Evaluating the utility of quantitative pupillometry in a neuro-critical care setting for the monitoring of intracranial pressure: A prospective cohort study

INTRODUCTION

Assessment of the pupillary light reflex (PLR) is key in intensive care monitoring of neurosurgical patients, particularly for monitoring intracranial pressure (ICP). Quantitative pupillometry using a handheld pupillometer is a reliable method for PLR assessment. However, many variables are derived from such devices. We therefore aimed to assess the performance of these variables at monitoring ICP.

METHODS

Sedated patients admitted to neurocritical care in a tertiary neurosurgical centre with invasive ICP monitoring were included. Hourly measurement of ICP, subjective pupillometry (SP) using a pen torch device, and quantitative pupillometry (QP) using a handheld pupillometer were performed.

RESULTS

561 paired ICP, SP and QP pupillary observations from nine patients were obtained (1122 total pupillary observations). SP and QP had a moderate concordance for pupillary size (κ=0.62). SP performed poorly at detecting pupillary size changes (sensitivity=24%). In 40 (3.6%) observations, SP failed to detect a pupillary response whereas QP did. Moderate correlations with ICP were detected for maximum constriction velocity (MCV), dilation velocity (DV), and percentage change in pupillary diameter (%C). Discriminatory ability at an ICP threshold of >22 mmHg was moderate for MCV (AUC=0.631), DV (AUC=0.616), %C (AUC=0.602), and pupillary maximum size (AUC=0.625).

CONCLUSION

QP is superior to SP at monitoring pupillary reactivity and changes to pupillary size. Although effect sizes were moderate to weak across assessed variables, our data indicates MCV and %C as the most sensitive variables for monitoring ICP. Further study is required to validate these findings and to establish normal range cut-offs for clinical use.

Automated pupillometry in space neuroscience

Modern pupillometers are automated, thereby providing an objective, accurate, and reliable evaluation of various aspects of the pupillary light reflex at precision levels that were previously unobtainable. There are many gaps in knowledge regarding pupil size and pupillary light reflex in nervous system changes related to space travel given the previous lack of a precise method to quantitatively measure it. Automated pupillometry has not been used previously in space. This novel tool has promising uses in altered gravity environments as a sensitive non-invasive tool to determine alterations due to headward fluid shifts and elevated intracranial pressure. This article discusses the potential use of automated pupillometry in space for monitoring of astronaut health and neurological pathology.

A benchtop brain injury model using resected donor tissue from patients with Chiari malformation

The use of live animal models for testing new therapies for brain and spinal cord repair is a controversial area. Live animal models have associated ethical issues and scientific concerns regarding the predictability of human responses. Alternative models that replicate the 3D architecture of the central nervous system have prompted the development of organotypic neural injury models. However, the lack of reliable means to access normal human neural tissue has driven reliance on pathological or post-mortem tissue which limits their biological utility. We have established a protocol to use donor cerebellar tonsillar tissue surgically resected from patients with Chiari malformation (cerebellar herniation towards the foramen magnum, with ectopic rather than diseased tissue) to develop an in vitro organotypic model of traumatic brain injury. Viable tissue was maintained for approximately 2 weeks with all the major neural cell types detected. Traumatic injuries could be introduced into the slices with some cardinal features of post-injury pathology evident. Biomaterial placement was also feasible within the in vitro lesions. Accordingly, this 'proof-of-concept' study demonstrates that the model offers potential as an alternative to the use of animal tissue for preclinical testing in neural tissue engineering. To our knowledge, this is the first demonstration that donor tissue from patients with Chiari malformation can be used to develop a benchtop model of traumatic brain injury. However, significant challenges in relation to the clinical availability of tissue were encountered, and we discuss logistical issues that must be considered for model scale-up.

Phenotyping patients with aortic stenosis using cluster analysis to determine mortality and suitability for transcatheter aortic valve replacement

Background

Current classification of aortic stenosis (AS) is based on guideline-recommended echocardiographic criteria. Heterogeneity of patients with AS is increasingly recognised. Clinical and demographic factors in addition to echocardiographic parameters can determine those who may derive the greatest benefit from transcatheter aortic valvular replacement (TAVR) and influence patient outcomes.

Purpose

Our study aims to define distinct AS echocardiographic and clinical phenotypes and to accurately identify patients most likely to die or benefit from TAVR.

Methods

Patients diagnosed with at least mild AS between 2009 and 2021 (pre-TAVR) from a multicentre echocardiographic database at a quaternary referral centre included. Unsupervised clustering analysis was performed using K-means, partitioning around medoids, density-based spatial clustering, hierarchical clustering algorithms on 56 demographic, echocardiographic and clinical variables. Associations between AS clusters and clinical outcomes (all-cause mortality, cardiovascular death, AS-related death), and effect of TAVR on clinical outcomes were assessed using Cox proportional hazards models.

Results

Four AS clusters were identified amongst 2,456 patients with median follow up of 4.7 years (median age: 77 years, male: 66%).

