The 2021 World Health Organization Classification of Tumors of the Central Nervous System: What Neuroradiologists Need to Know.

Neuroradiologists play a key role in brain tumor diagnosis and management. Staying current with the latest classification systems and diagnostic markers is important to provide optimal patient care. Publication of the 2016 World Health Organization Classification of Tumors of the Central Nervous System introduced a paradigm shift in the diagnosis of CNS neoplasms. For the first time, both histologic features and genetic alterations were incorporated into the diagnostic framework, classifying and grading brain tumors. The newly published 2021 World Health Organization Classification of Tumors of the Central Nervous System, May 2021, 5th edition, has added even more molecular features and updated pathologic diagnoses. We present, summarize, and illustrate the most salient aspects of the new 5th edition. We have selected the key "must know" topics for practicing neuroradiologists.

Tumefactive Primary Central Nervous System Vasculitis: Imaging Findings of a Rare and Underrecognized Neuroinflammatory Disease.

Primary central nervous system vasculitis (PCNSV) is a poorly understood neuroinflammatory disease of the CNS affecting the intracranial vasculature. Although PCNSV classically manifests as a multifocal beaded narrowing of the intracranial vessels, some patients may not have angiographic abnormalities. A rare subset of patients with PCNSV present with masslike brain lesions mimicking a neoplasm. In this article, we retrospectively review 10 biopsy-confirmed cases of tumefactive PCNSV (t-PCNSV). All cases of t-PCNSV in our series that underwent CTA or MRA were found to have normal large and medium-sized vessels. T-PCNSV had a variable MR imaging appearance with most cases showing cortical/subcortical enhancing masslike lesion (70%), often with microhemorrhages (80%). Diffusion restriction was absent in all lesions. In summary, normal vascular imaging does not exclude the diagnosis of t-PCNSV. Advanced imaging techniques including MR perfusion and MR spectroscopy failed to demonstrate specific findings for t-PCNSV but assisted in excluding neoplasm in the differential diagnosis. Biopsy remains mandatory for definitive diagnosis.

Effects of thiopental sedation on learning and memory.

Subjects who were administered thiopental showed a loss of memory for events discussed while they were under sedation. We tested the subjects for recognition memory of pictures and recall of associated pairs of letters and words, and found that the subsequent memory loss was correlated with the concentration of thiopental in the venous blood at the time the material was learned. Retention did not appear to be state-dependent because the subject, while under sedation, could recall material learned prior to sedation, and because recall was not facilitated by reinstatement of the sedation.

Hypertrophic olivary degeneration after surgical removal of cavernous malformations of the brain stem: report of four cases and review of the literature.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a pathological phenomenon that occurs after injury to the dentato-olivary pathway. Its hallmarks include hypertrophy of the olive with increased T2 signal intensity on magnetic resonance imaging, and it often manifests with palatal tremor and oscillopsia clinically. METHOD: We report the cases of four patients who developed delayed HOD after surgical resection of pontine lesions. FINDINGS: We discuss the anatomical and pathological details of this disease and review the few other reported cases of HOD after resection of lesions within the brainstem. CONCLUSIONS: HOD should be recognized as a possible complication of surgery within the brainstem and must be diagnosed promptly so that patients can be appropriately counseled and symptoms can be treated.

Multinodular and Vacuolating Neuronal Tumor of the Cerebrum: A New "Leave Me Alone" Lesion with a Characteristic Imaging Pattern.

Multinodular and vacuolating neuronal tumor of the cerebrum is a recently reported benign, mixed glial neuronal lesion that is included in the 2016 updated World Health Organization classification of brain neoplasms as a unique cytoarchitectural pattern of gangliocytoma. We report 33 cases of presumed multinodular and vacuolating neuronal tumor of the cerebrum that exhibit a remarkably similar pattern of imaging findings consisting of a subcortical cluster of nodular lesions located on the inner surface of an otherwise normal-appearing cortex, principally within the deep cortical ribbon and superficial subcortical white matter, which is hyperintense on FLAIR. Only 4 of our cases are biopsy-proven because most were asymptomatic and incidentally discovered. The remaining were followed for a minimum of 24 months (mean, 3 years) without interval change. We demonstrate that these are benign, nonaggressive lesions that do not require biopsy in asymptomatic patients and behave more like a malformative process than a true neoplasm.

Remote cerebellar hemorrhage.

