Spontaneous muscle activity in multifocal motor neuropathy - Insights from axonal excitability testing.

Clin Neurophysiol

Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Clinical Medicine and Neuroscience, University of Copenhagen, Denmark; Department of Neurology, Rigshospitalet, Copenhagen, Denmark.

Published: January 2025

Objective: To investigate motor axonal excitability in multifocal motor neuropathy (MMN) associated with involuntary muscle activity.

Methods: Two MMN patients with continuous involuntary finger movements (MMNifm) were compared to 11 patients without movements (MMNnfm). Clinical examination, EMG of the abductor pollicis brevis muscle, nerve conduction studies, motor unit number estimation, excitability studies, and mathematical modeling were conducted in the patients with MMN and compared to controls.

Results: Weakness, axonal loss, conduction block, or both occurred in the median nerve in the MMNifm and the MMNnfm patients. Ultrasound studies (US) in MMNifm showed enlargement of the nerves at the axilla/brachial plexus at the site of the conduction block. In MMNifm, EMG and the US showed continuous involuntary contractions, and excitability studies of the median nerve at the wrist showed increased threshold reduction during early depolarizing electrotonus and at early recovery cycle (superexcitability). Mathematical modeling was consistent with reduced fast K current more pronounced in MMNifm than in MMNnfm.

Conclusions: MMN may have a spectrum of changes associated with instability of the axonal membrane which may be due to paranodal myelin loosening.

Significance: In addition to motor conduction block and axonal loss, MMN has pathophysiological changes that suggest more widespread involvement of motor myelinated fibers.

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2024.12.019DOI Listing

Publication Analysis

Top Keywords

conduction block
12
multifocal motor
8
motor neuropathy
8
axonal excitability
8
continuous involuntary
8
excitability studies
8
mathematical modeling
8
axonal loss
8
median nerve
8
motor
6

Similar Publications

How to correct QT interval after cardiac resynchronisation therapy.

J Electrocardiol

January 2025

Victorian Heart Institute, Monash University, Clayton, VIC, Australia; Victorian Heart Hospital, Clayton, VIC, Australia. Electronic address:

Introduction: This study evaluates various formulae used to correct the QT interval in patients with wide QRS complexes to calculate corrected QT (QTc) following Cardiac Resynchronisation Therapy (CRT).

Methods: We included patients with severe heart failure and left bundle branch block, presenting with a QRS duration of at least 120 milliseconds, who underwent successful CRT implantation. Patients were excluded if they had non-lateral left ventricular lead placement, metabolic disorders, atrial fibrillation, atrial tachycardia, or high-degree atrioventricular block prior to implantation.

View Article and Find Full Text PDF

The trained heart adapts through geometric changes influenced by concentric and eccentric hypertrophy, depending on the predominance of the isometric or dynamic components of the exercise performed. Additionally, alterations in heart rhythm may occur due to increased vagal system activity. Cardiological evaluation with an electrocardiogram (ECG) aims to identify cardiac conditions that could temporarily or permanently disqualify an athlete from competition.

View Article and Find Full Text PDF

Spontaneous muscle activity in multifocal motor neuropathy - Insights from axonal excitability testing.

Clin Neurophysiol

January 2025

Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Clinical Medicine and Neuroscience, University of Copenhagen, Denmark; Department of Neurology, Rigshospitalet, Copenhagen, Denmark.

Objective: To investigate motor axonal excitability in multifocal motor neuropathy (MMN) associated with involuntary muscle activity.

Methods: Two MMN patients with continuous involuntary finger movements (MMNifm) were compared to 11 patients without movements (MMNnfm). Clinical examination, EMG of the abductor pollicis brevis muscle, nerve conduction studies, motor unit number estimation, excitability studies, and mathematical modeling were conducted in the patients with MMN and compared to controls.

View Article and Find Full Text PDF

Background: The Qnox index is a novel monitor to quantify intraoperative nociception based on an electroencephalographic algorithm. We evaluated the ability of the Qnox index to discriminate noxious from non-noxious stimuli, respond to stimuli, and discriminate different levels of analgesia in patients under propofol anaesthesia with neuromuscular block.

Methods: Qnox was compared with heart rate and mean arterial pressure with five designated stimuli: tetanic stimulations without (tetanic 1) and with sufentanil (tetanic 2), skin incision, tracheal intubation, and a non-noxious period.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!