Godse, Godse, and Patil: Skin writometer: A novel instrument for assessing provocation threshold in patients with symptomatic dermographism


Introduction

Physical urticaria is a diverse group of determinable conditions in which patients suffer from a chronic predisposition to develop localized or generalized urticaria upon contact with physical stimuli. Mechanical, thermal or electromagnetic stimuli can produce these responses. It accounts for nearly 20% to 30% of cases of chronic urticaria.1

Dermatographism can be simple or symptomatic.2 Simple dermatographism, a natural physiological response to physical stimuli is reported in about 1.5-5% healthy people.1, 2 On the other hand, symptomatic dermographism, can result in symptoms such as itching and burning due to wheal and flare response after slight pressure.1, 2 Symptomatic dermographism can impair the quality of life.3, 4 The severity of symptomatic dermographism differs among individuals.3

Current method for diagnosis of dermographism and its limitation

Conventionally, the diagnosis is made by stroking the skin with a wooden tongue blade 2 or a ballpoint pen with an empty refill.1 Use of ballpoint pen with empty refill is associated with some limitations in clinical practice. The length of the tip of ballpoint pen is fixed. Hence, the intensity of the stroke produced can be variable. Moreover, with traditional single stroke, there is chance of missing the diagnosis.1 Estimation of provocation threshold i.e. the lowest level of shear force required to produce a positive wheal response is difficult with instruments with single tips/arms. The other methods to diagnose symptomatic dermographism include Dermographic tester, a spring-loaded dermographometer and Fric Test.3 Dermographic tester also has only one tip5 whereas Fric Test dermographometer is not available in India.6

Considering the limitation of current method, a user friendly, simple but inexpensive method of eliciting dermographism is required.

Skin writometer

We propose a novel instrument, known as the skin writometer for eliciting dermographism. This can be used for diagnosis as well as evaluation of treatment response to dermographism/symptomatic urticaria.

This plastic instrument has 3 smooth arms of varying lengths i.e. 2.5 mm, 3.0 and 4 mms placed 2 cm apart. These arms can be used to strike on the skin in patients of urticaria. [Figure 1]

Figure 1

Skin writometer

https://s3-us-west-2.amazonaws.com/typeset-prod-media-server/4b457fa9-e4cc-4403-9906-7ed86a34ae3eimage1.png

Proposed use

  1. Hold the Skin writometer perpendicular to the forearm

  2. Apply pressure to the Skin writometer so that the tips are almost invisible

  3. Apply a single firm stroke of ~10 cm

  4. Taking the reading after 10 minutes

Precautions while using Skin writometer

  1. Skin at the test site should be unbroken

  2. Skin at the test site should be free of any obvious signs of infection.

Interpretation of the response

  1. Development of wheal with pruritus at the site of largest test arm can be considered as a positive response.

  2. A positive response with all the three arms including the shortest exerting lowest stroke stimulus can be considered as severe dermographism.

  3. A wheal with only the longest arm can be considered as a positive response, but of mild grade.

Table 1

Graded response with skinwritometer

Grade

Response after skin stroke of ~10 cm length after 10 minutes

Mild dermographism

Wheal and prutitus with only longest arm of Skin Writometer

Moderate dermographism

Wheal and pruritus with longest and middle arm or Skin Writometer

Severe dermographism

Wheal and pruritus with with all the three arms of the Skin Writometer

Skin writometer has been suggested by others as an alternative option to Fric Test. 7 Although found useful in clinical practice, a formal evaluation through a clinical study is needed to assess its usefulness compared ballpoint pen test.

The suggested approach for conducting clinical investigation may include giving a firm stroke of ~10 cm with the help of a ballpoint pen on one arm and same stroke with Skin writometer on the other arm. The extent of wheals can be measured on both the sides after 10 minutes. The sensitivity and specificity of Skin writometer in identification and diagnosis of symptomatic dermographism can be compared. Similar approach can be used for comparison with the Fric Test.

Conclusion

Skin writometer, may be used as a simple, user friendly and inexpensive instrument for accurate diagnosis of symptomatic dermographism.

Source of Funding

No financial support was received for the work within this manuscript.

Conflicts of Interest

There are no conflicts of interest.

References

1 

KiranV Godse Use of a ballpoint pen in the diagnosis of physical urticariaIndian J Dermatol20115611192010.4103/0019-5154.77576

2 

O Taskapan Y Harmanyeri Evaluation of patients with symptomatic dermographismJ Eur Acad Dermatol Venereol2006201586210.1111/j.1468-3083.2005.01372.x

3 

N Schoepke A Młynek K Weller MK Church M Maurer Symptomatic dermographism: an inadequately described diseaseJ Eur Acad Dermatol Venereol 20152947081210.1111/jdv.12661

4 

J Wallengren A Isaksson Urticarial Dermographism: Clinical Features and Response to Psychosocial StressActa Derm Venereol2007876493810.2340/00015555-0306

5 

A. Mlynek R Vieira dos Santos E Ardelean K Weller M Magerl MK Church A novel, simple, validated and reproducible instrument for assessing provocation threshold levels in patients with symptomatic dermographismClin Exp Dermatol2013384360610.1111/ced.12107

6 

K Godse A Mehta S Agarwal S Patil Feasibility and utility of the fric test in symptomatic dermographism: A pilot studyIndian J Dermatol201560663810.4103/0019-5154.169167

7 

G Gandhi R Vasani White dermographismIndian J Paediatr Dermatol2018191735



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Article History

Received : 18-03-2021

Accepted : 20-04-2021

Available online : 29-05-2021


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https://doi.org/10.18231/j.ijced.2021.035


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