1275 Machine Learning for Outcome Prediction in Epilepsy Surgery: A Systematic Review

Aim

A third of epilepsy patients suffer from medically refractory seizures. In patients eligible for surgical treatment, seizure freedom rates remain variable. Machine learning (ML) utilises large datasets to detect patterns to make predictions. We systematically review studies employing ML models for prediction of outcome following resective epilepsy surgery to evaluate their efficacy, applicability and value in determining surgical candidacy.

Method

MEDLINE, Cochrane and EMBASE databases were searched for literature published between 2010 – 2020 according to PRISMA guidance. Non-refractory epilepsy, non-clinical outcome prediction, or non-human studies were excluded. Clinical and demographic data, ML features, discrimination and prediction accuracy metrics were extracted.

Results

15 studies were included. Median cohort size was 49 (range 16 – 4211). Heterogeneous input data sources were utilised: MRI (n = 10) , electrophysiology (n = 4), PET (n = 2), clinical data (n = 2), and neuropsychological testing (n = 1). The most common ML model used was support vector machines (n = 7). All studies had good discrimination (AUC > 0.70, range: 0.79 [95% CI NR] - 0.94 [95% CI 0.92 – 0.96]), and good prediction accuracy (> 0.70, range: 0.76 [95% CI NR] – 0.95 [95% CI NR]). Limitations included small sample sizes, limited external validation and lack of comparison with clinician-predicted outcomes.

Conclusions

Machine Learning for outcome prediction could enhance clinical decision-making for surgical candidacy in epilepsy, and lead to improved precision medicine delivery. Outcome reporting remains inconsistent, and further work is required to externally validate such models to implement these to large-scale clinical populations.

875 Use of Oriented Priors Through Magnetic Tractography (MAGNET) In Deliniation Of Meyer's Loop and Correlation with Visual Field Deficit In Temporal Lobe Epilepsy (TLE) Surgery: A Pilot Study

Introduction

Pre-operative white matter tract reconstruction of the Meyer’s loop (ML) of the optic radiation using diffusion MRI (tractography) can be used to prevent post-operative visual-field deficit. Due to its complex anatomy, precise reconstruction of the ML is challenging and often underestimated. Previous work has suggested that an innovative tractography technique using oriented priors called MAGNET better approximates reconstruction to reported histological prosections. This proof-of-context study validates the MAGNET methodology in predicting visual-field deficits in patients undergoing TLE surgery.

Method

Diffusion MRI datasets were used to reconstruct pre-operative ML using MAGNET in five patients. These were overlaid on post-operative T2-MRI series demonstrating the surgically resected area to measure overlap between resection and reconstructed ML. A correlation with post-operative visual-field defects was established.

Results

There was no evidence of visual field deficit in the cases where there was no overlap between the reconstructed ML and the resected region. In the cases with overlap with reconstructed ML and resection, there was visual deficit found. There was no correlation between proportion of resected ML and visual deficit.

Conclusions

This pilot demonstrates that MAGNET accurately reconstructs ML in pre-surgical TLE cases compared to standard tractography techniques and can be used to augment neurosurgical planning and resection.

Does providing the correct diagnosis as feedback after self-explanation improve medical students diagnostic performance?

BACKGROUND

Self-explanation without feedback has been shown to improve medical students' diagnostic reasoning. While feedback is generally seen as beneficial for learning, available evidence of the value of its combination with self-explanation is conflicting. This study investigated the effect on medical students' diagnostic performance of adding immediate or delayed content-feedback to self-explanation while solving cases.

METHODS

Ninety-four 3rd-year students from a Canadian medical school were randomly assigned to three experimental conditions (immediate-feedback, delayed-feedback, control). In the learning phase, all students solved four clinical cases by giving i) the most likely diagnosis, ii) two main arguments supporting this diagnosis, and iii) two plausible alternative diagnoses, while using self-explanation. The immediate-feedback group was given the correct diagnosis after each case; delayed-feedback group received the correct diagnoses only after the four cases; control group received no feedback. One week later, all students solved four near-transfer (i.e., same final diagnosis as the learning cases but different scenarios) and four far-transfer cases (i.e., different final diagnosis from the learning cases and different scenarios) by answering the same three questions. Students' diagnostic accuracy (score for the response to the first question only) and diagnostic performance (combined score of responses to the three questions) scores were assessed in each phase. Four one-way ANOVAs were performed on each of the two scores for near and far-transfer cases.

