Teaching Case

A 54-year-old man was admitted because of a 18 hours history of repeated nausea, vomiting and headache. The patient's past medical history was unremarkable and there was no history of trauma. Otoscopy showed no abnormality of the ears. Routine blood chemistry revealed no abnormalities.

The patient underwent an emergency head multidetector computed tomography (MDCT) without intravenous contrast material administration due to allergy to iodine, demonstrated no tumour or haemorrhage. The left transverse sinus was more enlarged and hyperdense than the right one. Imaging findings were compatible with thrombosis of the transverse sinus. Further evaluation of the findings was decided and a magnetic resonance imaging (MRI) was performed. Contrast-enhanced T1WI confirmed a lack of flow.

Cerebral sinus venous thrombosis (CSVT) is a life-threatening disease and it occurs in 3-4 adults per 1, 000, 000 population. CSVT is often unrecognised at initial presentation. Risk factors include hormonal changes (e.g. oral contraceptives use), head trauma, local and generalised infections, cancer, acquired prothrombotic states (e.g. hyperhomocysteinaemia), haematological disorders, drugs and other situations. [1]
CVST has a nonspecific presentation and therefore it is important to recognise subtle imaging findings and indirect signs that may indicate the presence of thrombosis.
Patients with CSVT present with variable symptoms ranging from essentially asymptomatic to coma. Mainly patients complain of headache, nausea and vomiting.
MDCT is the first imaging modality to be used simply due to availability and also to exclude other conditions. Potential findings on unenhanced MDCT include cerebral oedema, venous haemorrhage and cordlike hyperattenuation within a dural venous sinus due to sinus thrombosis (cord sign). Contrast-enhanced MDCT demonstrate gyral enhancement and the empty delta sign (due to enhancement of the rich dural venous collateral circulation surrounding the thrombosed sinus). MRI combined with magnetic resonance venography (MRV) is considered the imaging modality of choice for assessing the disease. All the findings described in the MDCT section are also seen on MRI. The clot acutely is isointense on T1 and hypointense on T2, with subacute clot becoming hyperintense on T1. On spin-echo images a thrombus will manifest as absence of flow void. Contrast-enhanced 3D T1WI is a sensitive MRI sequence revealing a lack of flow. [1, 2, 3] Differential diagnosis mainly in patients with CSVT mainly include congenitally hypoplastic/atretic cerebral sinus.
Sinus hypoplasia or atresia is a common anatomic variation of the dural venous sinuses and in most patients, the right transverse sinus is larger than the left. When transverse sinus hypoplasia or aplasia is found, the ipsilateral sigmoid and jugular sinuses are usually also hypoplastic/aplastic. In addition, asymmetries of the sigmoid notches on non-contrast MDCT are a sensitive and specific measure of differentiating transverse sinus thrombosis from an atretic transverse sinus when absence of transverse sinus flow is visualised on MRV. Narrowing of the sigmoid plate notch on MDCT can suggest congenital narrowing or sinus atresia. [4]
The treatment includes systemic anticoagulation and occasionally thrombolysis. In conclusion, CSVT is a challenging condition with a wide clinical presentation, difficult diagnosis, variable aetiologies and prognosis that requires a high suspicion index. MDCT and MRI-MRV are valuable tools providing the proper diagnosis. [1, 3]

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