Agoraphobia and panic

BASIC INFORMATION
DEFINITION
Translated as ‘fear of the market place’, this common phobia (4% prevalence) presents as a fear of being away from home, with avoidance of travelling, walking down a road and supermarkets being common cues. This can be a very disabling condition, since the patient can be too unwell to ever leave home, particularly by themselves. It is often associated with claustrophobia, a fear of enclosed spaces.
In the U.S., agoraphobia is considered part of the continuum of panic attacks and panic disorder. In Europe, agoraphobia is conceptualized as a phobic condition independent of panic. A panic attack is a relatively brief, sudden episode of intense fear or apprehension, often associated with a sense of impending doom and various uncomfortable and disquieting physical symptoms. Panic disorder is diagnosed if at least one panic attack is followed by a significant degree of concern about future attacks or a major change in behavior related to these attacks. Agoraphobia is anxiety about, or avoidance of, places or situations in which the ability to leave suddenly is limited or impossible in the event of having a panic attack.

PANIC DISORDER

Panic disorder is diagnosed when the patient has repeated sudden attacks of overwhelming anxiety, accompanied by severe physical symptoms, usually related to both hyperventilation and sympathetic nervous system activity (palpitations, tremor, restlessness and sweating). The lifetime prevalence is 5%. Patients with panic disorder often have catastrophic illness beliefs during the panic attack, such as convictions that they are about to die from a stroke or heart attack. The fear of a stroke is related to dizziness and headache. Fear of a heart attack accompanies chest pain (atypical chest pain). The occasional patient with long-standing attacks may deny feeling anxious and simply report the physical symptoms.

SYNONYMS
Anxiety attacks
Fear attacks
EPIDEMIOLOGY & DEMOGRAPHICS
INCIDENCE (IN U.S.): 1% 1-mo incidence of panic attacks
PREVALENCE (IN U.S.):
• 15% lifetime prevalence of panic attacks
• Panic disorder much more uncommon, with a lifetime prevalence of 1.5% to 3.5%; chronicity of condition reflected by a similar 1-yr prevalence rate of 1% to 2%
• Agoraphobia relatively rare; 0.3% to 1% lifetime prevalence
PREDOMINANT SEX:
• Women more commonly affected (>85% of clinical population)
• Panic disorder twice as common in women
• Panic disorder with agoraphobia three times as common in women

3. Emergency or physician visits often occasioned by physical symptoms
• Agoraphobia
1. Rare complaints to physician
2. Activities usually self-limited by avoiding public situations where the patient might experience a panic attack and would be unable to exit readily, such as the following:
Crowded public areas (stores, public transportation, church)
Individual interactions (hair dresser, neighborhood meetings)
1. On exposure to or anticipation of exposure to such situations, significant anxiety occurs
ETIOLOGY
Hypotheses (note: There are sufficient data to support each model.)
1. Central dyscontrol of autonomic arousal (typically localized to the locus ceruleus)
2. Cognitive overreaction to relatively mild physiologic cues
3. Dysfunction of a central suffocation alarm mechanism
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS
• Medical conditions
1. Arrhythmias
2. Hyperthyroidism
3. Hyperparathyroidism
4. Seizure disorders
5. Respiratory diseases
6. Pheochromocytoma
• Therapeutic (theophylline, steroids) and recreational (cocaine, amphetamine, caffeine) drugs and drug withdrawal (alcohol, barbiturates, benzodiazepines)
• Phobias (e.g., specific phobia or social phobia)
• Obsessive-compulsive disorder (cued by exposure to the object of the obsession)
• Posttraumatic stress disorder (cued by recall of a stressor)
WORKUP
• Emergency presentation: cardiac, re-spiratory, or neurologic symptoms
• History and physical examination to rule out a concomitant medical condition
NOTE: Panic disorder and agoraphobia are not diagnoses of exclusion, but exclusion of other conditions is usually required.
LABORATORY TESTS
• Thyroid profile
• Electrolyte measures, including calcium
• Toxicology screen
• ECG
• Acute cases: possible monitoring and cardiac enzymes to rule out arrhythmia or ischemia
IMAGING STUDIES
• For temporal lobe dysfunction (e.g., temporal lesions or as ictal or interictal manifestation of temporal lobe seizures): brain CT scan or MRI and/or an EEG in some patients
• Holter monitor to rule out occult or episodic arrhythmias
• Chest x-ray examination, ABG, or pulmonary function tests if respiratory compromise suspected
TREATMENT
NONPHARMACOLOGIC THERAPY
• Psychotherapy: generally very effective; long-term follow-up studies of panic patients suggest that therapy is possibly superior to pharmacologic interventions
• Interpersonal and cognitivebehavioral therapy modalities: most extensively studied
ACUTE GENERAL Rx
• Benzodiazepines, particularly alprazolam: very effective in acute setting
• Low-dose alprazolam for patients with rare panic attacks and asymptomatic interattack periods (0.25 to 0.5 mg PO or sublingually prn)
CHRONIC Rx
• Because disorder patients, as a group, have a low likelihood of abusing benzodiazepines, uncomplicated cases managed with low-dose benzodiazepines on a schedule or prn
• Preferred pharmacologic agents: antidepressants with a significant serotonin reuptake inhibitory action
• Imipramine quite effective in both panic disorder and agoraphobia
• Newer antidepressants (paroxetine, sertraline, and fluoxetine) quite effective in preventing panic attacks and ameliorating agoraphobia
DISPOSITION
• Typical course chronic but with significant waxing and waning (common to have long periods of remission)
• Presence of agoraphobia associated with a more chronic course
• Findings with long-term follow-up studies: 6 to 10 yr after treatment some 30% in remission, 40% to 50% improved with residual symptoms, and the remainder either unchanged or worse.

PREDOMINANT AGE:
• Age of onset earlier in males (24 yr) than females (28 yr)
• Onset after age 45 yr rare
PEAK INCIDENCE:
• Chronic condition with a waxing and waning course
• Bimodal incidence peaks noted, with the first peak between ages 15 and 24 yr and second peak between 35 and 44 yr
GENETICS:
• Risk of developing panic disorder in first-degree relatives of individuals with panic disorder four to seven times that of general population
• Findings in twin studies: about 60% of contributing factors to panic are genetic
PHYSICAL FINDINGS & CLINICAL PRESENTATION
• Panic disorder
1. Present either with a panic attack or with fear and anxiety related to anticipation of a future panic attack
2. Typical presentation: unexpected, untriggered periods of intense anxiety and fear with associated physiologic changes (e.g., palpitations, sweating, tremulousness, shortness of breath, chest pain, GI distress, faintness, derealization, paresthesia).