Optic nerve tortuosity is often reported in children with neurofibromatosis type 1 (NF1). We describe quantitative and subjective criteria to determine the degree of optic nerve tortuosity in individuals with NF1.
To employ quantitative and subjective criteria to assess optic nerve tortuosity in individuals with NF1.
Materials and methods
A retrospective study over a period of 8 years was performed on children with NF1, with and without optic pathway glioma, compared to children without NF1. A tortuosity index was computed for the optic nerve in each subject using a high resolution 3D T1-weighted magnetization-prepared rapid gradient echo sequence, which was averaged and compared across groups.
The tortuosity index for subjects with NF1, regardless of an optic pathway glioma, was greater than those without NF1. There was no difference in the tortuosity index between NF1 subjects with optic pathway glioma and NF1 subjects without optic pathway glioma. There was also no correlation between subjective measures of tortuosity and the quantitative scoring (tortuosity index), or between the degree of tortuosity and subject age or gender.
Individuals with NF1 have increased optic nerve tortuosity relative to unaffected individuals. Quantitative tortuosity index is a superior measure to subjective assessment in the evaluation of optic nerve tortuosity in children with NF1.
NF1; optic glioma; MRI; brain tumor; cancer predisposition syndrome
Traumatic brain injury (TBI) is the most common cause of acquired disability in children. Metabolic defects, and in particular mitochondrial dysfunction, are important contributors to brain injury after TBI. Studies of metabolic dysfunction are limited, but magnetic resonance methods suitable for use in children are overcoming this limitation. We performed noninvasive measurements of cerebral blood flow and oxygen metabolic index (OMI) to assess metabolic dysfunction in children with severe TBI. Cerebral blood flow is variable after TBI but hypoperfusion and low OMI are predominant, supporting metabolic dysfunction. This finding is consistent with preclinical and adult clinical studies of brain metabolism and mitochondrial dysfunction after TBI.
brain imaging; brain trauma; cerebral blood flow
We have previously shown that mice challenged with a lethal dose of PR8-OVAI are protected by injection of 4 to 8 × 106
in vitro - generated Tc1 or Tc17 CD8+ effectors. Viral load, lung damage and loss of lung function are all reduced following transfer. Weight loss is reduced and survival increased. We sought here to define the mechanism of this protection. CD8+ effectors exhibit multiple effector activities, perforin-, FasL- and TRAIL- mediated cytotoxicity, secretion of multiple cytokines (IL-2, IL-4, IL-5, IL-9, IL-10, IL-17, IL-21, IL-22, IFN-γ and TNF) and chemokines (CCL3, CCL4, CCL5, CXCL9 and CXCL10). Transfer of CD8+ effectors into recipients, prior to infection, elicits enhanced recruitment of host neutrophils, NK cells, macrophages, and B cells. All of these events have the potential to protect against viral infections. Removal of any one, however, of these potential mechanisms was without effect on protection. Even the simultaneous removal of host T cells, host B cells and host neutrophils combined with the elimination of perforin mediated lytic mechanisms in the donor cells failed to reduce their ability to protect. We conclude that CD8+ effector T cells can protect against the lethal effects of viral infection by means of a large number of redundant mechanisms.
Optic pathway gliomas (OPGs) are common pediatric brain tumors that pose significant clinical challenges with regard to predicting which tumors are likely to become symptomatic and require treatment. These tumors can arise sporadically or in the context of the inherited cancer predisposition syndrome, Neurofibromatosis type 1 (NF1). Few studies have suggested biological or imaging markers which predict the clinical course of this disease.
In this cross-sectional study, we hypothesize that the clinical behavior of OPGs in children can be differentiated by diffusion-weighted (DWI) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).
27 patients with OPG were studied using DWI and DCE MRI protocols. Diffusivity and permeability were calculated and correlated to OPG clinical behavior.
Mean diffusivity values of 1.39 μm2/ms and mean permeability values of 2.10 ml min−1 per 100 cc of tissue were measured. “Clinically-aggressive” OPGs had significantly higher mean permeability values (P=.05) than “clinically stable” tumors. In addition, there was a strong correlation between clinical aggressiveness and the absence of NF1 (P < 0.01).
These results suggest that DCE might be a useful biomarker for “clinically aggressive” OPG, which should be confirmed in larger prospective longitudinal studies.
