Understanding and Managing Neurally Mediated Syncope in the Adolescent

Incidence

Neurally mediated syncope is relatively common among children and adolescents. Various studies report the incidence of NMS to be as high as 25% in adolescents (Johnsrude, 2000). The peak incidence of NMS is between the ages of 15 and 19 years (Tanel & Walsh, 1997). Although it is unclear why this is a peak time, the interplay of hormonal changes, rapid growth, and lifestyle has been implicated (Ross & Grubb, 1998).

Etiology

The mechanism underlying the vasodepressor response for NMS events has been theorized, but is not fully understood. It is generally presumed to be an exaggerated form of an otherwise normal response. Because NMS events happen while the individual is upright, diminished cerebral blood flow secondary to peripheral vascular pooling of blood in the lower extremities has been postulated as a cause. This pooling can result in a decrease in systemic venous return and may initiate a complex hemodynamic response resulting in marked sympathetic withdrawal. Subsequent events can include abrupt hypotension, relative bradycardia, and loss of consciousness. The theories that have been advanced to explain the mechanisms for these hemodynamic events are controversial and include, but are not limited to, (a) the ventricular theory, (b) the reduced blood volume theory, and (c) the baroreceptor reduction theory.

The ventricular theory was one of the first proposed to explain the sequence of events that precede a syncopal event. This theory suggests that a change to the upright position causes a decrease in blood pressure that in turn triggers a reflex increase in efferent sympathetic activity. Increased sympathetic tone enhances peripheral vascular resistance and produces an increase in both inotropic and chronotropic cardiac effects. This increase in heart rate and strength of myocardial contraction in a setting of relative ventricular hypovolemia is thought to result in an “empty chamber” phenomenon. The vigorous contractions of the ventricle are thought to stimulate left ventricular afferent fibers and to trigger an inhibitory response resulting in hypotension and bradycardia that together are referred to as Bezold-Jarisch-like reflex (Massin, 2003). Although this theory appears reasonable, experimental observations during witnessed syncopal events are not explained by this theory.

Another theory that has been proposed is that reduced blood volume is present in individuals with NMS. This suggests that abrupt changes in posture, such as standing quickly after a period of recumbence or prolonged standing, exacerbate NMS symptoms. This explanation is consistent with the beneficial response to an increase in salt and fluid intake that can be seen in some cases. However, additional research indicates that blood volume redistribution is more critical for the development of symptoms than reduced blood volume and postural changes (Mosqueda-Garcia, Furlan, Tank, & Fernandez-Violante, 2000).

An inability of the peripheral baroreceptor reflex to compensate for gravitational stress has been put forth as the basis for NMS in the “baroreceptor dysfunction theory” (Massin, 2003). More recent theories postulate diverse neurohumoral agents as being the provocative agents in NMS. Epinephrine, serotonin, and adrenomedullin are all being investigated as pivotal agents in the development of symptoms (Mosqueda-Garcia, Furlan, Tank, & Fernandez-Violante, 2000). What is currently referred to as NMS actually may be determined to be a constellation of conditions with a similar clinical expression.

Initial Assessment

The school nurse’s initial assessment of symptoms associated with NMS needs to be broad-based yet detailed. A concurrent illness, often a viral illness with fever or vomiting and decreased oral intake, can trigger the onset of these symptoms. Resolution of the viral illness generally leads to resolution of the symptoms, thus eliminating the need for further intervention. The use of alcohol or recreational drugs must be eliminated as the source of symptoms, because substance use can lead to syncope. Pregnancy should be unambiguously eliminated as the cause of NMS in girls with childbearing potential.

With the anxiety and uncertainty surrounding a first syncopal event, the differential diagnosis of neurally mediated syncope can be overlooked. Many expensive and unnecessary tests are performed when there is confusion regarding etiology, delaying the determination of the diagnosis, and providing opportunities for recurrent events. The tonic movements seen with NMS may be identified as seizures, which can prompt referral to a neurologist (Matoth, Taustein, Kay, & Shapira, 2002). Electroencephalograms, CT scans, and magnetic resonance imaging often are ordered at considerable expense and result in no substantive clarification of the diagnosis. Persistent, severe dizziness, lightheadedness, or vertigo from sustained low cerebral blood flow can prompt referral to an otolaryngologist. Misinterpretation of the events leading to syncope and concerns about the possibility of underlying structural cardiac disease, despite a non-contributory cardiac exam and family history, can prompt the clinician to order an echocardiogram, 24-hour Holter monitoring, or exercise stress testing. The diagnostic yield of these studies in the setting of NMS is extremely low (Ritter, Tani, Etheridge, Williams, Craig, & Minich, 2000).

