Recommendations on post-trial responsibility in implantable neural device research: a multidisciplinary consensus study.

Neuromuscular diseases (NMD) are defined as diseases that primarily affect the motor unit, i.e., the anterior horn cells of the spinal cord, peripheral nerves, the nerve-muscle junction or the muscle fibers. The predominant symptom of NMD is muscle weakness. Some forms of the disease are congenital, while other forms manifest in childhood or during adulthood. While most NMD are rare, together they comprise a group with an overall prevalence in the range of 1/2500–1/3500 and represent significant causes of mortality and morbidity in both children and adults. Orofacial dysfunction is an umbrella term covering various functional difficulties related to, for example, reduced muscle strength, range of motion, sensory function and/or anatomy of the mouth and facial area, and the consequences of these problems at the activity level including difficulties with eating (chewing, swallowing and handling boluses of different consistencies), using facial expressions, producing the sounds required for speech, oral cleansing, that is clear your mouth after eating, and salivary control. These impairments of orofacial function tend to co-occur and can have negative impacts on both oral and general health, with consequences that include malnutrition, aspiration, dehydration, communication difficulties, malocclusions and impaired dental health. Orofacial functions can be affected by impairments of the peripheral motor system and cranial nerves that result primarily in oral sensory-motor impairment, as well as secondarily due to difficulties with breathing or neck weakness. Orofacial dysfunction can have a major negative impact on an individual’s well-being and social participation. Several studies have demonstrated that orofacial dysfunction is common in cases of congenital or childhood-onset NMD, although some symptoms have been studied more extensively than others. A literature review reported that feeding impairment and dysphagia were studied more intensely than other orofacial dysfunctions such as dysarthria and salivary control, and that myopathies (including muscular dystrophies) were more frequently studied than diseases that affect other parts of the motor unit, such as anterior horn cell diseases, neuropathies and neurotransmission-related diseases. A study from The Netherlands described pooled overall prevalence rates of 31.5% for dysarthria and 47.2% for dysphagia for 295 children (age range, 2.6–18 years) with 14 different NMD, with difficulties noted in almost all the disease cases. Dysphagia and dysarthria vary in severity and timing for different NMD, and various orofacial dysfunctions tend to co-occur. There are also reports that objective orofacial measures, such as decreased tongue strength, appear before an individual with NMD is recognized as having functional difficulties, such as dysphagia. It is common for children and adults with NMD, their caregivers, and health professionals to be unaware of orofacial symptoms such as dysphagia, i.e., prolonged mealtimes and chewing difficulties, or reduced maximum mouth opening. This is because the symptoms often develop gradually. It is also common among children and adults with NMD that their caregivers are unaware of the risks and treatment options for orofacial dysfunctions, despite the fact that early detection can help prevent complications, reduce morbidity and improve the quality of life.