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This Month in Archives of Neurology
February 2003

This Month in Archives of Neurology

Arch Neurol. 2003;60(2):158-160. doi:10.1001/archneur.60.2.158
Hashimoto Encephalopathy: Syndrome or Myth?

Chong and colleaguesstudied a patient and reviewed the literature associated with this unusual syndrome to determine if it is an identifiable one. The combination of encephalopathy, high serum antithyroid antibody concentrations, and responsiveness to glucocorticoid therapy seems unlikely to be due to chance, as they point out in detail. Nevertheless, there is no evidence of a pathogenic role for the antibodies, which probably serve as a marker of autoimmunity. This review serves nicely to define the syndrome and to point out research issues for the future.

The Reach of Neurology

Fisherdefines complex behavioral syndromes and the neurologist's role in evaluating patients with temporal lobe epilepsy, electrical stimulation of the brain, delirium, neuroendocrine syndromes, drug toxicity, obscure pain, dyslexia, chronic fatigue syndrome, and hysteria. He emphasizes that neurology "abounds in phenomena created by nature's experiments" and illustrates these points with insightful case histories. His views of these points are important and invite thinking beyond the usual bounds of neurologic practice.

Cortex to Cortex

Lammeprovides a basic science review of the emerging field of recurrent corticocortical interactions and their specific role in the causation of neurologic disease. He emphasizes the key point that the cerebral cortex consists of a large number of areas, each subserving a more or less distinct function. The view is now that feed-forward connections are reciprocated by numerous feedback fibers, including extensive horizontal connections that link neurons separated by large distances. We finally have some neurophysiologic insight into how these recurrent interactions work, specifically, their functions and operations in visual perception, awareness, and attention. As this very insightful review points out, these observations have direct implications for understanding neurologic and neuropsychologic disease.

Apolipoprotein E ϵ4 as an Alzheimer Disease Risk Factor in Racial Groups

There are few studies that compare Alzheimer disease (AD) incidence among racial groups. Evans and colleagueshave undertaken a population-based study of disease incidence in white and black populations in Chicago. They have measured the effect of apolipoprotein E on the risk of AD and find a siginficant racial difference in the incidence of developing AD. Among whites, the presence of the ϵ4 alllele was associated with a 2.73-fold increase in risk, while among blacks, there was no increase in risk. Clearly, the molecular basis and other implications of this important finding deserve further investigation. Editorial perspective is provided by Richard Mayeux, MD, MSc.

Dietary Fats and Alzheimer Disease

Dietary intake and disease has been an important subject throughout medicine. The role of diet and Alzheimer disease (AD) has not been rigorously studied. Morris and colleagueshave specifically investigated dietary fats and the incidence of AD. They report that both saturated fat and transunsaturated fat were positively associated with the risk of AD, whereas the intake of ω-6 polyunsaturated fat and monounsaturated fat were inversely associated. Of note, persons in the upper fifth of saturated fat intake had 2.2 times the risk of incident AD compared with persons in the lowest fifth in a multivariable model adjusted for age, sex, race, education, and apolipoprotein E ϵ4 status. The oxidation of fatty acids may be a factor in disease causation. Thus, specific fat intake may be a key environmental factor—one correctable—in the cascade of events that result in AD.

Figure 1.
Relative risks (RRs) (95% confidence intervals [CIs]) for Alzheimer disease by quintile of polyunsaturated fat (P)–saturated fat (S) intake ratio based on a multivariable logistic model adjusted for time on study, age (years), sex, race, education (years), apolipoprotein E (APOE) ϵ4, and the interaction between race and APOE ϵ4.

Relative risks (RRs) (95% confidence intervals [CIs]) for Alzheimer disease by quintile of polyunsaturated fat (P)–saturated fat (S) intake ratio based on a multivariable logistic model adjusted for time on study, age (years), sex, race, education (years), apolipoprotein E (APOE) ϵ4, and the interaction between race and APOE ϵ4.

Antioxidant Vitamin Therapy and Alzheimer Disease Risk

The relationship between intake of carotenes, vitamin C, and vitamin E and Alzheimer disease (AD) was studied by Luchsinger and colleaguesin 980 elderly patients who were free of dementia at baseline and followed up for a mean of 4 years. Intake of carotenes and vitamins C and E in supplemental or dietary (nonsupplemental) form, or in both forms, was not related to a decreased risk of AD. These data were rigorously obtained and provide a definitive statement on the relevance of this purported form of intervention for AD.

Estrogen Levels and Cognition

Thal and colleagueshave investigated whether an association exists between estradiol and estrone levels and measures of cognitive functioning in women with Alzheimer disease (AD) treated with Premarin.They studied 120 postmenopausal, hysterectomized women with AD treated with Premarin for 1 year. Premarin did elevate estradiol and estrone levels, but there was no association between hormone levels and cognitive functioning after either 2 or 12 months of treatment. This issue has been the subject of several studies related to slowing the rate of AD, and this well-designed study defines the limitation of estrogen replacement therapy when applied in this specific manner.