The evaluation of a child or adolescent experiencing a syncopal event should begin with a careful and complete history. This includes the current event, as well as previous similar sensations, such as lightheadedness or dizziness upon arising in the morning or after a period of recumbence. The documentation also must include a thorough family history, including other family members who have fainted during their teenage years. The presence of familial structural heart disease such as hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, or long QT syndrome should be seen as significant warning signs. If the family is under the care of a cardiologist for these conditions, the school nurse should recommend that the provider be contacted and be informed of these new symptoms. Elements of the history that suggest a potential cardiac cause of syncope include a family history of early sudden death or arrhythmia, known congenital heart disease, a complaint of palpitations or chest pain prior to the event, lack of a prodrome, or experiencing a syncopal event during exercise (Table 2; Wren, 2002). Those adolescents with symptoms of syncope and a history of structural heart disease should be referred for immediate evaluation at a pediatric cardiology referral center, because the possibility of a cardiac origin increases significantly with concurrent disease (Massin, 2003).

When the acute evaluation is consistent with a diagnosis of NMS, referral to a cardiologist often is not necessary unless extreme parental or youth anxiety warrants. A screening electrocardiogram (ECG) is recommended by most pediatric cardiologists for any adolescent experiencing a syncopal event. A 12-or 15-lead surface ECG can be performed at the family’s convenience. A pediatric cardiologist who is familiar with age-dependent variations of the recording should interpret the ECG. The ECG can rule out more ominous conditions such as long QT syndrome, T-wave abnormalities, or Wolff-Parkinson-White or Brugada syndrome, as well as other conduction disturbances and the right ventricular hypertrophy that has been associated with pulmonary hypertension.

Pediatric Cardiology Evaluation

Adolescents with frequent true syncopal events or an atypical presentation of syncope should be referred to a pediatric cardiology center. The pediatric cardiology team can differentiate vasomotor syncope from that caused by arrhythmias or underlying structural heart disease. Pediatric cardiology evaluation generally includes an ECG if one has not been performed previously. Although many highly technical and expensive diagnostic tools can be employed in evaluating adolescents with recurrent syncope, the pediatric cardiology team’s elicitation of a detailed history of the event is key to the diagnosis of vasodepressor syncope for most patients. A complete cardiac examination is performed and findings that are suggestive of underlying heart disease can lead to further diagnostic testing. The pediatric cardiology team, familiar with the many facets of NMS, also can assess the adolescent in relation to the processes that can cause syncope, as well as for the teen’s capacity for self-management to prevent future syncopal events.

The general public often associates syncope with lethal events based on the death of a well-known athlete or young person in the area. The waiting time before a cardiology appointment can give the family an opportunity to consider more sinister diagnoses. A great deal of youth and family anxiety can be allayed prior to their appointment with the pediatric cardiology team. The school nurse can help the family by educating them about NMS as the probable cause of the adolescent’s symptoms. Changes in lifestyle such as an increase in salt and fluid intake can be recommended for the adolescent to try prior to the visit. The youth’s initial responses to such lifestyle changes can provide valuable information to the pediatric cardiology team when it comes time to decide on a treatment plan.

Self-Management

Most adolescents with NMS are minimally affected by their symptoms and can achieve an increased sense of wellness and a syncope-free life with subtle lifestyle changes. Sustained efforts at maintaining hydration, with frequent intake of fluids reaching approximately 120 ounces of noncaffeinated fluids each day, and liberalizing dietary salt may be all that is needed to alleviate NMS symptoms (Younoszai, Franklin, Chan, Cassidy, & Allen, 1998). Commercial sports drinks may be helpful for those adolescents who dislike salty foods. Younger adolescents may need help in developing a specific and feasible plan for increased fluid intake.

Prevention of the recurrence of NMS symptoms also requires that affected adolescents consciously monitor themselves for symptoms and apply preventive measures in a timely manner when these symptoms are perceived. They must be made aware of the physical and sensory changes that are linked to their episodes. Knowledge about the evolution NMS from prodrome to loss of consciousness, risk for injury from a fall, and the range of ways to alleviate symptoms will prevent progression of symptomatology and will minimize the risk for injury. This knowledge can then allow the adolescent to collaborate in the management of his or her health condition (Whittemore, Bak, Melkus, & Grey, 2003). Adolescents should be assessed with regard to their understanding of appropriate responses to symptoms. They can be encouraged then to utilize these responses to normalize life with NMS as much as possible. Self-management, defined by Schilling, Grey, and Knafl (2001) as “an active, daily, and flexible process in which youth and their parents share responsibility and decision-making for achieving disease control, health, and well-being through a wide range of illness-related activities” (p. 92), has been explored for other adolescent health conditions such as type 1 diabetes. Using this definition of self-management, the school nurse can empower the adolescent with NMS to implement a self-management plan that aims to decrease the incidence of events and thereby diminish the effect of NMS on the adolescent’s life. Education about NMS should address the mechanisms responsible for their symptoms and how they can work with their bodies to manage their symptoms.

