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NCT Number: NCT03895632

Eye Muscle Needle Electromyogram (EMu) Study

In some cases, strabismus, or squint, is treated with injections of Botulinum toxin (BTX) to temporarily relax the eye muscle responsible for causing the eye to be pulled to one side. Due to the deep location of the muscles, electromyogram (EMG) needle guidance is used to help ensure the toxin is delivered accurately. EMG needle guidance involves listening to the EMG signal from the tip of the delivery needle - when the needle is in the right place a sound akin to "rain on a tin roof" is heard and the BTX can be injected.

From previous research, clearly clinicians want to improve the technology of this procedure and increase the treatment efficacy and repeatability. After all, the current procedure is imprecise and subjective for what is a small target, with the eye muscles being around 2.5 mm to 4.7 mm in diameter. There may also be an increase in the likelihood of side effects such as droopy eyelids when the toxin spreads beyond the target muscle.

There is a strong need for new knowledge to improve EMG needle guidance in this context. It is hypothesised that the EMG signal could be cleaned and mined for information in real time during the procedure, thus providing the clinician with better information to guide the positioning of the needle before injecting. This pilot study will deliver the knowledge essential to indicate the feasibility of doing this. If feasible, this study will inform a full study with the aim of benefitting patients by allowing new technology to be developed to improve the treatment of strabismus with BTX.

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Key information

Conditions

Strabismus Cranial Nerve Diseases Eye Diseases Nervous System Diseases Ocular Motility Disorders

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Manchester Royal Eye Hospital

Manchester, M13 9WL, United Kingdom

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

i. Adults undergoing planned, routine EMG needle guided BTX injection into either lateral or medial rectus muscle for the treatment of strabismus.

ii. Patients being treated by Mr Yagan.

Exclusion criteria

  • Patients with Chronic progressive external ophthalmoplegia (CPEO) are excluded; a highly attenuated EMG signal is expected.

Treatment and study plan

Primary outcomes

  1. α (Slope) Parameter of the Electromyogram (EMG) Signal Power Spectral Density (PSD) Plot as Needle Approaches Then Enters Muscle.

    Time frame: Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal

    The continuous change in the EMG signal as the needle is (a) distal to, (b) approaches, and (c) enters, the target extraocular muscle.

    Welch's periodogram estimator (Hamming window, 256-point FFT, 50% overlap) was applied to each of the three signal segments described above to obtain an estimate of the PSD of the signal. A robust linear model was fit to estimate the α (slope) parameter of each PSD plot.

Secondary outcomes

  1. Clinical Score of EMG Change

    Time frame: Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal

    Clinician's score of the step change from baseline EMG to 'active' EMG level heard immediately prior to delivery of Botulinum toxin (BTX) from 1-5. Value from 1 = no significant step change heard, to 5 = a very clear step change heard.

  2. Clinical Score of Needle Placement Accuracy

    Time frame: Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal

    Clinician's score of their confidence in accurate needle placement with respect to the target muscle. Given as a percentage, a higher score indicates more confidence in accurate needle placement.

  3. Clinical Score of EMG Quality.

    Time frame: Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal

    Clinician's score of overall quality of the EMG signal heard during the procedure. A higher score indicates better quality of EMG signal, and is quantified as 1 to 5, where: 1 indicates signal not present and 5 indicates excellent quality EMG signal.

  4. Post-treatment Angle of Deviation

    Time frame: 2 weeks

    Change in participant's angle of deviation following treatment, measured in prism dioptres.

Sponsors and collaborators

Lead sponsor

Liverpool University Hospitals NHS Foundation Trust

Other Gov

Collaborators

  • Manchester University NHS Foundation Trust

Registry information

Official study title

A Data Collection and Analysis Pilot Study to Indicate Preliminary Characterisation of the Electromyogram Signal in Relation to Needle Position With Respect to the Extraocular Muscles, as Observed During Electromyogram Needle Guided Treatment of Strabismus in Adults

Acronym: EMu

Important dates

Study start
2019
Primary completion
2019
Study completion
2019
First posted
Mar 29, 2019
Registry last updated
Jul 18, 2022

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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