Sigmoid sinus thrombosis as a complication of acute mastoiditis

Clinical History

A 4-year-old female patient with right acute otitis media and mastoiditis, was admitted to the Radiology Department for investigation. She was febrile (38.5 °C) and the blood tests showed increased CRP (5.89 mg/dl) and d-dimer (763 mg/dl).

Imaging Findings

A non-enhanced CT of the brain and temporal bones revealed complete opacification of the right mastoid air cells and middle ear cavity, as well as right temporal swelling. There was no bone erosion (Fig. 1).
A MRI of the brain showed pancolpitis, bilateral mastoiditis, thrombosis of the right sigmoid sinus and slow flow in the right transverse sinus (Fig. 2, 3, 4). Moreover, enhancement of dura at the right side of cerebellar tentorium was depicted (Fig.5), a sign of intracranial extension of the infection. Post-auricular inflammation was also depicted.
The patient received intravenous antibiotic and anti-coagulant medication and her clinical situation was improved. Repeat MRI, as well as MRV 45 days later, showed a relatively small contrast filling defect (thrombus) in the right sigmoid sinus and elimination of cerebellar tentorium enhancement (Fig. 6, 7, 8). The medication was continued and follow-up MRI and MRV 2 months later, showed further improvement (Fig. 9, 10).

Discussion

Dural venous sinus thrombosis (DVST) is a rare complication of mastoiditis and acute otitis media in children.
The proximity of the middle ear and mastoid air cells to the dural venous sinuses, predisposes to venous thrombosis secondary to infection. It could result either from direct spreading of the inflammatory process from the mastoid through a bone dehiscence, or through small emissary veins in patients with an intact sigmoid sinus plate. In this way, a perisinus abscess could be formed. Adherence of blood cells, platelets and fibrin produce a mural thrombus. With the progress of infection and increase of thrombus size, it might result in thrombosis of the sigmoid sinus. [1, 2]
The clinical manifestations in patients with DVST are usually headache, otalgia, fever, nausea and vomiting. Focal neurological signs and symptoms like motor and cranial nerve deficits, papilloedema and decreasing level of consciousness may also occur. Meningeal signs are observed when there is intracranial spreading of the inflammatory process. Blood tests usually show leukocytosis and increased CRP and d-dimer. [3]
MRI in combination with MR venography (MRV) is the most sensitive examination and the method of choice for the diagnosis of DVST and follow up. It can also show the presence of inflammation in the brain and meninges [4]. The loss of normal "flow void" on T2 images is a sensitive parameter in detecting a thrombus. On non-enhanced T1, it is depicted as high signal intensity. On contrast enhanced T1 images, as well as on MRV reconstructions, a thrombus is depicted as a contrast filling defect. CT imaging of the brain and temporal bones can display the possible sigmoid sinus plate erosion. [1, 5]
DVST in the paediatric population is becoming more and more readily diagnosed, because of increasing clinical awareness and more widespread use of MRI, which is very useful in planning management. Treatment is usually conservative and includes intravenous and oral anticoagulants, as well as antibiotics, especially for septic cases. The duration and the dosage of medication depends on the severity of disease and response to treatment. [6]
In conclusion, in paediatric patients with clinical suspicion of DVST and other intracranial complications during acute otitis media and mastoiditis, MRI is considered indispensable to confirm the diagnosis and planning management.

Differential Diagnosis List

Final Diagnosis

Sigmoid sinus thrombosis due to acute mastoiditis

URL:	https://www.eurorad.org/case/15490
DOI:	10.1594/EURORAD/CASE.15490
ISSN:	1563-4086