Eye Muscle Needle Electromyogram (EMu) Study (EMu)

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

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.

Study Overview

• Status: Completed
• Conditions: Strabismus

• Study Type: Observational
• Enrollment (Actual): 25

Contacts and Locations

Study Locations

• United Kingdom
  • Manchester, United Kingdom, M13 9WL
    • Manchester Royal Eye Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients with strabismus being treated with injections of Botulinum toxin.

Description

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.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
α (Slope) Parameter of the Electromyogram (EMG) Signal Power Spectral Density (PSD) Plot as Needle Approaches Then Enters Muscle.	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.	Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Clinical Score of EMG Change	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.	Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal
Clinical Score of Needle Placement Accuracy	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.	Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal
Clinical Score of EMG Quality.	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.	Approximately 5 minutes, i.e. immediately prior to needle insertion until Botulinum toxin (BTX) delivery and needle withdrawal
Post-treatment Angle of Deviation	Change in participant's angle of deviation following treatment, measured in prism dioptres.	2 weeks

Collaborators and Investigators

• Sponsor: Liverpool University Hospitals NHS Foundation Trust
• Collaborators: Manchester University NHS Foundation Trust
• Investigators: Principal Investigator: Tristan G Payne, PhD, Liverpool University Hospitals NHS Foundation Trust

Publications and helpful links

General Publications

• Pinheiro, J. & Bates, D. (2000) Mixed-Effects Models in S and S-PLUS. Statistics and Computing. New York, NY, USA: Springer-Verlag

Study record dates

Study Major Dates

• Study Start (Actual): February 20, 2019
• Primary Completion (Actual): May 30, 2019
• Study Completion (Actual): May 30, 2019

Study Registration Dates

• First Submitted: January 16, 2019
• First Submitted That Met QC Criteria: March 27, 2019
• First Posted (Actual): March 29, 2019

Study Record Updates

• Last Update Posted (Actual): July 18, 2022
• Last Update Submitted That Met QC Criteria: July 1, 2022
• Last Verified: January 1, 2019

More Information

Terms related to this study

• Keywords: Monopolar; Strabismus; Electromyogram; Botulinum toxin; Extraocular muscle; Needle guidance
• Additional Relevant MeSH Terms: Nervous System Diseases; Eye Diseases; Cranial Nerve Diseases; Ocular Motility Disorders; Strabismus
• Other Study ID Numbers: 5686

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No