71 Trunk movements in people with HSP Introduction Hereditary spastic paraplegia (HSP) is a heterogeneous group of neurodegenerative disorders. Pure forms are clinically characterized by bilateral progressive spasticity. With disease progression, people with HSP often develop muscle weakness and contractures in the lower extremities (e.g., a pes equinovarus deformity). 1-3 Together with impaired proprioception, these motor impairments often lead to reduced balance and gait capacities, which are among the most disabling consequences of HSP. 4, 5 In complex forms, additional neurological symptoms are present, such as ataxia, mental retardation, peripheral neuropathy and/or optic atrophy. 1, 2 As the disease progresses, balance and gait problems become gradually more severe, and people with HSP typically develop a bilaterally spastic gait pattern. 5, 6 Increased truncal movements during gait in frontal, sagittal and transversal planes are reported from the early phases of the disease. 7-9 In daily clinical practice, the most pronounced trunk movements seem to be present in relatively young patients, and in patients without plantigrade foot contact during gait (‘toe walkers’). Muscle weakness and spasticity are rarely found in the trunk of people with HSP. Increased trunk movement during gait therefore likely reflect a secondary phenomenon or compensation strategy. 8, 10 The clinical determinants underlying increased trunk movements during gait in people with HSP have rarely been studied. Assumingly, trunk movement are partly made in a compensatory effort to improve foot clearance and step length, but there may be additional explanations. 8, 11, 12 Here, we explore the hypothesis that increased trunk movements during gait in people with HSP partly reflect balance correcting strategies, specifically, the recruitment of so-called hip strategies. Hip strategies consist of the rotation of upper body segments around the center of mass, for instance, by making trunk or arm movements, and are usually recruited when other balance strategies are unavailable or insufficient. 13, 14 To investigate this hypothesis, we assessed whether the magnitude of truncal movements during gait in people with HSP was associated to a reduced clinical balance capacity. In addition, we explored whether increased trunk movements coincided with a higher percentage of toe walking. Methods The Centre of Expertise for Rare and Genetic Movement Disorders at Radboudumc Nijmegen, part of the European Reference Network for Rare Neurological Diseases (ERN-RND), is a primary national referral centre for patients with HSP. In our expertise centre, the diagnosis of HSP is based on clinical physical examination 5
RkJQdWJsaXNoZXIy MjY0ODMw