Central nervous system lymphoma

The imaging diagnosis of CNS lymphoma is challenging because of the multiplicity of compartments that it may present in or spread to, the variety of imaging manifestations that may be produced, and the fact that the clinical picture may not focus the clinician or radiologist on the correct diagnosis. However, recent strides in diagnostic imaging made not only with CT but now with MR allow recognition of tumor spread that was not possible before. Examples to support this statement are the noninvasive recognition of cord compression on MR, the demonstration of intraspinal and intracranial leptomeningeal tumor spread, and the improved demonstration of subdural tumor deposits.     

Cardiovascular reactions to myelography with watersoluble contrast media

Summary Arterial blood pressure and heart rate were recorded for 5 to 7 h during myelography with iothalamate meglumine and metrizamide in 23 rabbits. After 0.6 ml iothalamate meglumine containing 280 mg I/ml a significant decrease in blood pressure and signs of circulatory failure were found. After identical doses of iothalamate meglumine to 0.4 ml containing 140 mg I/ml no significant fall in blood pressure was recorded. A decrease of blood pressure was always accompanied by a decrease of heart rate. Arterial blood pressure and heart rate during experimental myelography are suggested as useful variables in the evaluation and comparison of new contrast media for myelography.     

Central nervous reactions to a 6.5-hour altitude exposure at 3048 meters

In this study of CNS reactions to mild hypoxia, 7 subjects were decompressed to the equivalence of 3048 m altitude breathing air, for 6.5 h. On reaching 3048 m, and for every second h thereafter, a battery of neuropsychological tests were administered. In addition, blood and performance measures were sampled and a symptom check list was administered. The performance tests indicated significant effects of hypoxia. In contrast to earlier studies on grade of hypoxia and performance, no relationship between impaired performance and duration of exposure to hypoxia was found. Repeated testing throughout exposure indicated stable individual reactions. Endocrine variables did not support the hypothesis that activation or 'stress' caused the impairment observed. In addition to impaired neuropsychological test performance and impaired task performance, the subjects reported headache, weakness and some dizziness. Comparisons between different tests confirmed previous results showing that mild hypoxia yields varying degrees of impairment on different cognitive functions.     

Functional cervical myelography with iohexol

Summary Thirty patients underwent functional cervical myelography, i.e. radiographs in the lateral view were obtained in extension as well as in flexion of the neck. Sagittal tomography was performed in both positions. Widening of the subarachnoid space and decreased sagittal diameter of the spinal cord due to shortening were demonstrated in the lateral view in flexion. In some cases with advanced narrowing or spinal block in extension, such widening in flexion resulted in better diagnostic images by providing passage of the contrast medium caudally. Although iohexol (Omnipaque, Nyegaard & Co., Oslo) was regularly forced into the posterior cranial fossa by the movements, the frequency of side effects was approximately the same as in our former trials with iohexol in conventional cervical myelography. EEG changes occurred in two patients (7%). A sitting position for 3–4 min after the examination followed by an elevated head end of the bed was probably important for preventing side effects from the contrast medium. Specific questioning revealed twice as many subjective side effects as reported after general questions alone.     

Central nervous system tuberculosis: MRI

The MRI findings of 18 proven cases of central nervous system (CNS) tuberculosis were reviewed; 10 patients were seropositive for HIV. All had medical, laboratory, or surgical proof of CNS tuberculosis. Eleven patients had meningitis, of whom two also had arachnoiditis. Five patients had focal intra-axial tuberculomas: four brain masses and one an intramedullary spinal lesion. Two patients had focal extra-axial tuberculomas: one in the pontine cistern, and one in the spine. In all 11 patients with meningitis MRI showed diffuse, thick, meningeal enhancement. All intraparenchymal tuberculomas showed low signal intensity on T2-weighted images and ring or nodular enhancement. The extra-axial tuberculomas had areas isointense or hypoitense relative to normal brain and spinal cord on T2-weighted images. Although tuberculous meningitis cannot be differentiated from other meningitides on the basis of MR findings, intraparenchymal tuberculomas show characteristic T2 shortening, not found in most other space-occupying lesions. In the appropriate clinical setting, tuberculoma should be considered.     

Iohexol compared to metrizamide in cervical and thoracic myelography

Summary A randomized double blind study with iohexol (Omnipaque) and metrizamide (Amipaque) in cervical myelography was performed in 50 patients, 29 with iohexol and 21 with metrizamide. The myelographies were performed either with lumbar or with C₁–C₂ puncture in about equal groups, using 300 mg I/ml and 240 mg I/ml of the contrast media respectively. The image quality was equal with both contrast media, excellent in about 4/5 and good in 1/5 of the examinations. Subjective side effects were twice as frequent with metrizamide as with iohexol. The most frequent side effect was headache, occurring in 34% with iohexol and in 67% with metrizamide. Altogether 24% or the patients had EEG changes after iohexol as compared to 47% after metrizamide. All EEG changes were slight dysrythmia-except in three patients with spike activity after metrizamide. These were the only ones with mental reactions as well. It can be concluded that in this trial iohexol was better suited for cervical myelography than metrizamide.     

Central nervous system hypoxia in children due to near drowning

Fourteen children who experienced acute, profound central nervous system hypoxia secondary to near drowning, aspiration, or respiratory arrest underwent CT examination. During the first week after the episode, the most frequent finding was a loss of gray-white matter differentiation. Other findings included effacement of sulci and cisterns, focal areas of edema in the cerebral cortex or basal ganglia, and hemorrhagic infarctions of the basal ganglia. Subsequent CT scans obtained from two weeks to five months after the hypoxic episode showed progression of cerebral loss from cortical infarction with gyral hemorrhage and enhancement to global parenchymal atrophy. The prognosis is poor in these patients: seven children experienced severe neurologic deficits and seven died.     

Central nervous system involvement in Whipple's disease

Summary A case of Whipple's disease is presented manifesting itself predominantly with neurological and mental symptoms but without gastrointestinal complaints. Although the first cranial CT in the fourth year of the disease was normal, the second, 1.5 years later, revealed intensive hypodensity of the white matter and cortical enhancement. CT findings are compared with autopsy results and a review of the pertinent literature is given.     

Value of cervical myelography in lateral cervical root compression

The roentgenograms of preoperative cervical metrizamide myelography performed in 133 patients who had undergone surgery for a lateral cervical root compression (foraminotomy) were retrospectively re-evaluated without knowledge of the findings at surgery. Detailed criteria of the radiologic root cavity recess were compared with details of findings at surgery, in order to check the value of the information provided by the myelogram with regard to the morphological nature of the root compression. A review of the two main categories--"soft prolapse with or without primary sequestrum" and "hard protrusion" revealed different myelographic findings. It was not possible to establish an unequivocal diagnosis in individual cases and with regard to forms of root compression exhibiting a greater degree of differentiation.