Remote cerebellar hemorrhage (RCH) is a rare but benign, self-limited complication of supratentorial craniotomies that, to the best of our knowledge, has not been described in the imaging literature. RCH can be an unexpected finding on routine postoperative imaging studies and should not be mistaken for more ominous causes of bleeding such as coagulopathy, hemorrhagic infarction, or cortical vein occlusion. Cerebellar hemorrhage in the typical setting can be identified as RCH and does not require more extensive or invasive evaluation.

Intracranial neurenteric cysts: imaging and pathology spectrum.

BACKGROUND AND PURPOSE: Intracranial neurenteric (NE) cysts are rare congenital lesions that may be mistaken for other, more common non-neoplastic cysts as well as cystic neoplasms. We delineate the imaging spectrum, pathologic findings, and differential diagnosis of NE cysts. METHODS: History, imaging, surgical and pathologic findings were analyzed retrospectively in 18 patients with intracranial NE cysts. Fifteen were surgically proved cases; 3 exhibited classic imaging findings and are being followed clinically. RESULTS: Thirteen cysts were located in the posterior fossa; 12 of 13 were extra-axial. Size varied from 1.2 x 0.8 x 0.6 cm to 3.4 x 3 x 2.5 cm. Five were supratentorial, measuring from 7 x 5 x 3 to 9 x 6 x 7 cm. All were frontal and off the midline. Seven of 18 patients had CT scans. Cysts varied widely in attenuation. None enhanced. Eighteen of 18 had MR images. Sixteen of 18 were hyperintense, and 2 were isointense to CSF on T1-weighted imaging. Sixteen of 18 were hyperintense on T2-weighted imaging. All cysts were hyperintense to CSF on fluid-attenuated inversion recovery (FLAIR) sequences. Diffusion imaging was performed on 2 patients. One case showed mild restriction. Mild posterior rim enhancement was seen in 5 cases at the site where the cyst adhered to brain parenchyma. CONCLUSION: The imaging spectrum for NE cysts is broader than previously reported. Intracranial NE cysts should be considered in the differential diagnosis for intracranial extra axial cystic lesions both above and below the tentorium.

Cranial magnetic resonance imaging in severe preeclampsia vs eclampsia.

OBJECTIVE: This study was undertaken to evaluate the hypothesis that severe preeclampsia and eclampsia are associated with unique cranial magnetic resonance images. DESIGN: Case series of women with severe preeclampsia and eclampsia. SETTING: Referral center. PATIENTS: Sixteen women with severe preeclampsia and 10 women with eclampsia. RESULTS: Half of the women with severe preeclampsia had abnormal scans with nonspecific foci of increased signal in the deep cerebral white matter on T2-weighted images. However, women with eclampsia had either a multifocal area of increased signal at the gray-white matter junction on T2-weighted images or cortical edema and hemorrhage. These findings are consistent with necropsy descriptions of cortical edema and petechial hemorrhage. Basal ganglion lesions were also common. CONCLUSIONS: These findings appear to be unique to eclamptic women and should be considered of diagnostic significance in contrast to the nonspecific changes in patients with severe preeclampsia. Cranial magnetic resonance imaging may, thus, be of value in cases with diagnostic uncertainty, atypical presentation, or focal neurologic deficit.

Thrombosis of the deep venous drainage of the brain in adults. Analysis of seven cases with review of the literature.

OBJECTIVES: To characterize the clinical, radiographic, and pathologic findings in thrombosis of the deep venous drainage of the brain. To highlight clinical and radiographic findings that may lead to the diagnosis of disease and distinguish it from dural sinus thrombosis. To review the published literature on this disorder. DESIGN: Retrospective review of the medical and radiographic records of seven patients from three institutions over the past 10 years. Review of the English language literature from 1971 to the present. RESULTS: All seven patients had risk factors for cerebral venous thrombosis. Five patients presented with a short, rapidly progressing course characterized by headache, nausea and vomiting, and decline in level of consciousness. All five patients died or were rendered severely disabled. Computed tomographic scans, magnetic resonance imaging, and magnetic resonance angiography showed findings associated with deep cerebral vein thrombosis in three of four, in five of five, and in three of three patients, respectively. Transfemoral catheter angiography was diagnostic in two of two patients. Twenty-one reported cases of deep cerebral venous thrombosis were identified in the literature. CONCLUSIONS: When the two populations are combined and compared with large series of patients with dural sinus thrombosis, patients with deep venous system thrombosis are more commonly women, tend to present with a more rapidly declining time course, altered consciousness, and long tract signs. Death or long-term sequelae are far more likely to occur in internal cerebral vein thrombosis than with dural sinus thrombosis. Unenhanced computed tomography can demonstrate findings that are strongly suggestive of the diagnosis. Magnetic resonance imaging and magnetic resonance angiography are confirmatory. Angiography may still be necessary when the diagnosis is not clear.

