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.

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.

Acquired spinal subarachnoid cysts: evaluation with MR, CT myelography, and intraoperative sonography.

Fifteen patients with acquired spinal subarachnoid cysts (14 surgically proved, one presumed) were evaluated preoperatively with immediate and/or delayed CT myelography (seven patients), MR (11 patients), or both (three patients). CT myelography separated subarachnoid cyst from myelomalacia and/or intramedullary cysts in four cases but failed to diagnose them in three, while MR accurately diagnosed subarachnoid cyst in all 10 cases that were also surgically proved. The results of these preoperative examinations were evaluated to determine the efficacy of each study in diagnosing subarachnoid cysts, ascertaining their extent and internal architecture, and detecting associated abnormalities of the spinal cord. In addition, during surgery these cysts were studied with sonography to gain an understanding of the pathophysiological mechanisms involved in their formation and propagation and to guide the surgeon in their decompression. On the basis of our experience, MR appears to be the most efficient preoperative study in diagnosing and characterizing acquired subarachnoid cyst and associated abnormalities. Intraoperative sonography provides a reliable means of ensuring adequate decompression of these cysts.

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.

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.

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.

Lumbar disk herniation and canal stenosis: value of intraoperative sonography in diagnosis and surgical management.

One-hundred-four patients with preoperative diagnoses of lumbar canal stenosis, disk herniation, or a combination of both were evaluated with intraoperative sonography with the intent of (1) describing the sonographic characteristics of herniated disks and distinguishing these from bulging anuli, epidural fat, scar tissue, and spondylolisthesis; (2) establishing criteria for adequate decompression of canal stenosis; and (3) determining the usefulness of sonography in monitoring disk removal. Disk material demonstrates medium echogenicity, different in its sonographic features from bone, epidural fat, scar tissue, and epidural veins. A sonographic diagnosis of disk herniation was made in 43 cases, 41 of which were confirmed during surgery. Sonography established the presence or absence of disk herniation (confirmed by surgery) in 14 of 19 patients who had equivocal preoperative findings. After routine diskectomy, residual disk material was found in 17 (41%) of 41 patients, which led to further surgery in 16 patients with removal of the additional disk fragments. In 84 patients undergoing decompressive surgery for canal stenosis, sonography detected residual canal compression in 19 (23%), which led to a widened decompression in 15 of these patients. Sonography can differentiate disk material from other normal or abnormal structures in the canal; therefore, sonographic monitoring helps to ensure adequate bony decompression and complete diskectomy. We conclude that intraoperative sonography is an important tool in the surgical management of lumbar disk disease and stenosis.

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.

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.

Automated quantitation of the posterior scleral flattening and optic nerve protrusion by MRI in idiopathic intracranial hypertension.

BACKGROUND AND PURPOSE: Subjective determination of the posterior sclera flattening and optic nerve protrusion in MRI is challenging because of the 3D nature of the globe morphology. This study aims to develop and compare quantitative measures of globe flattening and optic nerve protrusion with subjective rating, and assess relationships with papilledema grade and intraocular and CSF pressures. MATERIALS AND METHODS: Data of 34 globes from 7 overweight female patients with idiopathic intracranial hypertension and 6 age- and weight-matched healthy female control subjects were assessed, as well as a subcohort of 4 of the patients with idiopathic intracranial hypertension who underwent follow-up MR imaging 2 weeks after lumbar puncture and initiation of treatment with acetazolamide. MR imaging examination included a 3D CISS sequence on 1.5T and 3T scanners with 0.6-mm isotropic resolution. Subjective ratings of globe flattening were obtained by experienced and inexperienced readers. Quantitative measures of globe flattening, nerve protrusion, and maximal deformation were derived by use of a 2D map of the distances from the globe center to the posterior wall. RESULTS: Contingency coefficients for globe flattening agreements with subjective rating by the experienced and inexperienced readers were 0.72 and 0.56, respectively. Mean values of the 3 deformation measures were significantly poorer in the idiopathic intracranial hypertension group, with nerve protrusion demonstrating the strongest difference (P = .0002). Nerve protrusion was most strongly associated with papilledema grade with a contingency coefficient of 0.74 (P = .01), whereas globe flattening was negatively correlated with intraocular pressure (R = -0.75, P < .0001). Maximal deformation was negatively associated with CSF opening pressure (R = -0.86, P = .0001). After treatment, only the changes in nerve protrusion and maximal deformation were significant. CONCLUSIONS: Automated measures of globe deformation improve reliability over subjective rating. Of the 2 globe deformation measures, nerve protrusion had the strongest predictive value for papilledema grade and had the highest sensitivity for assessment of treatment efficacy in idiopathic intracranial hypertension.

