Focal atrophy of the multifidus muscle in lumbosacral radiculopathy.

A patient with compelling clinical and electrodiagnostic evidence of a right L5 radiculopathy had focal atrophy of the multifidus at the appropriate level, which served to confirm the radicular nature of the process. The multifidus muscles are innervated by a single root, in contrast to the polysegmental innervation of the rest of the paraspinal muscle mass. Imaging studies may complement needle electromyography in the evaluation of this important structure.

Anatomy of the cranial nerves.

The anatomy of cranial nerves I and III through XII are presented. Each nerve is diagrammatically illustrated from its nuclear or its sensory origin and correlated with magnetic resonance and computed tomography images. The important identifying anatomical landmarks are demonstrated along the course of each nerve. Peripheral motor and sensory components are also discussed.

Cranial nerves III, IV, and VI.

Movements of the eye are produced by six extraocular muscles innervated by three cranial nerves: the oculomotor (III), the trochlear (IV), and the abducens (VI). These cranial nerves are discussed together because of the interrelated nuclear origins, neural pathways, and motor functions. The normal anatomic pathway of these three nerves is presented. The clinical and pathologic manifestations of lesions producing both isolated and complex palsies of these nerves are discussed along with imaging correlation.

Pulsatile tinnitus associated with congenital central nervous system malformations.

Pulsatile tinnitus as a manifestation of congenital central nervous system malformations has not been previously described. We present two patients with type I Arnold-Chiari malformation and one patient with congenital stenosis of the sylvian aqueduct with pulsatile tinnitus. Pulsatile tinnitus in these patients is believed to be secondary to increased intracranial pressure. Tinnitus subsided in one patient with Arnold-Chiari malformation after suboccipital decompression. The other two patients declined surgery. Audiologic and radiologic findings are presented, and our diagnostic algorithm for pulsatile tinnitus is described. The pathophysiology of pulsatile tinnitus can be a manifesting symptom in some patients with congenital central nervous system malformations.

Oral cavity: anatomy and pathology.

The oral cavity and oropharynx comprise the upper portion of the aerodigestive tract. These two regions are distinguished from each other because pathologic processes differ in their presentations, prognoses, and histologic grades. The normal anatomy of the oral cavity, vestibule, and oral cavity proper is discussed and is followed by a discussion of the sublingual and submandibular spaces. The diversity of pathologic processes that occur in these regions is then presented as well as the more common pitfalls.

Acquired intracranial herniations: MR imaging findings.

Many of the pathologic processes that increase intracerebral mass may eventually cause brain herniation. It is important to recognize brain herniation, as it can often produce the presenting clinical signs and symptoms and is often the cause of serious neurologic sequelae or death.

Brain imaging in AIDS.

Although central nervous system (CNS) involvement is common in the population with acquired immunodeficiency syndrome, the presenting neurologic signs and symptoms are often vague and nonfocal. This represents a significant diagnostic challenge for the primary care physician. Cross-sectional imaging now plays an important role in the diagnosis of pathologic processes involving the brain in HIV-infected patients. Involvement of the brain with atypical viruses, parasites, fungi, and neoplasms is more prevalent in AIDS patients. On identification of a brain lesion, it is the role of the imager to characterize it in an attempt to provide a limited differential diagnosis. We review the imaging findings of the pathogens that most commonly affect the brain in AIDS patients.

Bilateral orbital granulocytic sarcoma (chloroma) preceding the blast phase of acute myelogenous leukemia: CT findings.

Granulocytic sarcoma (chloroma) is an uncommon malignant neoplasm associated with myelogenous leukemias. Its appearance may precede the clinical manifestations of the acute leukemic phase by months to years. We report the CT findings of a case of bilateral intraorbital granulocytic sarcoma which preceded the blast phase of acute myelogenous leukemia (AML) and led to its diagnosis. An awareness of granulocytic sarcoma and its CT appearance may expedite the diagnosis of AML or prompt close monitoring of those cases of granulocytic sarcoma antedating the appearance of AML.

Radiology of maxillofacial trauma.