RESULTS

There was a significant effect of experimental condition on diagnostic accuracy on near-transfer cases (p < .05). The immediate-feedback and delayed-feedback groups performed equally well, both better than control (respectively, mean = 90.73, standard deviation =10.69; mean = 89.92, standard deviation = 13.85; mean = 82.03, standard deviation = 17.66). The experimental conditions did not significantly differ on far-transfer cases.

CONCLUSIONS

Providing feedback to students in the form of the correct diagnosis after using self-explanation with clinical cases is potentially beneficial to improve their diagnostic accuracy but this effect is limited to similar cases. Further studies should explore how more elaborated feedback combined with self-explanation may impact students' diagnostic performance on different cases.

Neurophysiological evidence of preserved connectivity in tuber tissue

We present a case of preserved corticospinal connectivity in a cortical tuber, in a 10 year-old boy with intractable epilepsy and tuberous sclerosis complex (TSC). The patient had multiple subcortical tubers, one of which was located in the right central sulcus. In preparation for epilepsy surgery, motor mapping, by neuronavigated transcranial magnetic stimulation (nTMS) coupled with surface electromyography (EMG) was performed to locate the primary motor cortical areas. The resulting functional motor map revealed expected corticospinal connectivity in the left precentral gyrus. Surprisingly, robust contralateral deltoid and tibialis anterior motor evoked potentials (MEPs) were also elicited with direct stimulation of the cortical tuber in the right central sulcus. MRI with diffusion tensor imaging (DTI) tractography confirmed corticospinal fibers originating in the tuber. As there are no current reports of preserved connectivity between a cortical tuber and the corticospinal tract, this case serves to highlight the functional interdigitation of tuber and eloquent cortex. Our case also illustrates the widening spectrum of neuropathological abnormality in TSC that is becoming apparent with modern MRI methodology. Finally, our finding underscores the need for further study of preserved function in tuber tissue during presurgical workup in patients with TSC.

Challenges of global surveillance during an influenza pandemic

Surveillance is an essential foundation for monitoring and evaluating any disease process, and is especially critical when new disease agents appear. The H1N1 influenza pandemic of 2009 tested the capacities of countries to detect, assess, notify and report events as required by the 2005 International Health Regulations (IHR). As detailed in the IHR, the World Health Organization drew on official reports from Member States as well as unofficial sources (e.g. media alerts) to quickly report and disseminate information about the appearance of the novel influenza virus. The pre-existing Global Influenza Surveillance Network for virological surveillance also provided crucial information for rapid development of a vaccine and for detection of changes in the virus. However, the pandemic also highlighted a number of shortcomings in global epidemiological surveillance for respiratory disease. These included the lack of standards for reporting illness, risk factor and mortality data, and a mechanism for systematic reporting of epidemiological data. Such measures would have facilitated direct comparison of data between countries and improved timely understanding of the characteristics and impact of the pandemic. This paper describes the surveillance strategies in place before the pandemic and the methods that were used at global level to monitor the pandemic. Enhancements of global surveillance are proposed to improve preparedness and response for similar events in the future.

Transfusion-transmitted malaria in the United States from 1963 through 1999

BACKGROUND

Transfusion-transmitted malaria is uncommon in the United States. After the report of three cases of complicated Plasmodium falciparum infection acquired by transfusion, we reviewed all cases of transfusion-transmitted malaria reported to the Centers for Disease Control and Prevention (CDC) from 1963 through 1999.

METHODS

Information on the patients was from surveillance reports sent to the CDC. Information about the implicated blood donors came from the National Malaria Surveillance System. To determine whether donors should have been excluded from donating blood, we compared their characteristics with the exclusion guidelines of the Food and Drug Administration and the American Association of Blood Banks.

