Petrous apex cholesterol granuloma: pictorial review of radiological considerations in diagnosis and surgical histopathology.

BACKGROUND: Petrous apex cholesterol granulomas are expansile, cystic lesions containing cholesterol crystals surrounded by foreign body giant cells, fibrous tissue reaction and chronic inflammation. Appropriate treatment relies on an accurate radiological diagnosis and an understanding of the distinguishing radiological features of relevant entities in the differential diagnosis of this condition. METHODS: Firstly, this paper presents a pictorial review of the relevant radiological features of petrous apex cholesterol granuloma, and highlights unique features relevant to the differential diagnosis. Secondly, it reviews the histopathological and radiological findings associated with surgical drainage of these lesions. RESULTS: Radiological features relevant to the differential diagnosis of petrous apex cholesterol granuloma are reviewed, together with radiological and histopathological features relevant to surgical management. Following surgical management, histopathological and radiological evidence demonstrates that the patency of the surgical drainage pathway is maintained. CONCLUSION: Accurate diagnosis of petrous apex cholesterol granuloma is essential in order to instigate appropriate treatment. Placement of a stent in the drainage pathway may help to maintain patency and decrease the likelihood of symptomatic recurrence.

Perfusion and permeability MR imaging of gliomas.

Conventional contrast-enhanced MR imaging is the current standard technique for the diagnosis and treatment evaluation of gliomas and other brain neoplasms. However, this method is quite limited in its ability to characterize the complex biology of gliomas and so there is a need to develop more quantitative imaging methods. Perfusion and permeability MR imaging are two such techniques that have shown promise in this regard. This review will highlight the underlying principles, applications, and pitfalls of these evolving advanced MRI methods.

The trigeminal nerve.

The trigeminal nerve is the largest of the cranial nerves, serving as a major conduit for sensory information from the head and neck and primarily providing motor innervation to the muscles of mastication. An understanding of the pathologic processes that may involve this nerve requires a detailed knowledge of its origin within the brain stem as well as its course intracranially. This article describes the neuroanatomy of the nerve and divides it into its various segments to provide a differential diagnosis of common and some uncommon pathologic processes.

Computed tomographic characteristics of chronic subdural hematomas.

Although medical history and physical examination should lead to diagnosis of chronic subdural hematomas, 40% of these patients are likely to be misdiagnosed because many of these symptoms occur in other disease processes, such as transient ischemic attacks, stroke, dementia, and tumors. Computed tomography remains one of the most useful tools in the evaluation of these patients because of its rapidity, cost, availability, and pathologic sensitivity.

Imaging of neurocysticercosis.

Neurocysticercosis produces a variety of neurologic syndromes resulting from the cysticerci infestation of the central nervous system by the larvae of Taenia solium. Because of increased immigration to the United States from endemic areas, the incidence of neurocysticercosis has increased, especially in California, Texas, Arizona, and other southwestern states. Neuroimaging studies play a significant role in the diagnosis and management of patients with neurocysticercosis.

Fungal infections of the central nervous system.

The diagnosis and treatment of central nervous system fungal infections typically pose problems for the clinician. With an increased incidence of fungal infections in immunocompromised patients, neuroradiologic imaging has become essential in determining complications and outcomes. This article provides a summary of the more common organisms encountered in fungal infections of the central nervous system and the imaging features primarily seen with CT and MR imaging.

Intracerebral Whipple's disease diagnosed by stereotactic biopsy: a case report and review of the literature.

OBJECTIVE AND IMPORTANCE: This case demonstrates the rare occurrence of intracerebral Whipple's disease in a patient lacking classic systemic manifestations of the disease. Because of the nonspecific presentation and the typically deep-seated location of cerebral lesions in these patients, definitive diagnosis is frequently problematic. We present the first reported use of stereotaxy-guided brain biopsy to confirm the diagnosis of isolated intracranial Whipple's disease. CLINICAL PRESENTATION: The patient was a 36-year-old man who presented with a 4-month history of progressive lethargy, hypersomnia, behavioral changes, and weight gain. The results of the physical examination were remarkable only for findings of hypogonadism. Subsequent laboratory evaluation confirmed the diagnosis of hypogonadotrophic hypogonadism, with low levels of testosterone, luteinizing hormone, cortisol, and prolactin. INTERVENTION: A magnetic resonance image of the brain demonstrated hyperintense lesions on T2-weighted images in the regions of the right fornix, hypothalamus, and putamen that subsequently enhanced with intravenously administered contrast medium. A biopsy was then obtained from the right putaminal lesion under stereotactic guidance. Histopathological analysis of the tissue revealed findings consistent with intracerebral Whipple's disease that were subsequently confirmed using electron microscopy. CONCLUSION: Intracerebral Whipple's disease should be included in the differential diagnosis of patients presenting with progressive dementia and cognitive decline. In these patients, lesions have typically been observed in the hypothalamus, cingulate gyrus, basal ganglia, insular cortex, and cerebellum. As evidenced by our case, stereotaxy affords clinicians the attractive option of a minimally invasive technique by which to obtain tissue from such deep-seated areas. A review of this rare neurosurgical entity is presented.

CT of head trauma.

The advent of CT in the early 1970s revolutionized the diagnosis and management of head trauma patients. CT remains to be the imaging modality of choice in the evaluation of patients with acute head trauma. High resolution CT is excellent for evaluating facial and skull fractures. Neurosurgically significant lesions such as epidural hematomas, subdural hematomas, or depressed skull fractures are already detected by CT. The early detection of extra-axial hematomas made possible by the increased availability of CT, results in early surgical interventions with marked improvement in morbidity and mortality in head trauma patients.

Unique CT imaging advantages. Hemorrhage and calcification.

Computed tomography remains the imaging modality of choice in the detection of two processes: acute intracranial hemorrhage and calcification; however, in the subacute and chronic stages of hemorrhage, MR imaging is more sensitive in aging and staging hemorrhage. FLAIR imaging increases the sensitivity of MR imaging in the detection of subarachnoid hemorrhage. The signal characteristics of calcification on MR imaging is variable, especially on T1-weighted images decreasing its detectability. CT is superior to MR imaging in the detection of calcification. A number of factors including slice thickness, as well as window width and level may affect the detectability of calcification on CT.