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. 2025 Sep;32(9):e70347.
doi: 10.1111/ene.70347.

Diagnostic Impasse and Wandering in Patients With Rare Neuromuscular Diseases: Insights Into Patient Characteristics From the French National Network for Rare Neuromuscular Diseases (FILNEMUS) and the French National Rare Disease Database (BNDMR)

Rémy Dumas  1 , Anne-Sophie Jannot  1   2   3 , Nabila Elarouci  1 , Emmanuelle Salort-Campana  4 , Lucie Pisella  4 , Céline Tard  5 , Sabrina Sacconi  6 , Françoise Bouhour  7 , Elisabeth Sarrazin  8 , Marco Spinazzi  9 , Pascal Laforet  10 , Yann Pereon  11 , Aleksandra Nadaj-Pakleza  12 , Andoni Echaniz-Laguna  13 , Ariane Choumert  14 , Laurent Magy  15 , Léonard Feasson  16 , Florence Esselin  17 , Claude Cances  18 , Caroline Espile  19 , Isabelle Desguerre  20 , Cécile Rouzier  21 , Pascal Cintas  18 , Tanya Stojkovic  22 , Guilhem Solé  19 , Shahram Attarian  4 ; FILNEMUS Study Group
Collaborators, Affiliations

Diagnostic Impasse and Wandering in Patients With Rare Neuromuscular Diseases: Insights Into Patient Characteristics From the French National Network for Rare Neuromuscular Diseases (FILNEMUS) and the French National Rare Disease Database (BNDMR)

Rémy Dumas et al. Eur J Neurol. 2025 Sep.

Abstract

Background: Diagnostic wandering and impasse are major challenges for rare disease management. This study describes the characteristics of patients with rare neuromuscular diseases (RNMDs) without a diagnosis being managed by the French national network for RNMDs (FILNEMUS).

Methods: Data for RNMD patients managed by FILNEMUS centers between January 2017 and November 2022 were extracted from the French National Rare Disease Database (BNDMR). A network-wide, standardized, and quality-controlled process was established to collect additional data for patients without a diagnosis. The demographic and socioeconomic characteristics of these patients were then compared with patients with a confirmed diagnosis.

Results: 13.5% of patients evaluated (n = 5696/42,256) had no confirmed diagnosis. Comparison with 25,682 managed in the same centers and during the same periods with a confirmed diagnosis revealed that socioeconomic characteristics and region of residence did not influence diagnostic status. However, lack of a confirmed diagnosis was more common in patients aged > 50 years, and older patients had longer periods between first symptom onset and first interaction with an expert center. Evaluation of medical records identified eight RNMDs associated with increased risk of diagnostic wandering and impasse.

Conclusions: The FILNEMUS national network of expert centers has enabled equality of care for RNMD patients across France, but further measures are needed to promote more rapid referral to these centers, reduce times to first consultation, and maintain patient engagement in the diagnostic process, particularly for later-onset RNMDs.

Keywords: diagnostic impasse; diagnostic wandering; epidemiology; neuromuscular disorder; rare disease.

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Conflict of interest statement

S.A. has been a speaker and board member for Alexion, argenx, Biogen, Janssen, LFB, Pfizer, Sanofi, UCB, Janssen (now Johnson & Johnson Innovative Medicine), LFB, Pfizer, Alnylam, Novartis, and Roche. The other authors have no conflicts of interest to declare in relation to this study.

Figures

FIGURE 1
FIGURE 1
Study flow chart. BNDMR, French National Rare Diseases Database; FILNEMUS, French National Network for rare neuromuscular diseases.
See this image and copyright information in PMC

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