Dados do Trabalho

Título

MOTOR UNIT NUMBER INDEX (MUNIX) AS A BIOMARKER FOR DISEASE PROGRESSION IN LATE-ONSET 5Q-SPINAL MUSCULAR ATROPHY TREATED WITH NUSINERSEN

Introdução

The Motor Unit Number Index (MUNIX) has emerged as a more sensitive biomarker for detecting motor unit loss in 5q-spinal muscular atrophy (SMA) compared to compound muscle action potential (CMAP). Recent studies have shown correlations between MUNIX values of various muscles and motor scales used to assess disease progression and treatment response.

Objetivo

This study is an investigation of the feasibility of MUNIX as a biomarker for disease progression in SMA types 3 and 4 treated with nusinersen.

Método

A four-year study involved 20 patients diagnosed with SMA types 3 and 4, ten treated with nusinersen and ten non-treated. Patients underwent evaluations using the Hammersmith Functional Motor Scale Expanded (HFMSE), the 6-minute walk test (6MWT), and assessments of CMAP and MUNIX in the abductor policis brevis (APB), adductor digiti minimi (ADM), and tibialis anterior (TA) muscles.

Resultados

A significant change was observed between the first and fourth years in CMAP values of the ADM muscle (p=0.012) in treated patients. In contrast, untreated patients experienced a significant reduction in mean CMAP values of the TA (p=0.015). Significant decreases in mean MUNIX values were found only in untreated patients, in the ADM (p=0.022) and TA (p<0.001). Treated patients experienced an average increase of 24.9 points in the MUNIX of the ADM (p=0.024) compared to non-treated patients. CMAP and MUNIX values for the TA muscle correlated with HFMSE scale results.

Conclusão

The MUNIX values of ADM and TA muscles are biomarkers for disease progression in 5q-SMA types 3 and 4 over a four-year follow-up period. Despite a significant increase in ADM CMAP values among treated patients, only ADM MUNIX could identify motor unit loss in untreated patients. Furthermore, MUNIX values remained stable among treated patients over the four-year follow-up period.

Referências

Mendonça RH, Machado LMS, Heise CO, Polido GJ, Matsui C Jr, Silva AMS, Reed UC, Zanoteli E. Motor unit number index (MUNIX) in children and adults with 5q-spinal muscular atrophy: Variability and clinical correlations. Neuromuscul Disord. 2021 Jun;31(6):498-504. doi: 10.1016/j.nmd.2021.02.019. Epub 2021 Feb 28. PMID: 33824074.

Palavras Chave

Spinal muscular atrophy; MUNIX; Biomarker