An observational study in Digital Nerve Injury, Sensory Neurography and S2PD, sponsored by Cecilia Mellstrand Navarro. Recruiting at 2 sites in Sweden. Open to participants aged 20 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Cecilia Mellstrand Navarro · Observational
The goal of this clinical comparative cross sectional study, is to investigate neurophysiological findings and S2PD (static two point discrimination test) measurements after digital nerve injury.
The main aim is to find out if there are measurable neurophysiological differences in fingers following digital nerve injury that correlate with discriminative sensory function (S2PD) as experienced by the patient. Secondary aim is to investigate how well neurophysiological measurements predict specific S2PD values in the affected fingers.
Participants with a sutured digital nerve injury will be examined with neurophysiology and S2PD testing. Both injured finger and corresponding uninjured finger on the other hand will be examined, i.e participants will be their own control.
Prior to the study the investigators will perform a test-re-test study on ten participants to ensure that the method is reliable (separate registration)
The aim of this project is to use neurophysiological assessment to gain a better understanding of what is actually measured by S2PD (static two-point discrimination). A neurophysiological examination can objectively measure any remaining function in an injured digital nerve. Using this method, axons responsible for pressure, vibration, and touch that are still able to conduct an action potential, are assessed.
The response can be measured both as the amplitude of the summed action potentials from the nerve's axons and as the area, which corresponds to the area under the curve formed by the recorded action potentials. The area is a somewhat more precise measurement method, as it includes all axons, both those with low and high conduction velocities. Amplitude measurements may give falsely low values if nerves with poorer degrees of myelination are included in the measurement. Amplitude is measured in µV and area in µV/ms.
The method currently used to assess discriminative sensation, S2PD, is influenced by many external factors, such as the clinician's level of experience, the patient's desire to give the correct answer, language barriers, and similar issues. Furthermore, this examination method does not clarify what is actually being measured beyond the patient's subjective discriminative sensation.
If neurophysiological assessment is used as a complement to S2PD and can provide an objective measurement tool with high reliability and reproducibility, it could become an important addition to the clinical arsenal for follow-up after nerve injury. Such knowledge would make it easier to clinically evaluate, understand, and monitor the healing process of the injured nerve. It would also facilitate the assessment and systematic follow-up of treatment outcomes.
The investigators also believe that patients would benefit from being able to follow nerve healing in a more objective manner, which could help motivate continued training and rehabilitation (such as tactile stimulation, mirror therapy, desensitization, etc.).
Participants will be identified through the national quality register for hand surgery (HAKIR), and will be invited to attend an examination at the Hand Surgery Outpatient Clinic at Sodersjukhuset by phone (postal invitation if no response). If the response rate is low, patients will be contacted by phone one additional time.
The visit, which is estimated to last approximately 60 minutes, will include assessment using static two-point discrimination (S2PD) and neurophysiological examination of the injured finger as well as the corresponding finger on the contralateral, uninjured hand. Sensory assessment with S2PD will be performed on the fingertip pulp, radially or ulnarly, using a discriminator. Sensory thresholds, measured in millimetres, will be recorded in the study protocol.
Finger temperature will be measured using an infrared thermometer (Testo 826-T2), and, if necessary, the fingers will be warmed (using a water bath or heating pad) to a target temperature of a minimum of 32 °C. The hands will then be gently abraded using a preparation gel (NuPrep). Conductive gel (Ten20) will be applied to the electrodes.
A recording electrode will be placed volarly over the wrist, a ground electrode in the palm, and a stimulating electrode on the finger (digits II, III, or IV). Electrical stimulation will be delivered in an orthodromic direction, from the finger toward the wrist. The stimulus intensity will be gradually increased as long as the recorded amplitude continues to rise, up to a maximum of 20% above the intensity at which no further increase in amplitude is observed. This approach ensures inclusion of all excitable axons in the recording, regardless of individual firing thresholds.
This is the only study on the registry with Cecilia Mellstrand Navarro as lead sponsor.
Counted across the registry records on this site, refreshed daily.
Patients treated surgically for a digital nerve injury at the Sodersjukhuset Hand Surgery Clinic from 2013 to 2023.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Injury: One year or more prior to inclusion
Injured finger: digit II, III or radial dig IV
Level of injury: base or middle phalanx
Age at injury>20
Age at inclusion\<60
Exclusion Criteria:
Neurologic disease
Dementia
Cognitive disability
Severe psychiatric disorder (not be able to participate)
Ongoing drug abuse
Not understanding swedish language
History of carpal tunnel syndrome
Negative experience of electric stimulation
The finger with an injured digital nerve will be examined with S2PD and sensory neurography
Diagnostic Test: Sensory neurography · Diagnostic Test: Static two point discrimination test, S2PD
The contralateral uninjured finger will be examined with S2PD and sensory neurography
Diagnostic Test: Sensory neurography · Diagnostic Test: Static two point discrimination test, S2PD
Participants will be examined with sensory neurography (orthodromic stimulation).
Participants will be examined with S2PD.
Is there a correlation between the amplitude of the sensory nerve action potential and S2PD?
A potential correlation between the sensory nerve action potential amplitude (microvoltage) measured with sensory neurography and S2PD (in millimeters) measured with a discriminator, will be analysed with test for correlation and presented as a value between -1 and 1
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
Is there a correlation between sensory nerve action potential area and S2PD?
A potential correlation between the sensory nerve action potential area (milliseconds\*microvoltage) measured with sensory neurography and S2PD (in millimeters) measured with a discriminator, will be analysed with test for correlation and presented as a value between -1 and 1
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
Does a certain value of S2PD correspond to a specific (percentage) value of the amplitude or area of the action potential?
We will evaluate the correlation between S2PD (in 1 mm steps) and the percentages of sensory neurography amplitude and area of the injured nerve.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
How does age affect the potential correlation between sensory neurography measures (amplitude and area) and S2PD?
A regression analysis will be used to evaluate what impact age (years) has on primary outcomes.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
How does participants' sex affect the potential correlation between sensory neurography measures (amplitude and area) and S2PD?
A regression analysis will be used to evaluate what impact participants' sex (male or female) has on primary outcomes.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
How does smoking affect the potential correlation between sensory neurography measures (amplitude and area) and S2PD?
A regression analysis will be used to evaluate what impact smoking (yes or no) has on primary outcomes.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
How does the type of injured nerve affect the potential correlation between sensory neurography measures (amplitude and area) and S2PD?
A regression analysis will be used to evaluate what impact type of injured nerve (digital nerves to second, third or radial side of the fourth finger) has on primary outcomes.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
How does time from injury affect the potential correlation between sensory neurography measures (amplitude and area) and S2PD?
A regression analysis will be used to evaluate what impact time from injury (in years) has on primary outcomes.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
How does the level of injury affect the potential correlation between sensory neurography measures (amplitude and area) and S2PD?
A regression analysis will be used to evaluate what impact level of injury (proximal or middle phalanx) has on primary outcomes.
Time frame: Participant assessments will be conducted during a single session lasting approximately 60 minutes
Plan to share: No — Data will be available in pseudonymized form
Started Sep 2026 (actual). Primary completion is estimated for Dec 2026, 3 months after the start.
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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