MRI evidence of impaired CSF homeostasis in obesity-associated idiopathic intracranial hypertension.

BACKGROUND AND PURPOSE: Impaired CSF homeostasis and altered venous hemodynamics are proposed mechanisms for elevated pressure in IIH. However, the lack of ventricular expansion steered the focus away from CSF homeostasis in IIH. This study aims to measure intracranial CSF volumes and cerebral venous drainage with MR imaging to determine whether increased CSF volume from impaired CSF homeostasis and venous hemodynamics occur in obesity-related IIH. MATERIALS AND METHODS: Two homogeneous cohorts of 11 newly diagnosed pretreatment overweight women with IIH and 11 overweight healthy women were prospectively studied. 3D volumetric MR imaging of the brain was used to quantify CSF and brain tissue volumes, and dynamic phase contrast was used to measure relative cerebral drainage through the internal jugular veins. RESULTS: Findings confirm normal ventricular volume in IIH. However, extraventricular CSF volume is significantly increased in IIH (290 ± 52 versus 220 ± 24 mL, P = .001). This is even more significant after normalization with intracranial volume (P = .0007). GM interstitial fluid volume is also increased in IIH (602 ± 57 versus 557 ± 31 mL, P = .037). Total arterial inflow is normal, but relative venous drainage through the IJV is significantly reduced in IIH (65 ± 7% versus 81 ± 10%, P = .001). CONCLUSIONS: Increased intracranial CSF volume that accumulates in the extraventricular subarachnoid space provides direct evidence for impaired CSF homeostasis in obesity-associated IIH. The finding of larger GM interstitial fluid volume is consistent with increased overall resistance to cerebral venous drainage, as evident from reduced relative cerebral drainage through the IJV. The present study confirms that both impaired CSF homeostasis and venous hemodynamics coexist in obesity-associated IIH.

Optic neuropathy and chiasmopathy in the diagnosis of systemic lupus erythematosus.

PURPOSE: To report the clinical presentation of acute visual loss in six patients who were ultimately diagnosed with systemic lupus erythematosus (SLE). METHODS: Retrospective case series. RESULTS: All patients had a positive antinuclear antibody and elevated anti-double stranded DNA titers. Five of six patients demonstrated gadolinium enhancement of the optic nerve and/or chiasm on magnetic resonance imaging (MRI). Most patients showed initial improvement after treatment with high-dose systemic corticosteroids, but five experienced recrudescences during steroid taper, requiring further treatment with immunosuppressive or cytotoxic medications. CONCLUSIONS: Visual loss owing to optic neuropathy or chiasmopathy may be the presenting sign of SLE or the event that leads to this diagnosis. Gadolinium-enhanced MRI is useful for identifying anterior visual pathway lesions in these patients. Corticosteroids are effective in the treatment of this condition; however, relapses requiring further treatment are common.

Enhancement of the eighth cranial nerve and labyrinth on MR imaging in sudden sensorineural hearing loss associated with human herpesvirus 1 infection: case report.

The case of a 61-year-old woman who presented with herpes labialis, subclinical meningitis, and sudden onset of bilateral sensorineural hearing loss is presented. Contrast-enhanced MR imaging showed marked bilateral enhancement of the intracanalicular portion of the eighth cranial nerve, right cochlea, and left vestibule. Polymerase chain reaction was positive for human herpesvirus 1 obtained from the cerebral spinal fluid, which suggested the diagnosis of viral neuritis.

Optic tract edema in a meningioma of the tuberculum sellae.

We report a case of tuberculum sellae meningioma with optic tract edema. Contrary to a prior report on this topic, edema along the optic tract is not only seen in craniopharyngiomas but may be seen (although rarely) in other common parasellar tumors, as in our case of a tuberculum sellae meningioma. The pathogenesis of this edema in meningioma is controversial.

MR imaging of infections of the cervical spine.

Spine infections are serious clinical conditions that carry high morbidity and mortality rates. Cervical spine infections usually require a more aggressive medical and surgical approach than infections in the rest of the spine. Often, more than one anatomic structure or compartment becomes affected. Topics discussed in this article include incidence and predisposing factors of spine infections, types of micro-organisms involved in several disease conditions, pathophysiology and clinical manifestations, and imaging findings and MR imaging features.

MRI of acute spinal epidural hematomas.

PURPOSE: The purpose of this work was to determine the MR findings that characterize acute spinal epidural hematomas (ASEHs). METHOD: The MR findings of 17 patients with ASEH (9 cervical, 7 thoracic, and 2 lumbar) were reviewed. Fifteen of the hematomas were secondary to trauma and two were spontaneous. Correlation with CT (8 cases) and surgical findings (11 cases) was also performed. RESULTS: Imaging findings in ASEH were the following: (a) a variable signal intensity (on T1-weighted images, 10 showed isointensity to cord and 7 were slightly hyperintense; T2-weighted images showed hyperintensity with areas of hypointensity); (b) capping of epidural fat; (c) direct continuity with the adjacent osseous structures; (d) compression of epidural fat, subarachnoid sac, and spinal cord; (e) usually posterolateral location in the spinal canal. CONCLUSION: Epidural hematomas in the spinal canal are lesions capable of producing sudden spinal cord and/or cauda equina compression. MR provides characteristic findings that allow a prompt diagnosis of acute epidural hematomas.

MR of vasculitis-induced optic neuropathy.