The adolescent can be helped to recognize more or less helpful ways of responding to the symptoms that can evolve to a full-blown NMS event, and, through role play, can practice the use of more effective and fitting means of responding to symptoms. For example, social embarrassment may diminish or may increase the adolescent’s compliance with the required precautions. Lying down when a prodrome is first identified can be awkward at best and is not always possible. If the adolescent can develop the understanding that substantial increases in fluid intake can help avoid these dilemmas and if he or she can devise an acceptable and feasible plan for accessing water throughout the day, self-management is more likely to be enacted.

Provider Support for Self-Management

Clinicians’ efforts to praise and otherwise support self-management efforts have been shown to be very effective in changing behavior during adolescence, a time in the lifespan when increased independence is highly valued (Christian & D’Auria, 1999). The school nurse can review and can distribute, to the adolescent as well as the family, information that is easy to understand and reinforces teaching about symptoms and treatment of NMS. The adolescent’s cognitive level will influence his or her ability to process and to understand the provided information and the NMS event. The school nurse must take cognitive ability into account when explaining the diagnosis, its implications, and treatment. Allowing the adolescent confidential and convenient access to the school nurse for clarification of the issues addressed and any related questions can empower adolescents to understand and to self-manage NMS.

Support for self-management of NMS provides excellent opportunities for the school nurse to establish a supportive relationship with affected students. By reiterating the treatment plan and praising the adolescent’s efforts at self-management, including lifestyle changes, the nurse can be a valuable member of a team of clinicians who are dedicated to alleviating an adolescent’s NMS symptoms and to decreasing school absenteeism related to NMS. However, the most commonly used coping strategies for adolescents with chronic illness have been identified as being self-reliance and social support, whereas seeking support from professionals has been identified as the least-used coping strategy (Grey, Lipman, Cameron, & Thurber, 1997). Therefore, actively seeking to help adolescents develop coping skills that contribute to self-management can be a way to help adolescents both achieve an increased sense of independence and negotiate a comfortable level of parental and professional involvement in health self-management.

Advanced practice nurses (APN) from the pediatric cardiology team can provide school nurses with education and consultation about NMS. Communicating essential and accurate information to the family and other school personnel, with permission from the family, can help to improve the school’s response to the adolescent’s NMS and attempts at self-management. The APN can reassure school personnel, including athletic coaches, about the appropriateness of the adolescent’s resumption of previous physical activities.

Optimal management for more significant NMS is evolving as new information is gained from research (Deal, Strieper, Scagliotti, Hulse, Auld, Campbell, Strasburger, & Benson, 1997; Table 3). For the adolescent unresponsive to salt and fluid management, several treatment options are available with varying efficacy. A common first-line medication for significant NMS is a corticosteroid with mineralocorticoid activity: fludrocortisone. This drug enhances central blood volume by increasing sodium and fluid retention and by increasing the vascular sensitivity to norepinephrine. Fludrocortisone is generally well tolerated at low doses, but girls may object to its side effects, which include fluid retention and mild weight gain.

Beta-blockers long have been used for syncope that is preceded by a feeling of increased heart rate and frequent presyncopal events. These drugs work by blunting the release of epinephrine and thereby reducing cardiac inotropy and mechanoreceptor activation, and increasing peripheral arterial resistance. They also are believed to block serotonin centrally. Atenolol is the only beta-blocker proven to be effective in clinical trials (Massin, 2003). There have been rare reports of the onset of depression after starting treatment with beta-blockers (Johnsrude, 2000). Symptoms are reversed with discontinuation of the medication. Competitive athletes may experience a decrease in endurance on beta-blockers (Massin). Patients with asthma also should be offered a different therapeutic option secondary to potential interference with asthma treatment from the beta blockade.

Selective serotonin reuptake inhibitors (SSRI) have been reported to be effective in the treatment of NMS. Serotonin is an important neurotransmitter in blood pressure regulation, and its activation can facilitate a vasodepressor response. SSRIs block serotonin reuptake in the synaptic cleft, thus reducing its effects on sympathetic activity and possibly moderating vasodepressor tendencies in NMS (Massin, 2003). SSRIs should be used cautiously, for they have been associated with anorexia, nausea, fatigue, and central nervous system stimulation.

