Lesson of the Week: Detection of bilateral isodense subdural haematomas

doi:10.1136/bmj.309.6957.792

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R J Davenport,
P F X Statham,
C P Warlow

Department of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU

Correspondence to: Dr Davenport.

Accepted 28 June 1994

Although cranial computed tomography is sensitive for detecting most subdural haematomas, those which are of the same density (isodense) as normal brain tissue may be difficult to identify in a scan. When the isodense haematoma is unilateral the presence of mass effect with a shift of the midline provides the diagnostic clue; with bilateral haematomas, however, the midline may remain undisturbed and the computed tomogram may be interpreted as either normal or showing generalised cerebral swelling of uncertain cause. We report on two patients with bilateral haematomas, both of whom were receiving anticoagulants, in whom the diagnosis was delayed even after computed tomography.

Case reports

Case 1

A 71 year old man was admitted as an emergency with a two month history of progressive headache; coughing and straining exacerbated the pain but he had no nausea, vomiting, or disturbance of vision and his headache was not related to posture or time of day. He had a two year history of intermittent, non-specific headache, and an unenhanced cranial computed tomogram done 18 months previously had shown cortical atrophy only (figure (top)); no firm diagnosis had been reached at that time. He was taking warfarin for recurrent pulmonary emboli; six days before admission clotting tests showed an international normalised ratio of >6. On examination he had no abnormal physical signs; he had an erythrocyte sedimentation rate …