Cognitive correlates of diffuse cerebral atrophy determined by computed tomography.

The relationship between severity of diffuse cerebral atrophy determined by computed tomography (CT) and severity of cognitive impairment was examined in 55 men, 50 to 77 years old. Partial correlations, controlling for the effects of age and education, indicated that increased cerebral atrophy was associated with decline in orientation, recent memory, and general level of intellectual functioning. Correlations between degree of atrophy and decline in immediate and remote memory were not significant. Despite significant associations between cerebral atrophy and some aspects of intellectual functioning, considerable variance in performance on cognitive tasks was not explained by cerebral atrophy. Therefore, the degree of diffuse cortical and central atrophy observed on CT scan did not closely predict the degree of cognitive dysfunction, nor did the observation of cerebral atrophy necessarily indicate the presence of dementia.

Fibromuscular dysplasia as a cause of stroke in infancy and childhood.

Two children had abrupt onset of hemiplegia due to childhood fibromuscular dysplasia (FMD). Although FMD is a recognized cause of strokes in adults, the disorder has not, to our knowledge, been reported previously in children. Our report reviews the pathology and diagnosis of FMD and discusses the complexities of its treatment.

Efficacy, safety, and tolerability of ioversol in intra-arterial digital subtraction angiography.

Twenty-two women and 18 men undergoing intra-arterial digital subtraction angiography were enrolled in an open-label, noncomparative study to assess the efficacy, safety, and patient tolerance of the contrast medium ioversol. The quality of radiographs generated was excellent in 60.0% of the studies, diagnostic in 37.5%, and nondiagnostic in 2.5%. There were no clinically significant drug-related changes in vital signs or laboratory tests among the patients, and no drug-related adverse effects were reported. Heat and pain related to injection of ioversol were graded on a four-point scale, with 0 indicating none and 3 indicating severe. The average scores were 1.3 for heat and 0.1 for pain. In this study, ioversol was a safe and effective contrast medium for angiography and was associated with a low incidence of patient discomfort.

Stereotaxic frame and computer software for CT-directed neurosurgical localization.

A clinical stereotaxic head frame designed for use with computed tomography (CT) body scanners is described. Frame geometry and a CT localization system provide an accuracy and versatility that should lead to optimal clinical usefulness. Initial phantom and clinical studies are presented.

Extracalvarial soft tissues in cranial computed tomography. Normal anatomy and pathology.

Computed tomography has emerged as the modality of choice for imaging soft tissues of the face and neck. However, the extracalvarial soft tissue anatomy has not been delineated. The CT appearance of normal anatomy and variants, including the cutaneous and subcutaneous tissues, muscle layers, and subgaleal space is described. A pathologic spectrum that includes congenital, inflammatory, traumatic, and neoplastic lesions is presented. When appropriate CT windows for viewing the extracalvarial soft tissues are utilized, significant clinical information may be provided.

Safety and efficacy of iopromide in cerebral arteriography.

RATIONALE AND OBJECTIVES: Iopromide is a new nonionic monomeric contrast medium for cerebral arteriography. This agent has been approved for sale in over 45 countries; however, it is still undergoing clinical review in the United States. This study evaluated the safety and efficacy of iopromide in comparison with two other nonionic contrast media. METHODS: A total of 173 patients participated in the study, which was prospective, double-blind, and randomized. In two centers, patients received iopromide or iohexol; in the other three centers, patients received iopromide or iopamidol. Adverse events were monitored by investigators, and efficacy was evaluated by grading the radiographic images. RESULTS: Most adverse events were mild or moderate in severity; all resolved completely. Twenty-one percent of patients given iopromide were reported to have a drug-related adverse event, versus 44% of patients given a comparator. No statistically significant difference emerged between iopromide and the comparators with regard to efficacy. CONCLUSIONS: These study results indicate that iopromide is a safe and effective contrast medium for cerebral angiography.

Simplified CT-guided stereotaxic biopsy.