Unusual case of cerebral aspergillosis with clinical and imaging findings mimicking lymphoma.

A 14-year-old female post-transplant patient with a history of post-transplant lymphoproliferative disease/lymphoma presented with fever and lethargy. Computed tomography of the brain demonstrated a hypodense lesion with surrounding edema in the right periventricular region not seen on a routine study performed two weeks earlier. On magnetic resonance imaging (MRI) this lesion was mainly iso-intense to gray matter on T2-weighted (T2W) images and demonstrated peripheral contrast enhancement. Diffusion restriction was seen within most of the lesion including, but not limited to, its periphery. Lesion location and MRI characteristics, particularly on T2W and diffusion sequences, were suggestive of lymphoma. The patient's history of post-transplant lymphoproliferative disorder also supported this diagnosis. However, in view of the patient's immunocompromised state, rapid onset of symptoms, and recent normal CT scan of the brain, infection was also entertained. Biopsy revealed short branching hyphae consistent with aspergillosis. This case is interesting as the MRI restriction pattern and the patient's history were more suggestive of lymphoma, but in reality the lesion represented an evolving aspergillosis abscess. Biopsy was necessary to further proceed with appropriate medical management, which is significantly different for the two entities.

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.

Magnetic resonance imaging findings in chronic inflammatory demyelinating polyneuropathy with intracranial findings and enhancing, thickened cranial and spinal nerves.

Chronic inflammatory demyelinating polyneuropathy is a rare autoimmune disorder characterized by chronically progressive or relapsing symmetric sensorimotor involvement. We describe the imaging findings in our patient. Magnetic resonance imaging showed presence of an intracranial white matter lesion and enhancing, thickened cranial and spinal nerves. This disorder has been described very infrequently in the radiology literature.

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.

Unretrieved gallstone presenting as an inguinal mass.

We describe a case of a patient 6 months after laparoscopic cholecystectomy who presented with inguinal pain and a mass. At inguinal exploration, the patient was found to have an unretrieved gallstone.

Correlative study of the computed tomographic, ultrasonographic, and pathological characteristics of cavernous versus capillary hemangiomas of the orbit.

Pathologic and ultrasonographic features of cavernous and capillary hemangiomas were correlated with the computed tomographic (CT) characteristics of these two tumors to show that these hemangiomas can be differentiated by their contrast enhancement characteristics. Specifically, all five cases of adult cavernous hemangiomas were enhanced proportionately less than extraocular muscles, whereas capillary hemangiomas were enhanced proportionately more than extraocular muscles. The capillary hemangioma that demonstrated the lowest relative enhancement was in an older child, it may have represented a more mature form of a capillary hemangioma. We correlated these CT findings with the ultrasonographic and pathologic features to explain the differences in these CT characteristics.

Acquired spinal subarachnoid cysts: evaluation with MR, CT myelography, and intraoperative sonography.

Fifteen patients with acquired spinal subarachnoid cysts (14 surgically proved, one presumed) were evaluated preoperatively with immediate and/or delayed CT myelography (seven patients), MR (11 patients), or both (three patients). CT myelography separated subarachnoid cyst from myelomalacia and/or intramedullary cysts in four cases but failed to diagnose them in three, while MR accurately diagnosed subarachnoid cyst in all 10 cases that were also surgically proved. The results of these preoperative examinations were evaluated to determine the efficacy of each study in diagnosing subarachnoid cysts, ascertaining their extent and internal architecture, and detecting associated abnormalities of the spinal cord. In addition, during surgery these cysts were studied with sonography to gain an understanding of the pathophysiological mechanisms involved in their formation and propagation and to guide the surgeon in their decompression. On the basis of our experience, MR appears to be the most efficient preoperative study in diagnosing and characterizing acquired subarachnoid cyst and associated abnormalities. Intraoperative sonography provides a reliable means of ensuring adequate decompression of these cysts.