Assessing residual neck mobility when wearing a cervical orthosis: an application in patients with Motor Neurone Disease

Severe weakness of the neck extensor muscles has been observed in neuromuscular pathologies, such as motor neurone disease (MND). This condition reduces the ability to perform daily activities and communicate, leading to the adoption of a cervical orthosis. However, commercially available devices are designed to immobilize the neck, which makes them uncomfortable and strenuous to wear for a long time. The lack of a device specifically designed for those patients led to the development of the Sheffield Support Snood (SSS) which enables to adjust the support given to the head, according to the task performed and to the disease progression. The following step toward the SSS commercialisation and adoption was an objective evaluation of its performance and the assessment with the end users, which was the aim of this thesis. To this purpose, an experimental protocol designed to quantitatively assess neck mobility when wearing cervical orthoses, has been developed. This protocol and the associated signal processing techniques proved to be suitable for the assessment of neck mobility through the measurement of head movements, both in laboratory and clinical settings. After having quantitatively assessed head movement limitation in MND patients, filling an existing gap in the current literature, the effects of the SSS were tested. Compared to controls, patients presented an overall impaired ability to perform head movements in terms of reduced velocity (mean values between 27% and 41% lower in movements performed reaching the maximum range of motion and between 34% and 48% lower in movements performed reaching the maximum angular velocity), reduced smoothness (mean values between 21% and 44% lower in movements performed reaching the maximum range of motion) and increased presence of coupled movements (mean values between 37% and 58% higher in movements performed reaching the maximum range of motion and between 44% and 53% in movements performed reaching the maximum angular velocity). The SSS was effective in facilitating the head movements in MND patients. Among those 9 individuals that were fitted with anterior or anterior plus lateral supports 5 of them had a reduced presence on coupled movements in at least one of the movements performed. However, a proper fitting of the orthosis appeared crucial and in the future it should be based on a quantitative approach similar to the one developed in this thesis. This study paved the way for improvements in the SSS design and for future quantitative assessment of the characteristics of motor control and movement strategies in MND patients and of how these change when using a device aiming at compensating for functional impairments.