Interpretable surface-based detection of focal cortical dysplasias: a Multi-centre Epilepsy Lesion Detection study

One outstanding challenge for machine learning in diagnostic biomedical imaging is algorithm interpretability. A key application is the identification of subtle epileptogenic focal cortical dysplasias (FCDs) from structural MRI. FCDs are difficult to visualize on structural MRI but are often amenable to surgical resection. We aimed to develop an open-source, interpretable, surface-based machine-learning algorithm to automatically identify FCDs on heterogeneous structural MRI data from epilepsy surgery centres worldwide. The Multi-centre Epilepsy Lesion Detection (MELD) Project collated and harmonized a retrospective MRI cohort of 1015 participants, 618 patients with focal FCD-related epilepsy and 397 controls, from 22 epilepsy centres worldwide. We created a neural network for FCD detection based on 33 surface-based features. The network was trained and cross-validated on 50% of the total cohort and tested on the remaining 50% as well as on 2 independent test sites. Multidimensional feature analysis and integrated gradient saliencies were used to interrogate network performance. Our pipeline outputs individual patient reports, which identify the location of predicted lesions, alongside their imaging features and relative saliency to the classifier. On a restricted 'gold-standard' subcohort of seizure-free patients with FCD type IIB who had T1 and fluid-attenuated inversion recovery MRI data, the MELD FCD surface-based algorithm had a sensitivity of 85%. Across the entire withheld test cohort the sensitivity was 59% and specificity was 54%. After including a border zone around lesions, to account for uncertainty around the borders of manually delineated lesion masks, the sensitivity was 67%. This multicentre, multinational study with open access protocols and code has developed a robust and interpretable machine-learning algorithm for automated detection of focal cortical dysplasias, giving physicians greater confidence in the identification of subtle MRI lesions in individuals with epilepsy.

Interictal and seizure-onset EEG patterns in malformations of cortical development: A systematic review

OBJECTIVES

Malformations of cortical development (MCDs) are common causes of drug-resistant epilepsy. The mechanisms underlying the associated epileptogenesis and ictogenesis remain poorly elucidated. EEG can help in understanding these mechanisms. We systematically reviewed studies reporting scalp or intracranial EEG features of MCDs to characterise interictal and seizure-onset EEG patterns across different MCD types.

METHODS

We conducted a systematic review in accordance with PRISMA guidelines. MEDLINE, PubMed, and Cochrane databases were searched for studies describing interictal and seizure-onset EEG patterns in MCD patients. A classification framework was implemented to group EEG features into 20 predefined patterns, comprising nine interictal (five, scalp EEG; four, intracranial EEG) and 11 seizure-onset (five, scalp EEG; six, intracranial EEG) patterns. Logistic regression was used to estimate the odds ratios (OR) of each seizure-onset pattern being associated with specific MCD types.

RESULTS

Our search yielded 1682 studies, of which 27 comprising 936 MCD patients were included. Of the nine interictal EEG patterns, five (three, scalp EEG; two, intracranial EEG) were detected in ≥2 MCD types, while four (rhythmic epileptiform discharges type 1 and type 2 on scalp EEG; repetitive bursting spikes and sporadic spikes on intracranial EEG) were seen only in focal cortical dysplasia (FCD). Of the 11 seizure-onset patterns, eight (three, scalp EEG; five, intracranial EEG) were found in ≥2 MCD types, whereas three were observed only in FCD (suppression on scalp EEG; delta brush on intracranial EEG) or tuberous sclerosis complex (TSC; focal fast wave on scalp EEG). Among scalp EEG seizure-onset patterns, paroxysmal fast activity (OR = 0.13; 95% CI: 0.03-0.53; p = 0.024) and repetitive epileptiform discharges (OR = 0.18; 95% CI: 0.05-0.61; p = 0.036) were less likely to occur in TSC than FCD. Among intracranial EEG seizure-onset patterns, low-voltage fast activity was more likely to be detected in heterotopia (OR = 19.3; 95% CI: 6.22-60.1; p < 0.001), polymicrogyria (OR = 6.70; 95% CI: 2.25-20.0; p = 0.004) and TSC (OR = 4.27; 95% CI: 1.88-9.70; p = 0.005) than FCD.