Estrogen Levels, Hippocampi, and Cognition

Estrogen levels in older women and men were studdied in relationship to hippocampal volume measured on magnetic resonance imaging and to cognitive performance. den Heijer and colleaguesstudied 210 women and 202 men, aged 60 to 90 years, with plasma levels of total estradiol and, in part, 162 women and 149 men with levels of bioavailable and free estradiol. Of note, women with higher total estradiol levels had smaller hippocampal volumes, poorer memory performance, smaller hippocampi, and more impaired word recall for the highest tertile compared with the lowest tertile. Similar inverse associations were found between bioavailable/free estradiol and hippocampal volumes and memory. In men, no association was observed between estradiol levels and hippocampal volume. In general, levels of endogenous estradiol in older women and men are not associated with hippocampal preservation and better cognition.

Low Blood Pressure and Dementia

Qiu et alexamined whether low blood pressure is prospectively associated with the occurrence of Alzheimer disease (AD) and other forms of dementia. One thousand two hundred seventy patients who were dementia free at baseline and aged 75 to 101 years were followed up for 6 years. Three hundred thirty-nine subjects, including 256 patients with AD, were diagnosed as having dementia. Subjects with hypertension (>180 vs 141-180 mm Hg) had an adjusted relative risk of 1.5 for AD and 1.6 for dementia. Low systolic pressure was not related to incident dementia. In contrast, high diastolic pressure (>90 mm Hg) was not associated with dementia incidence, whereas extremely low diastolic pressure (≤65 mm Hg vs 66-90 mm Hg) produced an adjusted relative risk of 1.7 for AD and 1.5 for dementia. Thus, both low diastolic and high systolic pressure are associated with an increased risk of AD and dementia in this elderly population. These are provocative findings. The condition is highly treatable and needs to be evaluated carefully in elderly patients.

Carbon Dioxide Reactivity and Cerebral Ischemia

Bisschops et alhave studied the association between the prevalence and size of ischemic lesions and cerebral vasomotor reactivity in patients with unilateral occlusion of the internal carotid artery. In 70 patients studied, ipsilateral to the internal carotid artery occlusion, there was an increased prevalence of internal and external border zone infarcts and territorial infarcts compared with the contralateral hemisphere. Of importance, hemispheres with a carbon dioxide reactivity less than or equal to 18% demonstrated a significant increase in prevalence and volume of internal border zone infarcts compared with hemispheres with carbon dioxide reactivity greater than or equal to 19%. Carbon dioxide reactivity and associated cerebral perfusion are significant physiologic factors to consider and measure and bear directly on potential patient management and outcome.

Perfusion-Weighted Imaging and Carotid Artery Occlusive Disease

Perfusion-weighted imaging was studied as a means of quantifying meaningful categories in patients with symptomatic and asymptomatic internal carotid artery (ICA) occlusive disease. Twenty-two patients with ICA occlusion and 16 patients with severe stenosis of the ICA were studied. Thirty-five patients were symptomatic (29 strokes, 6 transient ischemic attacks) and 3 were asymptomatic. Three patterns of perfusion abnormalities were identified, and the pattern of perfusion-weighted images related to the clinical signs and symptoms but not to the degree of ICA. Defining the degree of hypoperfusion as determined in this study can assist in determining the degree of patient morbidity. Clearly, hypoperfusion is a major contributing factor to the pathophysiologic characteristics of carotid artery occlusive disease, as demonstrated by Chaves and colleagues.

Development of Generalized Myasthenia Gravis After Ocular Disease

The effect of oral corticosteroid therapy on the frequency of developing generalized myasthenia gravis (MG) at 2 years, the incidence of thymoma, and the amount of edrophonium needed for a positive test result in patients with ocular MG were studied by Kupersmith and colleagues. They found that at 2 years, in 147 patients studied, prednisone reduced the incidence of generalized MG to 7% in contrast with 36% of patients who did not receive prednisone. A longer investigation needs to be conducted but these preliminary findings are encouraging and supportive of early prednisone therapy.

Total Cerebral Volume and Febrile Seizures

Theodore and colleagueshave measured total cerebral volume in patients with mesial temporal lobe epilepsy with and without a history of complex febrile seizures (CFSs). They report that patients with a history of CFSs had a significantly reduced total cerebral volume compared with patients without a history of CFSs. Thus, CFSs have a global effect on brain development. Neuropsychologic test scores were not lower in patients with CFSs, which is a positive and important point. Further, men might be more vulnerable to hippocampal damage from seizures than women, which these results support, as men with CFSs had a significantly lower total cerebral volume than controls.

Active Life Expectancy and Alzheimer Disease

Dodge and colleagueshave studied a large cohort of patients with Alzheimer disease (AD) (mean age, 75 years) and nondemented subjects for total life expectancy and active life expectancy. Alzheimer disease was found to reduce life expectancy, and the loss of active components of life was quantitiated. The concept of active life expectancy adds a useful new dimension to the study of outcomes in AD.

Patterns of Weakness in Polyneuropathy

Mygland and Monstadhave studied the pattern of weakness and the presence of immunoglobulin monoclonal protein (M protein) in 29 patients with chronic acquired symmetric polyneuropathy. Fifteen patients had chronic inflammatory demyelinating polyradiculopolyneuropathy (CIDP) and 14 had distal acquired demyelinating symmetric polyneuropathy (DADS). Patients differed significantly regarding spinal fluid protein level (CIDP>DADS), clinical remitting course (CIDP>DADS), disability scores at diagnosis (CIDP>DADS), and response to immunosuppressive treatment (CIDP>DADS). Thus, classification by the presence or absence of proximal weakness separates patients with chronic acquired symmetric demyelinating polyneuropathy into groups that are different in clinical course, disability, and treatment response.