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The Skin Wrinkle Test: a Simple Clinical Test of Regional Block Success

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03873896
Recruitment Status : Not yet recruiting
First Posted : March 14, 2019
Last Update Posted : August 21, 2019
Information provided by (Responsible Party):
Peter Collins, Memorial University of Newfoundland

Brief Summary:

Wrinkling of the hands and feet with exposure to moist environments is a commonly observed phenomenon. This "stimulated skin wrinkling" (SSW) is the result of direct stimulation of digital nerve sympathetic fibers. The resulting effect is a sympathetically mediated vasoconstriction with loss of finger pulp volume, overlying skin traction and wrinkling. It has been established that multiple disease states of the sympathetic nervous system such as diabetic neuropathy, leprosy and nerve injury can lead to impaired SSW of the affected limb. While this test has been successfully utilized for over 80 years to assess patients with sympathetic pathology, it has never been evaluated as a tool to determine the success of a regional nerve block. A regional nerve block is a method of anesthesia that involves injecting a local anesthetic around a particular nerve or nerve bundle in order to block the sensation of pain from that particular body part.

This is of particular importance in the paediatric or non verbal population. These patients may not be able to reliably confirm the effectiveness of their analgesia. Pediatric anesthesiologists often perform these regional blocks on already anesthetized children whereas the non-verbal or cognitively impaired population may not be able to verbalize block effectiveness.

This test, if proven effective as a means of determining block success, would be a quick, non-invasive and inexpensive method of ensuring adequate intra-operative and post operative analgesia for patients. As this is a pilot project focused on establishing the SSW test as an effective tool for assessing regional block success on awake volunteers, further studies would need to be performed to assess test effectiveness in different clinical situations.

Condition or disease Intervention/treatment Phase
Skin Manifestations Diagnostic Test: Stimulated skin wrinkling test Procedure: Digital Nerve Block Not Applicable

Detailed Description:

We estimated the sample size of four based on the use of a non-parametric analysis, and for the purpose to keep the sample of subjects to a minimum. Further that the effect size is expected to be a large effect (e.g. as it's a binary response yes/no wrinkling, previous experience and literature with the use of the cream for obtaining a pronounced effect of wrinkling (4-5) on the PING scale for an individual with normal peripheral nerve response on an unblocked digit. By using the non-parametric chi square statistical analysis it does not rely on means and standard deviation so it is more sensitive to even small differences beyond chance.

After informed written consent is obtained, volunteers will be subjected to a digital nerve block of ring finger of either the left or right hands. The hand to be blocked will be randomized using a coin toss. The nerve block will be performed by members of the research team with extensive experience in regional blockade. After full sterile preparation, 3 cc's of 2% plain lidocaine will be used to perform the digital nerve block. Five minutes after the performance of the block, the affected digit will be tested by both light touch and temperature to confirm block success. Ring fingers of both hands of the volunteer will then be wrapped in an occlusive dressing after 1mL (millilitre) of EMLA (Eutectic Mixture of Local Anesthetic) cream is applied to the pad of each finger. Photos of the blocked finger as well as the corresponding unblocked finger of the opposite hand will be taken with tangential lighting at 0, 10, 20 and 30 minutes from the time of exposure to EMLA cream. The EMLA cream and occlusive dressings will be removed for each photo then reapplied after the photo is completed. Photos will then be evaluated by two members of the research team blinded as to the finger blocked in each volunteer. Evaluators reviewing the photos of individual fingers will be asked to grade the degree of wrinkling on a scale from 0 to 4 described by Ping Ng et al (a previously established scale to assess stimulated skin wrinkling).

