In vivo proton MR spectroscopy evaluation of pyogenic brain abscesses: a report of 194 cases

BACKGROUND AND PURPOSE

The combination of nonspecific clinical findings and similarities in morphologic appearances on imaging often makes it difficult to distinguish abscesses from other brain lesions. We present a retrospective analysis of in vivo (1)H-MR spectroscopy data for characterization of the etiology of the brain abscess based on the established criteria and demonstrate the sensitivity and specificity of metabolite markers assigned to specific bacterial groups defined by the microbial culture in 194 patients.

MATERIALS AND METHODS

Conventional MR imaging and in vivo (1)H-MR spectroscopy data were evaluated from patients with pyogenic brain abscesses, with ages ranging from 3 to 60 years. Imaging and (1)H-MR spectroscopy were performed on a 1.5T scanner. After MR imaging was performed and analyzed, pus aspirates were obtained in all patients. The causative organisms were confirmed by pus cultures.

RESULTS

Resonance of AAs with or without other metabolites on in vivo (1)H-MR spectroscopy was observed in 80% of abscesses, with a sensitivity and specificity of 0.72 and 0.30, respectively. Most obligate anaerobes and some facultative anaerobes showed the presence of Lac/Lip, AAs, and Ac with or without Suc. Mostly obligate aerobes or facultative anaerobes showed the presence of Lac and AAs, with or without lipids.

CONCLUSIONS

The presence of AAs on in vivo (1)H-MR spectroscopy is a sensitive marker of pyogenic abscess, but its absence does not rule out a pyogenic etiology. The presence of Ac with or without Suc favors an anaerobic bacterial origin of the abscess; however, this may also be seen in some of the abscesses secondary to facultative anaerobes.

Extraction of actinides using N, N, N′, N′-tetraoctyl diglycolamide (TODGA): a thermodynamic study

The effect of temperature on the extraction behaviour of Am(III), Pu(IV) and U(VI) from nitric acid medium was studied employing N,N,N′,N′-tetraoctyl diglycolamide (TODGA) in n-dodecane. The two-phase equilibrium constants (log K′ex) were calculated and compared with those of other extractants proposed for actinide partitioning, viz. octyl-(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and N,N,N′,N′-dimethyl dibutyl tetradecyl malonamide (DMDBTDMA). Thermodynamic parameters, viz. ΔG, ΔH and ΔS for the extraction of actinides by TODGA were also compared with those of CMPO and DMDBTDMA. These studies indicate that the extraction processes of Am(III) and U(VI) are enthalpy driven whereas entropy factor counteracts the extraction. However, in the case of Pu(IV), the extraction process is enthalpy as well as entropy favoured. Role of diluent on the loading of Nd(III) in 0.1 M TODGA has also been investigated.

A retrospective study of multiple interbody grafting and long segment strut grafting following multilevel anterior cervical decompression

A retrospective study of 201 patients who underwent multilevel anterior cervical decompression and fusion by multiple interbody grafting and long segment strut grafting without plate fixation was conducted from January 1991 to December 2001. Previous studies have reported lower fusion rates for anterior cervical decompressions reconstructed with multiple interbody grafts as opposed to a single long strut graft. Our aim was a retrospective study of two fusion techniques with reference to radiological and clinical outcomes in patients operated by the senior author. Of 132 patients who underwent strut grafting, 124 achieved solid fusion (93.9%), whereas 48 of 69 patients who underwent multiple interbody grafting (69.6%) achieved solid fusion. There were five cases of graft displacement or extrusion among strut-grafted patients and one among patients with interbody grafts. More 'good' and 'excellent' clinical outcomes were found among patients who underwent strut grafting (87.1 v. 81.1%). Patients with pseudoarthrosis had significantly poorer clinical outcomes. Therefore, corpectomy or vertebrectomy and strut grafting should be considered after multilevel anterior cervical decompression to increase the likelihood of successful fusion and to improve clinical outcome.

Comparison Between Prevalence and Patterns of Cigarette Smoking Amongst Sixth form Students in the United Kingdom and Pakistan

Background:

Tobacco smoking is one of the major preventable causes of premature death and disease in the world. Adolescents are amongst the most vulnerable group of individuals in society and are highly susceptible to cigarette smoking. Sixth Formers being the most senior members of the school act as role models to younger pupils and could influence smoking behaviour.