A stereotaxic frame worn during computed tomographic (CT) scanning of the head produces landmarks in each section that are used to relate section coordinates to frame coordinates. A small, commercially available, programmable calculator is used to interrelate frame and CT section geometry. The system can be used with any CT scanner that can specify (x,y) coordinates of a pixel, obviating the need for extensive modifications of the CT computer software. Representative clinical cases are presented.

Uncovertebral and facet joint dislocations in cervical articular pillar fractures: CT evaluation.

Computed tomographic (CT) scans and plain radiographs of 21 patients with surgically treated fractures or dislocations of the cervical spine were reviewed. CT effectively demonstrated the locked or perched facets and half of the 13 articular pillar fractures. The fracture lines through the articular pillar were difficult to detect in some cases or to distinguish from a facet joint in others. However, distraction of an adjacent uncovertebral or facet joint was demonstrated by CT in each case of articular pillar fracture or locked or perched facet. Therefore, CT demonstration of a distracted facet or uncovertebral joint is an indirect sign of an unstable fracture or of a dislocation that may be more readily recognized on plain radiographs or pluridirectional tomograms.

Spinal nerve enhancement with Gd-DTPA: MR correlation with the postoperative lumbosacral spine.

PURPOSE: To search for a probable source of the recurrent signs and symptoms associated with lumbosacral postsurgical syndrome on intravenous gadolinium-enhanced MR. METHODS: A retrospective study of 120 patients with recurrent symptomatology following lumbar disk surgery was carried out with spin-echo MR pre- and postenhancement with gadopentetate dimeglumine (0.1 mmol/kg). In addition, 10 asymptomatic subjects were evaluated at least 6 months postoperatively using the same imaging protocol. RESULTS: 21.6% of the symptomatic subjects (N = 26) had enhancement of one or more spinal nerve root. This enhancement was focal or multisegmental, and involved single or multiple nerve roots. The abnormal neural enhancement was associated with otherwise isolated epidural fibrosis in 88.5%, and with herniated nucleus pulposus in the remaining 11.5%. The overall clinical correlation of single root enhancement with a monoradiculopathy and multiroot enhancement with a polyradiculopathy was 95.7%. However, 21.7% of these same cases also showed additional nerve root enhancement that did not have an overt clinical correlation. All of these latter patients were imaged relatively early in the postoperative period (5 days to 8 months). The 10 patients in the asymptomatic group all manifested degrees of postoperative epidural scarring on MR, but no abnormal radicular enhancement or other associated pathology. CONCLUSION: In the chronic postoperative phase (more than 6 to 8 months), the presence of radicular enhancement on MR imaging in symptomatic individuals, and its absence in asymptomatic subjects, suggests that neural enhancement serves as a marker for active neural pathology that may in certain individuals be related temporally to the signs and symptoms associated with the lumbosacral postsurgical syndrome.

Bithalamic hyperintensity on T2-weighted MR: vascular causes and evaluation with MR angiography.

PURPOSE: To determine whether MR angiography can be used to differentiate between the two vascular causes of bithalamic hyperintensity on T2-weighted MR images: "top of the basilar" artery occlusion and deep cerebral vein thrombosis. METHODS: A retrospective review identified six patients with bithalamic T2 hyperintensity of vascular causes. MR angiography was performed in four patients, MR angiography and conventional angiography in one patient, and conventional angiography in one patient. Data pertaining to clinical presentation and hospital course were collected. MR angiographic techniques were multislab overlapping three-dimensional time-of-flight, 2-D time-of-flight, and 2-D phase-contrast. RESULTS: Three cases of top of the basilar artery occlusion and three cases of deep cerebral vein thrombosis were recognized. In all cases, T2 hyperintensity in a vascular distribution suggested cerebral occlusive disease. Infarction involving the thalami and basal ganglia was present in two cases of deep cerebral vein thrombosis. Infarction of the thalami, mesodiencephalic region, and cerebellar hemispheres was present in two cases of basilar artery occlusion. Bithalamic infarction alone was seen in one case of deep cerebral vein thrombosis and one case of basilar artery occlusion. In the five cases in which MR angiography was used, this technique accurately distinguished the vessels involved (arterial or venous). CONCLUSION: MR angiography is a useful adjunct to MR imaging in the evaluation of bithalamic T2 hyperintensity. It does help distinguish between the two vascular causes: top of basilar artery occlusion and deep cerebral vein thrombosis.