Midodrine belongs to a class of drugs that have alpha agonist effects. This class of drugs promotes vasoconstriction, or at least impedes vasodilatation, and may be an option in the prophylaxis against NMS symptoms. Disadvantages of midodrine include three-times-a-day dosing, hypertension, headache, and scalp tingling. Midodrine has been shown to be beneficial in some individuals who are unresponsive to other medications (Sra, Maglio, Biehl, Dhala, Blanck, Deshpande, Jazayeri, & Akhtar, 1997).

Although various other medications have been used in the treatment of NMS, fludrocortisone, beta-blockers, SSRIs, and midodrine constitute the most commonly recommended treatments for the adolescent population. Permanent cardiac pacing has received sporadic support in the treatment of NMS, especially for the cardioinhibitory type. To date, evidence does not support improvement in NMS symptoms in the adolescent population with cardiac pacing. Most youths with NMS can be managed adequately through non-invasive medical therapy (Deal, Strieper, Scagliotti, Hulse, Auld, Campbell, Strasburger, & Benson, 1997).

The majority of adolescents with NMS will notice resolution of symptoms over 1 to 2 years. After a year without symptoms, medical management is gradually withdrawn, but self-management plans are left in place. A consciousness of the need for adequate hydration and symptom recognition should be maintained always.

A small number of adolescents will continue to experience NMS events despite multiple medical and self-management therapies. The care of this group of adolescents can be very frustrating and perplexing to providers. Episodes of NMS can, in some cases, increase in frequency as therapy is escalated. When this happens, adjustments in treatment by phone should be ceased and the adolescent should be reassessed in the clinic setting. The school nurse can begin the one-on-one discussion with the adolescent and the family to reassess their understanding of NMS, its treatment, and potential barriers to symptom resolution. Exploring factors that may be compromising adherence to the treatment plan or the occurrence of risk-taking behaviors should be discussed privately with the adolescent in a confidential atmosphere. Prodromal symptoms may have changed or shortened in duration with the addition of medications, or the adolescent may have habituated to the NMS symptoms, making it harder to recognize an impending event. The provider can emphasize the adolescent’s strengths and can encourage active problem-solving to deal with situations that impede treatment adherence. In Gilbert’s (1999) study on youth adjustment to chronic migraines, the importance of active problem-solving was reported. Both preventive and anticipatory action plans emerged from the data as frequently used strategies to avoid or to minimize the effects of migraine pain. These results provide insight into the management strategies that can be utilized by adolescents with recurrent NMS. The provider can support and validate positive coping behaviors and attempts at compliance by the adolescent to promote an increase in the adolescent’s self-efficacy. The circumstances around negative outcomes can be explored and the adolescent can be coached regarding ways to problem-solve and to find additional cues to an impending NMS event and ways to respond to the cues.

Psychosocial Aspects of Self-Management

The self-management of NMS requires that the individual take preventive measures, develop a conscious awareness of symptoms, and carry out supplementary actions in a timely manner when symptoms are perceived. Lack of preventive efforts and symptom awareness can result in recurrent NMS events. The unpredictable nature of NMS can evoke feelings of heightened emotional distress and uncertainty for the family. Adolescents may be unable to accurately recognize or to interpret the symptoms that precede an NMS event (Ross & Grubb, 1998) or may be reluctant to take the steps necessary to abort an impending event. The literature suggests that the level of anxiety and incapacitation in heart-healthy adults with symptoms perceived to be cardiac in origin can be equal to or higher than in those with actual cardiac disease (Eifert, Hodson, Tracey, Seville, & Gunawardane, 1996). Given the frequent occurrence and public awareness about acquired heart disease, adolescents and their families can become intensely anxious when the adolescent experiences an event that is perceived as being cardiac in nature. Some of this anxiety can be transmitted to teachers and other social contacts (Lewis & Dhala, 1999). For those who are mildly affected, the ability to process the benign nature of the diagnosis can reduce anxiety and can heighten compliance with medical and self-management.

Failure to grasp the diagnosis can have adverse effects. For example, misunderstanding of the benign nature of NMS can result in restriction of the adolescent’s participation in normal daily activities beyond that which is medically indicated. Self-or family-imposed limitations on activities, especially exercise, can lead to physical deconditioning. Recurrent NMS can be associated with an increased risk of poor school performance, absenteeism, and social withdrawal. Efforts by school nurses to augment understanding of the nature of the condition and to suggest suitable self-management plans can help to decrease anxiety and encourage positive coping behaviors. A more positive psychosocial outlook can then mitigate the risks.