There has been a rising incidence of maxillofacial injuries during the past decade as a result of an increasing number of assaults and motor vehicle accidents. The maxillofacial region is one of the most complex areas of the human body, and the radiographic imaging of this region becomes even more difficult in traumatized patients because of their clinical condition and their inability to cooperate. Imaging modalities used in the evaluation of the traumatized maxillofacial region include conventional (plain) films, tomography, panoramic radiography, computed tomography, three-dimensional computed tomography, DentaScan, and magnetic resonance imaging. Each modality is discussed with regard to technique, advantages, and disadvantages. Plain films and computed tomography, the modalities that are used most in evaluating maxillofacial structures, are discussed in more detail. The normal anatomy and radiologic features are presented for both of these modalities. Radiographic evaluation of maxillofacial injury begins with a knowledge of the direct and indirect radiographic signs of injury seen on most imaging modalities. Computed tomography also has allowed a method of classifying facial fractures that is based on the involvement of the facial buttresses or struts. Three horizontal, two coronal, and five sagittal oriented struts are described. Limited fractures are differentiated from transfacial fractures by the lack of involvement of the pterygoid plates in the limited fractures. Limited fractures also can be subclassified as solitary (fracture of a single strut) or complex (fractures of multiple struts). A portion of the orbit is involved in almost every form of facial fracture; therefore, evaluation of facial injuries should always include the orbital structures. Although both can occur simultaneously, orbital injuries can be divided into soft tissue and bony vault injuries. Similar to midface fractures, orbital fractures also can be classified as solitary (fracture involves a single wall) or complex (fracture involves more than one wall or a part of a midface fracture). Computed tomography is of great value in evaluating both forms of injury. Magnetic resonance imaging is becoming increasingly important in the evaluation of orbital soft tissue injuries. Classification of midface injuries includes the solitary strut fractures and the complex strut fractures. Solitary strut fractures include fractures of the nasal arch, zygomatic arch, and isolated sinus wall fractures. Complex strut fractures include the nasal complex fractures, zygomatic (tripod) and zygomaticomaxillary fractures, transfacial fractures (LeFort fractures), and facial smash fractures. Each fracture type and its radiographic appearance are discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Imaging the sphenoid bone and basiocciput: anatomic considerations.

The sphenoid bone is a complex structure with an intricate embryologic origin. It is centrally located within the skull base and articulates with almost every structure in the skull and face. The sphenoid bone contains multiple foramina and fissures accommodating numerous vessels and nerves. This report reviews the embryology of the sphenoid bone and its normal postnatal changes, and describes the normal anatomy of the sphenoid bone and its numerous foramina and fissures. Computed tomography (CT) and magnetic resonance (MR) are used to illustrate developmental changes and normal anatomy.

Imaging the sphenoid bone and basiocciput: pathological considerations.

Many diverse pathologic processes can involve the sphenoid bone because of its complex embryologic origin. In addition to primary neoplasia, the central location of the sphenoid predisposes it to involvement by many intracranial and extracranial lesions. The presence of multiple foramina and fissures offer "paths of least resistance" that allow the spread of pathology across the skull base. Sphenoid sinus disease also accounts for a number of pathologic entities occurring in this vicinity. This article reviews the more common lesions affecting the sphenoid bone as well as their CT and MR appearance.

The ostiomeatal unit and endoscopic surgery: anatomy, variations, and imaging findings in inflammatory diseases.

Recent and ongoing advances made in endoscopic surgical techniques require the radiologist to understand the anatomy and pathophysiology of the paranasal sinuses and nasal passage. Endoscopy and CT are complementary procedures, and, as such, the normal anatomic relationships and their CT appearances need to be well understood in order for radiologists to offer continued support as consultants to their clinical colleagues. In this article, we review the pertinent anatomy of the lateral nasal wall and paranasal sinuses, discuss the most frequently encountered normal variations that may predispose a patient to inflammatory sinus disease, outline imaging protocols for evaluation of this region, and introduce the reader to current endoscopic surgical techniques. Last, the imaging findings in various inflammatory processes involving the sinuses, as well as the local and regional complications associated with paranasal sinus inflammatory diseases, are presented.

Tumoral thrombosis of cerebral venous sinuses: preoperative diagnosis using magnetic resonance phase imaging.

Intracranial, dural-based neoplasms will not infrequently invade adjacent venous sinuses. Therefore, the preoperative diagnosis of venous invasion is important, as it will alter the surgical approach to the lesion. Magnetic resonance imaging is a noninvasive means of visualizing the cerebral venous sinuses. The preoperative diagnosis of venous thrombosis can, however, be difficult and confusing with conventional spin-echo magnetic resonance imaging because of variable appearances produced by blood clot degradation products as well as flowing blood. Phase magnetic resonance imaging is a simple method that can be acquired simultaneously with conventional spin-echo sequences, and is based primarily on whether protons are stationary or moving. In the context of venous sinus occlusion, phase imaging can demonstrate the presence or absence of blood flow more easily than spin-echo imaging. Three cases of dural-based neoplasms are presented that demonstrate the utility of phase imaging in diagnosing tumoral occlusion of the venous sinuses.

Intracranial vascular abnormalities: value of MR phase imaging to distinguish thrombus from flowing blood.

The interpretation of conventional spin-echo and gradient-echo MR images of intracranial vascular lesions can be complex and ambiguous owing to variable effects on image intensity caused by flowing blood or thrombus. MR phase images, obtained simultaneously with conventional-magnitude images, are useful for evaluating proton motion (i.e., blood flow), and therefore can simplify the diagnosis of the presence or absence of thrombosis within a vascular structure or lesion. Fourteen patients with a variety of intracranial vascular abnormalities (aneurysms, superior sagittal sinus thrombosis, neoplasms adjacent to venous sinuses, and vascular malformations) were evaluated with conventional MR and phase imaging for the presence of blood flow. The phase images correlated with angiography in all cases. Phase imaging was not necessarily better than conventional spin-echo imaging in all cases, but it simplified the evaluation of thrombus vs blood flow in many. In three of five aneurysms, the phase images were diagnostic for evaluating lumen patency whereas the conventional images were ambiguous. Phase imaging was advantageous for detecting tumor invasion of the venous sinus when venous blood was enhanced by gadopentetate dimeglumine. A laminar flow phantom experiment determined the lower limits of sensitivity of phase imaging to be 0.5 cm/sec in the slice-select and 2.5 cm/sec in the read gradient directions. Phase imaging is a simple, reliable technique that can distinguish thrombosis from flowing blood within intracranial lesions. It is easily performed and adds no additional time to the MR examination.