SIGNIFICANCE

Different MCD types can share similar interictal or seizure-onset EEG patterns, reflecting common underlying biological mechanisms. However, selected EEG patterns appear to point to distinct MCD types, suggesting certain differences in their neuronal networks.

Atlas of lesion locations and postsurgical seizure freedom in focal cortical dysplasia: A MELD study

OBJECTIVE

Drug-resistant focal epilepsy is often caused by focal cortical dysplasias (FCDs). The distribution of these lesions across the cerebral cortex and the impact of lesion location on clinical presentation and surgical outcome are largely unknown. We created a neuroimaging cohort of patients with individually mapped FCDs to determine factors associated with lesion location and predictors of postsurgical outcome.

METHODS

The MELD (Multi-centre Epilepsy Lesion Detection) project collated a retrospective cohort of 580 patients with epilepsy attributed to FCD from 20 epilepsy centers worldwide. Magnetic resonance imaging-based maps of individual FCDs with accompanying demographic, clinical, and surgical information were collected. We mapped the distribution of FCDs, examined for associations between clinical factors and lesion location, and developed a predictive model of postsurgical seizure freedom.

RESULTS

FCDs were nonuniformly distributed, concentrating in the superior frontal sulcus, frontal pole, and temporal pole. Epilepsy onset was typically before the age of 10 years. Earlier epilepsy onset was associated with lesions in primary sensory areas, whereas later epilepsy onset was associated with lesions in association cortices. Lesions in temporal and occipital lobes tended to be larger than frontal lobe lesions. Seizure freedom rates varied with FCD location, from around 30% in visual, motor, and premotor areas to 75% in superior temporal and frontal gyri. The predictive model of postsurgical seizure freedom had a positive predictive value of 70% and negative predictive value of 61%.

SIGNIFICANCE

FCD location is an important determinant of its size, the age at epilepsy onset, and the likelihood of seizure freedom postsurgery. Our atlas of lesion locations can be used to guide the radiological search for subtle lesions in individual patients. Our atlas of regional seizure freedom rates and associated predictive model can be used to estimate individual likelihoods of postsurgical seizure freedom. Data-driven atlases and predictive models are essential for evidence-based, precision medicine and risk counseling in epilepsy.

Seizure Outcome After Surgery for MRI-Diagnosed Focal Cortical Dysplasia: A Systematic Review and Meta-analysis

OBJECTIVE

Focal cortical dysplasia (FCD) has been associated with poorer post-surgical seizure outcomes compared to other pathologies. FCD surgical series have been assembled on the basis of a histological diagnosis, including patients with abnormal as well as normal pre-operative MRI. However, in clinical workflow, patient selection for surgery is based on pre-operative findings, including MRI. We performed a systematic review and meta-analysis of the literature to determine the rate and predictors of favorable seizure outcome after surgery for MRI-detected FCD.

METHODS

We devised our study protocol in accordance with PRISMA guidelines and registered the protocol with PROSPERO. We searched MEDLINE, EMBASE, and Web of Science for studies of patients followed for ≥12 months after resective surgery for drug-resistant epilepsy with MRI-detected FCD. Random-effects meta-analysis was used to calculate the proportion of patients attaining a favorable outcome, defined as Engel Class I, ILAE Classes 1-2, or "seizure-free" status. Meta-regression was performed to investigate sources of heterogeneity.

RESULTS

Our search identified 3,745 references. Of these, 35 studies (total of 1,353 patients) were included. Most studies (89%) followed patients for ≥24 months post-surgery. The overall post-surgical favorable outcome rate was 70% (95% CI: 64-75). There was high inter-study heterogeneity. Favorable outcome was associated with complete resection of the FCD lesion [risk ratio, RR=2.42 (95% CI: 1.55-3.76), p<0.001] and location of the FCD lesion in the temporal lobe [RR=1.38 (95% CI: 1.07-1.79), p=0013], but not lesion extent, intracranial EEG use, or FCD histological type. The number of FCD histological types included in the same study accounted for 7.6% of the observed heterogeneity.