Clinical Care Measures To ensure safety of the study participants, digital nerve blocks will be performed by anesthesiologists or anesthesiology residents with experience in performing these blocks and under strict aseptic conditions. A limited amount of lidocaine is utilized to ensure adequate block but minimize duration of block as well as risks of toxicity. The study participants will be fully monitored with continuous 3 lead ECG, NIBP (non-invasive blood pressure) measurements every 5 minutes and continuous pulse oximetry for 120 minutes period after the analysis. The participants will be attended by at least one physician for this entire period. A follow up telephone call will be performed 24 hours after the performance of the digital nerve block to assess for complications.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 4 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Intervention Model Description: Blinded control trial assessing aquagenic skin wrinkling after digital nerve blockade in healthy volunteers. Digital nerve blocks to be performed on the left or right ring fingers of volunteers (to be randomized with coin toss) with the unblocked finger of each volunteer acting as its own control
Masking: Single (Outcomes Assessor)
Masking Description: Photos of blocked digits will be taken and presented to blinded assessors to rate on a pre-determined scale of wrinkling
Primary Purpose: Diagnostic
Official Title: The Skin Wrinkle Test: a Simple Clinical Test of Regional Block Success
Estimated Study Start Date : September 1, 2019
Estimated Primary Completion Date : November 30, 2019
Estimated Study Completion Date : November 30, 2019

Arm Intervention/treatment
Experimental: Blocked finger
The experimental arm will be the ring finger of the volunteer that is blocked (randomized either right or left hand) with a digital nerve block (described elsewhere in the submission). The skin wrinkle test (diagnostic test) will be applied to this arm
Diagnostic Test: Stimulated skin wrinkling test
Stimulated skin wrinkling induced by the application of EMLA (eutectic mixture of local anesthetic) cream to the finger pads of blocked and unblocked fingers of study volunteers (test applied to both study arms)

Procedure: Digital Nerve Block
A digital nerve block is performed by injecting a total of 3 millilitres of 2% Lidocaine at the base of the ring finger of randomized hand of the volunteer. The effect of the block is confirmed clinically before proceeding with the study data collection. Please see the description for more details on the procedure

Active Comparator: Unblocked finger
The control arm will be the finger of the same volunteer that is not under the influence of digital nerve block. This will be the corresponding digit (the ring finger) on the opposite hand of the side that was blocked (determined by coin toss). The skin wrinkle test (diagnostic test) will be applied to this arm
Diagnostic Test: Stimulated skin wrinkling test
Stimulated skin wrinkling induced by the application of EMLA (eutectic mixture of local anesthetic) cream to the finger pads of blocked and unblocked fingers of study volunteers (test applied to both study arms)

Primary Outcome Measures :
  1. Change in observed skin wrinkling [ Time Frame: Assessed at baseline (prior to EMLA cream application) and 10, 20 and 30 minutes after its application ]
    Determined by judgements based on the "Wrinkling Assessment Scale" originally described by Ping Ng et. al. 2013: Grade 0: Wrinkling absent Grade 1: slight wrinkling and the fingertip is not smooth Grade 2: two or fewer lines of wrinkling on each side of the fingertip Grade 3: 3 or more lines of wrinkling on each side of the fingertip Grade 4: wrinkling completely distorts the pulp of the fingertip (see images presented in Wilder Smith et. al. 2015). A higher score indicates (3 or 4) full nerve function and the lower likelihood of nerve block. A lower score (0-2) indicate lower levels of nerve function and a higher likelihood of successful nerve blockade

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy 18-65 year old of either gender

Exclusion Criteria:

  • contraindication to regional block
  • preexisting nerve damage
  • hand or finger injury
  • active skin infection
  • allergy to local anesthetic
  • disease states known to affect aquagenic skin wrinkling including cystic fibrosis, diabetic neuropathy, leprosy, vascular disease and diseases of autonomic function
  • Patients with history of bleeding disorders or currently using anticoagulation agents
  • contraindications to EMLA cream
  • breaks in the skin on the finger EMLA is to be applied
  • allergy to its constituents
  • history of methemoglobinemia.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03873896

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Contact: Peter A Collins, MD 17096855180
Contact: Maria S Brazil, MD 17097432060

Sponsors and Collaborators
Memorial University of Newfoundland
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Principal Investigator: Peter A Collins, MD Memorial University

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Responsible Party: Peter Collins, Peter Collins, Assistant Professor, Principal Investigator, Memorial University of Newfoundland Identifier: NCT03873896     History of Changes
Other Study ID Numbers: 20190762
First Posted: March 14, 2019    Key Record Dates
Last Update Posted: August 21, 2019
Last Verified: August 2019
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Skin Manifestations
Signs and Symptoms