Brain lesions in chronic granulomatous disease.

In chronic granulomatous disease (CGD) enzyme-deficient neutrophils and mononuclear cells lack the respiratory burst required for biocidal activity. Recurrent infections lead to granulomas in various organs but brain lesions are rare. In the present case, a 23-year-old male with numerous infections since early childhood died of overwhelming pulmonary aspergillosis. He first began to experience neurological deficits at the age of 17. Computerized tomography and magnetic resonance imaging revealed fleeting white matter lesions that were interpreted as multiple sclerosis (MS). At post mortem, three types of brain lesions were found: (1) Pigmented macrophages in perivascular spaces and the leptomeninges similar to those reported previously. They contained fine, golden-brown, lipofuscin-like material whose chemical composition included a sulfur peak by X-ray analysis. (2) Focal, well-demarcated, "burnt out" white matter lesions with loss of both myelin and axons and intense sclerosis. (3) Diffuse areas of mild pallor in the centrum ovale which spared the U fibers. The pigmented macrophages are characteristic of those seen in the periphery in CGD. The origin of the discrete, destructive white matter lesions is unclear. They may have resulted from: (i) earlier activity by CGD macrophages; (ii) previous infections due to sepsis or embolism; or (iii) possibly post-infectious encephalomyelitis. The more diffuse, mild, white matter lesions are attributed to edema. Evidence for MS, progressive multifocal leukoencephalopathy, or human immunodeficiency virus encephalitis was lacking. This case is presented to alert us to look more carefully for brain lesions in CGD, characterize them and to help determine their cause.

CT and MR imaging of the central skull base. Part 2. Pathologic spectrum.

The radiologist must have a thorough knowledge of the normal anatomy and the pathologic spectrum of the skull base to determine the extent of abnormality and to help plan the surgical approach. The authors describe and present examples of congenital, benign, and malignant lesions that affect this region, including cephalocele, fracture, fistula, juvenile angiofibroma, meningioma, chordoma, pituitary adenoma, chondrosarcoma, nasopharyngeal carcinoma, and rhabdomyosarcoma. Metastatic, infectious, and other miscellaneous processes are also discussed. Imaging strategies with computed tomography and magnetic resonance imaging to aid in the diagnosis are suggested.

CT and MR imaging of the central skull base. Part 1: Techniques, embryologic development, and anatomy.

Recent advances in surgical techniques have enabled surgeons to approach previously inoperable deep-seated lesions of the skull base. The radiologist requires a thorough knowledge of the normal anatomy and the pathologic spectrum of this region and an understanding of imaging modalities in order to determine the extent of pathologic conditions and help plan the surgical approach. The embryologic development of the central skull base, normal gross anatomy, and anatomy as seen on computed tomographic and magnetic resonance images are presented.

Intrasellar primitive neuroectodermal tumor (PNET) in familial retinoblastoma: a variant of "trilateral retinoblastoma".

An infant with bilateral familial retinoblastomas was found at age 6 months to have a large mass within the region of the sella turcica. The histology, immunoreactivity and ultrastructure of the tumor showed primitive neuroectodermal cells. A small number of cells showed positive immunostaining to retinal S antigen. This represents a rare form of so-called trilateral retinoblastoma. In most cases of trilateral retinoblastoma, the intracranial non-metastatic tumor is within the pineal gland. The occurrence of such a tumor in the region of sella turcica is very unusual and its possible significance is discussed in regard to our current understanding of the susceptibility to carcinogenesis conferred by inheritance of the mutant retinoblastoma gene, Rb-1.

Perineural tumor extension through the foramen ovale: evaluation with MR imaging.

Perineural tumor extension is a form of metastatic disease in which primary tumors spread along neural pathways and gain access to non-contiguous regions. The treatment and prognosis are altered when perineural extension occurs. Awareness and proper evaluation are critical for the radiologist. The third (mandibular) division of the trigeminal nerve (V3), passing through the skull base via the foramen ovale, is a common route of perineural spread of head and neck lesions. Seven patients with perineural tumor involvement of the mandibular nerve were evaluated with magnetic resonance imaging with use of standard spin-echo pulse sequences emphasizing T1-weighted information. Three patients had adenoid cystic carcinoma, three had squamous cell carcinoma, and one had well-differentiated lymphocytic lymphoma of the orbit. MR imaging signs of perineural involvement included smooth thickening of V3, concentric expansion of the foramen ovale, replacement of the normal trigeminal cistern hypointensity by an isointense mass, lateral bulging of cavernous sinus dural membranes, and atrophy of masticator muscles.