Telehealth care is increasingly being employed in the management of long-term illness. Current systems are largely managed via “stand-alone” websites, which require additional log-ons for clinicians to view their patients’ symptom records and physiological measurements leading to frustrating delays and sometimes failure to engage with the record. However, there are challenges to the full integration of patient-acquired data into family physicians’ electronic medical records (EMR) in terms of reliability, how such data can best be summarized and presented to avoid overload to the clinicians, and how clarity of responsibility is managed when multiple agencies are involved.
We aimed to explore the views of primary care clinicians on the acceptability, clinical utility, and, in particular, the benefits and risks of integrating patient-generated telehealth care data into the family practice EMR and to explore how these data should be summarized and presented in order to facilitate use in routine care.
In our qualitative study, we carried out semi-structured interviews with clinicians with experience of and naïve to telehealth care following demonstration of pilot software, which illustrated various methods by which data could be incorporated into the EMR.
We interviewed 20 clinicians and found 2 overarching themes of “workload” and “safety”. Although clinicians were largely positive about integrating telehealth care data into the EMR, they were concerned about the potential increased workload and safety issues, particularly in respect to error due to data overload. They suggested these issues could be mitigated by good system design that summarized and presented data such that they facilitated seamless integration with clinicians’ current routine processes for managing data flows, and ensured clear lines of communication and responsibility between multiple professionals involved in patients’ care.
Family physicians and their teams are likely to be receptive to and see the benefits of integrating telehealth-generated data into the EMR. Our study identified some of the key challenges that must be overcome to facilitate integration of telehealth care data. This work particularly underlines the importance of actively engaging with clinicians to ensure that systems are designed that align well with existing practice data-flow management systems and facilitate safe multiprofessional patient care.
telehealth care; family practice; data management
Silent cerebral infarct (SCI) is the most commonly recognized cause of neurological injury in sickle cell anaemia (SCA). We tested the hypothesis that magnetic resonance angiography (MRA)-defined vasculopathy is associated with SCI. Furthermore, we examined genetic variations in glucose-6-phosphate dehydrogenase (G6PD) and HBA (α-globin) genes to determine their association with intracranial vasculopathy in children with SCA. Magnetic resonance imaging (MRI) of the brain and MRA of the cerebral vasculature were available in 516 paediatric patients with SCA, enrolled in the Silent Infarct Transfusion (SIT) Trial. All patients were screened for G6PD mutations and HBA deletions. SCI were present in 41.5%(214 of 516) of SIT Trial children. The frequency of intracranial vasculopathy with and without SCI was 15.9% and 6.3%, respectively (p<0.001). Using a multivariate logistic regression model, only the presence of a SCI was associated with increased odds of vasculopathy (p=0.0007, odds ratio (OR) 2.84; 95% Confidence Interval (CI)=1.55-5.21). Among male patients with SCA, G6PD status was associated with vasculopathy (p=0.04, OR 2.78; 95% CI=1.04-7.42), while no significant association was noted for HBA deletions. Intracranial vasculopathy was observed in a minority of children with SCA, and when present, was associated with G6PD status in males and SCI.
sickle cell anaemia; α-thalassaemia; glucose-6-phosphate dehydrogenase (G6PD); vasculopathy; silent cerebral infarcts
Difficulties with recruitment pose a major, increasingly recognised challenge to the viability of research. We sought to explore whether a register of volunteers interested in research participation, with data linkage to electronic health records to identify suitable research participants, would prove acceptable to healthcare staff, patients and researchers.
We undertook a qualitative study in which a maximum variation sampling approach was adopted. Focus groups and interviews were conducted with patients, general practitioners (GP), practice managers and health service researchers in two Scottish health boards. Analysis was primarily thematic to identify a range of issues and concerns for all stakeholder groups.
The concept of a national research register was, in general, acceptable to all stakeholder groups and was widely regarded as beneficial for research and for society. Patients, however, highlighted a number of conditions which should be met in the design of a register to expedite confidence and facilitate recruitment. They also gave their perceptions on how a register should operate and be promoted, favouring a range of media. GPs and practice managers were primarily concerned with the security and confidentiality of patient data and the impact a register may have on their workload. Researchers were supportive of the initiative seeing advantages in more rapid access to a wider pool of patients. They did raise concerns that GPs may be able to block access to personal patient data held in general practice clinical systems and that the register may not be representative of the whole population.