Objective:

In a cross sectional and comparative study we aimed to determine the differences in smoking prevalence and patterns between Sixth Form students in Pakistan (a developing country) and the United Kingdom (a developed country).

Method:

A self-administered questionnaire, adapted from the WHO questionnaire, about tobacco smoking for health professionals was distributed amongst the students. The responses were anonymised to encourage truthful answers; there was no pressure to respond.

Of the 235 participants in the UK, 38 (16%) were regular smokers. Of the 297 participants in Pakistan, 20 (7%) of participants were regular smokers. In both countries there was a significant difference between the genders, with males being more likely to smoke. In Pakistan it was identified that the main reason for smoking was due to peer pressure, where as in the UK it was for recreational and social purposes.

Conclusions:

The prevalence of smoking was higher in UK compared to Pakistan. There was a significant difference in the smoking behaviour patterns in the two countries.

Motor neglect associated with loss of action inhibition

Motor neglect, underuse of one side of the body not explained by weakness or sensory impairment, is a common consequence of stroke that is surprisingly little understood. Behavioural and neuroanatomical hallmarks of the disorder are investigated. Using a masked prime task, it was shown that when patients with left motor neglect plan to move their left hand, irrelevant right limb motor programmes intrude, causing delay. Lesion analysis reveals that such asymmetry of motor programming occurs after infarcts of the right putamen and motor association areas. This demonstration of failure to inhibit ipsilesional limb motor plans suggests potential benefit from interventions that might act to restore balance in action planning.

Characterization of tumefactive demyelinating lesions using MR imaging and in-vivo proton MR spectroscopy

Background and Objectives

Diagnosis of tumefactive demyelinating lesions (TDLs) is challenging to both clinicians and radiologists. Our objective in this study was to analyze and characterize these lesions clinically, biochemically, electrophysiologically, and on imaging.

Methods

A retrospective analysis with prospective follow-up of 18 cases of TDLs was performed. Imaging included T2-, T1-weighted, fluid-attenuated inversion recovery (FLAIR), post-contrast T1-weighted, diffusion weighted imaging (DWI), and proton magnetic resonance spectroscopy (PMRS).

Results

All the lesions appeared hyperintense on T2 and FLAIR images. Increased Apparent diffusion coefficient (ADC) (0.93–2.21 × 10−3 mm2/s) in centre of the lesion was seen in 14/18 cases; however, peripheral restriction (ADC values 0.55–0.64 × 10−3 mm2/s) was noted in 11/18 cases. In all, 13/18 cases showed contrast enhancement with open ring ( n = 5), complete ring ( n = 1), minimal ( n = 4), and infiltrative ( n = 3) pattern of enhancement. Nine of these 13 cases also showed venular enhancement. On PMRS, nine showed glutamate/glutamine (Glx) at 2.4 ppm.

Conclusion

Clinical features along with several MRI characteristics such as open ring enhancement, peripheral restriction on DWI, venular enhancement, and presence of Glx on spectroscopy may be rewarding in differentiating TDLs from neoplastic lesions.

Relationship between blood groups and coronary artery disease

There are mounting evidences of relationship of different blood groups to disease. For many years, ABO blood group has been associated with predisposition to both arterial and venous disorders, such as venous thromboembolism, peripheral vascular disease and coronary artery disease. To evaluate the relationship of ABO and Rhesus blood groups with coronary artery disease. Total ninety five patients with coronary artery disease admitted in the Cardiac Surgery Department of Zarina Sikhder Women Medical College, Dhaka, and ninety five healthy stuff of same Medical College were studied. Their ABO and Rhesus Blood Groups were determined by standard method in the department of Transfusion Medicine, Zarina Sikhder Women Medical College, Dhaka, Bangladesh with full support from the department of Transfusion Medicine, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. The results obtained in this study show that the prevalence of Coronary Artery Disease (CAD) in blood group O is invariably higher than in all other ABO blood groups (p<0.05). It is striking that despite the fact that the most prevalent blood group among Bangladeshi people is phenotype B, the prevalence of CAD risk is associated with phenotype O (Odd ratio 2.034, 95% confidence interval 1.127 to 3.67). This suggests that a certain CAD risk is associated with phenotype O. Thus we conclude that, in Bangladeshi people, blood group phenotype O is associated with a substantially increased risk for CAD.