CONCLUSIONS

70% of patients with drug-resistant epilepsy and MRI features of FCD attain a favorable seizure outcome following resective surgery. Our findings can be incorporated in routine pre-operative counselling and reinforce the importance of resecting completely the MRI-detected FCD where this is safe and feasible.

Effect of norethindrone acetate on hormone levels and markers of bone turnover in estrogen-treated postmenopausal women

There is controversy concerning the effects of progestins on bone. Norethindrone acetate (NETA) is synthetic progesterone that also has estrogenic and androgenic effects. We tested its effects on hormone levels, lipids and biochemical markers of bone turnover in postmenopausal women who were on estrogen replacement therapy. Women were treated with NETA, 5 mg/d for 9 weeks. Estrogenic effects included a marked lowering of follicle stimulating hormone and luteinizing hormone. Androgenic effects included a decrease in sex hormone binding globulin and HDL cholesterol. Bone turnover showed inconsistent responses. Among markers of bone formation, bone specific alkaline phosphatase decreased significantly by 23% while procollagen peptides and osteocalcin showed a non-significant increase. The marker of bone resorption, N-telopeptide crosslinks of collagen, decreased by 19% at 6 weeks. These results indicate that NETA does not have a potent short-term anabolic effect on bone but does have effects that are likely to be mediated through the estrogen and androgen receptors.

The effect of short-term treatment with micronized estradiol on bone turnover and gonadotrophins in older men

Evidence for the role of estrogen in male bone metabolism has been confirmed by studies on a man with a genetic defect in the estrogen receptor as well as men with aromatase defects. All exhibited tall stature, delayed epiphysial closure, decreased bone density and increased bone turnover. Estrogen is likely to affect bone turnover in men throughout life; therefore, we hypothesized that older men would show decreased bone resorption in response to estrogen therapy. To test our hypothesis, fourteen community-dwelling men with osteopenia of the femoral neck were treated for 9 weeks with micronized estradiol, 1 mg/d, a dose which is effective in postmenopausal women. Each subject served as his own control. Markers of bone resorption, N-terminal collagen crosslinks (NTX) and C-terminal collagen crosslinks (CTX) and markers of bone formation, osteocalcin (OC) and bone specific alkaline phosphatase (BSAP) were measured every 3 weeks during a 9-week treatment period and 9 weeks post-treatment. Sex hormones, gonadotrophins and calciotropic hormones were measured at baseline, 9 weeks on treatment and 9 weeks post- treatment. After 9 weeks of treatment, estradiol and estrone levels increased significantly by greater than 6-fold and 15-fold, respectively. SHBG levels increased significantly by 17%. Testosterone and free testosterone levels decreased significantly by 27% and 34%, respectively. Markers of bone resorption showed wide variation at baseline and while on treatment. There was no correlation between changes in bone markers and changes in estrogen levels. During treatment, 11 patients showed a decrease of NTX or CTX, but three showed an increase. These three and one other subject had high initial levels of FSH and LH, suggesting some degree of primary gonadal failure, which decreased during estrogen therapy. Thus, the change in NTX (and CTX) after 9 weeks of E2 treatment was correlated with initial FSH (r= -.66, p= .01) and LH (r= -.73, p= .003) values. In addition, the largest decrease in free testosterone at 9 weeks was correlated with the higher values for NTX, CTX and BAP (r=-0.66, -0.68, -0.70 respectively; p< or =.01 for each of the markers). Treatment was generally well tolerated. Side effects of treatment were minimal, and included breast tenderness and decreased libido which reversed after treatment. We conclude that it is feasible to give low dose estrogen to healthy older men, but that the effects on bone turnover are not consistent. Changes in central feedback and in endogenous sex hormone production may alter the response of bone turnover to exogenous estrogen in this population.

