by Randy A. Sansone, MD, and Lori A. Sansone, MD
Dr. R. Sansone is a professor in the Departments of Psychiatry and Internal Medicine at Wright State University School of Medicine in Dayton, Ohio, and Director of Psychiatry Education at Kettering Medical Center in Kettering, Ohio; Dr. L. Sansone is a family medicine physician (government service) and Medical Director of the Primary Care Clinic at Wright-Patterson Air Force Base. The views and opinions expressed in this column are those of the authors and do not reflect the official policy or the position of the United States Air Force, Department of Defense, or US government.
Psychiatry (Edgemont) 2009;7(8):33–37
ABSTRACT
Traditional panic attacks are characterized by multiple somatic symptoms involving the cardiac, respiratory, gastrointestinal, and vestibular systems. However, on occasion, panic disorder symptoms may congeal into one predominant system. These atypical presentations, in which symptoms manifest in a single system, are described as panic disorder subtypes. Four subtypes are commonly reported: 1) cardiac, 2) respiratory, 3) gastrointestinal, and 4) vestibular. In this edition of The Interface, we discuss how these subtypes may mimic organic diseases, leading to under-recognition, under-treatment, and over-utilization of healthcare resources.
KEY WORDS
panic disorder, panic disorder subtypes, panic attacks
INTRODUCTION
In psychiatric settings, panic disorders are typically characterized by multiple somatic symptoms. This traditional clinical presentation is consistent with the conceptualization offered by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR),[1] which states that the symptoms of panic disorder may include cardiac symptoms (e.g., palpitations, a pounding heart, an accelerated heart rate, chest pain or discomfort), respiratory symptoms (e.g., shortness of breath, the sensation of smothering, feelings of choking), gastrointestinal symptoms (e.g., nausea or abdominal distress), and vestibular symptoms (e.g., dizziness, unsteadiness, lightheadedness, or faintness). The remaining criteria for panic disorder are sweating, trembling or shaking, derealization, and depersonalization, as well as fears of losing control, going crazy, or dying. On occasion, and perhaps more often in the primary care setting, these somatic symptoms may congeal into a symptom profile that is localized to one organ or system. These atypical localizations of symptoms are described as panic disorder subtypes. In this edition of The Interface, we review four relatively common subtypes of panic disorder and their corresponding somatic mimics in the primary care setting.
PANIC DISORDER SUBTYPES
In the empirical literature, a number of authors describe panic disorder subtypes. For example, Katon[2,3] states that the three most common presentations of panic disorder in the primary care setting are the cardiac, neurological, and gastrointestinal subtypes. Aust[4] and Sequi et al[5] describe cardiovascular, gastrointestinal, and vestibular subtypes of panic disorder. Briggs et al[6] describe a respiratory subtype of panic disorder. Zaubler and Katon[7] describe cardiac, gastrointestinal, respiratory, and vestibular subtypes of panic disorder. Cox et al[8] describe vestibular and cardiorespiratory patient clusters. Finally, Bovasso and Eaton[9] describe cardiac and respiratory versions of panic disorder. While various authors propose different subtype classifications, four appear to be most notable: 1) cardiac, 2) respiratory, 3) gastrointestinal, and 4) vestibular.10 Because of their well circumscribed symptoms, somatic subtypes of panic disorder are more likely to be encountered by psychiatrists on consultation/liaison services and primary care physicians.
The cardiac subtype. Panic attacks can present with a broad array of cardiac symptoms including palpitations, chest tightness, fluttering of the heart, rapid heart beat, chest discomfort, and a pounding heart. Because of the acute and dramatic onset of symptoms as well as their crescendo-like characteristics, this subtype of panic attacks may mimic a heart attack.