Changes in normal daily activities, such as avoidance of school or gym, can be seen in the adolescent with recurrent NMS. Ongoing fear of fainting can generate self-or parental limitations and can result in the development of depressive symptoms, insomnia, and social withdrawal (Boehm, Morris, Kip, Karas, & Grubb, 2000). The fear of embarrassment at school or of being labeled as different may interfere with an adolescent’s involvement in the treatment plan and delay their return to normal activities (Rose, Koshman, Spreng, & Sheldon, 2000).

With the conflicting emotions associated with recurrent syncope and its possible implications for life changes, as well as the increasing need for independence in this population, parents may not be aware of the frequency of symptoms nor of the efforts taken by the adolescent to diminish or to prevent symptoms. Parents also may not be aware of the times that the child refuses to adhere to a suggested regimen due to fear of peer criticism or of being different. Also, it is not known what concessions or adaptations have been made by the child to achieve the appearance of normality. These are areas in need of further research.

Barriers to Self-Management of Syncope

Despite the positive prognosis and all efforts at management, a small percentage of adolescents may appear to be more significantly affected by this condition. Many of these cases are attributable to non-physiologic factors that impede resumption of normal functioning. In trying to understand this group, several thoughts should be considered, some of which originate from research on the adaptation of adolescents with type 1 diabetes. Hanson and others’ study (as cited in Siakowski-Amer, 1999) on adaptation and disease duration in diabetes shows that a high level of social competence and parental support can be correlated with an improved level of metabolic control. Based on these findings, lower levels of social competence and parental support can be a means to identify adolescents who are at an increased risk for more profound effects of NMS. Early identification of this group can direct the provider to intensify supportive care interventions early in the course of the condition.

Another factor to consider in cases of NMS that appear to be treatment resistant is the frequent incidence of comorbid psychological disease that has been associated with young adults with NMS (Kouakam, Lacroix, Klug, Baux, Marque, & Kacel, 2002). Researchers have begun to document the impact of recurrent vasodepressor syncope on the psychosocial functioning of adolescents and the incidence of comorbid psychological disease. Although depression and anxiety have been shown to occur more frequently in patients who experience syncopal events, it is difficult to know which comes first, syncope or anxiety and depression, and how each affects the other. The relationship between these phenomena has been described as a vicious circle of psychological distress and syncope that requires careful, ongoing evaluation, both medical and psychotherapeutic. Worsening anxiety can lead to withdrawal from key life activities. Continued withdrawal from these activities can exacerbate depression. Although the possibility of concurrent psychiatric disease often is overlooked at the initial assessment, such evaluation may become necessary in the adolescent with persistent syncopal events.

Psychogenic syncope also must be considered in the patient who appears unresponsive to treatment and begins to accelerate the number of events of syncope with increases in management. Close observation will reveal events without neurological (tonic movements), autonomic (pallor or diaphoresis), or cardiovascular (heart rate or blood pressure) changes. A diary of events will reveal occurrence in the presence of an audience, not dependent on posture, without injury, and not relieved by a recumbent posture (Tanel & Walsh, 1997). The adolescent’s description of the event may suggest a lack of loss of consciousness. These patients require psychological evaluation with subsequent individual and family therapy.

Unresponsive patients also must be assessed for contributing psychosocial factors, such as positive reinforcement by families. Positive reinforcement occurs when the family unknowingly or unintentionally reinforces the youth’s illness behaviors by allowing them to miss school, to delay homework, or to be excused from activities that they dislike. Family members also may pay increased attention to the adolescent and may encourage others to do the same when NMS symptoms are experienced. The uncertainty that is inherent in NMS, including its nonspecific symptoms, unknown etiology and unpredictable course, can support the reinforcement of NMS events (Brace, Smith, McCauley, & Sherry, 2000). Byars, Brown, Campbell, and Hobbs (2000) found that parents reported a greater level of adjustment difficulties than did youth in the setting of a chronic condition, and proposed that the parent’s overly solicitous nature inadvertently can reinforce the somatic behaviors of their children. It may be very difficult for providers to convince the family that positive reinforcement can take place. Together with parents, the adolescent and other providers, the school nurse’s efforts to diminish parental anxiety and to increase the adolescent’s self-efficacy for managing NMS can lead to the adolescent experiencing a decreased number of symptomatic incidents. An improved sense of well-being can encourage the adolescent to return to a normal and successful existence.