Which of the following further investigations would be helpful?
a. Echocardiogram
b. Holter study
c. Tilt table test
d. Electrophysiology study
e. All of the above

All are correct. Syncope is one of the most common cardiology referrals. Very often, preliminary investigations fail to reveal the exact underlying cause. Details of the syncope attacks are essential for a correct diagnosis and they often provide important clues to guide further investigations. For example, aura, evidence of convulsion and post-attack conscious state are important clues for neurological diagnoses.

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What further investigation would be helpful if all these tests are negative?

For cardiology work up, one has to rule out structural heart disease, bradycardia, tachyarrhythmia and vasovagal hypersensitivity. Echocardiography would be useful to rule out structural heart disease such as hypertrophic obstructive cardiomyopathy. Information on left ventricular function would be useful as patients with poor left ventricular systolic function are prone to ventricular arrhythmias. A Holter study would be useful to document any bradycardia and tachyarrhythmia. However, the yield is often low as it is difficult to catch the attacks in patients with attacks occurring less than a few times per week. Tilt table test is useful to elicit hypersensitivity responses like cardioinhibitory and cardiodepressive responses. On the other hand, electrophysiology study would be useful to rule out any tachyarrhythmia such as those of ventricular origin. Syncope is not a typical presentation of ischaemic heart disease but treadmill stress test, CT coronary angiogram and cardiac MRI are useful tests to rule out ischaemic heart disease.

In this patient, all of the above investigations results were normal. He was finally implanted with a loop recorder (Figure 1), which was inserted under the skin beneath the clavicle in the pectoral region, similar to a pacemaker but without leads. This device can record subcutaneous ECG for more than a year. It provides a high diagnostic yield to rule out or rule in cardiac arrhythmias or bradycardias. It is particularly suitable for those infrequent attacks (e.g. < once per week). It weighs less than 20 g and is only about 8 cc in volume. It is retrievable and may be taken out after a diagnosis has been made.

A 6-second asystole pause was documented in this patient during his next attack (Figure 2). A permanent pacemaker was implanted and the patient regained his independence, and later his driving license.

Figure 1

figure 2

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What is the most likely diagnosis and what are the differential diagnoses?

The diagnosis is prurigo nodularis (also known as nodular prurigo or Picker’s nodules) and the differential diagnoses include hypertrophic lichen planus, perforating dermatoses and multiple keratoacanthoma.

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What is the cause of this skin disorder?

Most cases are idiopathic, while some cases are secondary to underlying cutaneous (atopic diathesis or xerosis) or systemic causes of pruritus.

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What investigations will you consider?

In case of doubt, a diagnostic skin biopsy should be performed. Blood tests such as full blood count, liver, kidney and thyroid function tests may help to rule out any underlying cause of pruritus such as iron deficiency anaemia, renal or liver dysfunction, and hyper/hypothyroidism.

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What are the options for treatment?

This condition is quite often difficult to treat. To break the cycle of pruritus and scratching, one may try emollient and oral antihistamine, and correct any underlying cause of pruritus. Options for local treatment include potent topical steroids (with or without occlusion), intralesional steroid and cryotherapy. Antidepressants, phototherapy, thalidomide, acitretin and cyclosporin may be helpful in resistant cases.

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What may happen to the affected areas after the lesions resolve?

Permanent pigmentary change or superficial scarring may be seen after the resolution of the lesions.

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