This work suggests that patients, healthcare staff and researchers have a favourable view of the potential benefits of a national register to identify people who are potentially eligible and willing to participate in health related research. It has highlighted a number of issues for the developers to incorporate in the design of research registers.
Research register; Recruitment; Randomised controlled trial; Qualitative
Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, insight into the nonlinear behavior can be gleaned through exploration of higher order harmonics. Here, a method using band excitation scanning probe microscopy (SPM) to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The technique is demonstrated by probing the first three harmonics of strain for a Pb(Zr1-xTix)O3 (PZT) ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, measurements of the second harmonic reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of nth order harmonic SPM detection methods in exploring nonlinear phenomena in nanoscale materials.
How memory CD4 T cells contribute to protection upon pathogen challenge is not fully understood. Beyond traditional helper functions for CD8 T cell and B cell responses, memory CD4 T cells can have a potent impact on the character and magnitude of inflammatory responses. Here we discuss how memory CD4 T cell control of innate immunity at early time points after pathogen encounter can influence protective responses. We also discuss important aspects of the mechanism whereby memory CD4 T cells directly and indirectly impact the activation status of antigen presenting cells and production of inflammatory cytokines and chemokines from multiple cell types. We suggest that control of innate immune responses by the adaptive immune system is a powerful protective mechanism associated with the memory state and represents an important failsafe in the face of pathogens that fail to trigger robust inflammatory responses through conserved pattern recognition receptors.
Viral pathogens often generate strong CD4+ T cell responses that are best known for their ability to help B cell and CD8+ T cell responses. However, recent studies reveal additional roles for CD4+ T cells, some of which are independent of other lymphocytes, and indicate that memory cells are more effective in most functions than naïve CD4 T cells. Here, we review the full spectrum of antiviral functions of CD4+ T cells, including their helper activities, innate immune induction, and direct anti-viral roles, and suggest how these functions are integrated to provide highly protective responses against viral pathogens.
Brain enlargement has been observed in individuals with autism as early as two years of age. Studies using head circumference suggest that brain enlargement is a postnatal event that occurs around the latter part of the first year. To date, no brain imaging studies have systematically examined the period prior to age two. In this study we examine MRI brain volume in six month olds at high familial risk for autism.
The Infant Brain Imaging Study (IBIS) is a longitudinal imaging study of infants at high risk for autism. This cross-sectional analysis examines brain volumes at six months of age, in high risk infants (N=98) in comparison to infants without family members with autism (low risk) (N=36). MRI scans are also examined for radiologic abnormalities.
No group differences were observed for intracranial cerebrum, cerebellum, lateral ventricle volumes, or head circumference.
We did not observe significant group differences for head circumference, brain volume, or abnormalities of radiologic findings in a sample of 6 month old infants at high-risk for autism. We are unable to conclude that these changes are not present in infants who later go on to receive a diagnosis of autism, but rather that they were not detected in a large group at high familial risk. Future longitudinal studies of the IBIS sample will examine whether brain volume may differ in those infants who go onto develop autism, estimating that approximately 20% of this sample may be diagnosed with an autism spectrum disorder at age two.
autism; child psychiatry
Diabetes prevalence is increasing and current methods of management are unsustainable. Effective approaches to supporting self-management are required. The aim of this randomized controlled trial is to establish whether supported telemetric monitoring of glycemic control and blood pressure results in reductions in glycosylated hemoglobin (HbA1c; the primary outcome of a measure of long-term glycemic control) and secondary outcomes of blood pressure and weight among people with poorly controlled diabetes compared to a control group receiving usual care.
Design: multi-center, randomized controlled trial with embedded qualitative study.
Setting: primary care in Lothian, Kent, Glasgow and Borders regions in the UK.
Participants: people with type 2 diabetes and confirmed HbA1c >7.5% (58 mmol/mol).
Intervention/comparison: randomization to intervention or control groups will be performed by the Edinburgh Clinical Trials Unit. Participants in the intervention group will be shown how to use blood glucose and blood pressure monitors and weighing scales which use Bluetooth wireless technology to transmit readings via modem to a remote server. These participants will be asked to provide at least twice weekly measurements of morning and evening blood glucose and weekly measurements of weight and blood pressure. Measurements will be checked at least weekly by practice nurses who will contact the patients to adjust therapy according to guidelines and reinforce lifestyle advice. Participants in the control group will receive usual care. All participants will receive an individual education session.
