MRI and cerebral venous thrombosis.

Difficulties in the diagnosis of cerebral thrombosis are due to the nonspecificity of symptoms and signs and the infrequent occurrence on computed tomography (CT) of direct signs of cerebral sinus thrombosis, i.e. the empty delta sign and cord sign. We present two patients, a 2 4/12-year-old girl with nephrotic syndrome, coma, papilledema, and hyperdensity along the sagittal sinus on CT; and a 34-year-old man with headaches, episodic visual loss, papilledema and a normal CT following posterior fossa craniotomy. On MRI, there was increased signal in sagittal and straight sinuses in the first patient, and in the lateral sinus in the second patient. The increased signal from clot, and the absence of signal from flowing blood, make MRI the procedure of choice for the initial diagnosis of cerebral sinus thrombosis.