Sigmoid sinus thrombosis after mild closed head injury in an infant: diagnosis by magnetic resonance imaging in the acute phase--case report.

Intracranial sinus thrombosis following a mild closed head injury without a skull fracture or intracranial hematoma is extremely rare. A 23-month-old girl presented with vomiting and gait ataxia 1 day after occipital trauma. Computed tomography revealed a slightly increased density area in the region of the left sigmoid sinus. T1-weighted magnetic resonance (MR) imaging demonstrated an isointense area in the left sigmoid sinus and T2-weighted imaging showed a hyperintense area reflecting the characteristics of oxyhemoglobin. MR angiography and cerebral angiography indicated occlusion of the left sigmoid sinus. After 4 days of conservative treatment, her symptoms subsided completely. Follow-up MR angiography and cerebral angiography showed recanalization of the sigmoid sinus. The MR images and MR angiograms were useful for both early diagnosis and follow-up. Treatment should reflect the severity of individual cases, and early diagnosis will help achieve a good outcome.