Smaller size of high metabolic rate organs explains lower resting energy expenditure in Asian-Indian Than Chinese men.

BACKGROUND: In Singapore, the obesity prevalence is disproportionately higher in the Asian-Indians and Malays than the Chinese. Lower resting energy expenditure (REE) may be a contributory factor. OBJECTIVE: We explored the association between ethnicity and REE in Chinese, Asian-Indian and Malay men living in Singapore and determined the influence of body composition, mass/volume of high metabolic rate organs, represented by brain volume and trunk fat-free mass (FFM), and physical activity on ethnic differences. DESIGN: Two hundred and forty-four men from Singapore (n=100 Chinese, 70 Asian-Indians and 74 Malays), aged 21-40 years and body mass index of 18.5-30.0 kg m(-2), were recruited in this cross-sectional study. REE was assessed by indirect calorimetry and body composition by dual-energy X-ray absorptiometry. Brain volume was measured by magnetic resonance imaging. Physical activity was assessed by the Singapore Prospective Study Program Physical Activity Questionnaire. RESULTS: REE was significantly lower in Asian-Indians compared with that in Chinese after adjusting for body weight. FFM (total, trunk and limb) and total fat mass were important predictors of REE across all ethnic groups. Brain volume was positively associated with REE only in Malays. Moderate and vigorous physical activity was positively associated with REE only in Asian-Indians and Malays. The difference in REE between Asian-Indians and Chinese was attenuated but remained statistically significant after adjustment for total FFM (59±20 kcal per day), fat mass (67±20 kcal per day) and brain volume (54±22 kcal per day). The association between REE and ethnicity was no longer statistically significant after total FFM was replaced by trunk FFM (which includes heart, liver, kidney and spleen) but not when it was replaced by limb FFM (skeletal muscle). CONCLUSIONS: We have demonstrated a lower REE in Asian-Indians compared with Chinese who may contribute to the higher rates of obesity in the former. This difference could be accounted for by differences in metabolically active organs.

Disrupted salience network functional connectivity and white-matter microstructure in persons at risk for psychosis: findings from the LYRIKS study.

BACKGROUND: Salience network (SN) dysconnectivity has been hypothesized to contribute to schizophrenia. Nevertheless, little is known about the functional and structural dysconnectivity of SN in subjects at risk for psychosis. We hypothesized that SN functional and structural connectivity would be disrupted in subjects with At-Risk Mental State (ARMS) and would be associated with symptom severity and disease progression. METHOD: We examined 87 ARMS and 37 healthy participants using both resting-state functional magnetic resonance imaging and diffusion tensor imaging. Group differences in SN functional and structural connectivity were examined using a seed-based approach and tract-based spatial statistics. Subject-level functional connectivity measures and diffusion indices of disrupted regions were correlated with CAARMS scores and compared between ARMS with and without transition to psychosis. RESULTS: ARMS subjects exhibited reduced functional connectivity between the left ventral anterior insula and other SN regions. Reduced fractional anisotropy (FA) and axial diffusivity were also found along white-matter tracts in close proximity to regions of disrupted functional connectivity, including frontal-striatal-thalamic circuits and the cingulum. FA measures extracted from these disrupted white-matter regions correlated with individual symptom severity in the ARMS group. Furthermore, functional connectivity between the bilateral insula and FA at the forceps minor were further reduced in subjects who transitioned to psychosis after 2 years. CONCLUSIONS: Our findings support the insular dysconnectivity of the proximal SN hypothesis in the early stages of psychosis. Further developed, the combined structural and functional SN assays may inform the prognosis of persons at-risk for psychosis.

Processing of visually presented sentences in Mandarin and English studied with fMRI.

Comprehension of visually presented sentences in fluent bilinguals was studied with functional magnetic resonance imaging (fMRI) using a set of conceptually similar sentences in two orthographically and phonologically distinct languages, Mandarin and English. Responses were monitored during scanning. Sentence comprehension in each language was compared to fixation in nine subjects and Tamil-like pseudo-word strings in five subjects. Spatially congruent activations in the prefrontal, temporal, and superior parietal regions and in the anterior supplementary motor area were observed for both languages and in both experiments at the individual and group levels of analysis. Proficient bilinguals exposed to both languages early in life utilize common neuroanatomical regions during the conceptual and syntactic processing of written language irrespective of their differences in surface features.

Presurgical evaluation of temporal lobe epilepsy using interictal temporal spikes and positron emission tomography.