The role of the thalamus in amnesia: a tractography, high-resolution MRI and neuropsychological study

Although it is well established that thalamic lesions may lead to profound amnesia, the precise contribution of thalamic sub-regions to memory remains unclear. In an influential article Aggleton and Brown proposed that recognition memory depends on two processes supported by distinct thalamic and cortical structures. Familiarity is mediated by the mediodorsal (MD) thalamic nucleus and the entorhinal/perirhinal cortex. Recollection is mediated by the anterior thalamic nucleus (AN), the mamillothalamic tract (MTT) and the hippocampus. The authors also suggested that the lateral dorsal nucleus (LD) may contribute to the thalamic/hippocampus system, thereby implying that the LD may play a role in recollection. Given the finding that material specific amnesia can occur following thalamic lesions, we tested an extension of the Aggleton and Brown model. We predicted that patients with bilateral lesions with a bias to the left or right MD or AN/MTT/LD may exhibit impaired familiarity or recollection on verbal or non-verbal memoranda. We report two patients with highly focal thalamic lesions and profound memory impairments affecting verbal and non-verbal memoranda. For the first time, diffusion-weighted imaging was employed to perform tractography of the MTT along with high-resolution anatomical MRI and detailed assessments of verbal and non-verbal memory. Our data support only some aspects of the Aggleton and Brown model. Both patients had left MD nucleus and AN/MTT lesions and performed poorly on familiarity and recall for verbal memoranda, just as predicted by the model. However, both patients' performance for non-verbal memoranda (human faces and topography) is more difficult to reconcile with the model. Patient 1 had damage to the right AN/MTT/LD with sparing of the MD: familiarity should therefore have been preserved but was not. Patient 2 had damage to the right MD with sparing of AN/MTT: recollection should have been preserved but was not. This finding raises the possibility that fractionation of familiarity and recollection to separate thalamic nuclei may not fully capture the role of thalamic sub-regions in memory function.

Assessment of therapeutic response in brain tuberculomas using serial dynamic contrast-enhanced MRI

AIM

To assess the most useful dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) index in the evaluation of the therapeutic response in brain tuberculoma (BT) patients.

SUBJECTS AND METHODS

Twenty-three patients with 25 BT lesions were serially evaluated using DCE MRI. All lesions were classified into two groups: group I (n=15) included patients who showed clinical, as well as imaging, improvement; and group II (n=10) included patients with either clinical or radiological deterioration. The group I and group II lesions were examined for up to 12 months at 4 monthly intervals. However, the lesions in five patients of group II were excised following clinical deterioration after 4 months of therapy. The perfusion indices, i.e., relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), permeability (k(trans)), and leakage (v(e)), were quantified at each time point. The cellular, necrotic, and total volumes of lesion, together with the oedema volume, were also calculated.

RESULTS

All patients in group I and three in group II showed a significant decrease in all perfusion indices, together with the oedema volume, after 1 year. In these three patients in group II, increase in rCBV was associated with increased cellular volume fraction whereas the k(trans), v(e), and oedema volume decreased significantly after 4 months. In five patients in group II who underwent excision of the lesion after 4 months of therapy due to clinical deterioration, the decrease in rCBV was associated with significant increase in k(trans) and oedema volume without any significant change in lesion volume. The rCBV correlated significantly with the cellular volume, whereas k(trans) showed a significant correlation with the v(e) and oedema volume at each time point.

CONCLUSION

In BT, changes in k(trans) and oedema volume are associated with a therapeutic response at 4 months, even when there is a paradoxical increase in the lesion volume.

Scalp meningioma

Primary extracranial meningiomas occur very rarely. We present a rare case of extracranial meningioma of the transitional variant which was excised satisfactorily. There was no suggestion of any connection to the intracranial compartment or cranial nerves. The underlying galea was uninvolved, suggesting the true extracranial nature of this tumour. This rare diagnosis should nonetheless be kept in the differential diagnosis of scalp tumors.