Follow-up: measurements will be performed at practices 9 months after randomization by research nurses blinded to allocation. The primary outcome measure is HbA1c and secondary outcomes measure are daytime systolic and diastolic blood pressure, weight and cost per quality-adjusted life year.
Analysis: intention-to-treat analyses will be performed. The sample size of 320 participants allows for 20% drop-out and has 80% power at 5% significance to detect a 0.5% absolute (6 mmol/mol) fall in HbA1c in the intervention group. The qualitative study will explore the experiences of patients and professionals using the intervention.
Trial registration number ISRCTN71674628
Diabetes; Hypertension; Glycaemic control; Blood pressure; Weight; Self-management; Telehealth
Irregular, sporadic episodes of ischemic brain injury are known to occur in sickle cell anemia (SCA), resulting in overt stroke and silent cerebral infarction. Ongoing ischemia in other organs is common in SCA but has never been documented in the brain.
To test the hypothesis that acute silent cerebral ischemic events (ASCIEs) are frequent and potentially transient.
Cross-sectional and cohort study of children with SCA screened by magnetic resonance imaging (MRI) of the brain for a randomized clinical trial.
Clinical trial setting in tertiary care centers.
Asymptomatic children with SCA without known stroke, neurologic injury, or epilepsy not receiving treatment with transfusions or hydroxyurea.
Main Outcome Measure
Incidence of ASCIEs calculated using single diffusion-weighted MRI scans (acute ischemic events that occurred within 10 days of the MRI).
Acute silent cerebral ischemic events were detected on 1.3% of MRIs (10 of 771) in 652 children (mean age, 10.0 years), with an incidence of 47.3 events per 100 patient-years (95% CI, 22.7–87.2). Two of 10 children with ASCIEs had follow-up MRIs of the brain; only 1 had silent cerebral infarction in the same location as the previously detected ASCIE.
Children with SCA experience ongoing (chronic, intermittent) cerebral ischemia, sometimes reversible, far more frequently than previously recognized. The brain in SCA is at constant threat of ischemia.
There is unequal access to health care in Australia, particularly for the one-third of the population living in remote and rural areas. Video consultations delivered via the Internet present an opportunity to provide medical services to those who are underserviced, but this is not currently routine practice in Australia. There are advantages and shortcomings to using video consultations for diagnosis, and general practitioners (GPs) have varying opinions regarding their efficacy.
The aim of this Internet-based study was to explore the attitudes of Australian GPs toward video consultation by using a range of patient scenarios presenting different clinical problems.
Overall, 102 GPs were invited to view 6 video vignettes featuring patients presenting with acute and chronic illnesses. For each vignette, they were asked to offer a differential diagnosis and to complete a survey based on the theory of planned behavior documenting their views on the value of a video consultation.
A total of 47 GPs participated in the study. The participants were younger than Australian GPs based on national data, and more likely to be working in a larger practice. Most participants (72%-100%) agreed on the differential diagnosis in all video scenarios. Approximately one-third of the study participants were positive about video consultations, one-third were ambivalent, and one-third were against them. In all, 91% opposed conducting a video consultation for the patient with symptoms of an acute myocardial infarction. Inability to examine the patient was most frequently cited as the reason for not conducting a video consultation. Australian GPs who were favorably inclined toward video consultations were more likely to work in larger practices, and were more established GPs, especially in rural areas. The survey results also suggest that the deployment of video technology will need to focus on follow-up consultations.
Patients with minor self-limiting illnesses and those with medical emergencies are unlikely to be offered access to a GP by video. The process of establishing video consultations as routine practice will need to be endorsed by senior members of the profession and funding organizations. Video consultation techniques will also need to be taught in medical schools.
videoconferencing; general practice; patient appointments; health care
There is a paucity of randomized controlled trials (RCTs) to evaluate models of palliative care. Although interventions vary, all have faced a variety of methodological challenges including: adequate recruitment, missing data, and contamination of the control group. We describe the ENABLE II intervention, methods, and sample baseline characteristics to increase intervention and methodological transparency, and to describe our solutions to selected methodological issues.
