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The neuroimaging of hydrocephalus from the perspective of the pediatric neurosurgeon is discussed. Processes with new developments in therapy and imaging are described, including congenital causes of hydrocephalus, unilateral hydrocephalus, trapped fourth ventricle, and benign external hydrocephalus.
A curvature abnormality may be the initial or major presenting feature in a child with disease of the spinal column or spinal neuraxis. A simplified classification of common spinal curvature abnormalities of childhood include idiopathic, congenital/dysraphic, skeletal dysplasia, neurofibromatosis, and painful. The great majority of childhood scoliosis falls into the idiopathic category. Atypical clinical or radiographic features in a presumed idiopathic scoliosis may indicate an otherwise occult tumor or hydrosyringomyelia, or may be a consequence of increasing curvature with disk protrusion, nerve impingement, or cord attenuation. Neuroimaging beyond plain films is commonly necessary for atypical idiopathic scoliosis and for the other categories of scoliosis listed.
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OBJECTIVE: To examine published imaging criteria that separate cranial computed tomographic (CT) scans into grades of increasing support for a diagnosis of vascular dementia (VaD). DESIGN: Patients were divided into 4 grades of increasing extent of vascular lesions on CT. The frequency of VaD was compared between these grades. SETTING: A university department of neurology. PATIENTS: Forty-two consecutive patients who underwent neuropsychological assessment for possible dementia and who had a CT scan performed within 6 months following any stroke causing dementia. Patients with delirium, severe aphasia, and motor and/or sensory deficits that impaired neuropsychological testing and patients with mass lesions or nonvascular white matter disease shown on CT were excluded. MAIN OUTCOME MEASURE: The National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria for probable VaD. RESULTS: The frequency of VaD was greater in patients with grade 1 (7 [50%] of 14, P = .01), grade 2 (2[50%] of 4, P = .2), and grade 3(7[78%] of 9, P = .002) scans than the frequency of VaD with grade O scans (1[7%] of 15). There was a linear association of the frequencies of VaD between imaging grades (P = .0008). In a subgroup of patients with neuropsychological deficits caused by cerebrovascular disease, there was a linear association of the severity of the deficits between imaging grades (P = .007). CONCLUSIONS: We conclude that our criteria can separate CTs into increasing levels of support for a diagnosis of VaD. The extent of vascular lesions on CT reflects the severity of associated neuropsychological deficts.
BACKGROUND: Rabies encephalitis is a feared, virtually uniformly fatal form of central nervous system infection. The incidence of rabies encephalitis in the United States is almost certainly underestimated because of the predominance of bat-borne rabies, which can be spread without traumatic exposure. Because of its rarity in developed countries, rabies encephalitis has been seldom studied with modern imaging techniques. SETTING: University-based teaching hospital. PATIENT: A case of pathologically confirmed rabies encephalitis is presented. Diagnosis of rabies was made by seroconversion testing while the patient was alive and was confirmed postmortem by the presence of rabies antigens and Negri bodies in the brain. The patient had 2 magnetic resonance studies done that showed dramatic abnormalities in the medulla and pons that correlated with features of the neurologic examination and hypothalamic-pituitary abnormalities. RESULT: The patient had a fulminant encephalitic course that ended in death. CONCLUSION: Rabies is an uncommon cause of fatal encephalitis. Anatomic imaging studies such as computed tomographic and magnetic resonance scans have generally been negative in confirmed cases of rabies. We report a case of confirmed rabies with extensive brainstem and hypothalamic-pituitary abnormalities on magnetic resonance imaging. Although these findings are nonspecific, they should raise the clinical suspicion of rabies in the setting of aggressive encephalitis of unclear cause, and appropriate diagnostic tests should be performed.
OBJECTIVE: To demonstrate spontaneous regression of large, clinically symptomatic optic pathway gliomas in patients with and without neurofibromatosis type 1 (NF-1). METHODS: Patient cases were collected through surveys at 2 consecutive annual meetings of the North American Neuro-Ophthalmology Society (NANOS) and through requests on the NANOSNET Internet listserv. Serial documentation of tumor signal and size, using magnetic resonance imaging in 11 patients and computed tomography in 2 patients, was used to evaluate clinically symptomatic optic pathway gliomas. All tumors met radiologic criteria for the diagnosis of glioma and 4 patients had biopsy confirmation of their tumors. In 3 patients, some attempt at therapy had been made many years before regression occurred. In one of these, radiation treatment had been given 19 years before tumor regression, while in another, chemotherapy had been administered 5 years before signal changes in the tumor. In the third patient, minimal surgical debulking was performed 1 year before the tumor began to shrink. RESULTS: Spontaneous tumor shrinkage was noted in 12 patients. Eight patients did not have NF-1. In an additional patient without NF-1, a signal change within the tumor without associated shrinkage was detected. Tumor regression was associated with improvement in visual function in 10 of 13 patients, stability of function in 1, and deterioration in 2. CONCLUSIONS: Large, clinically symptomatic optic gliomas may undergo spontaneous regression. Regression was seen in patients with and without NF-1. Regression may manifest either as an overall shrinkage in tumor size, or as a signal change on magnetic resonance imaging. A variable degree of improvement in visual function may accompany regression. The possibility of spontaneous regression of an optic glioma should be considered in the planning of treatment of patients with these tumors.
Five children between ages 3 and 17 years developed slowly progressive oculomotor nerve palsies. No cause was found on initial clinical or neuroradiologic investigations. Subsequent computed tomography or 1.5-T magnetic resonance imaging revealed a mass along the course of the involved oculomotor nerve in three of the five cases. The clinical and radiologic characteristics of these tumors are consistent with the diagnosis of schwannoma or, less likely, meningioma. Children with acquired oculomotor nerve palsies of initially unknown etiology should undergo imaging every two years with the expectation of eventually detecting a small tumor somewhere along the course of the oculomotor nerve.
The mechanisms by which optic nerve-sheath fenestration is effective remain speculative. Possibilities include surgical production of a cerebrospinal fluid filtration outlet or scarring in the subarachnoid space around the nerve in the vicinity of the fenestration site, with shifting of the pressure gradient from the nerve head to the retrobulbar portion. Two patients who underwent successful optic nerve-sheath fenestration developed a cystlike structure contiguous to the fenestration site, apparently in direct communication with the optic nerve sheaths. This was shown on magnetic resonance imaging (one patient) and orbital echography (both patients). These previously unreported observations may support the hypothesis that fenestration works by creating a filtration apparatus that controls the intravaginal pressure in the subarachnoid space surrounding the orbital segment of the optic nerve.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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A fundamental problem in the study of learning is that learning-related changes may be confounded by nonspecific time effects. There are several strategies for handling this problem. This problem may be of greater significance in functional magnetic resonance imaging (fMRI) compared to positron emission tomography (PET). Using the general linear model, we describe, compare, and discuss two approaches for separating learning-related from nonspecific time effects. The first approach makes assumptions on the general behavior of nonspecific effects and explicitly models these effects, i.e., nonspecific time effects are incorporated as a linear or nonlinear confounding covariate in the statistical model. The second strategy makes no a priori assumption concerning the form of nonspecific time effects, but implicitly controls for nonspecific effects using an interaction approach, i.e., learning effects are assessed with an interaction contrast. The two approaches depend on specific assumptions and have specific limitations. With certain experimental designs, both approaches may be used and the results compared, lending particular support to effects that are independent of the method used. A third and perhaps better approach that sometimes may be practically unfeasible is to use a completely temporally balanced experimental design. The choice of approach may be of particular importance when learning-related effects are studied with fMRI.