Cluster 1 (n=542) had the lowest aortic valvular area (AVA, mean 0.89 cm2), highest peak velocity (Vmax) (4.3 m/s), mean gradient (45 mmHg), and the most bicuspid valves (12.7%). Cluster 2 (n=827) had 50% women, mostly in sinus rhythm and less severe echo findings. Cluster 3 (n=592) had predominantly males (85%) with a mean AVA of 1.65 cm2 and the most cardiovascular risk factors (hypertension, diabetes, hyperlipidaemia, stable angina, acute coronary syndrome, and atherosclerosis). Cluster 4 (n=495) had the highest left atrial size (mean 32 cm2), the most atrial fibrillation (82%), heart failure (80%), rheumatic heart disease (26%) and chronic kidney disease (55.8%), but only moderate AS (AVA 1.3 cm2, Vmax 3 m/s). All-cause mortality was highest in Cluster 4 (Hazard ratio (HR) 1.57, 95% CI: 1.33–1.85) and AS-related death was highest in Cluster 1 (HR 3.96, 95% CI: 2.61–5.99, Figure 1A). TAVR reduced AS-related death in only Cluster 1 (HR 0.22, 95% CI: 0.05–0.88, p=0.033, Figure 1B).

Conclusions

We demonstrated that phenotypic classification via a combination of demographics, echocardiography and comorbidities can significantly improve management of AS. This personalised approach can be implemented to identify patients most likely to die and most likely to benefit from TAVR.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): National Heart Foundation of Australia (ID: 102578)National Health and Medical Research Council of Australia (ID: 1191044)

Astrocyte Activation in Neurovascular Damage and Repair Following Ischaemic Stroke

Transient or permanent loss of tissue perfusion due to ischaemic stroke can lead to damage to the neurovasculature, and disrupt brain homeostasis, causing long-term motor and cognitive deficits. Despite promising pre-clinical studies, clinically approved neuroprotective therapies are lacking. Most studies have focused on neurons while ignoring the important roles of other cells of the neurovascular unit, such as astrocytes and pericytes. Astrocytes are important for the development and maintenance of the blood-brain barrier, brain homeostasis, structural support, control of cerebral blood flow and secretion of neuroprotective factors. Emerging data suggest that astrocyte activation exerts both beneficial and detrimental effects following ischaemic stroke. Activated astrocytes provide neuroprotection and contribute to neurorestoration, but also secrete inflammatory modulators, leading to aggravation of the ischaemic lesion. Astrocytes are more resistant than other cell types to stroke pathology, and exert a regulative effect in response to ischaemia. These roles of astrocytes following ischaemic stroke remain incompletely understood, though they represent an appealing target for neurovascular protection following stroke. In this review, we summarise the astrocytic contributions to neurovascular damage and repair following ischaemic stroke, and explore mechanisms of neuroprotection that promote revascularisation and neurorestoration, which may be targeted for developing novel therapies for ischaemic stroke.

Clinical outcomes from antihypertensive therapies in moderate or severe aortic stenosis: a systematic review and meta-analysis

Background

Hypertension can negatively affect prognosis in moderate or severe aortic stenosis (AS), but antihypertensive therapy (AHT) is often avoided due to possible deleterious effects such as reduced coronary perfusion, left ventricular dysfunction and haemodynamic compromise.

Purpose

We systematically assessed and compared clinical outcomes in adults with moderate or severe AS treated with and without AHT.

Methods

Two independent reviewers performed screening, data extraction and risk of bias assessments from a systematic search of the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and grey literature without language restrictions up to September 9, 2019. Conflicts were resolved by the third reviewer. Outcomes of interest included mortality, left ventricular (LV) mass index, systolic blood pressure, diastolic blood pressure, and LV ejection fraction. Meta-analysis with pooled effect sizes using random-effects model, were estimated in R.

Results

Of 3,024 citations, 30 studies (26,224 patients) were included in the qualitative synthesis and 23 studies in meta-analysis. AHT was associated with favourable clinical outcomes and was well tolerated. AHT was associated with lower risk of all-cause mortality (Risk Ratio (RR)=0.69, 95% CI: 0.53–0.90, p=0.01, Figure). The effect size appears to differ with type of aortic valve replacement (AVR). AHT was associated with lower risk of acute kidney injury post-transcatheter AVR (RR=0.13, 95% CI:0.05–0.35, p=0.007). Favourable outcomes such as improved haemodynamic and echocardiographic parameters were demonstrated in some studies, but when pooled in meta-analysis, the differences did not reach statistical significance. However, heterogeneity was significant across studies.

Conclusion

This is the first systematic review and meta-analysis to demonstrate that AHT is safe and has a clinical benefit in patients with advanced stages of AS with significant improvement in survival or reduction in mortality without haemodynamic compromise. Further studies are required to determine the best AHT for patients with moderate or severe AS.

Forest plot of AHT effect on mortality.

Funding Acknowledgement

Type of funding source: None

Effects of patient characteristics and comorbidities on temporal trends of low-flow, low-gradient aortic stenosis phenotypes

Background

Aortic stenosis (AS) is a common primary heart valve disease in the elderly. Low-flow, low-gradient (LFLG) AS is an increasingly important phenotype.

Purpose

To evaluate the temporal changes in incidence of severe AS phenotypes: paradoxical LFLG, classical LFLG and non-LFLG and explore risk factors that contribute to temporal trends.

Methods

We analyzed 25,507 consecutive transthoracic echocardiograms over 6½ years between 2013 and 2019 divided into deciles. LFLG-AS was defined as mean transvalvular pressure gradient <40 mmHg and stroke volume index (SVi) <35 mL/m2, aortic valve area (AVA) <1 cm2 or indexed AVA <0.6 cm2/m2, with either normal (paradoxical LFLG) or decreased (<40%; classical LFLG) left ventricular ejection fraction. Trends and associations with patients characteristics and comorbidities were assessed over time in deciles.