Half of the participants recruited from our rural, US comprehensive cancer center and affiliated clinics were randomly assigned to a phone-based, nurse-led educational, care coordination palliative care intervention model. Intervention services were provided to half of the participants weekly for the first month and then monthly until death, including a bereavement follow-up call to the caregiver. The other half of the participants were assigned to care as usual. Symptoms, QOL, mood, and functional status were assessed every 3 months until death.
Baseline data of 279 participants were similar to normative samples. Solutions to methodological challenges of recruitment, missing data, and "usual care" control group contamination are described.
It is feasible to overcome many of the methodological challenges to conducting a rigorous palliative care RCT.
Palliative Care; Randomized Controlled Trial; Advanced Cancer; Methodological Issues; Intervention Study; Rural
Evidence from prospective high-risk infant studies suggests that early symptoms of autism usually emerge late in the first- or early in the second-year of life after a period of relatively typical development. This is the first neuroimaging study to prospectively examine white matter fiber tract organization during this interval in infants who develop autism spectrum disorder (ASD) by 24 months.
Participants included 92 infant siblings from an ongoing imaging study of autism. All participants had diffusion tensor imaging at 6 months and behavioral assessments at 24 months, with a majority contributing additional imaging data at either or both 12 and 24 months. At 24 months, 28 infants met criteria for ASD; 64 infants did not. Microstructural properties of white-matter fiber tracts reported to be associated with ASD or related behaviors were characterized by fractional anisotropy (FA) and radial and axial diffusivity.
FA trajectories differed significantly between infants who did versus did not develop ASD for 12 of 15 fiber tracts. Development for most fiber tracts in infants with ASD was characterized by elevated FA at 6 months followed by slower developmental change overtime relative to infants without ASD. Thus, by 24 months of age, lower FA values were evident for those with ASD.
These results suggest that the aberrant development of white matter pathways precede the manifestation of autistic symptoms in the first year of life. Longitudinal data are critical to characterizing the dynamic age-related brain and behavior changes underlying this neurodevelopmental disorder.
To explore the experiences of patients and professionals taking part in a randomised controlled trial (RCT) of remote blood pressure (BP) telemonitoring supported by primary care. To identify factors facilitating or hindering the effectiveness of the intervention and those likely to influence its potential translation to routine practice.
Qualitative study adopting a qualitative descriptive approach.
25 patients, 11 nurses and 9 doctors who were participating in an RCT of BP telemonitoring. A maximum variation sample of patients from within the trial based on age, sex and deprivation status of the practice was sought.
6 primary care practices in Scotland.
Data were collected via taped semistructured interviews. Initial thematic analysis was inductive. Multiple strategies were employed to ensure that the analysis was credible and trustworthy.
Prior to the trial, both patients and professionals were reluctant to increase the medication based on single BP measurements taken in the surgery. BP measurements based on multiple electronic readings were perceived as more accurate as a basis for action. Patients using telemonitoring became more engaged in the clinical management of their condition. Professionals reported that telemonitoring challenged existing roles and work practices and increased workload. Lack of integration of telemonitoring data with the electronic health record was perceived as a drawback.
BP telemonitoring in a usual care setting can provide a trusted basis for medication management and improved BP control. It increases patients’ engagement in the management of their condition, but supporting telemetry and greater patient engagement can increase professional workloads and demand changes in service organisation. Successful service design in practice would have to take account of how additional roles and responsibilities could be realigned with existing work and data management practices. The embedded qualitative study was included in the protocol for the HITS trial registered with ISRCTN no. 72614272.
Primary Care; Qualitative Research
To compare the costs and cost-effectiveness of managing patients with uncontrolled blood pressure (BP) using telemonitoring versus usual care from the perspective of the National Health Service (NHS).
Within trial post hoc economic evaluation of data from a pragmatic randomised controlled trial using an intention-to-treat approach.
20 socioeconomically diverse general practices in Lothian, Scotland.
401 primary care patients aged 29–95 with uncontrolled daytime ambulatory blood pressure (ABP) (≥135/85, but <210/135 mm Hg).
Participants were centrally randomised to 6 months of a telemonitoring service comprising of self-monitoring of BP transmitted to a secure website for review by the attending nurse/doctor and patient, with optional automated patient decision-support by text/email (n=200) or usual care (n-201). Randomisation was undertaken with minimisation for age, sex, family practice, use of three or more hypertension drugs and self-monitoring history.
