William R. Kinkel

Significance of hyperintense vessels on FLAIR MRI in acute stroke

Objective: To describe hyperintense vessels sign (HVS) in patients with acute stroke on fluid-attenuated inversion recovery (FLAIR) MRI and determine its clinical significance and utility. Background: Enhancement of vessels on postcontrast MRI in patients with acute stroke is considered an indicator of early brain ischemia. Recently, the FLAIR technique has shown promise in earlier and better detection of ischemic brain parenchymal lesions. Methods: Two observers retrospectively reviewed 304 MRI of patients with stroke and identified 30 patients with acute middle cerebral artery stroke and HVS on FLAIR obtained within 24 hours of symptom onset. These patients were evaluated with contrast-enhanced MRI (n = 9), MR angiography of carotid and intracranial circulation (n = 30), cerebral angiography (n = 8), transcranial Doppler (n = 17), and SPECT (n = 16). The extent of HVS was compared with final infarct size and NIH Stroke Scale score. Results: HVS on FLAIR was seen in 10% of the patients with acute stroke. HVS was associated with large vessel occlusion or severe stenosis (>90%). Intravascular enhancement on contrast MRI was observed in vessels that were hyperintense on FLAIR. Both cortical and subcortical infarcts demonstrated HVS. MR angiographic and cerebral angiographic findings of large vessel occlusion or severe stenosis (>90%), slow flow, low velocities by transcranial Doppler, and hypoperfusion on SPECT correlated with HVS. HVS was the earliest ischemic change in three patients scanned within 3 hours of ictus. Final infarct size was smaller than the area showing HVS in all patients. Conclusion: HVS on FLAIR MRI is an indicator of slow flow and early ischemia as a result of large vessel occlusion or stenosis and inadequacy of collateral circulation. HVS does not mean that infarction has occurred but indicates brain tissue at risk of infarction. It should prompt consideration of revascularization and flow augmentation strategies.

Correlations of nuclear magnetic resonance imaging, computerized tomography, and clinical profiles in multiple sclerosis

Nuclear magnetic resonance (NMR) imaging was superior to CT for imaging the brain lesions of 27 patients with MS. The incidence of abnormal examinations was 78% by NMR and 63% by CT. In cases in which both studies were abnormal, NMR usually demonstrated many more lesions and more extensive involvement than CT. The appearance and locations of lesions identified by NMR were similar to those of autopsy studies of MS and may be relatively specific for this disease. Some lesions identified by CT disappeared during serial examinations, but lesions identified by NMR did not resolve over time. Seventy-five percent of the lesions were clinically “silent”; only 5% were definitely related to the clinical symptoms and signs. All of those lesions were located in the brainstem or cerebellar peduncles and were identified by NMR, but missed by CT.

Occipital Lobe Seizures as the Major Clinical Manifestation of Reversible Posterior Leukoencephalopathy Syndrome: Magnetic Resonance Imaging Findings

Summary: Purpose: Reversible posterior leukoencephalopathy syndrome (RPLS) is an increasingly recognized brain disorder most commonly associated with malignant hypertension, toxemia of pregnancy, or the use of immunosuppressive agents. When associated with acute hypertension, RPLS typically occurs concurrently with the fulminant clinical syndrome of hypertensive encephalopathy. We describe occipital lobe seizures, in the setting of only moderate elevations of blood pressure, as the major clinical manifestation of RPLS.

MRI FINDINGS IN LUMBAR PUNCTURE HEADACHE SYNDROME: ABNORMAL DURAL-MENINGEAL AND DURAL VENOUS SINUS ENHANCEMENT

Intracranial hypotension (IH) is a treatable cause of persistent headaches. Persistent cerebrospinal fluid (CSF) leak at a lumbar puncture (LP) site may cause IH. We present postcontrast MRI of a patient with post-lumbar-puncture headache (LPHA) showing abnormal, intense, diffuse, symmetric, contiguous dural-meningeal (pachymeningeal) enhancement of the supratentorial and infratentorial intracranial dura, including convexities, interhemispheric fissure, tentorium, and falx. MRI also showed abnormal dural venous sinus enhancement, a new finding in LPHA, suggesting compensatory venous expansion. Thus, IH and venodilatation may play a role in the development of LPHA.

Autopsy correlations of computerized tomography Experience with 6,000 CT scans

Seventy-nine autopsy correlations of CT scans showed (1) excellent correlations in normal brains, but the size of the lateral ventricles consistently larger during life than after death; (2) a distinctive pattern differentiating obstructive from nonobstructive hydrocephalus; (3) infarctions appearing as areas of decreased densities of parenchyma in vascular distributions; (4) distinctive high density appearances of hemorrhages that differentiated them from infarctions and, in general, all other pathologic processes; (5) supratentorial, intraventricular, and posterior fossa tumors appearing as masses that displaced, distorted, collapsed, and enlarged normal spaces and structures such as ventricles and pineal gland; (6) 11 false-negative CT scans in some cases of brain stem infarction, brain stem hemorrhage, and small metastasis; and (7) an overall accuracy of 86.2 percent of CT scanning in correctly identifying pathology of the brain.