Results

Of 891 cases that fulfilled severe AS criteria, there were 536 cases of LFLG-AS (85 classical and 451 paradoxical LFLG-AS). There was a statistically significant increase in incidence of paradoxical LFLG-AS between each time interval (p<0.0001), while significant reduction in incidence of non-LFLG-AS (p=0.009) that was not seen with classical LFLG-AS (p=0.7) (Figure). More comprehensive echocardiographic assessment of relevant parameters over time assisted with identification of LFLG-AS cases. Intrinsic patient factors such as age and E/e' contributed towards the increasing trend of paradoxical LFLG-AS. There was a rising population aged over 70 years (p=0.01). Multivariate logistic regression analysis showed that age, sex, E/e', obesity, atrial fibrillation and heart rate were potential risk factors responsible for temporal trend towards rising paradoxical LFLG-AS incidence. There was also a gradual increase in number of patients with low transvalvular flow rate (<200mL/s) over time (p=0.04).

Conclusion

The incidence of paradoxical LFLG-AS is rising in a hospital echocardiogram service. The parallel increase in LV filling pressure and age in AS patients suggests the increment in LFLG-AS is related to changes to the LV myocardium.

Subtypes of aortic stenosis over time

Funding Acknowledgement

Type of funding source: None

CHA2DS2-VASc and CHADS2 scores for risk stratification of major adverse cardiovascular events in the COMPASS trial

Background

The COMPASS (Cardiovascular Outcomes for People Using Anticoagulation Strategies) trial demonstrated that the combination therapy of rivaroxaban and aspirin reduced major adverse cardiovascular events (MACE) compared to aspirin alone in patients with chronic coronary artery disease (CAD) and/or peripheral artery disease (PAD).

Purpose

We assessed whether the CHA2DS2-VASc (congestive heart failure (CHF), hypertension, age ≥75 years, diabetes, stroke/transient ischemic attack (TIA)/thromboembolism, vascular disease, age 65–75 years, and sex category) and CHADS2 (CHF, hypertension, age ≥75 years, diabetes, stroke/TIA) scores used to predict the risk of stroke in patients with atrial fibrillation, can be used identify vascular patients at highest risk of recurrent events who may derive greatest benefits of treatment.

Methods

In COMPASS patients, the predictive accuracy of CHA2DS2-VASc and CHADS2 scores were assessed for MACE, bleeding and net clinical benefit using Cox proportional hazards model. Kaplan-Meier estimates of cumulative risk and absolute risk differences were used to examine the effects of rivaroxaban plus aspirin compared with aspirin alone over 30 months according to risk score categories.

Results

In 27,395 participants with CAD and/or PAD, a high CHA2DS2-VASc score (6–9) was associated with 3 times greater absolute risk of MACE compared to a low score (1–2) (hazard ratio=3.39, 95% CI: 2.54–4.51, p<0.0001). The effects of combination therapy with rivaroxaban and aspirin on MACE, bleeding and net clinical benefit were consistent across CHA2DS2-VASc and CHADS2 score categories, with the greatest benefit in those with the highest risk scores (Figure 1). The greatest reduction in MACE with rivaroxaban and aspirin compared to aspirin only was observed in patients treated for 30 months with highest CHA2DS2-VASc score (6–9) (23 events per 1000 patients prevented) or highest CHADS2 score (3–6) (25 events per 1000 patients prevented). There was increased bleeding in patients with higher CHA2DS2-VASc and CHADS2 scores, but net clinical benefit was preserved across all risk categories and was greatest in those with the highest risk scores.

Conclusion

The CHA2DS2-VASc or CHADS2 scores can be used in patients with chronic CAD and/or PAD to identify patients who are at highest risk of MACE, and therefore likely to achieve the greatest benefit of dual pathway inhibition with the combination of rivaroxaban and aspirin compared with aspirin alone.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): This study was sponsored by Bayer AG.

WP1-22 DuraGen™ as an encapsulating material for neural stem cell delivery

Objectives

Achieving neural regeneration after spinal cord injury (SCI) represents a significant challenge. Neural stem cell (NSC) therapy offers replacement of damaged cells and delivery of pro-regenerative factors, but >95% of cells die when transplanted to sites of neural injury. Biomaterial scaffolds provide cellular protective encapsulation to improve cell survival. However, current available scaffolds are overwhelmingly not approved for human use, presenting a major barrier to clinical translation. Surgical biomaterials offer the unique benefit of being FDA-approved for human implantation. Specifically, a neurosurgical grade material, DuraGen™, used predominantly for human duraplasty has many attractive features of an ideal biomaterial scaffold. Here, we have investigated the use of DuraGen™ as a 3D cell encapsulation device for potential use in combinatorial, regenerative therapies.

Methods

Primary NSCs were seeded into optimised sheets of DuraGen™. NSC growth and fate within DuraGen™ were assessed using 3D microscopic fluorescence imaging techniques.

Results

DuraGen™ supports the survival (ca 95% viability, 12 days) and 3D growth of NSCs. NSC phenotype, proliferative capacity and differentiation into astrocytes, neurons and oligodendrocytes were unaffected by DuraGen™.

Conclusions

A ‘combinatorial therapy’, consisting of NSCs protected within a DuraGen™ matrix, offers a potential clinically translatable approach for neural cell therapy.

Identification and validation of two peptide markers for the recognition of Clostridioides difficile MLST-1 and MLST-11 by MALDI-MS

OBJECTIVES

Clostridioides difficile infection (CDI) has become the main cause of nosocomial infective diarrhoea. To survey and control the spread of different C. difficile strains, there is a need for suitable rapid tests. The aim of this study was to identify peptide/protein markers for the rapid recognition of C. difficile strains by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS).

