A 37-year-old man with an unremarkable past medical history was brought to the emergency department by ambulance after being found in a coma state. After initial evaluation and stabilisation including intubation, investigations to identify the cause(s) of this coma state were carried out. On physical examination, the patient was afebrile, haemodynamicaly stable, with no evidence of trauma; neurologically there was no neck stiffness, he had slightly miotic but reactive pupils (size 2–3), there was localisation of painful stimuli but no clear neuromotor deficit. Initial laboratory tests including urinary toxin screening, complete blood count, serum electrolytes, liver function tests, calcium, magnesium, erythrocyte sedimentation rate, C-reactive protein and cardiac enzymes were all within normal limits except for a slightly elevated blood sugar level of 220 mg/dl. Chest x ray and electrocardiogram did not reveal abnormalities. An initial brain computed tomography scan was normal. The patient was suspected of having had a stroke (ischaemic type) and was started on heparin (unfractionated). Later a magnetic resonance imaging scan of the brain was obtained revealing right-sided thromboses of the sigmoid sinus (fig 1). The patient’s neurological status improved gradually and 4 days later he was successfully extubated and transferred to a regular ward and maintained on heparin therapy.

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Figure 1 Magnetic resonance image of the brain with intravenous contrast material showing thrombosis in the sigmoid sinus on the right.

Cerebral venous thrombosis is a rare type of cerebrovascular disease that accounts for 0.5% of all strokes.1 Its diagnosis is still commonly overlooked or delayed because of the remarkable diversity of its clinical symptoms, modes of onset and neuroimaging signs. It is recognised as a non-septic disorder with various clinical presentations and with a difficult to predict outcome. A cause cannot be found in approximately 15% of cases. It has a mortality rate of less than 10%.