RESULTS

Of 93 cases of transfusion-transmitted malaria reported in 28 states, 33 (35 percent) were due to P. falciparum, 25 (27 percent) were due to P. vivax, 25 (27 percent) were due to P. malariae, 5 (5 percent) were due to P. ovale, 3 (3 percent) were mixed infections, and 2 (2 percent) were due to unidentified species. Ten of the 93 patients (11 percent) died. There were potentially 91 donors (in two cases, two patients received blood from the same donor), 67 of whom (74 percent) could be identified as infective. Of 64 implicated donors whose country of origin was reported, 38 (59 percent) were foreign born. Among those for whom complete information was available, 37 of 60 donors (62 percent) would have been excluded from donating according to current guidelines (in place since 1994), and 30 of 48 donors (62 percent) should have been excluded under the guidelines in place at the time of donation.

CONCLUSIONS

Careful screening of donors according to the recommended exclusion guidelines remains the best way to prevent transfusion-transmitted malaria.

Specific protein-protein interaction between basic helix-loop-helix transcription factors and homeoproteins of the Pitx family

Homeoproteins and basic helix-loop-helix (bHLH) transcription factors are known for their critical role in development and cellular differentiation. The pituitary pro-opiomelanocortin (POMC) gene is a target for factors of both families. Indeed, pituitary-specific transcription of POMC depends on the action of the homeodomain-containing transcription factor Pitx1 and of bHLH heterodimers containing NeuroD1. We now show lineage-restricted expression of NeuroD1 in pituitary corticotroph cells and a direct physical interaction between bHLH heterodimers and Pitx1 that results in transcriptional synergism. The interaction between the bHLH and homeodomains is restricted to ubiquitous (class A) bHLH and to the Pitx subfamily. Since bHLH heterodimers interact with Pitx factors through their ubiquitous moiety, this mechanism may be implicated in other developmental processes involving bHLH factors, such as neurogenesis and myogenesis.

Oversight and monitoring of blood safety in the United States

The US blood safety vigilance system is composed of a network of interwoven programs, now organized under a formal structure, with the Assistant Secretary of Health and DHHS Blood Safety Committee bearing overall responsibility. It takes advantage of the breadth of expertise and close collaborative relationship of transfusion medicine and infectious disease scientists within and outside of the government. Core elements include an array of ongoing surveillance programs for monitoring established as well as new and emerging infectious agents that may pose a risk to blood safety, and the existence of historical and contemporary repositories of donor and recipient specimens that enable rapid investigation of putative new risks. This report summarizes the historical events that shaped the US blood safety oversight system, reviews the current organization and decision-making processes related to blood safety issues, and highlights key surveillance systems and research programs which monitor the US and global blood supplies for known and potential emerging risks.

An investigation into the possibility of transmission of tick-borne pathogens via blood transfusion. Transfusion-Associated Tick-Borne Illness Task Force

BACKGROUND

Tick-borne illnesses were diagnosed in a group of National Guard members, including some who had donated blood a few days before the onset of symptoms. A voluntary recall of those blood components was issued and a multistate investigation was conducted to determine if transfusion-transmitted illness had occurred.

STUDY DESIGN AND METHODS

Donors and recipients were asked to complete questionnaires regarding symptoms and risk factors for infection and to provide blood samples for laboratory analysis.

RESULTS

Among National Guard personnel who donated blood, 12 individuals were found to have a confirmed or probable case of Rocky Mountain spotted fever or ehrlichiosis. A total of 320 units (platelets or packed red cells) from 377 donors were transfused into 129 recipients. Although 10 recipients received units from National Guard personnel with confirmed or probable infection, none became ill.

CONCLUSION

Transfusion-transmitted illness did not occur. Despite the awareness of the risk for tick-borne diseases and the use of tick-preventive measures, many National Guard personnel reported exposure to ticks. In addition to augmenting current tick-preventive measures, scheduling blood drives before rather than after field exercises could further reduce the potential for transmission of tick-borne pathogens.