METHODS

We analysed 44 well-characterized strains, belonging to eight different multi-locus sequence types (MLST), using ultrahigh-resolution Fourier transform ion cyclotron resonance (FTICR) MS. The amino acid sequence of two peptide markers specific for MLST-1 and MLST-11 strains was elucidated by MALDI-TOF-MS/MS. The investigation of 2689 C. difficile genomes allowed the determination of the sensitivity and specificity of these markers. C18-solid-phased extraction was used to enrich the MLST-1 marker.

RESULTS

Two peptide markers (m/z 4927.81 and m/z 5001.84) were identified and characterized for MLST-1 and MLST-11 strains, respectively. The MLST-1 marker was found in 786 genomes of which three did not belong to MLST-1. The MLST-11 marker was found in 319 genomes, of which 14 did not belong to MLST-11. Importantly, all MLST-1 and MLST-11 genomes were positive for their respective marker. Furthermore, a peptide marker (m/z 5015.86) specific for MLST-15 was found in 59 genomes. We translated our findings into a fast and simple method that allowed the unambiguous identification of the MLST-1 marker on a MALDI-TOF-MS platform.

CONCLUSIONS

MALDI-FTICR MS-based peptide profiling resulted in the identification of peptide markers for C. difficile MLST-1 and MLST-11.

A fusion of minicircle DNA and nanoparticle delivery technologies facilitates therapeutic genetic engineering of autologous canine olfactory mucosal cells

Olfactory ensheathing cells (OECs) promote axonal regeneration and improve locomotor function when transplanted into the injured spinal cord. A recent clinical trial demonstrated improved motor function in domestic dogs with spinal injury following autologous OEC transplantation. Their utility in canines offers promise for human translation, as dogs are comparable to humans in terms of clinical management and genetic/environmental variation. Moreover, the autologous, minimally invasive derivation of OECs makes them viable for human spinal injury investigation. Genetic engineering of transplant populations may augment their therapeutic potential, but relies heavily on viral methods which have several drawbacks for clinical translation. We present here the first proof that magnetic particles deployed with applied magnetic fields and advanced DNA minicircle vectors can safely bioengineer OECs to secrete a key neurotrophic factor, with an efficiency approaching that of viral vectors. We suggest that our alternative approach offers high translational potential for the delivery of augmented clinical cell therapies.

Dermatoglyphic variation among the Limboo of Sikkim, India

Variations in finger and palmar dermatoglyphic patterns are investigated among the Limboo (18-60 years, 150 males and 150 females), a little known population of Sikkim. The results for Limboo were compared with other North-East Indian populations. The most commonly occurring pattern was loop (males: 64.33%; females: 75.00%) followed by whorl (males: 31.00%; females: 21.33%) and finally arch (males: 4.67%; females: 3.66%). There were no significant differences between sexes in pattern types. The overall values of pattern intensity (P.I.I.), Dankmeijer's (D.I.) and Furuhata's (F.I.) indices were 14.08, 12.60 and 96.06 respectively. The P.I.I. was within the range for East Asian populations of North-East India. The D.I. was similar to those reported for Rajbanshi, Kalita, Rabha and Newar populations, while F.I. was higher than in other populations of Eastern Himalaya and North-East India. The most frequently occurring mainline formulae in all palm prints (left and right combined) were 7.5'.5.- followed by 9.7.5.- and finally 11.9.7.- (p>0.05) and these were similar to the reported values for other North-eastern populations of India. The mean values of total finger ridge count (TFRC) and absolute finger ridge count (AFRC) were greater among males (138.03; s=42.26 and 198.78; s=77.4) than females (137.91; s=44.15 and 194.47; s=86.71). The a-b ridge count was greater among females than males. Sex differences in AFRC and a-b ridge count were both statistically significant (p<0.05). The mean TFRC values were within ranges for populations of North-East India. Cluster analysis based on P.I.I., D.I. and F.I. shows affinity of the Limbo to some of the populations of Assam and North-East India.

The usefulness of the Loewenstein Occupational Therapy Cognition Assessment in evaluating cognitive function in patients with stroke

OBJECTIVE

We wished to evaluate the usefulness of the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) in early detection of the Vascular Cognitive Impairment, No Dementia (VCIND) in patients with stroke. We also wanted to compare LOTCA with the Mini-Mental State Examination (MMSE).

PATIENTS AND METHODS

Thirty patients with stroke and cognitive impairment comprised the cognitive impairment group. Another 30 patients with stroke and no cognitive impairment served as the stroke control group, while 30 healthy individuals served as the normal control group.

RESULTS

The age, gender, and education level were comparable among three study groups. All subjects were assessed with both tests. Total LOTCA scores strongly and positively correlated with total MMSE scores in patients with cognitive impairment (r = 0.934, p < 0.001). The correlations were also present between every sub-items of LOTCA and those of MMSE (p < 0.01). In addition, total scores and sub-item scores in LOTCA were significantly lower in the cognitive impairment group compared with both stroke control and normal control groups (p < 0.01), especially, with regard to scores of thinking operations, orientation, and visuomotor organization. The sub-item scores in LOTCA, including thinking operations, visuomotor organization, attention, orientation, and spatial perception were significantly lower in the stroke control group compared with normal control group (p < 0.01), especially in thinking operations and visuomotor organization. There is a good agreement between LOTCA and MMSE.

CONCLUSIONS

Compared with MMSE, LOTCA can detect VCIND earlier and more comprehensively, and can, thus, be used clinically for VCIND detection.