Comparative evaluation of fungal, tubercular, and pyogenic brain abscesses with conventional and diffusion MR imaging and proton MR spectroscopy

BACKGROUND AND PURPOSE

It is difficult to differentiate the cause of brain abscesses with the use of CT and MR imaging. We did a comparative evaluation of pyogenic, tubercular, and fungal brain abscesses by using conventional, diffusion-weighted imaging (DWI), and proton MR spectroscopy (PMRS) with an aim to define the unique features that may differentiate among the pyogenic, tubercular, and fungal brain abscesses.

MATERIALS AND METHODS

We performed a retrospective analysis on 110 patients with surgically proved brain abscesses. Imaging studies included T2, T1, postcontrast T1, DWI, and PMRS. Apparent diffusion coefficient (ADC) of the wall and cavity of the abscesses were quantified. The morphologic, physiologic, and metabolite features of pyogenic (n=91), tubercular (n=11), and fungal (n=8) abscesses were compared.

RESULTS

The pyogenic abscesses had smooth (55/91) and lobulated (36/91) walls, whereas the tubercular abscesses had smooth (4/11), lobulated (6/11), or crenated walls (1/11) with no intracavitary projections. The fungal abscesses showed irregular walls (lobulated 4/8, crenated 4/8) with intracavitary projections (8/8). The wall as well as the cavity showed low ADC in the pyogenic and tubercular abscesses. In the fungal abscesses, the wall and projections showed low ADC (8/8); however, the cavity itself showed high ADC (8/8). PMRS showed cytosolic amino acids (89/91), acetate (25/91), and succinate (18/91) in the pyogenic abscesses, whereas lipid/lactate (11/11) was seen in the tubercular abscesses. The fungal abscesses showed lipid (4/8), lactate (7/8), amino acids (4/8), and multiple peaks between 3.6 and 3.8 ppm assigned to trehalose (5/8).

CONCLUSION

Based on the morphologic, ADC, and metabolite information, it may be possible to differentiate among the pyogenic, tubercular, and fungal brain abscesses.

Looking at human eyes affects contralesional stimulus processing after right hemispheric stroke

Human eyes are a powerful social cue that may automatically attract the attention of an observer. Here we tested whether looking toward open human eyes, as often arises in standard clinical "confrontation" tests, may affect contralesional errors in a group of right brain-damaged patients showing visual extinction. Patients were requested to discriminate peripheral shape-targets presented on the left, right, or bilaterally. On each trial they also saw a central task-irrelevant stimulus, comprising an image of the eye sector of a human face, with those seen eyes open or closed. The conditions with central eye stimuli open (vs closed) induced more errors for contralesional peripheral targets, particularly for bilateral trials. These results suggest that seeing open eyes in central vision may attract attentional resources there, reducing attention to the periphery, particularly for the affected contralesional side. The seen gaze of the examiner may thus need to be considered during confrontation testing and may contribute to the effectiveness of that clinical procedure.

In vivo demonstration of neuroinflammatory molecule expression in brain abscess with diffusion tensor imaging

BACKGROUND AND PURPOSE

Neuroinflammatory molecules, including tumor necrosis factor-alpha, interleukin1-beta, lymphocyte function associated molecule-1, and intercellular cell adhesion molecule-1 contribute to the development of brain abscess. We hypothesized that the high fractional anisotropy (FA) in the brain abscess cavity reflects the upregulation of these neuroinflammatory molecules.

MATERIALS AND METHODS

Diffusion tensor imaging (DTI) was performed in 24 patients with brain abscess and Staphylococcus aureus-treated as well as nontreated Jurket cell lines (at 4 time points: 1, 24, 48, and 72 hours). Neuroinflammatory molecules were quantified from the brain abscess cavity aspirate of the patients as well as from the heat-killed S aureus-treated and nontreated cell lines and correlated with DTI measures.

RESULTS

The DTI-derived FA strongly correlated with the presence of neuroinflammatory molecules in the pus as well as in S aureus-treated cell lines; no such correlation was observed in nontreated cell lines.

