Electrocorticographic correlates of cognitive control in a stroop task—intracranial recording in epileptic patients

The human brain executes cognitive control, such as selection of relevant information in the presence of competing irrelevant information, and cognitive control is essential for us to yield a series of optimal behaviors in our daily life. This study assessed electrocorticographic γ‐oscillations elicited by cognitive control in the context of the Stroop color‐naming paradigm, with a temporal resolution of 10 msec and spatial resolution of 1 cm. Subjects were instructed to overtly read a color word printed in an incongruent color in the reading task, and to overtly name the ink color of a color word printed in an incongruent color in the Stroop color‐naming task. The latter task specifically elicited larger γ‐augmentations in the dorsolateral‐premotor, dorsolateral‐prefrontal and supplementary motor areas with considerable inter‐subject spatial variability. Such Stroop color‐naming‐specific γ‐augmentations occurred 500 to 200 msec prior to overt responses. Electrical stimulation of the sites showing Stroop color‐naming‐specific γ‐augmentations resulted in temporary naming impairment more frequently than that of the remaining sites. This study has provided direct evidence that a critical process of cognitive control in the context of Stroop color‐naming paradigm consists of recruitment of neurons essential for naming located in variable portions of the dorsolateral premotor and prefrontal areas. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.     

Statistical mapping of ictal high-frequency oscillations in epileptic spasms

Purpose: We assessed 636 epileptic spasms seen in 11 children (median 44 spasms per child) and determined the spatial and temporal characteristics of ictal high‐frequency oscillations (HFOs) in relation to the onset of spasms. Methods: Electrocorticography (ECoG) signals were sampled from 104–148 cortical sites per child, and the dynamic changes of ictal HFOs were animated on each individual’s three‐dimensional (3D) magnetic resonance (MR) image surface. Key Findings: Visual assessment of ictal ECoG recordings revealed that each spasm event was characterized by augmentation of HFOs. Time‐frequency analysis demonstrated that ictal augmentation of HFOs at 80–200 Hz was most prominent and generally preceded those at 210–300 Hz and at 70 Hz and slower. Recruitment of HFOs in the rolandic cortex preceded the clinical onset objectively visualized as electromyographic deflection. The presence or absence of ictal motor symptoms was related more to the amplitude of HFOs in the Rolandic cortex than in the seizure‐onset zone. In a substantial proportion of epileptic spasms, seizure termination began at the seizure‐onset zone and propagated to the surrounding areas; we referred to this observation as the “ictal doughnut phenomenon.” Univariate analysis suggested that complete resection of the sites showing the earliest augmentation of ictal HFOs was associated with a good surgical outcome. Significance: Recruitment of HFOs at 80–200 Hz in the rolandic area may play a role in determining seizure semiology in epileptic spasms. Our study using macroelectrodes demonstrated that ictal HFOs at 80–200 Hz preceded those at 210–300 Hz.     

Bisphosphonates in phenytoin-induced bone disorder

Chronic administration of phenytoin (PHT) has been associated with bone loss. Bisphosphonates [alendronate (ALD), ibandronate (IBD) and risedronate (RSD)] are potential candidates to prevent PHT-induced bone disorders, and the present study evaluated their effect on the antiepileptic efficacy of PHT. The PHT-induced depletion in folic acid (FA), vitamin B6 and vitamin B12 results in hyperhomocysteinemia. The elevated circulating homocysteine (hcy) could be a risk indicator for micronutrient-deficiency-related osteoporosis via generation of free radicals. Thus, an attempt was also made to unravel the PHT's and bisphosphonates' effect on hcy. Male mice received PHT (35 mg/kg, p.o.) for 90 days to induce bone loss. ALD, RSD and IBD were administered orally at doses 0.65 mg/kg, 0.33 mg/kg, and 0.17 mg/kg respectively, for prevention and 1.3mg/kg, 0.65 mg/kg, and 0.33 mg/kg respectively, for treatment of PHT-induced bone loss. The bone loss was confirmed by bone mineral density (BMD) analysis and bone turnover markers. Serum levels of hcy and FA were estimated along with hydrogen peroxide levels and total antioxidant capacity in order to assess the antioxidant profile of bisphosphonates. The induction of bone loss by PHT was marked by lowered BMD and altered bone turnovers. ALD and RSD administration to PHT treated groups significantly reverted the bony adverse effects. No such effects were observed with IBD. In the bisphosphonates treated groups, hcy levels were statistically at par with the control group. PHT at 35 mg/kg, p.o. could compromise bone mass and thus, could be a model of bone demineralization in mice. The ALD, IBD and RSD have no pharmacodynamic interaction when administered along with PHT at the experimental level. Thus, their usage in the management of PHT-induced bone disease could be worthwhile if clinically approved.     

Scientific evidence and best patient care practices should guide the ethics of Lyme disease activism

Johnson and Stricker published an opinion piece in the Journal of Medical Ethics presenting their perspective on the 2008 agreement between the Infectious Diseases Society of America (IDSA) and the Connecticut Attorney General with regard to the 2006 IDSA treatment guideline for Lyme disease. Their writings indicate that these authors hold unconventional views of a relatively common tick-transmitted bacterial infection caused by the spirochete Borrelia burgdorferi. Therefore, it should come as no surprise that their opinions would clash with the IDSA's evidence-based guidelines for the diagnosis and treatment of Lyme disease. Their allegations of conflict of interest against the IDSA resemble those made against the National Institutes of Health, the Food and Drug Administration and the Centers for Disease Control and Prevention in 2000, which were found to be baseless. It is the responsibility of all physicians and medical scientists to stand up to antiscientific, baseless and unethical attacks on those who support an evidence-based approach to caring for patients.     

Primary meningococcal polyarthritis in a young man

We report a rare occurrence of primary meningococcal polyarthritis in a 19-year-old man. The fluid in the elbow joint showed Gram-negative diplococci but the culture was sterile. The diagnosis was confirmed by polymerase chain reaction targeting crgA gene of Neisseria meningitidis.