MR imaging of postpartum cortical blindness

Cortical blindness is an unusual feature of the toxemia of pregnancy syndrome. We present the CT and magnetic resonance (MR) findings in two women who developed postpartum blindness as a manifestation of this condition. Though both CT and MR display reversible edematous changes in the occipital lobes, follow-up MR documents areas of hemorrhagic and nonhemorrhagic infarction where the corresponding CT images are normal.

MR imaging of intracranial tuberous sclerosis

The role of MR in evaluating tuberous sclerosis is reviewed in 15 patients. These studies were compared with CT scans, which were available in 14 patients. Four characteristic findings were noted on the MR images obtained. Subependymal nodules projecting into the lateral ventricles were seen in 12 of 15 patients on T1-weighted images. This was the most specific finding. Distortion of the normal cortical architecture was seen in 10 of 11 patients in whom T1-weighted images were obtained using a 256 X 256 matrix. These foci corresponded to multiple cortical areas of increased signal on T2-weighted images. Dilated ventricles were seen in five patients. In one patient, a known astrocytoma showed increased signal on the T2-weighted images, allowing differentiation from a benign subependymal nodule. MR depicted the cortical hamartomas more completely than did CT. The MR scans were abnormal in all cases, and a diagnosis could be confidently made in all 11 cases scanned using a 256 X 256 matrix. Our preliminary experience suggests that MR will at least equal and probably exceed CT, both for sensitivity and specificity, given the use of a 256 X 256 matrix.

Dural sinus thrombosis: study using intermediate field strength MR imaging

The magnetic resonance (MR) images of six patients with thrombosis of a dural sinus were reviewed. The diagnosis had been verified by computed tomographic scans in three patients and arteriograms in two; in the sixth patient, only MR imaging was used to confirm the clinical syndrome. In all patients, high-intensity signal was seen from the thrombus within the affected dural sinus on all echoes. This persistent signal intensity allowed intravascular clot to be distinguished from normal causes of increased signal such as flow-related enhancement (entry phenomenon) and even-echo rephasing. MR imaging demonstrated the cause of the thrombosis in three patients: two were secondary to adjacent tumors, and one was secondary to unsuspected mastoiditis. Complications such as infarction were also demonstrated. Using MR imaging, one can easily and safely diagnose thrombosis of a dural sinus. MR should be the imaging method of choice in patients suspected of having thrombosis of a dural sinus.

Pyogenic abscess of the medulla oblongata

Pyogenic brain stem abscess is rare. A case of spontaneous abscess of the medulla oblongata is reported in which the diagnosis was made preoperatively by computed tomography. Surgical drainage resulted in good functional recovery and radiological resolution of the lesion. This is the first reported case of survival in a patient with an abscess of the medulla oblongata. The pathophysiology, clinical symptoms, and radiological appearance of the entity are discussed. Prompt diagnosis and drainage are emphasized as important factors influencing survival.