How to assess and relieve that perplexing rashless itch

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doi:10.12788/jfp.0096

Applied Evidence

How to assess and relieve that perplexing rashless itch

J Fam Pract. 2020 November;69(9):430-437 | 10.12788/jfp.0096

By

Matasha Russell, MD

Mohammad Zare, MD

Your patient’s pruritus absent skin lesions might be self-limiting—or indicate systemic disease. Probing the nature of the symptom can point to targeted treatment.

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PRACTICE RECOMMENDATIONS

› Undertake a diagnostic work-up for systemic causes of pruritus in patients who have a chronic, generalized itch and abnormal findings on physical examination. C

› Prescribe gabapentin for its effectiveness in treating pruritus caused by uremic and neurologic itch. B

› Consider prescribing one of the bile-acid sequestrants in patients with cholestatic pruritus because these agents can provide moderate relief of the symptom. B

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

References

1. Tarikci N, Kocatürk E, Güngör S, et al. Pruritus in systemic diseases: a review of etiological factors and new treatment modalities. ScientificWorldJournal. 2015;2015:803752.

2. Yosipovitch G, Bernhard JD. Clinical practice. Chronic pruritus. N Engl J Med. 2013;368:1625-1634.

3. Silverberg JI, Kantor RW, Dalal P. A comprehensive conceptual model of the experience of chronic itch in adults. Am J Clin Dermatol. 2018;19:759-769.

4. Matterne U, Apfelbacher CJ, Vogelgsang L, et al. Incidence and determinants of chronic pruritus: a population based cohort study. Acta Derm Venereol. 2013;93:532-537.

5. Moses S. Pruritus. Am Fam Physician. 2003;68:1135-1142.

6. Combs SA, Teixeira JP, Germain MJ. Pruritus in kidney disease. Semin Nephrol. 2015;35:383-391.

7. Shevchenko A, Valdes-Rodriguez R, Yosipovitch G. Causes, pathophysiology, and treatment of pruritus in the mature patient. Clin Dermatol. 2018;36:140-151.

8. Reamy BV, Bunt C. A diagnostic approach to pruritus. Am Fam Physician. 2011;84:195-202.

9. Jovanović M. Current concepts of pathophysiology, epidemiology and classification of pruritus. Srp Arh Celok Lek. 2014;142:106-112.

10. Fett N, Haynes K, Propert KJ, et al. Five-year malignancy incidence in patients with chronic pruritus: a population-based cohort study aimed at limiting unnecessary screening practices. J Am Acad Dermatol. 2014;70:651-658.

11. Larson VA, Tang O, Ständer S, et al. Association between itch and cancer in 16,925 patients with pruritus: experience at a tertiary care center. J Am Acad Dermatol. 2019;80:931-937.

12. Rosen JD, Fostini AC, Chan YH, et al. Cross-sectional study of clinical distinctions between neuropathic and inflammatory pruritus. J Am Acad Dermatol. 2018;79:1143-1144.

13. Oaklander AL. Neuropathic itch. Semin Cutan Med Surg. 2011;30:87-92.

14. Ferm I, Sterner M, Wallengren J. Somatic and psychiatric comorbidity in patients with chronic pruritus. Acta Derm Venereol. 2010;90:395-400.

15. Jafferany M, Davari ME. Itch and psyche: psychiatric aspects of pruritus. Int J Dermatol. 2019;58:3-23.

16. Koo J, Lebwohl A. Psychodermatology: the mind and skin connection. Am Fam Physician. 2001;64:1873-1878.

17. Bewley AP, Lepping P, Freudenmann RW, et al. Delusional parasitosis: time to call it delusional infestation. Br J Dermatol.2010;163:1-2.

18. Clerc C-J, Misery L. A literature review of senile pruritus: from diagnosis to treatment. Acta Derm Venereol. 2017;97:433-440.

19. Bernhard JD, Bordeaux JS. Medical pearl: the ice-pack sign in brachioradial pruritus. J Am Acad Dermatol. 2005;52:1073.

20. Sanders KM, Nattkemper LA, Yosipovitch G. Advances in understanding itching and scratching: a new era of targeted treatments [version 1]. F1000Res. 2016;5 F1000 Faculty Rev–2042.

21. Hegade VS, Kendrick SFW, Dobbins RL, et al. Effect of ileal bile acid transporter inhibitor GSK2330672 on pruritus in primary biliary cholangitis: a double-blind, randomised, placebo-controlled, crossover, phase 2a study. Lancet. 2017;389:1114-1123.

Pruritus, defined as a sensation that induces a desire to scratch¹ and classified as acute or chronic (lasting > 6 weeks),² is one of the most common complaints among primary care patients: Approximately 1% of ambulatory visits in the United States are linked to pruritus.³

Chronic pruritus impairs quality of life; its impact has been compared to that of chronic pain.⁴ Treatment should therefore be instituted promptly. Although this condition might appear benign, chronic pruritus can be a symptom of a serious condition, as we describe here. When persistent pruritus is refractory to treatment, systemic causes should be fully explored.

In this article, we discuss the pathogenesis and management of pruritus without skin eruption in the adult nonpregnant patient. We also present practice recommendations to help you determine whether your patient’s pruritus is indicative of a serious systemic condition.

An incomplete understanding of the pathophysiology of pruritus

The pathophysiology of pruritus is not fully understood. It is generally recognized, however, that pruritus starts in the peripheral nerves located in the dermal–epidermal junction of the skin.⁵ The sensation is then transmitted along unmyelinated slow-conducting C fibers to the dorsal horn of the spinal cord.^5,6 There are 2 types of C fibers that transmit the itch impulse⁶: A histamine-dependent type and a non-histamine-dependent type, which might explain why pruritus can be refractory to antihistamine treatment.⁶

Once the itch impulse has moved from the spinal cord, it travels along the spinothalamic tract up to the contralateral thalamus.¹ From there, the impulse ascends to the cerebral cortex.¹ In the cortex, the impulse triggers multiple areas of the brain, such as those responsible for sensation, motor function, reward, memory, and emotion.⁷

Although this condition might appear benign, chronic pruritus can be a symptom of a serious condition.

Several chemical mediators have been found to be peripheral and central inducers of pruritus: histamine, endogenous opioids, substance P, and serotonin.² There are indications that certain receptors, such as mu-opioid receptors and kappa-opioid receptors, are key contributors to itch as well.²

A diverse etiology

The International Forum for the Study of Itch (IFSI) has established 6 main categories of causes of pruritus(TABLE 1)²:

dermatologic
systemic
neurologic
psychogenic
mixed
other.

Continue to: In this review...