Hindlimb patterning and mandible development require the Ptx1 gene

The restricted expression of the Ptx1 (Pitx1) gene in the posterior half of the lateral plate mesoderm has suggested that it may play a role in specification of posterior structures, in particular, specification of hindlimb identity. Ptx1 is also expressed in the most anterior ectoderm, the stomodeum, and in the first branchial arch. Ptx1 expression overlaps with that of Ptx2 in stomodeum and in posterior left lateral plate mesoderm. We now show that targeted inactivation of the mouse Ptx1 gene severely impairs hindlimb development: the ilium and knee cartilage are absent and the long bones are underdeveloped. Greater reduction of the right femur size in Ptx1 null mice suggests partial compensation by Ptx2 on the left side. The similarly sized tibia and fibula of mutant hindlimbs may be taken to resemble forelimb bones: however, the mutant limb buds appear to have retained their molecular identity as assessed by forelimb expression of Tbx5 and by hindlimb expression of Tbx4, even though Tbx4 expression is decreased in Ptx1 null mice. The hindlimb defects appear to be, at least partly, due to abnormal chondrogenesis. Since the most affected structures derive from the dorsal side of hindlimb buds, the data suggest that Ptx1 is responsible for patterning of these dorsal structures and that as such it may control development of hindlimb-specific features. Ptx1 inactivation also leads to loss of bones derived from the proximal part of the mandibular mesenchyme. The dual role of Ptx1 revealed by the gene knockout may reflect features of the mammalian jaw and hindlimbs that were acquired at a similar time during tetrapod evolution.

[Clinical reasoning learning (CRL) sessions. An example of a contextualized teaching activity adapted to clinical stages in medicine]

Clinical reasoning learning (CRL) sessions stem from an educational reform brought about since 1987 at the Faculty of Medicine of the Université de Sherbrooke. This reform is student-centered and based on situated learning and teaching. The objective of the CRL sessions, designed and implemented at the clerkship level, is to help students develop problem solving competencies through the use of effective general clinical reasoning strategies and the development of a highly organized network of specific knowledge. These sessions also strive to offset the difficulties of random clinical exposure and often highly complex cases encountered by trainees during clinical rotations in teaching hospitals. Formed of small groups, sessions recreate a clinical consultation setting focused on a specific priority problem and clinical condition identified among the mandatory objectives of the rotation. Emphasis is placed on early generation and subsequent testing of diagnostic hypothesis, and the active search and gradual disclosure of clinical data using hypothesis-driven inquiry strategy. Students are asked to verbalize their reasoning process under the close supervision of a clinical expert in the field under discussion. Implemented in 5 different clinical disciplines since 1990 in Sherbrooke, assessment data are now available and support the relevance and usefulness of CRL sessions.

Emerging issues in blood safety

Improvements in donor selection, testing of donors for markers of infection, and viral inactivation of plasma-derived products have helped reduce the risk of transfusion-associated infections, including hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency viruses (HIV). The potential for transmission of emerging infections is illustrated by current concerns about group O strains of HIV, nonenveloped viruses, newly discovered microbial agents, prions, Chagas' disease, tick-borne infections, and the need to assess the frequency of transfusion reactions associated with bacterial contamination.

Antagonism between Nur77 and glucocorticoid receptor for control of transcription

Two important functions of glucocorticoids (Gc), namely, suppression of immune system function and feedback repression of the hypothalamo-pituitary-adrenal (HPA) axis, are mediated through repression of gene transcription. Previous studies have indicated that this repression is exerted in part through antagonism between the glucocorticoid receptors (GR) and the AP-1 family of transcription factors. However, this mechanism could not account for repression of the pro-opiomelanocortin (POMC) gene, an important regulator of the HPA axis. Our recent identification of the orphan nuclear receptor Nur77 as a mediator of CRH induction of POMC transcription led us, in the present work, to show that Gc antagonize this positive signal at two levels. First, Gc partly blunt the CRH induction of Nur77 mRNA, and second, they antagonize Nur77-dependent transcription. GR repression is exerted by antagonism of Nur77 action on the NurRE element of the POMC gene. Gc antagonism of NurRE activity was observed in response to physiological stimuli in both endocrine (CRH induction of POMC) and lymphoid (T-cell receptor activation) cells. In transfection experiments, transcriptional activation by Nur77 and the repressor activity of liganded GR titrated each other on their cognate DNA target. In vitro binding experiments as well as mutation analysis of GR suggest that the mechanism of GR antagonism of Nur77 is very similar to that of the antagonism between GR and AP-1. The convergence of positive signals mediated by Nur77 (and also probably by related family members) and negative signals exerted by GR appears to be a general mechanism for control of transcription, since it is active in both endocrine and lymphoid cells.

