Imaging manifestations of progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by reactivation of JC virus in immunosuppressed patients. The diagnosis is usually suggested on imaging and confirmed by cerebrospinal fluid polymerase chain reaction (PCR) for JC virus DNA. In this article, we review the imaging manifestations of PML on computed tomography (CT), magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), MR spectroscopy, single photon-emission computed tomography (SPECT) and positron-emission tomography (PET), and outline the role of imaging in follow-up and prognostication.

Encephalocraniocutaneous lipomatosis and the Proteus syndrome: distinct entities with overlapping manifestations.

We have studied three children with cutaneous (epidermal nevi), subcutaneous (lipomas, plantar skin thickening), vascular (hemangioma, lymphangioma), skeletal (osteoma, exostosis, localized hypertrophy), and neurological (hydrocephaly, lissencephaly, partial agenesis of the corpus callosum) developmental defects associated with the Proteus syndrome and related hamartoneoplastic conditions. We compared our findings in these three patients with those of 50 others with Proteus syndrome and nine with encephalocraniocutaneous lipomatosis (ECCL) reported in the literature. We found that Proteus syndrome and ECCL have distinct identities even though some clinical manifestations are shared by both and a few patients have manifestations of both conditions.

Magnetic resonance imaging in patients with low-tension glaucoma.

OBJECTIVE: To study diagnoses and anatomic findings found on magnetic resonance imaging in patients with low-tension glaucoma. PATIENTS: We included in this study magnetic resonance images of 20 consecutive patients with low-tension glaucoma. We individually matched each patient with low-tension glaucoma to a control with normal ocular findings who had magnetic resonance imaging for reasons unrelated to the visual pathway. DESIGN: We studied axial and coronal images of the orbit and optic nerve with digitizing software (Image-Pro Plus, Media Cybernetics, Silver Spring, Md). Statistical evaluation was with a Wilcoxon Signed Rank Test for anatomic findings and a McNemar Test for diagnosis. RESULTS: We found no difference between groups in the optic nerve diameter or length, the carotid artery area, or the distance from the optic nerve to the carotid artery (P > .05). Left optic nerve area was greater in the control patients than patients with low-tension glaucoma (P = .026). The prevalence of intracranial abnormalities, including meningioma, aneurysm, and arteriovenous abnormality, was similar between groups (P > .05). However, diffuse cerebral small-vessel ischemic changes were found more in patients with low-tension glaucoma (n = 8) than control patients (n = 1) (P = .0196). CONCLUSIONS: This study proposes a hypothesis that cerebral small-vessel ischemia is more common in patients with low-tension glaucoma and potentially reflects indirectly a vascular cause of the optic nerve head damage at least in a subgroup of patients. Importantly, further research still is required to provide direct evidence for a vascular cause involved in low-tension glaucoma.

Subacute combined degeneration of the spinal cord: MR findings.

The authors present the initial and follow-up MR findings in a patient with subacute combined degeneration of the spinal cord, a complication of vitamin B12 deficiency, and a rare cause of demyelination of the dorsal and lateral columns of the spinal cord. Initial study showed high intensity in the dorsal columns of the cervical and thoracic spinal cord on T2-weighted image. Five months after treatment, the abnormal signal intensity was noted to have decreased.

Cystlike white matter lesions in tuberous sclerosis.

PURPOSE: To investigate the presence of small cystlike structures in the cerebral hemispheric white matter on MR images of patients with tuberous sclerosis. METHODS: The MR images of 18 consecutive patients with tuberous sclerosis were reviewed retrospectively. RESULTS: Eight of the 18 patients were found to have cystlike structures in the cerebral white matter. The signal intensity of these lesions was isointense with cerebrospinal fluid on T1-, proton density-, and T2-weighted images. Four patients were imaged with a fluid-attenuated inversion recovery sequence, which in each case also showed fluid-type signal in these areas. Three of the patients had CT for correlation, and these scans supported the diagnosis of cystic lesions. Cysts ranged in number from one to 12 per patient and were usually smaller than 1 cm. The most common location was adjacent to the occipital horn or trigone of the lateral ventricle (six of eight patients). Less frequent sites were near the frontal horns, in the corpus callosum, and in the deep white matter near the body of the lateral ventricle. Cysts in five patients were either immediately adjacent to a cortical tuber or in the center of a white matter dysplastic lesion. A cyst in one patient had septa, and none of the cysts enhanced. CONCLUSIONS: Cystlike structures in the cerebral hemispheric white matter were seen on the MR images of 44% of 18 patients with tuberous sclerosis. Whether these findings represent cystic degeneration of dysplastic tissue or are unrelated to the disease process of tuberous sclerosis is unknown. More than one pathogenesis may exist.

Cranial MR imaging of osteopetrosis.