CONCLUSIONS

These data indicate that neuroinflammatory molecules confer high diffusion anisotropy inside the brain abscess cavity. We propose that increased FA reflects upregulated inflammatory response in brain abscess.

Synthesis of carbon nanotubes using Ni95Ti5 nanocrystalline film as a catalyst

Carbon nanotubes (CNTs) were synthesized by low-pressure chemical vapour deposition (LPCVD) using N2:C2H2:H2 gas mixtures on nanocrystalline Ni95Ti5 film. This nanocrystalline film was deposited on silicon substrate using vapour condensation method. The growth temperature and growth time was kept at 800 degrees C and 30 mins, respectively and the pressure was maintained at 10 Torr. The growth mechanism of CNTs was investigated using FESEM, TEM, HRTEM, and Raman Spectroscopy. From FESEM image of Ni95Ti5 nanocrystalline film, it is clear that the particle size varies from 5-10 nm. EDX analysis suggests that Ni95Ti5 alloy contains Ni and Ti both. It is clear from TEM images that CNTs are multiwalled with the diameter varying from 10-30 nm and length of several micrometers. HRTEM image shows that the structure of these multi-walled nanotube (MWNTs) is bamboo-shaped and the catalyst exists at the tip of MWNTs. Fourier Transform Raman Spectroscopy confirmed that graphitic structure of as-prepared CNTs. Field emission measurements reveal that the carbon nanotubes grown for 30 mins showed a turn-on field of 7.2 V/microm, when the current density achieves 10 microA/cm2. The field enhancement factor was calculated to be 708.50 for carbon nanotubes grown for 30 mins.

Neuro-endoscopic management of intraventricular neurocysticercosis (NCC)

OBJECTIVE

Various approaches including endoscopy have been used for the treatment of intraventricular and cisternal NCC. We present our technique of Neuro-endoscopic management of intraventricular NCC.

METHODS

Twenty-one cases, 13 females and 8 males (age range 12-50 years; mean, 25.7 years), of intraventricular NCC [lateral (n = 6), third (n = 6), fourth (n = 10) ventricles including a patient with both lateral and third ventricular cysts] producing obstructive hydrocephalus formed the group of study. Gaab Universal Endoscope System along with 4 mm 0 degrees and 30 degrees rigid telescopes were used through a frontal burr-hole for removal of intraventricular including intra-fourth ventricular (n = 10) NCC. Endoscopic third ventriculostomy (ETV) was done for internal cerebrospinal fluid (CSF) diversion. Average follow up was 18 months.

RESULTS

Complete (n = 18) or partial (n = 2) removal of NCC was done in 20 patients, while a cyst located at foramen of Monro slipped and migrated to occipital or temporal horn in 1 patient. Thirty-degree 4-mm rigid telescope provided excellent image quality with ability to address even intra-fourth ventricular NCC through the dilated aqueduct using a curved tip catheter. No patient required further surgery for their hydrocephalus. There was no operative complication and post-operative ventriculitis was not seen in any case despite partial removal of NCC.

CONCLUSION

Neuro-endoscopic surgery is an effective treatment modality for patients with intraventricular NCC. It effectively restores CSF flow and is capable of removing cysts completely or partially from accessible locations causing mass effect. Partial removal or rupture of the cyst does not affect the clinical outcome of the patients.

Involvement of prefrontal cortex in visual search

Visual search for target items embedded within a set of distracting items has consistently been shown to engage regions of occipital and parietal cortex, but the contribution of different regions of prefrontal cortex remains unclear. Here, we used fMRI to compare brain activity in 12 healthy participants performing efficient and inefficient search tasks in which target discriminability and the number of distractor items were manipulated. Matched baseline conditions were incorporated to control for visual and motor components of the tasks, allowing cortical activity associated with each type of search to be isolated. Region of interest analysis was applied to critical regions of prefrontal cortex to determine whether their involvement was common to both efficient and inefficient search, or unique to inefficient search alone. We found regions of the inferior and middle frontal cortex were only active during inefficient search, whereas an area in the superior frontal cortex (in the region of FEF) was active for both efficient and inefficient search. Thus, regions of ventral as well as dorsal prefrontal cortex are recruited during inefficient search, and we propose that this activity is related to processes that guide, control and monitor the allocation of selective attention.

