No abstract

No coherent theory has been advanced to explain either the particular localization of the myelinolytic lesions of central pontine myelinolysis or their pathogenesis. However, several lines of evidence support the generalization that the centre of the basis pontis has a special susceptibility to a metabolic fault. The constancy of localization of the lesion and its bilateral symmetry are the very attributes that characterize other metabolic (nutritional) disorders, such as the assymmetrical degeneragion of the papillomacular bundles within the optic nerves and tracts in deficiency amblyopia and the specific affection of the paraventricular regions in the Wernicke-Korsakoff syndrome. And clinically, the frequent occurrence of central pontine myelinolysis in a setting of severe metabolic derangement, particularly of the serum sodium, points in the same direction.

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As a result of a court order, computerized summaries of approximately 1,300 cases reported as Guillain-Barré syndrome by state health departments to the Centers for Disease Control during the intensive national surveillance instituted following the swine influenza vaccination program in 1976-1977 became available for further study. Although the data were not uniformly adequate to confirm the diagnosis of Guillain-Barré syndrome, they were sufficient to enable classification according to extent of motor involvement. Vaccinated cases with "extensive" paresis or paralysis occurred in a characteristic epidemiologic pattern closely approximated by a lognormal curve, suggesting a causal relationship between the disease and the vaccine. Cases with "limited" motor involvement showed no such pattern, suggesting that this group included a substantial proportion of cases which were unrelated to the vaccine. The effect attributed to the vaccine lasted for at least six weeks and possibly for eight weeks but not longer. The relative risk of acquiring "extensive" disease over a six-week period following vaccination ranged from 3.96 to 7.75 depending on the particular baseline estimate of expected normal or endemic incidence that was chosen. Correspondingly, the number of cases that could be attributed to the vaccine over the six-week period ranged from 211 to 246, or very slightly higher over an eight-week period if the lowest baseline estimate was used. The total rate of Guillain-Barré syndrome cases attributed to prior use of the vaccine was 4.9 to 5.9 per million vaccinees.

The clinical and pathologic findings in 20 patients with hypertensive encephalopathy were reviewed. The dominant central nervous system (CNS) symptoms were altered state of consciousness and severe headache. Nausea, vomiting, and visual disturbances were less common. Seizures and focal signs were infrequent. The changes seen were invariably accompanied both by the characteristic ophthalmoscopic alterations of malignant hypertension and by uremia. The neuropathologic changes consisted of severe vascular alterations (fibrinoid necrosis of arterioles, thrombosis of arterioles and capillaries), and of parenchymal lesions (microinfarcts, petechial hemorrhages) secondary to the vascular lesions. The vascular changes were not confined to the brain but were diffuse, affecting the eyes, kidneys, and other organs. In the CNS the brainstem was most severely affected. Cerebral edema was not observed, even in those patients who had increased cerebrospinal fluid pressure and papilledema.