Histopathologic changes following neoadjuvant chemotherapy in locally advanced breast cancer

AIMS

To compare the clinical and pathologic assessment of response to neoadjuvant chemotherapy and describe the various histopathologic changes observed.

MATERIALS AND METHODS

We studied a group of 40 patients with locally advanced breast cancer who had their initial workup in the form of clinico-imaging assessment of the size and pretreatment biopsy from the lesion. All the patients received two to six cycles of neoadjuvant chemotherapy, either cyclophosphamide 50 to 60 mg/m 2 IV, doxorubicin 40 to 50 mg/m 2 IV and 5-fluorouracil 500 to 800 mg/m 2 IV (CAF) or cyclophosphamide, epirubicin, and 5-fluorouracil (CEF). Clinical and pathologic assessment of response to chemotherapy was done based on the UICC guidelines.

RESULT

Complete clinical response (cCR) was seen in 10% cases (4/40), thirty percent patients had (12/40) partial response and 60% (24/40) had stable disease after neoadjuvant chemotherapy. Pathologic complete response (pCR) with no evidence of viable tumor was observed in 20% patients (8/40). Fifteen patients (37.5%) showed partial response and 42.5% patients (17/40) had a stable disease. No patient progressed during the course of chemotherapy. Changes in the tumor type were observed following chemotherapy, most common being the mucinous change. Histologic changes like dyscohesion, shrinkage of tumor cells, elastosis, collagenization, necrosis, lymphocytic reaction, giant cell response are some of the common observations seen following treatment with neoadjuvant chemotherapy.

CONCLUSION

Pathologic assessment of response to neoadjuvant chemotherapy is a better predictor than the clinical response. The chemotherapy drugs can be modified based on the response observed after 1-2 cycles of neoadjuvant, the response being based on both tumor and patient's responsiveness.

Benign vs malignant soft tissue neoplasms: limitations of magnetic resonance imaging

AIMS

Various features have been described in the literature to differentiate benign from malignant lesions. The aim of the present study was to study the accuracy of each of these features and that of magnetic resonance imaging (MRI) in diagnosing malignant lesions.

MATERIALS AND METHODS

Fifty-five consecutive patients presenting with neoplastic (both benign and malignant) lesions diagnosed clinically and on ultrasound were studied and their MRI features were compared with the findings on surgical exploration and histopathologic examination.

RESULTS

There were 32 (58%) benign and 23 (42%) malignant masses. Malignant masses were more common in patients older than 20 years (83%), and these had symptoms of less than 6 months duration (75%), as against benign lesions. The swelling was painful in 8 malignant masses and these were more common in the upper limbs (61%). Various features of malignant lesions were size more than 5 cm in 83%, change in signal intensity from homogenous on T1-weighted images to heterogenous on T2-weighted images in 74%, irregular margins in 74%, and heterogenous contrast enhancement in 91%. The accuracy of these features was 76%, 58%, 78%, and 60%, respectively. Most benign and malignant lesions were intramuscular in location. A significant number (38%) of benign lesions were located in the intermuscular facial plane. Definitive diagnosis was made in 42% of the lesions.

CONCLUSIONS

MRI is an excellent modality for evaluating soft tissue neoplasms; however, prediction of a specific diagnosis and differentiation of malignant and benign lesions is not always possible.

Free phenytoin concentration measurement in brain extracellular fluid: a pilot study

This article investigates the relationship between brain extracellular fluid free phenytoin concentration and plasma free phenytoin concentration in adults with acute brain injury. Daily cerebral microdialysate free phenytoin concentration was measured in eight adults with acute brain injury and compared with simultaneous measurement of plasma free phenytoin concentration. The group data revealed no significant correlation between microdialysate and plasma free phenytoin concentration (r = 0.34, p = 0.41). However, in two patients, with a sufficient number of samples for intra-individual analysis, there was a significant correlation between microdialysate and plasma free phenytoin concentration (r = 0.92, p < 0.001 and r = 0.88, p < 0.01). In vitro microdialysis relative recovery for phenytoin was 2.1%. In the context of acute brain injury, measurement of free plasma phenytoin concentration may not provide an accurate reflection of regional brain extracellular fluid free phenytoin concentration and may have limitations with respect to achieving reproducible brain extracellular fluid free phenytoin concentrations. This has implications for dosing regimens relying on plasma phenytoin levels.

Pathogenesis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage: putative mechanisms and novel approaches

Cerebral vasospasm is a potentially incapacitating or lethal complication in patients with aneurysmal subarachnoid hemorrhage (SAH). The development of effective preventative and therapeutic interventions has been largely hindered by the fact that the underlying pathogenic mechanisms of cerebral vasospasm remain poorly understood. However, intensive research during the last 3 decades has identified certain mechanisms that possibly play a role in its development. Experimental data suggest that calcium-dependent and -independent vasoconstriction is taking place during vasospasm. It appears that the breakdown products of blood in the subarachnoid space are involved, through direct and/or indirect pathways, in the development of vasospasm after SAH. Free radicals reactions, an imbalance between vasoconstrictor and vasodilator substances (endothelium derived substances, e.g., nitric oxide, endothelin; arachidonic acid metabolites, e.g., prostaglandins, prostacyclin), inflammatory processes, an upheaval of neuronal mechanisms that regulate vascular tone, endothelial proliferation, and apoptosis have all been put forward as causative and/or pathogenic factors. Translational research in the field of vasospasm has traditionally aimed to identify agents/interventions in order to block the cascades initiated after SAH. The combination of novel approaches such as cerebral microdialysis, magnetic resonance spectroscopy, proteomics, and lipidomics could serve a dual purpose: elucidating the complex pathobiochemistry of vasospasm and providing clinicians with tools for early detection of this feared complication. The purpose of this Mini-Review is to provide an overview of the pathogenesis of cerebral vasospasm and of novel approaches used in basic and translational research.