OBJECTIVE: Our goal was to determine the role of fludeoxyglucose F 18-positron emission tomography (18FDG-PET) and interictal temporal spikes in lateralizing the epileptogenic region in patients who (1) were diagnosed as having temporal lobe epilepsy based on clinical symptoms and exclusively temporal interictal spikes and (2) did not have a structural lesion on magnetic resonance imaging. DESIGN: This was a retrospective study of 40 consecutive patients fulfilling the above criteria who underwent 18FDG-PET scanning. A firm electrophysiologic diagnosis and 1 complete year of postsurgical follow-up, where applicable, were required. Outcome measures included surgical outcome and final electrophysiologic diagnosis. RESULTS: Unilateral, interictal temporal spikes (ITS) were present in 33 (82.5%) of 40 patients. Seven patients (17.5%) had bitemporal, independent spikes. Thirty-one (77.5%) of 40 patients had unilateral temporal hypometabolism (TH). Twenty-eight (70%) patients had concordant TH and ITS. One year after surgery, 31 of 33 patients with unilateral ITS were greatly improved; two of five who had bitemporal ITS showed similar improvement. In 28 patients, unilateral TH and unilateral ITS were concordant. The paired result always concurred with the final neurophysiologic assessment. Surgical outcome between patients with 18FDG-PET showing unilateral TH (26 of 30 greatly improved) and those not showing unilateral TH (six of eight greatly improved) was not significantly different. CONCLUSION: In temporal lobe epilepsy not associated with a mass lesion, unilateral ITS are reliable lateralizing features and suggest a good surgical outcome. Use of 18FDG-PET provides corroborative lateralizing information but 18FDG-PET that fails to show unilateral TH does not preclude a good surgical outcome.

Lateralizing signs in intractable partial epilepsy: blinded multiple-observer analysis.

We evaluated the accuracy and interobserver variability of selected ictal and postictal behavioral changes. Three observers, blinded to clinical history, EEG, and side of surgical resection, analyzed videotapes of 166 seizures in 38 patients, looking for lateralizing signs. Twenty-seven patients with temporal lobe resections were seizure-free for > or = 1 year postoperatively, and 11 with extratemporal resections had at least 90% reduction in seizures > or = 1 year postsurgery. The epileptogenic region (ER) was lateralized by analyzing lateralizing signs in 78% of patients; positive predictive value (PPV) was 94% (90% CI = 87% to 100%). Overall kappa was 0.68. Signs were considered present if seen by two or more observers. Forty-five percent had version, ie, forced and sustained head deviation (kappa = 0.76, PPV = 94%); 37% had dystonic posturing of the upper extremity (kappa = 0.47, PPV = 93%); and 34% had unilateral mouth deviation (kappa = 0.83, PPV = 92%). These signs indicated a contralateral ER. Twenty-one percent had unilateral upper extremity automatisms, all ipsilateral to the ER (kappa = 0.65, PPV = 100%); 21% had postictal dysnomia, indicating a dominant-hemisphere ER (kappa = 0.89, PPV = 100%); and 16% had ictal speech, usually indicating a nondominant-hemisphere ER (kappa = 0.75, PPV = 83%). Dystonic posturing, postictal dysnomia, ictal speech, and unilateral upper extremity automatisms may indicate a higher probability of temporal lobe epilepsy. Analysis of lateralizing signs shows good interobserver agreement and provides useful clinical information.

Right hemisphere language in a neurologically normal dextral: a fMRI study.

Dextrals with right cerebral hemisphere dominance for language are rare. Eight neurologically intact dextrals underwent BOLD-fMRI while being presented auditory and visual words. Fortuitously, in one subject, right hemisphere activations with visually presented words were seen in the inferior frontal, premotor regions together with predominantly left cerebellar activation. These were a mirror image of activations obtained from the seven other dextrals. Also mirrored was temporal activation from auditory words which extended more posteriorly on the right side than the left. These results showing mirror organization of language were replicated in another scanning session and also by using a second word task. Although rare, mirrored organization of language can occur in normal dextrals without penalizing language function.

Dorsolateral prefrontal cortex and the implicit association of concepts and attributes.

The Implicit Association Test (IAT) examines the differential association of two object categories (e.g. flower and insect) with attribute categories (e.g. pleasant and unpleasant). When items from congruent categories (e.g. flower + pleasant) share a response key, performance is faster and more accurate than when items from incongruent categories (e.g. insect + pleasant) share a key. Performing incongruent word classification engages inhibitory processes to overcome the prepotent tendency to map emotionally congruent items to the same response key. Using fMRI on subjects undergoing the IAT, we show that the left dorsolateral prefrontal cortex, and to a lesser extent the anterior cingulate cortex, mediate inhibitory processes where manipulation of word association is required.

