LATE BREAKING NEUROLOGIC NEWS

The primary motor cortex does not generate or maintain essential tremor, indicated a study in the April 1 Lancet. The authors suggested that "the effectiveness of neurosurgery in essential tremor can not be explained on the basis of thalamic oscillations entraining the activity of neurons in the primary cortex." During the study, six controls and six patients with essential tremor were evaluated by magnetoencephalography while they extended their arm, hand, and abducted fingers, maintaining the position against gravity.

Standard panoramic dental x-ray films can identify calcification of carotid arteries, according to researchers at the University at Buffalo School of Dental Medicine, New York. They are currently investigating the link between the appearance of carotid artery calcification on dental x-ray films and death due to heart attack or stroke among Pima Indians of the Gila River Indian Community in Arizona. Calcification was identified by dental x-ray film in 7.5% of the 818 participants (calcification is found in 3% of the general population). Participants with plaque in the carotid arteries are at twice the risk of death from heart attack or stroke than are those without plaque, reported the researchers.

Significant differences were found between migraineurs, patients with tension-type headache, and healthy controls in the wavelengths of light that were uncomfortable during headache-free periods. According to a report in the March Headache, migraineurs had lower discomfort thresholds for low and high wavelengths of light and for unfiltered (white) light between attacks than the other groups. Participants with aura and without aura did not report differences in discomfort. Migraine attacks can be triggered by light, noted the authors, adding that it has been hypothesized that "the light that can provoke attacks has similar spectral characteristics to the light that patients find uncomfortable."

Restless leg syndrome (RLS) may affect more than 15% of patients in a standard medical practice population, according to researchers at Stanford University, California, and Johns Hopkins University in Baltimore, Maryland. Previous studies indicated that between 3% and 10% of the population was affected. Newer dopamine agonists used to treat Parkinson's disease are the most effective therapeutic options for the syndrome, the researchers reported.

Inhalation of helium from an unregulated high-pressure cylinder may lead to cortical infarction, according to a case report in the March Annals of Emergency Medicine. After inhalation of helium, a 27-year-old man underwent cerebral arterial gas embolism, causing loss of consciousness and vision as well as central pleuritic chest pain. Imaging showed "patchy areas of cortical infarction" in the right occipital lobe and pulmonary barotrauma. After regaining consciousness, the patient was treated with hyperbaric oxygen and lidocaine. Three days after the embolic event, his vision was "almost back to normal" and a diffusion-weighted MRI scan indicated almost normal signal in the right occipital lobe. The authors suggested that "lidocaine administration be considered when unequivocal arterial gas embolism presents in the emergency department."

Methamphetamine abuse causes long-term brain damage, according to a report in the March 28 Neurology. Twenty-six subjects with a history of methamphetamine abuse were evaluated after a period of abstinence. Concentrations of N-acetyl compounds were reduced by 5% in the basal ganglia and 6% in the frontal lobes; creatine, by 8% in the basal ganglia; and choline-containing compounds by 13% and myoinositol by 11% in the frontal gray matter. "Subjects who had used the largest amounts of methamphetamine during their drug careers showed the lowest concentrations of N-acetyl-aspartate in the frontal white matter," said study author Thomas Ernst, PhD. It is unknown if methamphetamine damage is reversible with treatment or with long-term abstinence.

Damage to the right somatosensory-related cortices, which process perception of touch, pain, temperature, and other body states, inhibits the ability to judge people's emotions from their facial expression, according to a report in the April 1 Journal of Neuroscience. The University of Iowa researchers asked 108 brain-damaged participants and 18 controls to identify and rate the intensity of emotions represented by happy, surprised, afraid, angry, disgusted, and sad faces. "To figure out how someone else feels—for example from looking at their face—requires us to imagine what it would feel like if we made that same face," said lead author Ralph Adolphs, PhD.

Exelon® (rivastigmine tartrate) has been approved by the Food and Drug Administration (FDA) for the treatment of mild to moderate Alzheimer's disease. The cholinesterase inhibitor was proven effective in multiple phase III trials in the key domains used to assess the disease—global functioning (including activities of daily living and behavior) and cognition. In clinical trials, on average, patients treated with rivastigmine (6 to 12 mg/day) were considered clinically improved compared with placebo at the end of six months. At 26 weeks, 81% of those treated with rivastigmine had greater improvements and less worsening in cognitive functioning than did placebo-treated patients. Exelon is marketed by Novartis Pharmaceuticals.

A diagnosis of AIDS based on specific illnesses rather than on low immune-cell counts is a predictor of cognitive decline, indicated a Ohio State University study. Differences in attention, dexterity, and verbal learning and recall were evaluated in a group of 200 homosexual men with AIDS, over six months. Those with AIDS-defining illnesses demonstrated greater cognitive decline than did those who were seronegative, were asymptomatic seropositive, symptomatic seropositive, or were diagnosed from CD4 cell counts. According to the report in the February Journal of Clinical and Experimental Neuropsychology, the six-month evaluation may have been too brief to reveal differences in attention and dexterity.

A high prevalence of depression and dementia was found in elderly patients referred to a geriatric clinic because of abuse or neglect. According to the report in the February Journal of the American Geriatric Society, 82% of the 45 patients had experienced self-neglect, 62% were diagnosed with depression, and 51% were diagnosed with dementia. The authors noted that depression affects decision-making capacity and may cause patients to refuse medical treatment or assistance in the home. Although depression is more difficult to diagnose in older patients than in younger patients, it is easily treated in the elderly, according to the authors.

