Motor Unit Number Index (MUNIX) – ein neuer elektrophysiologischer Marker zur Abschätzung der Anzahl motorischer Einheiten: Eine Literaturübersicht

Zusammenfassung

„Motor Unit Number Index“ (MUNIX) ist eine neue quantitative elektrophysiologische Methode zur Schätzung der Anzahl motorischer Einheiten, um den Motoneuronverlust bei neuromuskulären Erkrankungen wie der Amyotrophen Lateralsklerose (ALS) zu verfolgen. Diese Übersicht soll einen Überblick über diese Methode und deren Anwendungsmöglichkeiten, Vorteile und Grenzen verschaffen. MUNIX bietet gegenüber anderen quantitativen Methoden zur Bestimmung der Anzahl motorischer Einheiten (motor unit number estimation, MUNE) einige Vorteile. Dazu gehören die technisch einfache Methodik, schnelle Durchführbarkeit, fehlende Invasivität und die Möglichkeit, mehrere Muskeln bei vertretbarem Zeitaufwand untersuchen zu können. Nachteile sind die notwendige Kooperation durch die Patienten, die Voraussetzung einer sicheren Handhabung von Routine-Neurografien und technische Besonderheiten als mögliche Fehlerquelle. Die bisherigen Daten zeigen für mehrere Muskeln eine gute inter-rater und intra-rater-Reliabilität bei gesunden Probanden wie auch bei ALS-Patienten. Bei ALS-Patienten konnte in mehreren Longitudinalstudien gezeigt werden, dass die Abnahme der MUNIX-Werte tendenziell ausgeprägter war als andere Verlaufsparameter und funktionelle Bewertungsskalen. Somit könnte diese Technik zukünftig als sensitiverer Progressionsmarker/Biomarker in longitudinalen ALS-Studien und anderen progredienten neuromuskulären Erkrankungen verwendet werden.

Abstract

The “motor unit number index” (MUNIX) is a new electrophysiological method to track motor neuron loss over time in neuromuscular diseases like amyotrophic lateral sclerosis (ALS). This review gives an overview about this method and its advantages and limitations. Compared to other motor unit number estimation (MUNE) techniques, MUNIX is easy and quickly performed, non-invasive and applicable to several muscles in a reasonable amount of time. However, the patient’s cooperation and accurately and carefully performed standard neurographical procedures are required and technical features have to be kept in mind in order to obtain reliable results. The available literature demonstrates a good inter- and intra-rater reproducibility in healthy volunteers and ALS patients. In ALS pa­tients, longitudinal data suggests that the decline of MUNIX exceeds other established markers of disease progression and functional rating scales. This supports the concept that MUNIX is able to detect early motor neuron loss before clinical symptoms like weakness and atrophy and therefore before functional deterioration occurs. This makes the method a favourable candidate as a sensitive biomarker in longitudinal ALS trials and other progressive neuromuscular disorders.

Schlüsselwörter

MUNIX - Amyotrophe Lateralsklerose - Motoneuronerkrankungen - Biomarker

Key words

MUNIX - amyotrophic lateral sclerosis - motor neuron disease - biomarker

• Literatur

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