Epidemiology and pathophysiology of falls in facioscapulohumeral disease

Abstract

Muscle weakness is a potentially important, yet poorly studied, risk factor for falls. Detailed studies of patients with specific myopathies may shed new light on the relation between muscle weakness and falls. Here, we examined falls in patients with facioscapulohumeral disease (FSHD), who suffer from lower limb muscle weakness. This study provides insights into the prevalence, relevance and pathophysiology of falls in FSHD. We used a validated questionnaire as well as a prospective 3 month follow-up to examine the prevalence, circumstances and consequences of falls in 73 FSHD patients and 49 matched healthy controls. In a subgroup of 28 subjects, we also examined muscle strength and electrophysiologically assessed balance using body-worn gyroscopes. In the questionnaire, 30% of the patients reported to fall at least once a month, whereas none of the controls did. Injuries occurred in almost 70% of the patients. The prospective study showed that patients fell mostly at home, mainly due to intrinsic (patient-related) causes, and usually in a forward direction. Fallers were unstable while climbing stairs, rising from a chair and standing with eyes closed, whereas non-fallers had normal balance control. Frequent fallers had greater muscle weakness than infrequent fallers. These findings demonstrate the high prevalence and clinical relevance of falls in FSHD. We also highlight the relation between muscle weakness and instability among fallers. Because patients fell mainly at home, fall prevention strategies should focus on home adaptations. As mainly intrinsic causes underlie falls, the impact of adopting balance strategies or balance training should be explored in this patient group.