In a number of studies, investigators have found that acute cardiac symptoms (e.g., chest pain) without abnormal diagnostic findings (e.g., normal coronary arteries, normal event monitor, no detectable cardiac malfunction) suggest panic attacks or disorder. In support of this impression, Beitman et al[11] examined cardiology patients with atypical or nonanginal chest pain and found that 43.3 percent suffered from panic disorder. Ayuso Mateos et al[12] examined 112 patients who were admitted for atypical chest pain and found that 47.3 percent had panic disorder. Beitman and Al-Basha[13] examined 94 patients with chest pain and normal angiographic studies, and reported that 34 percent met the criteria for panic disorder. Barsky et al[14] examined 145 patients undergoing Holter monitoring and found that the lifetime prevalence of panic disorder in this cohort was 27.6 percent. Potts and Bass[15] examined 46 patients with chest pain and normal coronary arteries and, during follow up 11 years later, confirmed that 15 percent met the criteria for current panic disorder.
In a small series of 22 chest-pain patients, Ho et al[16] found that 15 percent suffered from panic disorder. In a study of 199 consecutive patients with chest pain who were referred for outpatient evaluation, Brinager et al[17] found that 29.6 percent had panic disorder. Husser et al[18] examined 37 consecutive patients with chest pain and normal coronary angiograms, and found the 8.1 percent had panic disorder. Among chest-pain patients without any detectable cardiac etiology, Hocaoglu et al[19] found that 47.1 percent had panic disorder. Finally, among 229 chest-pain patients without identifiable cardiac etiology, White et al[20] found that 21.8 percent had a lifetime diagnosis of panic disorder. Summarizing these data, it appears that anywhere from 8 to 47 percent of patients with noncardiac chest pain have a diagnosis of panic disorder.
In addition to the high prevalence of panic disorder among those with noncardiac chest pain, there is also a high prevalence of this Axis I disorder among the first-degree relatives of such individuals. In this regard, Kushner[21] confirmed that among 65 chest-pain probands and 544 of their first-degree relatives, the prevalence of panic disorder was significantly higher than rates among the relatives of controls.
As for a final commentary, Huffman and Pollack[22] reviewed the studies in this area between 1970 and 2001. They concluded that five specific variables correlate with high rates of panic disorder in individuals who present with chest pain. These were 1) the absence of coronary artery disease;
2) atypical quality of the chest pain; 3) female gender; 4) young age; and 5) a high level of self-reported anxiety.
It appears that, in the primary care setting, panic disorder can clearly impersonate cardiac disease, and normal diagnostic findings may unmask this somatic deception. This mimicry appears to be evident worldwide, as the preceding studies include patient and community samples from the US, United Kingdom, Spain, Singapore, Norway, Germany, and Turkey.
The respiratory subtype. In stark contrast to the other subtypes of panic disorder, the respiratory subtype does not appear to have a somatic mimic. This may be due to the acute and short-lived nature of the symptoms, which are readily recognized and clinically diagnosed as hyperventilation. On a side note, this subtype appears to be the most described and empirically studied. For example, the literature indicates that individuals with this subtype of panic disorder are more sensitive to carbon dioxide challenge;[23-25] have lower resting end-tidal carbon dioxide levels;[26] and exhibit an epidemiological profile characterized by female gender, low education, and comorbid depressive and alcohol-use disorders.[27]
The gastrointestinal subtype. During some panic attacks, symptoms may isolate to the gastrointestinal tract and include acute and fleeting nausea and dyspepsia. These types of episodic and concentrated symptoms can be easily misconstrued as irritable bowel syndrome (IBS), perhaps with atypical features—another potential somatic impersonator of panic disorder.
In support of this type of mimicry, in 1994, Lydiard et al28 performed an intriguing study that explored the prevalence of gastrointestinal symptoms among individuals with panic disorder (n=194), another psychiatric disorder (n=1,932), or no psychiatric disorder at all (n=8,973) (Table 1). In this study, individuals with panic disorder had a significantly higher rate of endorsement of various gastrointestinal symptoms, including those typically associated with IBS, than those participants with another or no psychiatric disorder.