Fulminant Guillain-Barré syndrome with quadriplegia and total paresis of motor cranial nerves as a result of segmental demyelination.

Guillain-Barré syndrome (GBS) is a subacute demyelinating polyneuropathy with a monophasic course. Rarely, demyelination may be so severe as to produce electrically unexcitable nerves. We present a patient with fulminant onset of symptoms who was quadriplegic and had bilateral involvement of all motor cranial nerves. Serial EMGs indicated that segmental demyelination was responsible for these clinical findings.

Speech and the dominant superior frontal gyrus: correlation of ictal symptoms, EEG, and results of surgical resection.

Two patients with seizures characterized by speech arrest had astrocytoma in the superior frontal gyrus (SFG) of the left hemisphere. Preoperative video EEG monitoring of seizures using subdural electrode arrays showed that comprehension, crude vocalization, and limb and tongue movements were preserved during speech arrest. One patient had difficulty writing during seizures. Ictal EEG onset was localized to the SFG without involvement of Broca's area. Electrical stimulation of SFG electrodes reproduced the speech arrest and writing difficulty. Resection of this region reduced seizures but did not result in lasting speech deficit. Cessation of speech with electrical stimulation of the superior frontal gyrus occurs by interrupting control of muscles required for speaking, which occurs independently of simple 'negative' motor effects. We postulate that functional redundancy is the basis for resection of this region without producing significant speech deficits.

Culture positive tuberculous meningitis: clinical indicators of poor prognosis.

Few studies have evaluated culture positive tuberculous meningitis (TBM) as a group. We evaluated certain clinical factors in culture positive TBM which could be associated with a poorer outcome. Out of 40 consecutive TBM patients seen over a period of 4 years in a tertiary referral hospital, 18 culture positive and non-human immunodeficiency virus (HIV) related cases were studied. The mean age was 37.9 +/- 14.9 years (range 9-63); five were males and 13 females. None had any associated active chronic medical illness. Patients (44.4%) started on antituberculous treatment within 24 h of admission. Treatment was initiated at a median time of 48 h upon admission in hospital. Univariate analysis revealed a significant correlation between hydrocephalus (P = 0.007) and poor morbidity and mortality. The other clinical factors were not statistically significant: age (P = 0.36): sex (P = 0.49); symptom duration (P = 0.69); BCG vaccination (P = 0.65); cerebral infarct (P = 0.63); extrameningeal spread (P = 1.00); steroids (P = 1.00); time to treatment (P = 0.94) and stage of disease (P = 0.11). Hydrocephalus was the only significant factor predisposing culture positive TBM patients to a poorer outcome. There was also a trend towards a poorer prognosis in those with advanced stage of the disease.

Acute ophthalmoplegia with pupillary areflexia associated with anti-GQ1b antibody.

Raised anti-GQ1b antibody is associated with Miller Fisher syndrome, Guillain-Barre syndrome (GBS) with ophthalmoplegia, Bickerstaff's brain stem encephalitis, acute ophthalmoparesis without ataxia and ataxic GBS without opthalmoplegia. We report a rare case of acute ophthalmoplegia associated with anti-GQ1b antibody that also had pupillary areflexia. A 35-year-old Chinese lady presented with external ophthalmoplegia, pupillary areflexia and no other abnormalities of cranial nerves, muscle tone, deep tendon reflexes, limb power or cerebellar dysfunction. Anti-GQ1b IgG antibody titre was significantly elevated, while neuroimaging of brain and orbital structures, nerve conduction study and cerebral spinal fluid examination were normal. Pupillary areflexia should be recognized as another feature that may be present in conditions associated with raised anti-GQ1b antibody.

Mesial temporal lobe epilepsy in Singapore.

Mesial temporal lobe epilepsy due to mesial temporal sclerosis is a distinctive syndrome and a surgically remediable form of epilepsy. We present 26 Singaporean cases of mesial temporal lobe epilepsy defined by clinical, electroencephalographic and MR features and validated by good surgical outcome (12 seizure free, 5 with two or fewer seizures) in all 17 patients who have so far undergone surgery and who have been followed up for at least 6 months. Sixty-five percent of patients experienced their first seizure in the setting of a febrile illness. Seventy-three percent of patients had seizure onset before the age of 10 years and the median interval between seizure onset and intractability of seizures was 3.75 years. 80.7% of patients had an aura and an equal number had at least one lateralizing sign during their seizures. Sixty-four percent of patients had predominantly unilateral anterior temporal interictal spikes. Eighty-eight percent of patients had seizures which were lateralised on scalp ictal EEG. MRI abnormalities were most frequently seen in the head and body of the hippocampal formation. Asymmetric hippocampal atrophy was more common than hippocampal T2 or T2* signal changes. There is much similarity in characteristics of mesial temporal lobe epilepsy in our population compared to what has been published regarding Caucasian subjects.