Magnetic resonance imaging findings in acute cerebellitis

Cerebellitis, also known as acute cerebellar ataxia, is an inflammatory syndrome of cerebellar dysfunction that may reflect an infectious, post-infectious, or post-vaccination disorder. We present serial magnetic resonance imaging (MRI) findings in a partially reversible, idiopathic cerebellitis. Bilateral cerebellar parenchymal abnormalities were noted, including hyperintensities on T2-weighted images and cerebellar swelling. After contrast administration, the cerebellum showed abnormal bilateral enhancement. The authors state this represents the first report of abnormal contrast enhancement in this condition. The MRI lesions most likely reflect the reversible, inflammatory nature of the syndrome.

Cranial magnetic resonance imaging findings in bacterial endocarditis: the neuroimaging spectrum of septic brain embolization demonstrated in twelve patients.

Infective endocarditis (IE) is an elusive systemic disorder that is often associated with neurologic complications. The contribution of brain magnetic resonance imaging (MRI) to the diagnosis of IE and the spectrum of such findings has been only sparsely described previously. The authors report cranial MRI findings in 12 patients with IE. Each of the patients had MRI evidence of cerebral embolization, with multiple brain lesions noted in most patients (n = 1 0). Cortical branch infarction was the most common lesion (n = 8), which usually involved the distal middle cerebral artery tree. The next most common finding (n = 7) was numerous small embolic lesions which typically lodged in the supratentorial gray‐white junction, some of which were clinically silent and many of which enhanced (probable microabscesses). Brain hemorrhages were noted in four patients, most commonly subarachnoid hemorrhage (n = 3). Two patients developed multiple frank parenchymal macroabscesses/cerebritis lesions. A previously unreported finding in septic embolization, a stroke that became infected with abscess formation (“septic infarction”), was noted in two patients. MRI showed orbital cellulitis in two patients. Most patients studied with gadolinium showed enhancement of lesions (n = 5/8). The authors conclude that cranial MRI may be a valuable tool in the evaluation of patients with IE. The presence of characteristic cranial MRI lesions, especially of multiple types, may prompt early diagnosis and treatment. Key words: MRI, brain, endocarditis, septic emboli, abscess, stroke, orbital infection.

Cognitive impairment after acute supratentorial stroke : a 6-month follow-up clinical and computed tomographic study

SummaryTo document the occurrence, time course, and predictors of global cognitive impairment following a supratentorial stroke, we prospectively studied 41 consecutive patients with acute cerebral ischemia and no evidence of pre-existing intellectual disturbances. The Graded Neurologic Scale and Mattis Dementia Rating Scale were used to assess neurologic and cognitive deficits within the first week, 3 weeks and 6 months after the onset of symptoms. CT was performed at each examination and semiquantitative measurements of infarct volumes and brain atrophy were obtained. Sixty-one percent of patients were found to be cognitively impaired within the first week. After 6 months this deficit had resolved in 24%, but was still present in 37% of individuals. Initial findings associated with a high risk of longterm intellectual dysfunction were: 1. moderately severe cognitive impairment, 2. diminished alertness in the acute stroke stage, 3. infarction involving the temporal lobe, 4. evidence of multiple brain infarcts and 5. pronounced ventricular enlargement. Logistic regression analysis revealed temporal infarcts and evidence of multiple ischemic lesions as the most powerful predictors of persistent cognitive impairment. By these two factors alone, 85.4% of study participants could be correctly classified regarding their cognitive outcome. These results suggest cognitive dysfunction to be a frequent sequela of supratentorial stroke. Its long-term persistence may be predicted on the basis of certain features.

CEREBRAL VENOUS INFARCTIONS PRESENTING AS ENHANCING SPACE-OCCUPYING LESIONS : MRI FINDINGS

Cerebral venous thrombosis is an unusual form of cerebrovascular disease that may cause cerebral venous infarction (CVI). Magnetic resonance imaging (MRI) of the brain may improve the often elusive diagnosis of CVI. However, the sensitivity, specificity, and full spectrum of such MRI findings are poorly understood. The authors present the cases of three patients with CVI whose MRI scans showed abnormally enhancing tumor‐like brain lesions. Two of the CVIs were hemorrhagic and exerted mass effect. One patient showed increasingly nodular and heterogeneous ring‐like enhancement progressing from the single‐dose to the triple‐dose gadolinium contrast images. The CVI of a second patient also showed ring‐like enhancement. Biopsy was performed on one of these patients and was strongly considered for the other two patients to exclude neoplastic disease. Careful examination of the MRI appearance of venous structures and the use of specialized MRI techniques improved the recognition of CVI for two patients and prevented biopsy. This represents the first description of abnormal tripledose MRI contrast enhancement in CVI. Consideration of CVI in the care of patients with enhancing tumor‐like masses may lead to earlier diagnosis and treatment, preventing unnecessary invasive diagnostic procedures. CVI should be added to the differential diagnosis of supratentorial ring‐enhancing masses.

Neurosarcoidosis presenting as a large suprasellar mass: Magnetic resonance imaging findings

We present unusual magnetic resonance imaging (MRI) findings in a case of neurosarcoidosis. MRI revealed a large solitary suprasellar mass which resembled a neoplasm. The lesion was isointense and hyperintense on T1-weighted images, hypointense on T2-weighted images, and intensely homogeneously enhancing. Biopsy revealed a polymorphous inflammatory lesion with giant cells, which extended from the hypothalamus, consistent with neurosarcoidosis. The diagnosis of neurosarcoidosis should be considered in patients presenting with large midline tumor-like suprasellar mass lesions.