Michael D. F. Deck

MRI changes in intracranial hypotension

We report seven patients with the syndrome of intracranial hypotension who were referred to Memorial Sloan-Kettering, primarily because of suspicion of meningeal tumor or infection raised by the finding of meningeal enhancement on MRI. In three patients, symptoms occurred after lumbar puncture; in four, there was no clear precipitating event. Lumbar puncture after MRI in six patients revealed low CSF pressure (six patients) and pleocytosis or high protein, or both (four patients). Three patients had subdural effusions. Six patients had measurable descent of the brain on midsagittal images. Postural headache resolved in all seven patients, six of whom had follow-up MRIs. Meningeal enhancement resolved or diminished in all six. Subdural effusions resolved spontaneously in two and were evacuated (but were not under pressure) in one. Downward brain displacement improved or resolved in all patients. The clinical syndrome and MRI abnormalities generally resolve on their own. An extensive workup is not helpful and may be misleading. Patients should be treated symptomatically.

Metastasis to the base of the skulk clinical findings in 43 patients

we studied 43 patients with metastases to the base of the skull to determine whether clinical symptoms localized the lesions accurately. We identified five clinical syndromes: orbital, parasellar, middle fossa, jugular foramen, and occipital condyle. The orbital and parasellar syndromes were characterized by frontal headache, diplopia, and first-division trigeminal sensory loss. Proptosis occurred with the orbital but not the parasellar syndrome. The middle-fossa syndrome was characterized by facial pain or numbness. The jugular foramen syndrome was characterized by hoarseness and dysphagia, with paralysis of the ninth through eleventh cranial nerves. The occipital condyle syndrome was characterized by unilateral occipital pain and unilateral tongue paralysis.

MRI assessment of human callosal surgery with neuropsychological correlates

MRI imaging using recovery and spin-echo techniques was carried out on three patients after surgical section of the corpus callosum to control intractable epilepsy. The scans revealed that the total callosotomy had been obtained in two patients, while partial sparing of splenial and rostra1 fibers was seen in the third.

Nonmetastatic superior sagittal sinus thrombosis complicating systemic cancer

Seven patients with cancer complicated by nonmetastatic sagittal sinus thrombosis were encountered in a 7-year period. Five had hematologic malignancies and two had solid tumors. There were two different presentations. In the first, neurologic signs and symptoms (e.g., headaches, seizures, hemiparesis, lethargy) occurred suddenly in five patients shortly after initiation of cancer therapy. Four of these five patients recovered with minimal residua; the fifth died as a direct result of the sinus thrombosis. The second presentation occurred in the two patients with terminal cancer who declined gradually without focal signs; both patients died. Only arteriography can reliably establish the diagnosis of sagittal sinus occlusion. In patients with cancer, sagittal sinus occlusion probably results from a “hypercoagulable state” associated with the systemic neoplasm.

Computed Tomography in Metastatic Disease of the Brain

Computed tomography has been found to be a more accurate diagnostic tool in the analysis of brain metastases than radionuclide scanning. Of 1,100 patients studied by CT scan, 57 showed evidence of intracerebral metastasis, and 14 showed evidence of hydrocephalus. Density levels below that of normal brain tissue were found in cases of metastases from the lung (13), breast (7), melanoma (4), kidney (3), lymphoma (3), and nasopharynx (1); levels above normal were found in cases of metastases from melanoma (8), lung (3), colon (3), chorionic carcinoma (2), osteogenic sarcoma (1), and kidney (1).

Magnetic resonance imaging of arachnoid cysts.

A retrospective review of magnetic resonance imaging (MRI)-computed tomography (CT) correlation was performed in 29 patients with arachnoid cysts. Short TR, short TE spin echo (SE) pulse sequences provided the best anatomic definition whereas multiple echo long TR, TE sequences allowed comparison of the signal intensity of the cyst with that of cerebrospinal fluid (CSF). Simple arachnoid cysts were isointense while neoplastic, hemorrhagic or inflammatory cysts were hyperintense relative to CSF. The CT differential diagnosis of an arachnoid cyst (depending upon its location) may include other cystic collections such as craniopharyngioma, epidermoid, astrocytoma, and chronic subdural hematoma. However, on MRI the combination of extra-axial location, morphological features, and signal intensity matching that of CSF allows one to make the diagnosis of an uncomplicated arachnoid cyst with confidence.

Radiological Evaluation of Paragangliomas of the Head and Neck

Paragangliomas can be differentiated angiographically from most other tumors in the head and neck by their profuse vascularity; specific classification is based on their position and displacement of adjacent vessels. Subtraction usually aids in diagnosis. In most cases, bilateral carotid angiography should be performed, since the ipsilateral carotid artery may have to be ligated and an asymptomatic contralateral tumor may also be found during surgery. Studies of multiple vessels will often show an additional blood supply. Computed tomography can demonstrate the tumors vascular nature and position and is valuable in follow-up after radiation therapy.

Determination of ventricular volume following metrizamide CT ventriculography.

Volume averaging, relatively slight differences in the mean attenuation coefficients of CSF and white/grey matter, and the irregular contours of the human ventricular system have so far seriously limited the accuracy of CT estimation of ventricular volume. Taking advantage of the high attenuation of metrizamide-con-taining CSF, we have developed three methods for computing ventricular volume after metrizamide CT ventriculography; these methods depend upon computer analysis of X-ray absorption data obtained from contiguous CT brain slices. All three methods were validated by CT scanning a formalin-fixed cadaver brain containing an epoxy-resin cast of the ventricular system. Calculated ventricular volumes were compared with the actual measured volume of the ventricular cast.

Changes in the Ventricular Size During Fractional Pneumoencephalography

Measurements of 40 lateral ventricles, 49 third ventricles, and 46 fourth ventricles were made at different stages during the introduction of air via the lumbar route. Results showed that ventricular air filling during pneumoencephalography is accompanied by ventricular enlargement. The incremental increases were most marked as the initial fractions were introduced and less marked as the later fractions were introduced. It is concluded that the “true” resting size of the ventricles prior to the first fraction of injected air is smaller than the ventricular size commonly recorded at pneumoencephalography. These observations are discussed in relation to basic physical principles involved in ventricular air filling.

Computed tomography versus magnetic resonance imaging of the brain a collaborative interinstitutional study

A retrospective study (1983-1984) of magnetic resonance imaging (MRI) and computed tomography (CT) examinations in 471 patients with known pathology in the brain and craniocervical junction was conducted in order to determine the relative efficacy of MRI versus CT. All MRI examinations involved slice thickness greater than 10 mm, and only single-slice single-echo or multislice single-echo imaging techniques were available. These studies were evaluated independently by two neuroradiologists from a panel of six for anatomic abnormalities, lesion contrast, and radiologists impression. Results, which excluded microadenomas of the pituitary and approximately 9% of studies in which consensus was not achieved by the readers, were as follows: (1) 14% of the studies were positive on MRI but normal on CT; (2) in 55% of the studies, MRI was better than CT; (3) MRI was equal or better than CT in 95% of the studies; and (4) CT was better than MRI in 5% (21/421) of the examinations. There were no patients in this series where CT was positive but MRI missed the abnormality.