Since the publication of the Lydiard et al[28] data, other investigators have verified a high prevalence of gastrointestinal/IBS-like symptoms in patients with panic disorder. For example, in a study of panic disorder patients, Kaplan et al[29] determined that 46.3 percent met the criteria for IBS—a significant difference when compared to the 2.5-percent rate encountered in the control group. Overall, Lydiard states that approximately 40 percent of patients with panic disorder have IBS.[30]
From a different epidemiological perspective, the prevalence of panic disorder is relatively high among those with IBS. In this regard, Garakani et al[31] found that 46 percent of his sample of IBS patients suffered from panic disorder. In a Japanese study, Kumano et al[32] surveyed 4,000 subjects and determined that 6.1 percent had IBS; among this subsample, investigators found a significantly higher prevalence of panic disorder compared to controls without IBS. Creed et al[33] examined 257 IBS patients entering into psychological treatment and found that 12 percent met the criteria for panic disorder. Endo[34] stated that, based upon clinical experience, 27 percent of IBS patients have comorbid panic disorder.[3] Finally, Lydiard30 summarized that between 25 to 30 percent of patients with IBS suffer from panic disorder.
The explicit relationship, if any, between panic disorder and IBS remains unclear; in addition, whether this relationship exists outside of those seeking treatment is unknown.[35] However, there may be a bi-directional relationship (i.e., there is an increased prevalence of panic disorder in those with IBS and there is an increased prevalence of IBS in those with panic disorder). In addition, it is possible that some individuals who present with gastrointestinal symptoms are misdiagnosed with IBS and actually suffer from the gastrointestinal subtype of panic disorder.
Similar to the cardiac subtype of panic disorder, it is conceivable that patients with the gastrointestinal subtype of panic disorder may be misdiagnosed with IBS. Therefore, it appears that in some cases, panic disorder may impersonate IBS.
The vestibular subtype. Vestibular symptoms are common among individuals with panic disorder and may include dizziness, unsteadiness, lightheadedness, or faintness. When symptoms solely present in the vestibular system, panic disorder may impersonate vestibular disease. In support of these impressions, a number of investigators have indicated high rates of panic disorder among patients presenting with dizziness,[36-38] 5 to 15 times the rate encountered in the general population.[39] As for specific studies, Clark et al[40] examined 50 patients in an otolaryngology clinic who presented with dizziness; 20 percent met the criteria for panic disorder. Yardley et al[41] examined a community sample of 128 individuals with dizziness and found that nearly two-thirds had panic attacks and around one-quarter met the criteria for panic disorder. Staab and Ruckenstein[42] retrospectively examined the medical records of 132 patients and determined that anxiety disorders were the sole cause of dizziness in 33 percent. Finally, Garcia et al[43] examined 60 patients with dizziness and found that 15 percent suffered from panic disorder. To conclude, the preceding data suggest that panic disorder may impersonate vestibular disorders.
CAVEATS
The available empirical data suggest that panic disorder may mimic other types of medical syndromes, especially cardiac disease, IBS, and vestibular disorders. These symptom-focused subtypes may be more likely to present in primary care and specialty clinic settings. While the symptoms among these various subtypes of panic disorder are seemingly diverse, they are all united by a consistent texture: 1) symptoms are intense, dramatic, and episodic; 2) symptoms have no accompanying abnormal diagnostic studies; and 3) symptoms recur without medical deterioration over the course of illness.
While these are the most commonly described subtypes, panic disorder has been known to manifest via other atypical somatic venues as well. For example, Sansone and Malik[44] described the case of an individual whose panic-disorder symptoms were limited to a fleeting full body rash. We have also encountered other atypical physical symptoms that were eventually associated with panic disorder, including bilateral cheek numbness and new-onset stuttering in an adult following a traumatic automobile accident.
CONCLUSION
Among the four described subtypes of panic disorder, three (cardiac, gastrointestinal, and vestibular) have corresponding somatic mimics. These deceptive somatic impersonators may not only lead to the under-recognition of panic disorder, but may also increase healthcare utilization through multiple appointments, unnecessary diagnostic procedures, and misguided medication trials. While these somatic mimics appear very different from each other, they share the common texture of all panic symptoms. The symptoms are acute (i.e., last 10–15 minutes), intense, and dramatic; have no accompanying abnormal diagnostic studies; and are recurrent without medical deterioration over the course of the disorder. Indeed, it may be that any somatic symptom that displays this characteristic texture may be a somatic variant of panic disorder. In conclusion, all clinicians need to be suspicious of somatic symptoms that have the texture of panic attacks because panic disorder can, indeed, be a prolific and deceptive somatic mimic.
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