[Severe rhabdomyolysis in a patient receiving lovastatin, danazol, and doxycycline]

Combinations of lovastatin and other drugs have been reported to cause rhabdomyolysis and myoglobinuria. The authors report such a case in a 72-year-old man who had been receiving atenolol, acetylsalicylic acid (ASA), dipyridamole, lovastatin, danazol, prednisone and doxycycline. The ASA, lovastatin and danazol were discontinued. The symptoms resolved, and laboratory test results were normal within 2 weeks. Lovastatin was strongly suspected; danazol was the most likely potentiator by diminishing the metabolism of lovastatin and its metabolites in the liver or by having a direct toxic effect on the muscles.

[Paraneoplastic pemphigus and adenocarcinoma of the colon]

An increased incidence of cancer has been observed in patients with pemphigus and described mostly since the 1970. Lymphoreticular malignancies and thymomas were the most often reported neoplasms. Paraneoplastic pemphigus is a newly described syndrome with specific characteristics. In this report, a patient with pemphigus and colonic adenocarcinoma is described. In this case, clinical and histologic features suggest the diagnosis of paraneoplastic pemphigus which would be for the first time described in association with colonic adenocarcinoma.

Novel glucocorticoid receptor complex with DNA element of the hormone-repressed POMC gene

Previous studies defined a DNA element necessary for glucocorticoid repression of the pro-opiomelanocortin (POMC) gene. The glucocorticoid receptor (GR) binds this negative glucocorticoid response element (nGRE) with an in vitro affinity similar to that of GR for positive GREs. However, whereas GR binds GREs as homodimers, a novel GR complex which forms with nGRE appears to contain three GR molecules. Biochemical characterization of this complex as well as equilibrium binding studies suggest that it is formed by sequential binding of a GR homodimer followed by binding of a GR monomer on the opposite side of the double helix. The DNA-binding domain (DBD) of GR is sufficient for differential binding of GRE and nGRE, as bacterially-expressed DBD formed unique nGRE complexes that contain three GR polypeptides. Thus, the POMC nGRE provides the first example of an interaction between GR and DNA in which GR binds otherwise than as a homodimer. Despite its high affinity for GR, the nGRE differs significantly from GREs in that it does not activate transcription in any context. As the nGRE appears insufficient on its own to confer hormone responsiveness, other POMC promoter elements are likely to be required to mediate glucocorticoid repression.

[Residents and the teaching role: review of the literature]

We reviewed the available data on residents' teaching role in the clinical setting to develop programs to improve their teaching skills. Articles published from 1966 to 1989 were identified through a computerized search of MEDLINE, and the bibliographies of identified papers were reviewed. Articles directly related to the topic were included and analysed. Taking into account their quality, we extracted data relevant to specific issues. Approximately 15% to 25% of an average work week was spent by residents in different teaching activities. Students acknowledged the importance of their contribution to clinical teaching. Residents benefitted from teaching by increasing their medical knowledge and promoting the development of important attitudes. Insufficient preparation for this task and the numerous practical problems faced by residents may explain their modest performance as teachers. Nevertheless, programs directed to residents might improve the quality of their teaching. We suggest some guidelines for the development of programs to improve their teaching skills and for future research.

Tissue-specific activity of the pro-opiomelanocortin gene promoter

The pro-opiomelanocortin (POMC) gene is specifically expressed in corticotroph cells of the anterior pituitary. To define the POMC promoter sequences responsible for tissue-specific expression, we assessed POMC promoter activity by gene transfer into POMC-expressing pituitary tumor cells (AtT-20) and fibroblast L cells. The rat POMC promoter was only efficiently utilized and correctly transcribed in AtT-20 cells. 5'-End deletion analysis revealed two promoter regions required for activity in AtT-20 cells. When tested by fusion to a heterologous promoter, DNA fragments corresponding to both regions exhibited tissue-specific activity, suggesting the presence of at least two tissue-specific DNA sequence elements within the promoter. In summary, POMC promoter sequences from -480 to -34 base pairs appear sufficient to mimic the specificity of anterior pituitary expression.

