To demonstrate the evolution of sigmoid sinus thrombosis, we performed a prospective observational study on a 6-year-old girl who presented with mastoiditis, epidural abscess, and occipital osteomyelitis from multiple drug-resistant Streptococcus pneumoniae. She underwent mastoidectomy and partial occipital craniectomy. This procedure produced a window in the occipital bone that allowed serial ultrasonography of the sigmoid sinus during medical treatment. Computed tomography was performed, followed by weekly Doppler ultrasonography used to monitor resolution of sigmoid sinus thrombosis. The natural history of a treated episode of sigmoid sinus thrombosis was illustrated. Venous occlusion resolved over a 4- to 6-week period without surgical drainage or venous anticoagulants. Collateral flow, reversal of normal venous flow, and ultimate return to normal venous transport characterized the period of resolution. We conclude that an occluded sigmoid sinus from mastoiditis can naturally recanalize. Aberrant venous flow can be demonstrated during the period of resolution. This case supports a conservative approach to management of the occluded sinus and suggests that 4 to 6 weeks of antibiotic therapy after removal of perisinus infection is sufficient for cure.