Camptocormia as a Phenotypic Variant of FSHD in the Elderly: Clinical, Genetic, and Imaging Features

Camptocormia, a pathological forward flexion of the spine, is a relatively common but often unexplained postural abnormality. Facioscapulohumeral muscular dystrophy (FSHD), one of the most prevalent adult myopathies, is caused by a contraction of D4Z4 repeats on chromosome 4 and typically presents with facial, scapular, and lower limb weakness. However, atypical phenotypes are increasingly recognized. We investigated camptocormia as a presenting feature of FSHD in a large neuromuscular cohort.

This cross-sectional study assessed clinical, genetic, and muscle imaging features in patients with FSHD presenting with camptocormia and compared them to patients with typical FSHD.

Among 87 patients with genetically confirmed FSHD, 8 (9.1%) had camptocormia as the predominant and initial manifestation. FSHD also accounted for 47% (8/17) of all cases of camptocormia due to axial myopathy. Compared to classical FSHD, camptocormic patients exhibited later disease onset, moderately contracted D4Z4 repeats, and marked axial involvement, with predominant spinal extensor weakness and relatively preserved abdominal strength. Muscle MRI revealed more severe paravertebral involvement and milder serratus anterior involvement than typically observed in FSHD.

Camptocormia represents a relatively frequent and distinct phenotypic variant of FSHD, particularly in older adults. Conversely, FSHD is a common cause of camptocormia due to axial myopathy. These findings expand the clinical spectrum of FSHD and underscore the importance of considering FSHD in the differential diagnosis of camptocormia, even in the absence of typical clinical signs of FSHD. Muscle imaging may assist in identifying FSHD-associated camptocormia.