Mood and alcohol consumption: an experience sampling test of the self-medication hypothesis

In this investigation the authors applied the experience sampling method to prospectively test the self-medication hypothesis. In vivo reports gathered in the context of daily life demonstrated that nervousness was the only negative mood state to predict increases in alcohol consumption later in the course of the day. Further examination of this within-person relationship demonstrated that men were more likely to consume alcohol when nervous than were women, but this association was unrelated to family history of alcoholism, problem drinking patterns, or trait anxiety and depression. Consistent with the self-medication hypothesis, cross-sectional analyses also confirmed that alcohol consumption was generally associated with lower levels of nervousness; this effect varied by several demographic and clinical variables. These findings are discussed in terms of the diversity of reasons for alcohol consumption and their potential for explaining problem drinking.

Mood states associated with transitory changes in asthma symptoms and peak expiratory flow

OBJECTIVE

This study examined the within-person relations between transitory changes in mood, asthma symptoms, and peak expiratory flow rate (PEFR).

METHODS

Thrice-daily for 21 consecutive days, 48 adults with moderate to severe asthma entered information in palm-top computers about their mood and asthma symptoms. A multidimensional model of mood, ie, the mood circumplex, informed the assessment of mood arousal and mood pleasantness. At each observation, participants also recorded their PEFR with peak flow meters that stored blinded data. Albuterol doses were also monitored electronically. Before and after the 21-day study, spirometric measures of airways obstruction were taken under controlled conditions.

RESULTS

Random effects regression models revealed a significant, but weak, within-person relation between symptoms and PEFR. Changes in mood vectors with an arousal component were significantly related to PEFR changes, whereas changes in mood vectors with a pleasantness component tracked changes in asthma symptom reports, even after adjustment for contemporaneous PEFR and after controlling for time of day and albuterol dosing. Comparison of spirometric assessments with unsupervised PEFR suggested that part of the relation between mood arousal and PEFR may be attributable to the "effort-dependence" of peak flow self-monitoring.

CONCLUSIONS

Different dimensions of mood were associated with transitory changes in asthma symptoms and PEFR. This may be one reason why individuals with asthma misperceive the severity of their symptoms in relation to underlying airways obstruction.

Perception of airway obstruction in asthma: sequential daily analyses of symptoms, peak expiratory flow rate, and mood

BACKGROUND AND OBJECTIVE

Studies have demonstrated a weak correlation between the degree of airways obstruction and the severity of asthma symptoms. Although the causes for this disparity are probably multiple, mood has been hypothesized to modulate symptoms. This investigation was designed to evaluate the effect of mood and other patient characteristics on the perception of airways obstruction.

METHODS

We compared mood variables, symptom severity, albuterol use, and peak expiratory flow rate (PEFR) measured three times daily over a 21-day period in 21 adults with moderate to severe asthma. Electronic equipment was used for data collection. Analyses included both individual patient assessments and a within-subjects, time series, pooled regression of concurrent and time-lag data.

RESULTS

After pooling 1323 observations, there was a weak concurrent relationship between symptoms and PEFR (beta = -0.17, p < 0.001). Only five patients (24%) were accurate perceivers, defined by a statistically significant relationship between symptoms and PEFR across time. Higher forced expiratory flow at 25% to 75% of capacity predicted perception accuracy (p = 0.004); active mood was marginally associated with accuracy (p = 0.06). These two variables together explained 41% of the variation in perception accuracy (p = 0.004). Mood did not independently predict symptoms, but conversely, increased symptoms predicted less pleasant mood (beta = 0.08, p < 0.001), less active mood (beta = -0.11, p < 0.001), and less active-pleasant mood (beta = 0.06, p < 0.001). PEFR did not predict mood, and only pleasant mood independently predicted higher PEFR (beta = 0.04, p < 0.05). Symptoms, but not PEFR, were concurrently associated with albuterol use (beta = 0.24, p < 0.001).

