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251 Combined Unilateral Conjugate Gaze Palsy and Internuclear OphthalmoplegiaDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineCombined lesions of the abducens nucleus or PPRF and adjacent MLF on one side of the brain stem cause an ipsilateral horizontal gaze palsy and INO, so that the only preserved horizontal eye movement is abduction of the contralateral eye; hence the name one-and-a-half syndrome.
252 Sites and Manifestations of LesionsDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineDisturbances of vertical eye movements from midbrain lesions are usually caused by damage to one or more of three main structures: the posterior commissure, the rostral interstitial nucleus of the medial longitudinal fasciculus, or the INC.
253 Wallenberg's SyndromeDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineLesions of the vestibular nuclei commonly affect neighboring structures, in particular the cerebellar peduncles and perihypoglossal nuclei.
254 Saccadic Oscillations from Pontine LesionsDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineSaccadic oscillations that lack an intersaccadic interval, such as opsoclonus and ocular flutter, probably result from pontine lesions in the pause cell region
255 Eye Movements in Stupor and ComaDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineThe ocular motor examination is especially useful for evaluating the unconscious patient, because both arousal and eye movements are controlled by neurons in the brain stem reticular formation.
256 Walsh & Hoyt: SizeSteven A. Newman, M.D., University of Virginia School of MedicineSaccular intracranial aneurysms vary in size from less than 2 mm to more than 60 mm in diameter; the size tends to increase with the age of the patient. This finding is consistent with serial angiographic studies that show progressive enlargement of aneurysms during intervals ranging from 2 weeks to...
257 Walsh & Hoyt: Multiple AneurysmsSteven A. Newman, M.D., University of Virginia School of MedicineThe majority of intracranial aneurysms are solitary lesions. At least 15% of patients with one aneurysm harbor one or more aneurysms at another site. Numerous angiographic and autopsy studies have documented the occurrence of multiple aneurysms in both adults and children. The reported prevalence of...
258 Walsh & Hoyt: Location and LateralitySteven A. Newman, M.D., University of Virginia School of MedicineAneurysms may originate from any of the intracranial arteries. Although there is some discrepancy not only between clinical (angiographic) and autopsy studies but also among individual clinical or autopsy studies, it is clear that about 85% of all intracranial aneurysms originate from the ICA or one...
259 Walsh & Hoyt: Sex and Age DistributionSteven A. Newman, M.D., University of Virginia School of MedicineOverall, saccular intracranial aneurysms occur slightly more often in women than in men, in a ratio of about 1.3 to 1. However, aneurysms are more common in males during the first 4 decades of life (70% under age 15). After the 5th decade women are affected more frequently than men, and this female ...
260 Walsh & Hoyt: Manifestations of Ruptured Saccular AneurysmsSteven A. Newman, M.D., University of Virginia School of MedicineFew events in human disease can be so sudden and potentially catastrophic as the spontaneous rupture ofa major intracranial artery. Depending on the size and nature of the mural defect, the escaping blood may dissect within the vessel wall, ooze slowly around the site, or gush forth under high press...
261 Ehlers-Danlos Syndrome, Marafan's Syndrome, and Pseudoxanthoma ElasticumSteven A. Newman, M.D., University of Virginia School of MedicineEhlers-Danlos syndrome encompasses a group of inherited disorders of connective tissue, all of which have abnormalities of collagen composition.
262 Walsh & Hoyt: Treatment and ResultsSteven A. Newman, M.D., University of Virginia School of MedicineThe treatment of a patient with an intracranial saccular aneurysm depends on a number of factors, including the age and general condition of the patient, the size, shape, and location of the aneurysm, and whether or not the aneurysm has ruptured. A patient who has experienced SAH, intracerebral hemo...
263 Walsh & Hoyt: Associated Risk FactorsSteven A. Newman, M.D., University of Virginia School of MedicineProgressive aneurysm growth and the potential for rupture may be influenced by a number of systemic conditions. Aneurysm appearance on angiography does not predict the potential for growth. Some associations may serve as useful diagnostic markers and may influence management ofspecif ic patients. Hy...
264 Walsh & Hoyt: Natural HistorySteven A. Newman, M.D., University of Virginia School of MedicineIn order to determine the appropriate treatment for a patient with an unruptured symptomatic or asymptomatic aneurysm, one must know the risk ofrupture of the aneurysm as well as the morbidity and mortality of such an initial rupture. Similarly, treatment ofa patient with a ruptured, intracranial, s...