Infiltrative ophthalmopathy and primary hypothyroidism: a rare clinical manifestation of a common disease

The association of infiltrative ophthalmopathy with primary hypothyroidism is uncommon. We describe two such cases manifesting at different times during the course of primary hypothyroidism. The successful outcome of the present cases suggests that the timely addition of levothyroxine treatment alone or in combination with steroids is useful and effective in the management of hypothyroid Graves' ophthalmopathy.

Human milk fortification and gastric emptying in the preterm neonate

Fortification of expressed breast milk (EBM) is widely recommended for preterm feeding. Fortification of EBM results in increased caloric density and osmolarity, both of which may retard gastric emptying. As gastric emptying is a major determinant of feed tolerance, we investigated the effect of fortification (with Lactodex HMF) of EBM on gastric emptying in preterm neonates. The half gastric emptying time was measured using real time ultrasonography in 25 consecutive preterm neonates first on EBM alone, then on EBM + Lactodex HMF. Each baby served as its own control. The students t-test was used for statistical analysis. The mean gestation age was 34.48 +/- 0.77 weeks. The mean birth weight was 1.92 +/- 0.14 kg. The mean half gastric emptying time at an age of 5.4 +/- 0.86 days on EBM was 24.00 +/- 5.00 min and 24.40 +/- 5.06 min on EBM + human milk fortifier (HMF). The same at 2nd assessment (15.2 +/- 1.79 days), with EBM was 22.80 +/- 4.58 min vs. 23.60 +/- 4.89 min when given EBM + HMF. These differences were not statistically significant. Fortification of EBM with Lactodex HMF does not affect the gastric emptying in preterm neonates and therefore is unlikely to affect feed tolerance in them.

Metabolic failure precedes intracranial pressure rises in traumatic brain injury: a microdialysis study

BACKGROUND

Cerebral microdialysis (MD) is able to detect markers of tissue damage and cerebral ischaemia and can be used to monitor the biochemical changes subsequent to head injury. In this prospective, observational study we analysed the correlation between microdialysis markers of metabolic impairment and intracranial pressure (ICP) and investigated whether changes in biomarker concentration precede rises in ICP.

METHODS

MD and ICP monitoring was carried out in twenty-five patients with severe TBI in Neurointensive care. MD samples were analysed hourly for lactate:pyruvate (LP) ratio, glutamate and glycerol. Abnormal values of microdialysis variables in presence of normal ICP were used to calculate the risk of intracranial hypertension developing within the next 3 h.

FINDINGS

An LP ratio >25 and glycerol >100 micromol/L, but not glutamate >12 micromol/L, were associated with significantly higher risk of imminent intracranial hypertension (odds ratio: 9.8, CI 5.8-16.1; 2.2, CI 1.6-3.8; 1.7, CI 0.6-3, respectively). An abnormal LP ratio could predict an ICP rise above normal levels in 89% of cases, whereas glycerol and glutamate had a poorer predictive value.

CONCLUSIONS

Changes in the compound concentrations in microdialysate are a useful tool to describe molecular events triggered by TBI. These changes can occur before the onset of intracranial hypertension, suggesting that biochemical impairment can be present before low cerebral perfusion pressure is detectable. This early warning could be exploited to expand the window for therapeutic intervention.

S100B in neuropathologic states: the CRP of the brain?

In recent years there has been a proliferation of interest in the brain-specific protein S100B, its many physiologic roles, and its behaviour in various neuropathologic conditions. Since the mid-1960s, its wide variety of intracellular and extracellular activities has been elucidated, and it has also been implicated in an increasing number of central nervous system (CNS) disorders. S100B is part of a superfamily of proteins, some of which (including S100B) have been implicated as calcium-dependent regulatory proteins that modulate the activity of effector proteins or cells. S100B is primarily an astrocytic protein. Within cells, it may have a role in signal transduction, and it is involved in calcium homeostasis. Information about the functional implication of S100B secretion by astrocytes into the extracellular space is scant but there is substantial evidence that secreted glial S100B exerts trophic or toxic effects depending on its concentration. This review summarises the historic development and current knowledge of S100B, including recent interesting findings relating S100B to a diversity of CNS pathologies such as traumatic brain injury, Alzheimer's disease, Down's syndrome, schizophrenia, and Tourette's syndrome. These broad implications have led some workers to describe S100B as 'the CRP (C-reactive protein) of the brain.' This review also examines S100B's potential role as a neurologic screening tool, or biomarker of CNS injury, analogous to the role of CRP as a marker of systemic inflammation.

Extracellular N-acetylaspartate depletion in traumatic brain injury

N-Acetylaspartate (NAA) is almost exclusively localized in neurons in the adult brain and is present in high concentration in the CNS. It can be measured by proton magnetic resonance spectroscopy and is seen as a marker of neuronal damage and death. NMR spectroscopy and animal models have shown NAA depletion to occur in various types of chronic and acute brain injury. We investigated 19 patients with traumatic brain injury (TBI). Microdialysis was utilized to recover NAA, lactate, pyruvate, glycerol and glutamate, at 12-h intervals. These markers were correlated with survival and a 6-month Glasgow Outcome Score. Eleven patients died and eight survived. A linear mixed model analysis showed a significant effect of outcome and of the interaction between time of injury and outcome on NAA levels (p = 0.009 and p = 0.004, respectively). Overall, extracellular NAA was 34% lower in non-survivors. A significant non-recoverable fall was observed in this group from day 4 onwards, with a concomitant rise in lactate-pyruvate ratio and glycerol. These results suggest that mitochondrial dysfunction is a significant contributor to poor outcome following TBI and propose extracellular NAA as a potential marker for monitoring interventions aimed at preserving mitochondrial function.

