Lateral venous sinus thrombosis associated with MRI abnormalities in the mastoid air sinus.
Background: Lateral venous sinus thrombosis can be associated with mastoiditis. We encountered several cases of lateral sinus thrombosis associated with MRI abnormalities in the ipsilateral mastoid air sinus that had no clinical evidence of mastoiditis. The relationship between lateral sinus thrombosis and mastoid abnormalities was evaluated systematically. Method: The clinical records and radiology of all adult cases of cerebral venous sinus thrombosis (CVT) diagnosed or treated at Auckland Hospital 1990–1999 were reviewed retrospectively. Results: Twenty-six cases of CVT were identified. Thrombosis was present in 23 lateral sinuses in 20 cases. Mastoid abnormalities were detected ipsilateral to nine of 23 thrombosed lateral sinuses (39%) and were associated with none of 29 unaffected lateral sinuses (p<0.001). Clinical evidence of mastoiditis was not present in any case. One case with mastoid abnormality and lateral sinus thrombosis received antibiotics; eight did not. All made uneventful recoveries. Reversal of the MRI abnormality after anticoagulation but without antibiotic treatment was demonstrated. Conclusion: Lateral venous sinus thrombosis is commonly associated with ipsilateral MRI abnormalities in the mastoid air sinus. These abnormalities are most likely to be due to venous congestion as a consequence of venous thrombosis and do not inevitably represent infective mastoiditis. Patients presenting with lateral sinus thrombosis and mastoid congestion should have a thorough clinical assessment for the presence of mastoiditis. When there is no clinical evidence of infection, treatment should be directed at the underlying cerebral venous thrombosis; additional treatment with antibiotics is not required.