Low-frequency Repetitive Nerve Stimulation in Myotonic Dystrophy Type 1

Not Applicable

Completed

• Conditions: Myotonic Dystrophy 1
• Interventions: Diagnostic Test: Low frequency repetitive stimulation

• Registration Number: NCT05662150
• Lead Sponsor: Vrije Universiteit Brussel

Brief Summary

The study design is a prospective cohort study. It aims to evaluate the neuromuscular junction in dystrophic myotonia 1 (DM 1) using low-frequency repetitive nerve stimulation (RNS) on several nerve-muscle pairs of the one side including proximal and distal muscles of upper and lower extremities. First, it will be investigated whether a decrement with 3 Hz stimulation, as described in literature, is reproducible in our patient population. If this is the case, it will be examined whether it is the consequence of a dysfunction of the neuromuscular junction or rather linked to a hypo-excitability of some muscle fibers due to myotonia. For this purpose, additional tests including short exercise test (to observe any decrement resulting from an inexcitability in myotonic muscle fibers) and needle EMG (for mapping myotonic discharges in the muscles tested with repetitive nerve stimulation) will be performed. Single fiber-EMG will not be provided in this study as an abnormal result does not necessarily indicate a dysfunction of the neuromuscular junction but could just as well be due to the muscular dystrophy in the context of DM1. Finally, it will be investigated if there is a correlation between the decrement

with 3 Hz stimulation and clinical signs as fixed muscle weakness (via Medical Research Counsil (MRC) scale, DM-activ scale \[30\]) and fatigue (via MG-ADL scale).

Detailed Description

Not available

Study Timeline

• Study Start: 2021-09-01
• Primary Completion: 2022-06-11
• Study Completion: 2022-06-20
• Study First Submitted: 2022-10-14
• Status Verified: 2022-12
• Study First Submitted QC: 2022-12-21
• Last Update Submitted: 2022-12-21
• Study First Posted: 2022-12-22
• Last Update Posted: 2022-12-22

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 9

Inclusion Criteria

* genetically confirmed DM1

Exclusion Criteria

• minor age
• auto-immune diseases
• medical conditions involving the neuromuscular junction: (myasthenia gravis, Lambert-Eaton myasthenic syndrome, congenital myasthenia syndromes).

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Questionnaires	Low frequency repetitive stimulation	Patients with DM1 were asked to complete a questionnaire to rate a 25-item activity scale (DM1-Activ) and the Myasthenia Gravis Activity of Daily Life scale (MG-ADL) to rate their level of functional burden. For the DM1-Activ a score of 40 alludes no impairment and a score of 0 indicates the highest functional burden of physical activity. This scale has proven to be practical, reliable and valid. For the MG-ADL the total score ranges from 0 to 24, a score of 0 denotes no and 24 the highest functional burden. It should be noted that this scale is not adjusted for DM1. The rationale was to gain information about muscle fatigue and consequently the neuromuscular junction.
short exercise test	Low frequency repetitive stimulation	The subject was asked to contract the ADM muscle as hard as possible in isometric conditions for 10 seconds. CMAP's was recorded 2 seconds after the end of the exercise and then every 10 seconds for 50 seconds.
needle EMG	Low frequency repetitive stimulation	The electrical myotonia of each examined muscle was scored according to the Streiss and Sun scale.
grip strength via dynamometer	Low frequency repetitive stimulation	The isometric grip strength was tested by using a dynamometer. The subject will be asked to perform an increasing force against the dynamometer over a period of several seconds.

Primary Outcome Measures

Name	Time	Method
Reproducibility of rapid decrement at low frequency stimulation.	1 year	Low stimulation frequency was tested in 6 muscles, to verify the presence of an anomalie of the neuromuscular transmission.

Secondary Outcome Measures

Name	Time	Method
Correlation of decrement with grade of EMG-myotonia	1 year	Search of correlation between decrement, obtained bij low frequency stimulation, and EMG-myotonia (via needle EMG), to differentiate muscle fiber hypoexcitability in the context of myotonia, from neuromuscular junction block resulting in decrement of the CMA
Is there any clinical expression (muscle fatigability) of a possible neuromuscular junction dysfunction	1 year	Search of correlation between muscle fatique (questionnaires and grip strength via dynamometer) and decrement of CMAP (compound muscle action potential).

Trial Locations

Locations (1)

UZ Brussel; 🇧🇪 Jette, Brussels Hoofdstedelijk Gewest, Belgium