Extracellular fluid S100B in the injured brain: a future surrogate marker of acute brain injury?

The authors describe the measurement of S100B protein in brain extracellular fluid (ECF) of patients with acute brain injury (traumatic brain injury and subarachnoid haemorrhage) using the technique of microdialysis. To our knowledge, this is the first report of S100B measurement in the human brain. Acute Brain Injury (ABI) is a leading cause of death and disability and the need for a practical and sensitive biochemical marker for monitoring these patients is urgent. The calcium binding astrocyte protein, S100B, may be a candidate for this role. Previous serum studies have shown S100B to be a sensitive predictor of mortality and rise in intracranial pressure in ABI, but it has never before been measured directly within the brain. The ECF reflects the local biochemistry of the brain parenchyma, and the use of intracerebral microdialysis opens up the possibility of studying many novel surrogate markers of injury in the laboratory, in addition to the conventional markers it measures at the bedside (lactate, pyruvate, glucose, and glycerol). In this preliminary report of two cases, the authors demonstrate the quantification of S100B in ECF microdialysate, and investigate whether changes in hourly S100B profile can be related to secondary brain injury. It is shown that extracellular concentrations of S100B change markedly in response to secondary brain injury. Further investigation is required to determine whether extracellular S100B measurement in ABI could assist in patient management.

Axonal pathology in subarachnoid and intracerebral hemorrhage

Electrically active axons degenerate in the presence of nitric oxide (NO) in vitro. High CSF NO concentrations have been observed in patients with hemorrhagic brain injury such as subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH). This study investigated the evidence for axonal injury in SAH and ICH and related this to CSF NO levels. In this study, neurofilament phosphoforms (NfH(SMI34), NfH(SMI35), NfH(SMI38), NfH(SMI310)), surrogate markers for axonal injury, and NO metabolites (nitrate, nitrite = NOx) were measured by ELISA in cerebrospinal fluid (CSF) from patients with SAH and ICH and from a group of controls. Injury severity was classified using the Glasgow Coma Scale, and survival was used as the outcome measure. Compared to the control group, a higher proportion of patients with SAH and ICH had elevated NfH(SMI34) levels from day 0 to day 6 (p < 0.001), elevated NfH(SMI35) levels from day 1 to 6 (p < 0.001), and elevated NfH(SMI310) levels at day 0, 1, 4, and 6 (p < 0.001). The NOx levels were higher in the SAH and ICH patients than in the controls (p < 0.05) and distinguished the non-survivors from the survivors (p < 0.05). No direct correlation was found for NOx with any of the NfH phosphoforms. This study provides evidence for primary and secondary axonal injury in patients with SAH and ICH, with non-survivors also having higher NOx levels. CSF NfH phosphoforms might emerge as a putative surrogate marker for monitoring the development for secondary axonal degeneration in neurocritical care and guiding targeted neuroprotective strategies.

Chromogranin A, a Marker of the Therapeutic Success of Resection of Neuroendocrine Liver Metastases: Preliminary Report

Recent publications indicate that life may be prolonged by surgical debulking of neuroendocrine tumors. A minimum 90% reduction of liver metastases has been suggested to alleviate symptoms of the carcinoid. We have used the tumor marker chromogranin A (CgA) to assess hepatic resection in patients with neuroendocrine metastatic tumor disease. Since 1998, seven patients (3 men) of median age 73 years (range 64-84 years) with carcinoid primary tumors in the ileum who had solitary (n = 2) or multiple (n = 5) liver metastases underwent hepatic resections. Two patients had synchronous small intestinal and liver resections; the rest had deferred hepatic resections after intestinal resection. Hormonal manifestations in the form of loose stools or diarrhea or flushing were observed in five patients, and five had abdominal symptoms from partial obstruction of the small bowel. The resection was deemed radical in five patients. Two patients with non-radical resection needed postoperative octreotide treatment, and symptoms were alleviated or improved in the others. All seven patients are alive with an observation period from 6 to 64 months (median 36 months). Median CgA (normal < 30 ng/ml) was 292 ng/ml (range 79-14,000 ng/ml) before liver surgery. Postoperatively, CgA became normal in three of the radically resected patients, whereas in two others, it decreased to a lowest median level of 79 ng/ml (range 52-105 ng/ml). In two palliatively resected patients, one had a near normalization to 65 ng/ml, and the last patient had a reduction from 14,000 to 2400 ng/ml following debulking surgery. A similar postoperative reduction was noted for 24 hr urinary 5-HIAA excretion. Postoperative octreotide scintigraphy suggested residual hepatic or extrahepatic tumors in three of the patients thought radically resected, whereas two had no clear sign of disease corresponding to a normal CgA value. The CgA values, however, reflected the extent of positive scintigraphy findings. Serum CgA levels monitored the extent and short-term course of the disease and corresponded well with scintigraphy findings and 5-HIAA excretion, but prolonged follow-up in more patients may be necessary before decisive conclusions are allowed to be drawn.