Dumbbell-shaped paraganglioma of the cervical spine in a child

Paragangliomas are tumors arising from extra-adrenal paraganglia and account for 0.3% of all neoplasms. The carotid body and temporal bone are the most frequent sites of paraganglioma, though it has been reported to occur in almost every part of the body. Spinal paragangliomas are uncommon and mainly take the form of intradural compression of the cauda equina or thoracic cord. Extradural paragangliomas are still rare; only few cases involving the dorsolumbar spine have been reported. We are reporting an interesting case of a dumbbell-shaped primary extradural paraganglioma of the cervical spine in an 8-year-old boy that presented with progressively increasing spastic quadriparesis.

Visual neglect after right posterior cerebral artery infarction

OBJECTIVES

To investigate the characteristics and neuroanatomical correlates of visual neglect after right-sided posterior cerebral artery (PCA) infarction.

METHODS

15 patients with acute PCA strokes were screened for the presence of neglect on a comprehensive battery of cognitive tests. Extra tests of visual perception were also carried out on six patients. To establish which areas were critically associated with neglect, the lesions of patients with and without neglect were compared.

RESULTS

Neglect of varying severity was documented in 8 patients. In addition, higher-order visual perception was impaired in 5 of the 6 patients. Neglect was critically associated with damage to an area of white matter in the occipital lobe corresponding to a white matter tract connecting the parahippocampal gyrus with the angular gyrus of the parietal lobe. Lesions of the thalamus or splenium of the corpus callosum did not appear necessary or sufficient to cause neglect, but may mediate its severity in these patients.

CONCLUSIONS

PCA stroke can result in visual neglect. Interruption of the white matter fibres connecting the parahippocampal gyrus to the angular gyrus may be important in determining whether a patient will manifest neglect.

Prevalence and social correlates of postnatal depression in a low income country

BACKGROUND

Postnatal depression is an important public health problem worldwide. Recent evidence suggests that rates may be relatively higher in developing countries. We aimed to explore the prevalence of postnatal depression and its association with social support and other risk factors in a sample of Pakistani women.

METHODS

Population-based survey of 149 women at 12 weeks postnatal using the Edinburgh Postnatal Depression Scale (EPDS), Multidimensional Scale of Perceived Social Support (MSPSS) and Personal Information Questionnaire (PIQ).

RESULTS

Thirty six percent women scored > or =12 on EPDS. High depression score was associated with lower social support, increased stressful life events in the preceding year and higher levels of psychological distress in the antenatal period.

CONCLUSIONS

There is a high prevalence of postnatal depression in Pakistani women. Early interventions should be developed that target the antenatal period and strengthen social support networks in women at risk.

Cognitive Processes in Saccade Generation

The analysis of saccades offers an opportunity to study a number of different cognitive processes, such as visuospatial attention, working memory, and volitional conflict. A study of saccades in patients with visuospatial hemineglect, who performed a visual search task, showed repeated fixations on targets previously discovered, yet they often failed to retain the information that a particular target had previously been discovered. High-resolution structural brain scanning showed that this abnormality was due either to a lesion in the right intraparietal sulcus or the right inferior frontal lobe. Detailed analysis of the scanpaths suggested that the former location was associated with an accumulating impairment in remapping target locations across saccades or impaired memory of previously inspected target locations, whereas the latter location was more consistent with a failure to inhibit responses to rightward locations. When combined with a spatial bias to the right, such deficits might explain why many neglect patients often reexamine rightward targets, at the expense of items to their left. The functions of the supplementary eye field (SEF), in the medial frontal lobe, in relation to saccade generation are controversial. A series of studies in a patient with a focal lesion of the right SEF has indicated an important role for the SEF in the rapid self-control of saccadic eye movements and in set-switching (i.e., implementing control in situations of response conflict when ongoing saccadic plans have to be changed rapidly), rather than monitoring errors. In a recent fMRI study of normal subjects, it was shown that the SEF is involved in implementing the resolution of any volitional conflict, whereas other presupplementary motor areas are involved in the generation of volitional plans and processing volitional conflict.