PURPOSE: To describe the MR characteristics of optic neuropathy caused by vasculitis. METHODS: Nine cases of optic neuropathy with diagnosis of vasculitis (six with systemic lupus erythematosis and one each with rheumatoid arthritis, Sjögren disease, and radiation vasculitis) were reviewed retrospectively. Patients were 31 to 62 years old, and all but one were women. All patients had MR imaging through the orbits and anterior visual pathways, five with fat suppression, with and without gadopentetate dimeglumine. Five patients also had MR imaging of the entire brain. The size and enhancement of various segments of the optic nerve and anterior visual pathways were studied. RESULTS: MR imaging with contrast material showed enhancement and enlargement of segments of the optic nerves and/or chiasm in six of the nine patients (all but three with systemic lupus erythematosis). Enlargement of a segment of the anterior visual pathway never occurred without enhancement, but enhancement alone did occur in three cases. Of the five patients who had MR imaging of the whole brain, abnormalities were seen in three: periventricular hyperintensity in two and a lacunar infarct in one; none had vessel abnormalities. CONCLUSION: Because the MR enhancement seen represents disruption of the blood-brain barrier within the optic nerve, MR imaging with gadopentetate dimeglumine and fat suppression should be performed to detect increased permeability of the blood-brain barrier in acute optic neuropathy.

MR characteristics of histopathologic subtypes of spinal ependymoma.

PURPOSE: To examine MR characteristics and enhancement patterns of spinal ependymomas and compare these data with histopathologic subtypes. METHODS: The MR images from 26 cases of pathologically proved spinal ependymomas were evaluated with respect to seven criteria: signal characteristics, enhancement pattern, length of involvement, cysts or syrinxes, hemorrhage, bony changes, and type of cord expansion. Signal characteristics were then correlated with histologic subtype. RESULTS: In the category of enhancement pattern, our results differed markedly from published data, with only 38% of cases demonstrating classic homogeneous enhancement. The remainder of our cases (62%) demonstrated other enhancement patterns, including heterogeneous (31%), rim (19%), minimal (6%), and no enhancement (6%). Pathologic comparison revealed that one histologic subtype, the myxopapillary ependymoma, demonstrated unique imaging characteristics on T1-weighted images. A highly statistically significant percentage of this variant was hyperintense on T1, whereas most nonmyxopapillary ependymomas were hypointense. CONCLUSION: The radiologist should be aware of alternative patterns of enhancement of spinal ependymomas and not be dissuaded from the diagnosis in appropriate clinical settings. In addition, one histologic subtype, myxopapillary, often exhibits signal characteristics different from nonmyxopapillary types, appearing hyperintense on T1 probably because of their intracellular and perivascular accumulation of mucin.

Acute spinal subdural hematoma: MR and CT findings with pathologic correlates.

PURPOSE: To determine the MR and CT findings that characterize acute spinal subdural hematoma (ASSH). METHODS: The MR, CT, and clinical findings in three patients with surgically proved ASSH were reviewed and also correlated with the postmortem MR, CT, and cryomicrotome findings in three other patients, two with ASSH and one with an acute spinal epidural hematoma. RESULTS: Imaging findings in ASSH included: (a) hyperdense lesions on plain CT within the dural sac, distinct from the adjacent low-density epidural fat and silhouetted against the lower-density spinal cord and cauda equina, which it compressed; (b) lack of direct continuity with the adjacent osseous structures; (c) clumping, loculation, and streaking of blood within the dural sac on both MR and Ct; and (d) an inhomogeneous and variable signal intensity to the ASSH on all MR pulse sequences, but, nevertheless, a striking low signal intensity on T2-weighted spin-echo or T2-weighted gradient-echo to a major part of the ASSH because of deoxyhemoglobin. Plain CT was most helpful in compartmentalizing the hematoma. CONCLUSION: When MR and plain CT are obtained as complementary studies, they provide characteristic findings that allow the prompt diagnosis of ASSH.

Magnetic resonance applications in cerebral injury.

CT and MR imaging are complementary in the evaluation of cerebral head trauma. CT is still more useful for the initial evaluation of the acutely unstable patient who has a head injury. However, many lesions are identified by MR imaging such as cortical contusions, small subdural hematomas, and diffuse axonal injuries that may not be seen on CT examinations. In addition, MR angiography can play an important role in the diagnostic evaluation of the trauma patient. MR angiography can be clinically useful in delineating vascular abnormalities such as arterial occlusions, arteriovenous fistulae, dissecting aneurysms, and venous sinus occlusion. In pediatric trauma, MR imaging appears to be superior to CT in assessing head injuries, particularly those due to child abuse.

Complications of epidural anesthesia: MR appearance of abnormalities.

Eight patients with acquired intradural arachnoid abnormalities caused by epidural anesthesia were evaluated with magnetic resonance (MR) imaging (eight patients) and intraoperative ultrasound imaging (four patients). Subarachnoid cysts were found in the lower cervical and thoracic spine in six patients. Irregularity of the surface of the cord was noted in seven cases. Associated intramedullary cysts and myelomalacia were seen in two patients. Arachnoiditis was unsuspected clinically in four patients; findings at MR imaging first suggested the cause of the patients' symptoms. The underlying mechanism for the intradural and cord abnormalities in seven of the eight patients was a chemically induced arachnoiditis produced by the administration of epidural anesthesia; in the eight case, an infection introduced at the time of the epidural injection was the cause of the abnormalities. The authors postulate that the preservative agents in the vials of anesthetic may have been the causative factor of this inflammation in the majority of the cases.