IS ASPECT RATIO A RELIABLE PREDICTOR OF INTRACRANIAL ANEURYSM RUPTURE?

OBJECTIVE

This study was undertaken to assess the reliability of the aspect ratio (AR) (i.e., aneurysm depth to aneurysm neck) in predicting aneurysm rupture. It has been shown that the AR is a key factor in predicting intraaneurysmal blood flow and aneurysm rupture.

METHODS

Seventy-five patients with subarachnoid hemorrhage and multiple aneurysms were studied. The sizes of the aneurysms and their ARs were determined by examining the angiographic films. By comparing the difference between ruptured and unruptured aneurysms in the same individual, each patient in effect served as his or her own control. Each ruptured aneurysm was confirmed during surgery.

RESULTS

There were 75 ruptured and 107 unruptured aneurysms. The mean AR was 2.70 for ruptured aneurysms, compared with 1.8 for unruptured aneurysms. This difference between the ARs was statistically significant (P < 0.001). The difference in aneurysm sizes in the two groups also was significant (P < 0.001).

CONCLUSION

AR on its own is as reliable a variable as the size of the aneurysm for predicting aneurysm rupture.

Use of a herbicide or lysine plus threonine for non-antibiotic selection of transgenic chickpea

A desensitized aspartate kinase (AK) gene has been developed as a non-antibiotic selection marker for use in the production of transgenic chickpea ( Cicer arietinum L.). Transgenic shoots regenerated from embryo explants bombarded with the desensitized AK gene were selected on media containing two amino acids, lysine and threonine (LT). Approximately 15% of the putative transgenic shoots of vars. P-362 and P-1042 survived after 4 weeks of growth on MSB5 medium (MS mineral salts and B5 vitamins) containing 2 microM thidiazuron (TDZ) and 2 mM lysine and 2 m M threonine. These shoots were subsequently grown on MSB5 medium supplemented with 2 micro M TDZ and 5 mM lysine and 5 mM threonine, and nearly 1% continued to grow after 16 weeks of selection. A phosphinothricin (PPT) selection system for Agrobacterium-mediated chickpea transformation was also developed. Three varieties of chickpea, P-362, P-1042 and P-1043, were successfully used for Agrobacterium transformation. Following Agrobacterium infection, 3-8% of the regenerated shoots remained green and continued to grow on MSB5 medium supplemented with 2.5 mg l(-1 )PPT. Increasing the concentrations of PPT to 15 mg l(-1) reduced transgenic shoot production in P-362, P-1042 and P-1043 to 0.7%, 1.2% and 1.1%, respectively. Selected putatively transformed shoots of all three varieties were rooted and grown to maturity. Southern hybridization analysis revealed single as well as multiple integration of genes in selected transgenic lines. The level of AK activity detected in LT-selected plants was higher than that detected in the non-transformed control.

Triple-H therapy in the management of aneurysmal subarachnoid haemorrhage

Cerebral vasospasm is a recognised but poorly understood complication for many patients who have aneurysmal subarachnoid haemorrhage and can lead to delayed ischaemic neurological deficit (stroke). Morbidity and mortality rates for vasospasm are high despite improvements in management. Since the middle of the 1970s, much has been written about the treatment of cerebral vasospasm. Hypervolaemia, hypertension, and haemodilution (triple-H) therapy in an intensive-care setting has been shown in some studies to improve outcome and is an accepted means of treatment, although a randomised controlled trial has never been undertaken. In this review, the rationale for this approach will be discussed, alongside new thoughts and future prospects for the management of this complex disorder.

Clinical profile in gelatinous bone marrow transformation

OBJECTIVE

To study the clinical spectrum associated with gelatinous bone marrow transformation (GMT).

METHODS

All subjects whose bone marrow aspiration showed pink purple material on Leishman stain underwent a detail history, clinical examination and investigation (biochemical/microbiological/radiological). Additionally, in each subject the smear was stained with special stains of Periodic Acid Schiff and Alcian blue.

RESULTS

Out of total 1498 marrows, 65 showed evidence of GMT. All of these had anaemia. The associated clinical spectra of diseases noticed were: Infection (31 cases), Nutritional deficiency (5 cases), Haematological disorders (Aplastic/toxic depression) (17 cases), Malignancies (3 cases), and Miscellaneous (9 cases).

CONCLUSION

Based on the heterogenecity of associated clinical disorders, GMT indicates severe illness and not a particular disease. GMT may be a result of bioregulatory process (which presently needs further prospective studies) that are activated in different pathologic conditions but resulting in similar lesion in the bone marrow and so till then it may be concluded that GMT is a symptom of bone marrow.

A prospective study of the rate of falls before and after cataract surgery

BACKGROUND

There has been considerable interest in the development of intervention programmes aimed at reducing the risk of falls. The primary objective was to ascertain whether cataract surgery reduced the risk of falls in elderly patients with age related cataract.

METHODS

97 patients scheduled for cataract surgery were enrolled in this prospective clinical study. The patients were assessed for established risk factors for falls preoperatively and postoperatively. Patients were issued with a diary to record any falls and phoned at 2 monthly intervals during the 6 month preoperative and postoperative periods.

RESULTS

Of the 84 patients who completed the study, 31 recorded falls during the preoperative period (37%). This group showed a statistically significant reduction in the number of fallers in the postoperative period (n = 6, p<0.001)

CONCLUSION

These results suggest that cataract surgery is an effective intervention to reduce the risk of falls in elderly patients with cataract related visual impairment.