265 Walsh & Hoyt: Fusiform Aneurysms: General ConsiderationsSteven A. Newman, M.D., University of Virginia School of MedicineLarge arteries of the carotid and vertebrobasilar systems may occasionally become enlarged and tortuous. This process is called by a variety ofnames, the most common of which are dolichoectasia (from the Greek words dolichos, meaning ""elongation,"" and ectasia, meaning ""distension""), ectasia, and...
266 Walsh & Hoyt: DefinitionsSteven A. Newman, M.D., University of Virginia School of MedicineAneurysms are persistent, localized dilations of the wall of a vessel. They may be classified by shape as either saccular or nonsaccular. Saccular aneurysms are pouchlike dilations that usually affect only a portion of the vessel wall. Initially called ""miliary aneurysms"" by Virchow and Charcot, t...
267 Walsh & Hoyt: Traumatic AneurysmsSteven A. Newman, M.D., University of Virginia School of MedicineTrauma may lead to development of a ""false aneurysm"" from disruption of an entire vascular wall. Occasionally, the appearance and the course may resemble that ofother saccular aneurysms. The histology of the aneurysm depends on the extent of the initial disruption of the wall. Unlike other aneurys...
268 Walsh & Hoyt: Connective Tissue DiseasesSteven A. Newman, M.D., University of Virginia School of MedicineIf weakness of the wall of the artery underlies development of an aneurysm, aneurysms should develop with higher frequency in patients with diseases that affect collagen. Indeed, some connective tissue diseases, particularly fibromuscular dysplasia (FMD), Ehlers-Danlos syndrome, Marfans syndrome, an...
269 Walsh & Hoyt: Saccular Aneurysms: DiagnosisSteven A. Newman, M.D., University of Virginia School of MedicineThe diagnosis of aneurysmal SAH should be suspected in any patient with the acute onset ofheadache, change in mentation or a stiff neck. Lumbar puncture once was the mainstay of diagnosis in such patients, but it has been replaced to some extent by CT scanning or MR imaging for several reasons. With...
270 Walsh & Hoyt: HistorySteven A. Newman, M.D., University of Virginia School of MedicineThe first description of aneurysmal dilation of the cerebral vessels dates to the mid-18th century. In 1907, C. F. Beadles delivered a lecture entitled ""Aneurisms of the Larger Cerebral Arteries"" to the Royal College of Surgeons of England, based on a review of 555 cases. He included two cases ofl...
271 Walsh & Hoyt: Neoplastic AneurysmsSteven A. Newman, M.D., University of Virginia School of MedicineCancerous erosion of an arterial wall can cause formation of an aneurysm. Intracranial neoplastic aneurysms are most often caused by hematogenous emboli from cardiac myxoma or choriocarcinoma. Cerebral metastases of choriocarcinoma occur in 1020% ofpatients with metastatic choriocarcinoma, some ofwh...
272 Walsh & Hoyt: ArteritisSteven A. Newman, M.D., University of Virginia School of MedicineInflammatory conditions of the arterial wall unassociated with a specific infectious agent may lead to the development ofan aneurysm. Isolated cases have been reported with systemic lupus erythematosus (SLE), Behcets disease, relapsing polychondritis, and polyarteritis. Most ofthe aneurysms associat...
273 Walsh & Hoyt: ConclusionsSteven A. Newman, M.D., University of Virginia School of MedicineIntracranial aneurysms occur with high frequency and have a significant impact on public health. Most aneurysms present with subarachnoid hemorrhage, but 10% cause symptoms by mass effect, distal embolization, or thrombosis. Early clinical recognition and the use of improved and improving diagnostic...
274 Walsh & Hoyt: Clinical Manifestations, Treatment, and Prognosis According to SiteSteven A. Newman, M.D., University of Virginia School of MedicineDolichoectasia of the intracranial portions ofthe ICAs and their branches may be asymptomatic, or it may cause a variety ofsymptoms and signs that are related to the location and extent of the condition. Thus, dolichoectasia of the petrous portion ofthe ICA may produce lower cranial neuropathies, wh...
275 Walsh & Hoyt: PrevalenceSteven A. Newman, M.D., University of Virginia School of MedicineThe frequency with which ruptured and unruptured saccular aneurysms occur is the subject ofnumerous studies. Most of these studies are autopsy results from single medical centers. Stehbens (273) reviewed the results of 14 such studies and found that the prevalence of intracranial saccular aneurysms ...
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