole (combination therapy) on day 6, to effectively cover a wide number of potential organisms including Proteus mirabilis. He underwent urgent functional endoscopic sinus surgery (FESS) and stopped spiking temperature 24 hours later. Nasal swab culture during FESS grew mixed faecal flora of indeterminate significance. He was discharged home on day 16 to complete antibiotics and anticoagulation for another 4 weeks. On review after 8 weeks he had complete resolution of his symptoms with normal MRI venogram.

CST of septic origin is associated with significantly high mortality (23%) despite advances in medical care.2 Retrospective studies on anticoagulation in septic CST have shown some benefit in reducing mortality and morbidity such as blindness, opthalmoplegia, seizures and stroke; hence experts suggest anticoagulation for a minimum of 4 weeks. 3

The authors’ main purpose of this letter is to raise awareness around diagnosis of this condition as septic CST can only be identified with high index of suspicion, requires early imaging with correct modality (either CT or MRI Venogram) and prompt initiation of antibiotics as well as surgical intervention and potential anticoagulation, all of which are paramount to preventing long-term complications and mortality.