Main outcome measures
Mean difference in total NHS costs between trial arms and blinded assessment of mean cost per 1 mm Hg systolic BP point reduced.
Home telemonitoring of BP costs significantly more than usual care (mean difference per patient £115.32 (95% CI £83.49 to £146.63; p<0.001)). Increased costs were due to telemonitoring service costs, patient training and additional general practitioner and nurse consultations. The mean cost of systolic BP reduction was £25.56/mm Hg (95% CI £16.06 to £46.89) per patient.
Over the 6-month trial period, supported telemonitoring was more effective at reducing BP than usual care but also more expensive. If clinical gains are maintained, these additional costs would be very likely to be compensated for by reductions in the cost of future cardiovascular events. Longer-term modelling of costs and outcomes is required to fully examine the cost-effectiveness implications.
International Standard Randomised Controlled Trials, number ISRCTN72614272.
Health Economics; Health Services Administration & Management
Ossification of the stylohyoid ligament is very common in the Caucasian population. More than 9000 descriptions of apparently isolated case reports on PubMed have been cited over the last 20 years, often associated with an incidental finding on imaging after neck trauma. No cases of familial ossification have been described. We document a family with several affected members, each with an ossified stylohyoid ligament, confirming that ossification may be hereditary in some families and is most likely due to an autosomal dominant gene.
We describe simulations of large-scale networks of excitatory and inhibitory spiking neurons that can generate dynamically stable winner-take-all (WTA) behavior. The network connectivity is a variant of center-surround architecture that we call center-annular-surround (CAS). In this architecture each neuron is excited by nearby neighbors and inhibited by more distant neighbors in an annular-surround region. The neural units of these networks simulate conductance-based spiking neurons that interact via mechanisms susceptible to both short-term synaptic plasticity and STDP. We show that such CAS networks display robust WTA behavior unlike the center-surround networks and other control architectures that we have studied. We find that a large-scale network of spiking neurons with separate populations of excitatory and inhibitory neurons can give rise to smooth maps of sensory input. In addition, we show that a humanoid brain-based-device (BBD) under the control of a spiking WTA neural network can learn to reach to target positions in its visual field, thus demonstrating the acquisition of sensorimotor coordination.
brain-based computational model; spiking neuronal networks; winner-take-all; motor control and learning/plasticity; spike-timing-dependent plasticity; sensorimotor control; large-scale spiking neural networks; neurorobotics
Animal behavior often involves a temporally ordered sequence of actions learned from experience. Here we describe simulations of interconnected networks of spiking neurons that learn to generate patterns of activity in correct temporal order. The simulation consists of large-scale networks of thousands of excitatory and inhibitory neurons that exhibit short-term synaptic plasticity and spike-timing dependent synaptic plasticity. The neural architecture within each area is arranged to evoke winner-take-all (WTA) patterns of neural activity that persist for tens of milliseconds. In order to generate and switch between consecutive firing patterns in correct temporal order, a reentrant exchange of signals between these areas was necessary. To demonstrate the capacity of this arrangement, we used the simulation to train a brain-based device responding to visual input by autonomously generating temporal sequences of motor actions.
neurorobotics; sequence learning; spiking network; winner-take-all; motor control and learning/plasticity; spike-timing dependent plasticity; sensorimotor control; large-scale spiking neural networks
Memory CD4+ T cells combat viral infection and contribute to protective immune responses through multiple mechanisms, but how these pathways interact is unclear. We found that several pathways involving memory CD4+ T cells act together to effectively clear influenza A virus (IAV) in otherwise unprimed mice. Memory CD4+ T cell protection was enhanced through synergy with naive B cells or CD8+ T cells and maximized when both were present. However, memory CD4+ T cells protected against lower viral doses independently of other lymphocytes through production of IFN-γ. Moreover, memory CD4+ T cells selected for epitope-specific viral escape mutants via a perforin-dependent pathway. By deconstructing protective immunity mediated by memory CD4+ T cells, we demonstrated that this population simultaneously acts through multiple pathways to provide a high level of protection that ensures eradication of rapidly mutating pathogens such as IAV. This redundancy indicates the need for reductionist approaches for delineating the individual mechanisms of protection mediated by memory CD4+ T cells responding to pathogens.