Seeing how we think about words using BOLD contrast fMR imaging.

This review examines how blood oxygen level-dependent functional magnetic resonance imaging (fMRI) may be harnessed to study the brain when it engages in language processing tasks. This method makes clinical and scientific contributions to understanding language function. Issues such as the lateralisation of language function, brain plasticity in health, ageing and neurological disease, and as well as how 2 different languages are processed, may all be evaluated by fMRI.

Neuronal migration disorder presenting with epilepsy: a report of five illustrative cases.

Neuronal migration disorders are an uncommon but well-recognised cause of medically intractable epilepsy. The increasing availability of magnetic resonance imaging of the brain has made it possible to diagnose this condition ante-mortem. There are several types of migration disorders, each with different radiological and clinical features. A case each of focal cortical dysplasia, focal subcortical heterotopia, double cortex syndrome, periventricular nodular heterotopia and closed lip schizencephaly is presented to highlight the distinctive features of each entity.

Computed tomography in patients with recurrent seizures.

Eighty patients had Computed Tomography (CT) performed for evaluation of epileptic seizures. Abnormal scans were found in 37 of the 80 patients (46.3%). Focal CT abnormalities were seen in 26 of the 80 patients (32.5%). Tumors were present in four and arteriovenous malformation (AVM) in three. Simple partial motor seizures were most strongly correlated with abnormal scans (five, 45.4%). Nineteen out of 21 patients with focal electro-encephalographic (EEG) abnormalities had focal CT abnormality compared to one out of 15 of those with generalised abnormality. 88.9% of patients with hemiplegia had abnormal scans. Whilst focal EEG abnormalities and abnormal neurologic signs pointed to a higher likelihood of CT abnormality, two subjects who were shown to have vascular malformations had normal EEG and neurologic exams. Routine CT scanning for evaluation of patients with recurrent seizures is advocated.

Nuclear third nerve palsy and somnolence due to stroke--a case report.

We describe a 40 year-old male with a ball-cage mitral valve prosthesis who suddenly developed bilateral ptosis, bilateral dilated and unreactive pupils, right third nerve palsy, bilateral failure of vertical gaze, somnolence and mild ataxia without major motor deficits. Computed Tomography (CT) revealed bilateral thalamic infarcts in the distribution of the rostral basilar artery. Infarction in this case occurred despite adequate anticoagulation. The recognition of the entity of rostral basilar artery occlusion is important as interruption of anticoagulation may be avoided.

Persistent mutism and dysphagia of acute onset due to bilateral internal capsule infarction.

Acute mutism with paralysis of the bulbar and facial muscles following discrete bilateral internal capsular infarction is a rare stroke syndrome. We describe a 62 year-old male who suddenly became unable to speak or swallow. The paucity of facial expression and inability to voluntarily move the facial, lingual and pharyngeal muscles were persistent and contrasted with a relatively mild limb paresis which recovered. High resolution CT scan revealed infarcts in the posterior limbs of both internal capsules. It is important to recognise this stroke syndrome because of the permanence of dysarthria and dysphagia associated with it.

Mandarin and English single word processing studied with functional magnetic resonance imaging.

The cortical organization of language in bilinguals remains disputed. We studied 24 right-handed fluent bilinguals: 15 exposed to both Mandarin and English before the age of 6 years; and nine exposed to Mandarin in early childhood but English only after the age of 12 years. Blood oxygen level-dependent contrast functional magnetic resonance imaging was performed while subjects performed cued word generation in each language. Fixation was the control task. In both languages, activations were present in the prefrontal, temporal, and parietal regions, and the supplementary motor area. Activations in the prefrontal region were compared by (1) locating peak activations and (2) counting the number of voxels that exceeded a statistical threshold. Although there were differences in the magnitude of activation between the pair of languages, no subject showed significant differences in peak-location or hemispheric asymmetry of activations in the prefrontal language areas. Early and late bilinguals showed a similar pattern of overlapping activations. There are no significant differences in the cortical areas activated for both Mandarin and English at the single word level, irrespective of age of acquisition of either language.