BACKGROUND AND PURPOSE: The purpose of this study was to describe the cranial MR imaging manifestations of osteopetrosis. These features have not previously been reported in the literature. METHODS: Cranial MR studies, obtained with a uniform imaging protocol, were reviewed in 47 patients with osteopetrosis. Thirty-four patients had autosomal recessive (malignant) osteopetrosis (AROP), seven had intermediate osteopetrosis (IOP), and six had either type I or type II autosomal dominant osteopetrosis (ADOP I or II). The prevalence of abnormalities was tabulated and compared with the specific osteopetrosis variants. RESULTS: All patients with osteopetrosis had thickening and sclerosis of the calvaria. Ventriculomegaly, tonsillar herniation, proptosis, and dural venous sinus stenosis were observed in the majority of patients with AROP and ADOP I. Optic nerve sheath dilatation occurred in many of the patients with AROP and in all patients with ADOP I. Acquired cephaloceles were also observed only in these two groups. Optic nerve atrophy and optic canal stenosis were observed in a majority of patients with AROP, IOP, and ADOP II. Middle ear fluid was prevalent in AROP and IOP, present in over half the patients in each group. Features seen most prevalently, or exclusively, in AROP included stenosis of the internal carotid and vertebral arteries and extramedullary hematopoiesis. CONCLUSION: The cranial MR imaging features of osteopetrosis are both shared and unique among the various subtypes of the disease. The specific cranial and intracranial manifestations reflect the predominant calvarial or skull base patterns of bone thickening. The unique features seen in patients with AROP probably reflect the early age of onset and the greater severity of this form of the disease.

Progressive venous occlusion in a neonate with Sturge-Weber syndrome: demonstration with MR venography.

Progressive cerebral sinovenous occlusion in a neonate with Sturge-Weber syndrome was documented by using two-dimensional time-of-flight MR venography. There was no evidence of intraluminal thrombus on routine spin-echo images obtained either before or after the onset of seizures, despite MR venographic evidence in both studies of venous abnormalities.

MR of nasolabial cysts.

We report the MR imaging findings in two cases of nasolabial cysts. Demonstration of their extraosseous location with cross-sectional imaging should prevent confusion with maxillary cysts and obviate unwarranted dental or maxillary surgery.

Auditory dysfunction caused by multiple sclerosis: detection with MR imaging.

We reviewed the MR examinations of 167 patients who presented over a 3-year period with a chief symptom of hearing loss and/or tinnitus. In 14 of these patients the only MR abnormality was the presence of multiple parenchymal high-signal foci on T2-weighted images. Nine of the 14 had clinical evidence of multiple sclerosis; the remaining five had no clinical evidence of multiple sclerosis. Lesions in the auditory pathways, potentially responsible for the patients' symptoms, were identified in only five cases. We recommend T2-weighted images of the whole brain in addition to T1-weighted images of the internal auditory canals and cerebellopontine angles in patients with hearing loss. In some patients, lesions found at higher levels in the periventricular white matter may provide the only clue to the origin of auditory abnormalities.

MR of cystic aberrant cervical thymus.

The clinical, MR imaging, surgical, and histologic findings in two cases of cystic aberrant cervical thymus were reviewed. Aberrant cervical thymic tissue was sharply circumscribed and extended deep to the posterior pharyngeal wall at the level of the piriform sinus in both cases. Both lesions had cyst contents that were of increased signal intensity on T1-weighted images. Solid components displayed MR signal characteristics identical to normal thymus.

Paraplegia due to ossification of ligamenta flava in X-linked hypophosphatemia. A case report.

STUDY DESIGN: Spinal canal decompression at the most prominent of multiple posterior calcified thoracic lesions in a case of X-linked hypophosphatemia was undertaken for treatment and diagnosis purposes, as well as to assess possible nature of the pathophysiology underlying the presenting deficits. OBJECTIVES: To discuss the clinical assessment diagnostic and treatment aspects of this rare coincidence of ossification of ligamenta flava in the patient with the skeletal deformities of X-linked hypophosphatemia. SUMMARY OF BACKGROUND DATA: The patient with the stigmata and chemical findings of an X-linked hypophosphatemia presented with paraplegia and multiple calcified posterior spinal thoracic lesions. This was studied with magnetic resonance imaging and electrophysiologic studies of the spinal sensory pathways of the legs. These data constituted the preoperative information required to assess later results of surgical intervention. METHODS: Presurgical clinical, imaging and electrophysiologic studies and laboratory and pathologic investigations of the surgical specimens. RESULTS: Resolution of the paraplegia with walking and return to work in a physically demanding job for the last 4 or 5 years of postoperative follow-up after surgical decompression of the spinal cord only at the worst and highest of the effected spinal levels. CONCLUSION: The coincidence of X-linked hypophosphatemia and ossification of ligamenta flava has been reported only in two or three cases in the literature. Removal of the offending ossifying lesion is known to result in resolution of the clinical deficits but similar lesions at other spinal levels are suspected of producing recurrences. The return of function and of the corresponding electrophysiologic correlates indicate a neurono-apractic nature of the neurologic symptoms.

Congenital and acquired abnormalities of the dural venous sinuses.