Structure of the rat pro-opiomelanocortin (POMC) gene

The gene encoding pro-opiomelanocortin (POMC) presents unique regulatory features. In particular, glucocorticoids inhibit transcription of the POMC gene in the anterior pituitary, but not in the intermediate pituitary. In order to study the mechanism leading to transcriptional inhibition of POMC by glucocorticoid and the interaction of the glucocorticoid receptor complex with specific DNA sequences along the POMC gene, we have cloned the rat POMC gene and determined its structure. The gene is composed of three exons and appears to be present at a single copy per haploid genome. Besides the usual regulatory signals like 'TATA' and 'CCAAT' boxes, the upstream region contains sequences homologous to known enhancer sequences and to the glucocorticoid receptor binding site observed in glucocorticoid-responsive genes.

Gene structure of human cardiac hormone precursor, pronatriodilatin

Atrial cardiocytes contain granules typical of protein-secreting cells, and atrial extracts are known to contain a powerful natriuretic and diuretic activity and to possess smooth muscle relaxant activity. A variety of active atrial peptides have been isolated, including a family of related peptides showing natriuretic, diuretic and smooth muscle relaxant activities in rat and human atria; these peptides were named atrial natriuretic factor (ANF). Another unrelated peptide from pig atria, cardiodilatin, is thought to possess only smooth muscle relaxant activity. Its partial amino acid sequence shows no homology with ANF sequences. The sequence analysis of a large form (106 amino acids) of ANF and of ANF complementary DNA clones indicates that cardiodilatin and ANF peptides are synthesized from a common precursor. This precursor also contains a signal peptide sequence expected of a secretory protein. We now describe the complete structure and sequence of the human gene for this novel hormone precursor that we call pronatriodilatin.

Molecular cloning and characterization of DNA sequences encoding rat and human atrial natriuretic factors

A cDNA copy of the message encoding rat atrial natriuretic factor (ANF) has been cloned in Escherichia coli, and its nucleotide sequence was determined. ANF appears to be synthesized as a larger precursor, atrial pronatriodilatin. The cDNA has an open reading frame potentially encoding a protein of 152 amino acids, of which the first 24 amino acids strongly resemble a signal sequence. This is followed by a sequence with 80% homology to a second vasoactive protein, porcine cardiodilatin. The ANF peptide is contained in the COOH-terminal portion of the protein. The DNA sequence corresponding to human ANF is also presented and displays a high degree of homology to its rat counterpart. These data provide further evidence for the expression in cardiac atria of a multifactor system that may contribute to the regulation of blood pressure and extracellular fluid volume.

Acquired immunodeficiency syndrome (AIDS) associated with transfusions

Of 2157 patients with the acquired immunodeficiency syndrome (AIDS) whose cases were reported to the Centers for Disease Control by August 22, 1983, 64 (3 per cent) with AIDS and Pneumocystis carinii pneumonia had no recognized risk factors for AIDS. Eighteen of these (28 per cent) had received blood components within five years before the onset of illness. These patients with transfusion-associated AIDS were more likely to be white (P = 0.00008) and older (P = 0.0013) than other patients with no known risk factors. They had received blood 15 to 57 months (median, 27.5) before the diagnosis of AIDS, from 2 to 48 donors (median, 14). At least one high-risk donor was identified by interview or T-cell-subset analysis in each of the seven cases in which investigation of the donors was complete; five of the six high-risk donors identified during interview also had low T-cell helper/suppressor ratios, and four had generalized lymphadenopathy according to history or examination. These findings strengthen the evidence that AIDS may be transmitted in blood.

Combined serotyping and biotyping of Serratia marcescens

The API (Analytab Products, Inc., New York, N.Y.) biotypes of 117 clinical isolates of Serratia marcescens were determined and fell into 13 different patterns. The O and H antigens were determined by tube agglutination, and 27 serotypes were identified. The biotype and serotype appeared to vary indepently. Serotyping and biotyping combined divided these isolates into 56 different types. There was a problem interpreting the end points for inositol fermentation and urease production, which could affect reproducibility of API biotypes. Biotyping is a simple way of screening for possible nosocomial outbreaks of S. marcescens.