CONCLUSION

The relationship between changes in PEFR and symptoms over time was generally poor. Those patients with lower FEF25-75 values tended to be less accurate perceivers. Mood states were influenced by asthma symptoms, but the converse was not true.

The effect of inhaled albuterol in moderate to severe asthma

BACKGROUND

Some recent clinical investigations suggest that regular use of inhaled bronchodilators may lead to deterioration in asthma control.

OBJECTIVE

The purpose of this study was to evaluate the effect of albuterol dosing schedule on clinical outcome in subjects with moderate to severe stable asthma.

METHODS

Seventeen adults were randomized to two 15-week treatment periods in a double-blind crossover design. Throughout the study, subjects were instructed to take two inhalations four times daily from an unlabeled "test" canister. In the four times daily and as-needed (QID + PRN) period, this canister contained albuterol; in the as-needed (PRN) period, it contained placebo. A "rescue" albuterol canister was available for as-needed use at all times. Inhaler actuations from both the test and rescue canisters were electronically recorded. Outcome measures included prednisone requirements, morning and evening symptoms and peak expiratory flow rates, total and nighttime rescue albuterol use, and asthma-specific quality of life.

RESULTS

The two treatment periods did not differ in symptoms, nighttime albuterol use, or asthma quality of life. During the QID+PRN period both morning and evening peak expiratory flow rates were significantly higher (p < 0.01 and 0.001, respectively) and total rescue use of albuterol was significantly less (p < 0.05) than the PRN period. Days on prednisone tended to be lower in the regular dosing period (p = 0.08).

CONCLUSION

In our sample of patients with moderate to severe asthma, four times daily dosing of albuterol did not lead to deterioration of asthma control.

Personality, stress, coping, and sense of coherence among nephrology nurses in dialysis settings

The goal of this study was to examine the relationships among personality types, personal and work-related stress, coping resources, and sense of coherence (SOC) among nephrology nurses in dialysis settings. Nurses (n = 49) from 13 dialysis units in New Mexico completed a demographic data form, Perceived and Nursing Stress Scales, SOC Scale, Coping Resources Inventory, and the Myers-Briggs Type Indicator (MBTI). The results indicated that there was a positive correlation between perceived personal stress and work-related stress, especially work load. Conversely, there were negative correlations between (a) both personal and work-related stress with SOC, and (b) both coping resources and SOC with burnout. High levels of personal and work-related stress were related to inadequate coping resources. Regression analysis indicated that the main contributing factors to emotional exhaustion (a major component of burnout) were low SOC, lack of staff support, personal stress, and heavy work load. Increased utilization of coping resources may facilitate the nurses' management of personal and work-related stressors.

Photographic, stereological and statistical methods in evaluation of aggregation of red cells in disease: part I: kinetics of aggregation

Kinetics of red cells aggregation were studied by microphotography of blood contained between parallel-plates in a slit of 12.5 micrometers. Blood samples, anticoagulated with EDTA, were adjusted to haematocrit of 0.30 using native plasma. Blood was allowed to flow at shear rate of 2000 sec-1, flow was stopped, and sequential photography carried out. Full development of aggregation required from 2 to 10 minutes, depending on the blood sample. Blood studied included normal donors and patients with polycythaemia, lymphoma, hyperparathyroidism, Waldenström's macroglobulinaemia, influenza. The quantitative evaluation of colour slides was carried out on Microvideomat No. 2 with Zeiss Interference Monochromator, using light wave length of 460 or 560 nanometers. The stereological parameters defined included d(Heyn), Lamda, and S/V. Linear regressions of stereological parameters against square root of stasis time showed correlation coefficients of 0.8 up to 0.99. Linear regressions for different blood samples were compared, and significance of differences between slopes or between elevations was defined using F-distribution. Such differences were significant up to P less than 0.001. Rate of aggregation was much higher in macroglobulinaemia or lymphoma than in normals, and it was lowest in the hyperparathyroid disease.