The imaging features of a variety of dural venous sinus (DVS) abnormalities are reviewed. Congenital and heritable diseases affecting the DVS, tumor-related sinus compression, and traumatic injuries of the DVS are discussed. The causes, clinical manifestations, and imaging findings in cerebral sinovenous thrombosis are described, and pertinent imaging techniques and pitfalls are illustrated. Etiologic theories about the formation of dural arteriovenous malformations are discussed and their imaging features are demonstrated.

Nonneoplastic intracranial cysts and cystic lesions.

This article reviews the gamut of cystic lesions, unrelated to neoplastic disease, that are found in the brain, subarachnoid space, and ventricles. The utility of MRI in diagnosing these entities is shown.

Normal and variant anatomy of the dural venous sinuses.

The normal and variant anatomy of the cerebral veins and dural venous sinuses is poorly understood by many radiologists. Beginning with a discussion of cerebral venous anatomy, this review illustrates clinically pertinent anatomy of the cerebral sinovenous system. Various methods of imaging cerebral veins and dural venous sinuses are described. Techniques and pitfalls of MR venography are emphasized.

Imaging of vascular lesions of the head and neck.

The imaging armamentarium for imaging head and neck vascular lesions and the imaging features of each have been reviewed. Imaging is an indispensable part of the diagnosis and treatment planning of these lesions. The architecture and vascularity of these lesions are keys to their correct diagnosis. High-flow lesions (AVMs and hemangiomas) can be distinguished readily from low-flow lesions (venous malformations and lymphatic malformations) with these techniques, without the need for conventional angiography in the majority of cases. More-over, the architecture of the lesions depicted on imaging studies can lead to a reasonably specific diagnosis. MR imaging is the best tool for this assessment, but complementary information from ultrasound or CT can help arrive at the correct diagnosis when the results of MR imaging are equivocal. Ultrasound can correctly characterize the lesion as high flow or low flow but is limited in its ability to determine the full extent of the lesion. The usefulness of CT is more limited. Application of newer CT techniques (multidetector helical CT with image reconstruction) may increase the role of CT in high-flow lesions, but the greater soft tissue contrast sensitivity of MR imaging remains its strong suit. Conventional angiography is usually reserved for pretherapeutic evaluation.

Cervical spinal cord compression and the Hoffmann sign.

Little information exists about the ability of the Hoffmann sign to predict cervical spinal cord compression. The objective of this study was to determine the correlation between the Hoffmann sign and cervical spinal cord compression in a consecutive series of patients seen by a single spine surgeon. All new patients with complaints related to their cervical spine were included. Hoffmann sign was elicited by flicking the nail of the middle finger. Any flexion of the ipsilateral thumb and/or index finger was considered positive. All imaging studies were reviewed for spinal cord compression. Cord compression was defined as flattening of the AP diameter of the spinal cord coexisting with obliteration of CSF around the cord compared to normal levels. Of 165 patients, 124 patients had imaging of their spinal canal. Review by the spine surgeon found sensitivity of the Hoffmann sign relative to cord compression was 58%, specificity 78%, positive predictive value 62%, negative predictive value 75%. 49 studies were also read by a "blinded" neuroradiologist, the sensitivity was 33%, specificity 59%, positive predictive value, 26%, negative predictive value 67%. Although attractive as a simple method of screening for cervical spinal cord compression, the Hoffmann sign, in the absence of other clinical findings, is not in our experience a reliable test.

Endoscopic resection of intracranial dermoid cysts.

INTRODUCTION: Nasal dermoid cysts are congenital lesions which are often diagnosed in infancy or childhood. However, a small number present in adulthood, and some extend intracranially. Traditional treatment for the intracranial portion of these cysts includes frontal craniotomy. CASE REPORTS: Two intracranial dermoid cysts were resected via a transnasal endoscopic approach, using 70° nasal endoscopy for complete visualisation and intracranial tumour removal. We describe our technique for the procedure itself and for reconstruction of the skull base defect. DISCUSSION AND CONCLUSION: The endoscopic transnasal skull base approach is an excellent alternative to a traditional frontal craniotomy, to achieve complete resection of intracranial dermoid cysts.

A compartment-based approach for the imaging evaluation of tinnitus.

Tinnitus affects 10% of the US general population and is a common indication for imaging studies. We describe a sequential compartment-based diagnostic approach, which simplifies the interpretation of imaging studies in patients with tinnitus. The choice of the initial imaging technique depends on the type of tinnitus, associated symptoms, and examination findings. Familiarity with the pathophysiologic mechanisms of tinnitus and the imaging findings is a prerequisite for a tailored diagnostic approach by the radiologist.

Diffusion tensor imaging in hypertrophic olivary degeneration.

SUMMARY: We report DTI and fiber tractography findings in a case of hypertrophic olivary degeneration. A 51-year-old man presented with an abnormal gait and visual difficulties. MR imaging showed enlargement of the right medullary olive and a vascular lesion in the right pontine tegmentum. Fiber tractography showed decreased volume of the right central tegmental tract, supporting a diagnosis of HOD.