Patients with Parkinson's disease may have a shorter life expectancy than does the general population, suggested a report in the April Archives of Neurology. The authors compared the survival of 59 patients with Parkinson's disease to the survival of 118 controls in a Sicilian population. Median survival from baseline was 73 months for patients with Parkinson's disease and 84.5 months for controls; median age at death was age 81 for patients with Parkinson's disease and age 82.5 for controls. While heart disease was the most frequent cause of death in both groups, pneumonia was significantly associated with death in Parkinson's disease.

Dengue infection should be considered in patients who present with the clinical features of encephalitis in dengue endemic areas, according to a study at the Centre for Tropical Diseases, in Ho Chi Minh City, southern Vietnam. Four percent of patients admitted with suspected central nervous system infections were infected with dengue viruses, compared to 1.4% of controls. Reduced consciousness and convulsions were the most common neurologic manifestations of dengue, according to the report in the March 24 Lancet. Linked to the mosquito vector Aedes aegypti, dengue viruses affect almost every country between the tropics of Capricorn and Cancer and infect an estimated 100 million people each year.

Chronic progressive brain atrophy in patients with long-term multiple sclerosis may be a predictor of cumulative disability, suggested a report in the March Radiology. In the study of 36 patients with multiple sclerosis, the annual rate of brain tissue loss was similar for patients with relapsing-remitting multiple sclerosis (17.3 mL) and patients with secondary progressive multiple sclerosis (23.6 mL). While there was a correlation between brain atrophy and Expanded Disability Status Scale (EDSS) score in patients with secondary progressive multiple sclerosis, there was no correlation between brain atrophy and T2 lesion volume.

A correlation between nonrheumatic atrial fibrillation and cognitive impairment in older patients without previous transient ischemic attack or stroke was indicated by a study in the April Journal of the American Geriatrics Society. The Italian study included 255 subjects, 42 of whom comprised the nonrheumatic atrial fibrillation group and 214 of whom (with sinus rhythm) comprised the reference group. The authors suggested that this association may be caused by silent lacunar infarction and white matter ischemia. Two hypotheses about the correlation between atrial fibrillation and cognitive impairment—thromboembolic and hemodynamic—warrant further investigation, they said.

Eating tofu more than once a week may double the risk of cognitive decline in old age, reported researchers with the Honolulu Heart Program. The isoflavones in tofu may affect tyrosine kinase, an enzyme involved in learning, they suggested. In an accompanying editorial in the April Journal of the American College of Nutrition, Francine Grodstein, MD, noted that the importance of understanding the link between diet and cognition is increasing as the population ages.

Heme oxygenase-1 expression may serve as a useful biologic marker in early sporadic Alzheimer's disease, reported Montreal researchers in the March Neurology. Because heme oxygenase-1 immunoreactivity increases in neurons and astrocytes of the hippocampus and cerebral cortex and localizes to senile plaques and neurofibrillary tangles of individuals with Alzheimer's disease, the researchers compared systemic heme oxygenase-1 regulation in subjects with Alzheimer's disease and controls. They found that plasma heme oxygenase-1 protein concentrations and lymphocyte heme oxygenase-1 messenger ribonucleic acid levels (mRNA) were significantly lower in subjects with Alzheimer's disease than in normal elderly controls. They found that sensitivity and specificity of lymphocyte heme oxygenase-1 mRNA measurements for diagnosis of early sporadic Alzheimer's disease are 88% and 75%, respectively.

The p21 gene may be linked to a number of cancers and age-related diseases such as atherosclerosis, arthritis, and Alzheimer's disease, according to a report in the April 11 Proceedings of the National Academy of Sciences. "Turning on this one gene brought about changes in numerous other genes that have already been implicated in aging and age-related diseases," said Igor Roninson, PhD, senior author of the study. The University of Illinois at Chicago researchers found that the p21 gene inhibited more than 40 genes associated with DNA replication and cell division, while increasing the activity of about 50 other genes.

A study has been initiated to identify Gulf War veterans with amyotrophic lateral sclerosis (ALS) and other motor neuron diseases and to determine the rate of ALS among Gulf War veterans. Directed by the Epidemiologic Research and Information Center at the Durham, North Carolina, Veterans Affairs Medical Center, the one-year study will involve the departments of Defense and Health and Human Services and the Centers for Disease Control and Prevention. Further information about the study can be obtained by calling 877-DIAL-ALS (1-877-342-5257).

Children and adolescents with certain severe disruptive behavior disorders that are marked by explosive temper caused by irritable mood swings demonstrated significant behavior improvements when treated with divalproex, according to a preliminary study reported in the May American Journal of Psychiatry. In a study of 20 outpatients ages 10 to 18 who met specific criteria for explosive temper and mood variations, researchers found that 80% or more of those receiving the anticonvulsant responded positively and with improved behavior and responses. "Since children and adolescents with disruptive disorders are at high risk for delinquency and addiction, identifying a subgroup that can be helped with medications as a part of their comprehensive psychosocial treatment, could have major public health implications," said lead researcher Stephen J. Donovan, MD.

—Kathryn Blair
Associate Editor

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