Motor Neurone Disease (MND) is a group of disorders with unknown origin. There is a progressive degeneration of nerve cells in the upper and lower motor neurones, leading to muscle weakness and wasting, eventually leading to death. It is thought to affect seven people in every one hundred thousand and after diagnosis, life expectancy is approximately three to five years (Macpherson, 2001). As this is a progressive disease there is an emphasis on the patients quality of life rather than rehabilitation. This essay will examine the benefits of physiotherapy using evidence based practice for different types of exercise programmes, management of spasticity, respiratory function and management of contractures.
Motor neurone disease results in degeneration of the anterior horn cells of the spinal cord, which affects the lower motor neurones, the corticospinal tracts, affecting the upper motor neurones and certain motor nuclei of the brainstem, leading to bulbar palsy (Stokes, 1998). The clinical presentation acts in accordance with the affected part of the central nervous system and four types of MND have been identified. Amytrophic lateral sclerosis (ALS) is the most common form accounting for 66 percent of patients with MND (Stokes, 1998). It affects both the upper and lower motor neurones and is characterised by muscle weakness, fasciculation, spasticity, over active reflexes and rapidly changing emotions.
Progressive muscular atrophy is caused by degeneration of the lower motor neurones leading to muscle weakness and wasting, progressive bulbar palsy affects either the upper or lower neurones in the bulbar region, resulting in dysarthria and dysphagia and lastly primary lateral sclerosis, where upper neurone damage results in spastic paralysis of the limbs, however this is extremely rare (Motor Neurone Disease Association, 2004). The majority of the research into MND focuses on ALS, as it is the most common, and will therefore be the focus of this essay. However, the treatments will be fairly similar for all the conditions because although the disease begins locally it tends to become more generalised.
The Excerpta Medica MND Advisory Group (1999) has stated four principles for general management for these patients. They include care for the whole person and those that matter to them, quality of life and prompt provision of treatments to secure symptom control, respect for patient autonomy and choice, emphasis on open and sensitive communication and planning for the future with timely liaison with the palliative care team. There are a growing number of palliative care services in the UK and a recent survey, carried out by Higginson et al (2000), looked at forty three day care services and what they provide. Amongst other professions, physiotherapy was one of the most common, with half the centres offering physiotherapy everyday and over three quarters offering it once a week. Physiotherapy is therefore a recognised treatment in the palliative stage of the disease but this essay will focus predominantly on the earlier stages of the disease.
MND patients often have a delayed referral to physiotherapy due to diagnosis difficulties. Diagnosis can be assisted through nerve conduction tests and electromyography but often the patients need to be reviewed for some time before a diagnosis is made. By this stage the muscle wasting has begun and nerve regeneration can no longer compensate for the degenerating neurones. It is important that the physiotherapist realises that each individual will progress and clinically present differently as the disease does not follow a set pattern.
To maintain the patient’s quality of life, they will often wish to remain independent and continue with activities of daily living for as long as possible. Their wishes should be discussed and made specific to that individual. In the early stages of the disease the focus of physiotherapy is to assess the patient’s range of movement, motor power, chest function and their functional abilities. As the disease progresses, these issues need to be continually reassessed and during the terminal stage more emphasis is placed on positioning, chest care and support for the patient and carer.
There has been extensive research into exercising patients with neuromuscular diseases and but is limited for ALS. The question is whether exercise is beneficial for patients with ALS so as to maintain their muscle strength for activities of daily living. These patients lose skeletal muscle fibres as a result of the disease but are also thought to atrophy due to disuse of the muscles (Kilmer, 1998). The muscle fibres will therefore lose myofibril size, resulting in reduced fibre cross sectional area, less force production and reduced muscle endurance (Appell 1990).
By introducing an exercise regime there may be an element of reversing the effects of disuse as well as altering the natural history of the disease itself. Research in this area examines the type of exercise these patients should be subject to. A case report was carried out by Bohannon (1983) on resistance exercises of the upper limb using proprioceptive neuromuscular facilitation patterns. Two sets of ten repetitions were performed four days a week with a total of sixty five training sessions.
The study found an increase in static strength in fourteen of the muscle groups and diminished strength in four. It was thought that the muscle strength decline was due to the progression of the disease rather than overwork, as this usually occurs following highly repetitive activities (Bennet 1958). This suggests that strengthening exercises are useful, however it is a single case study and should not be generalised, especially as this disease is so individual. Lenman (1959) also looked at performing isometric training exercises on the elbow flexors and extensors on six patients with motor neurone disease.
Three improved and three showed no improvement or loss of strength. This study is also limiting as there is uncertainty about the diagnosis of the patient’s conditions and it is limited to two muscle groups. More recently a study was carried out on mice who had the genetic form of ALS, caused by mutations in the SOD1 gene. They were made to exercise on the treadmill for thirty minutes a day before the onset of the disease until they were too weak to run. These mice showed an increased life span compared to non exercised mice. This is useful evidence but cannot be generalised to the human population (Moraes, 2003).
ALS is classified as a rapidly progressing neuromuscular disease but further research has been carried out in slowly progressive neuromuscular diseases. …….. () found that a twelve week moderate resistance programme resulted in strength gains of up to twenty percent whereas, in the same population, a twelve week high resistance exercise programme showed no beneficial effects and there was evidence of overwork weakness in some patients ……(). This is relevant to ALS patients as there is continual muscle degeneration and the risk for overwork weakness is great. We can therefore conclude from this evidence that submaximal exercises are beneficial to ALS patients but overwork should be avoided at all costs.
Patients should be advised of the signs of fatigue, which include severe muscle cramping, prolonged shortness of breath, feeling weaker rather than stronger within thirty minutes post exercise and excessive soreness twenty four to forty eight hours following exercise (Carter et al 1998). To combat the issue of disuse, low impact aerobic exercise should be advised at early intervention such as walking and swimming. This will improve cardiovascular performance and increase muscle efficiency. A common feature in ALS is joint stiffness that results in pain, and therefore exercising is also beneficial for maintaining joint range of movement.
Efforts should be made from the outset to prevent contractures as they limit the mobility of joints and therefore limit the patient’s lifestyle. In neuromuscular conditions spasticity, immobilisation and muscle weakness are the three main factors leading to the development of contractures (Farmer et al 2001). Spasticity is a common clinical feature in ALS due to upper motor neurone involvement. It is defined as ‘ a motor disorder characterised by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflex as a component of the upper motor neuron syndrome’ (Barnes et al 2001).
Spasticity in these patients produces an imbalance due to the spastic muscle continuously contracting, pulling the affected limb into a deformed position. This will eventually result in contractures. This increased stiffness over time is thought to be due to an increased amount of interdigitation between actin and myosin (Farmer, 2001). As patients become weaker they will tend to spend more time in one postion, in particular, sitting, which will lead to contractures at the hip and knee. With prolonged immobilisation fibrous adhesions occur and the joint cartilage thins at the point of contact (Akeson, 1987). Lastly, the continual muscle weakness caused by the disease and immobilisation leads to muscle shortening as muscles are often unopposed by an antagonist.
Prevention of contractures can be controlled in the early stages of the disease by maintaining good range of movement via exericise as mentioned earlier. However as the disease progresses and the patient becomes increasingly immobilised there are a variety of treatment techniques including passive stretching, serial plastering, splinting and electrical stimulation. The negative features are now recognised to be more diasabling than the changes to muscle tone. In the past treatment focused on inhibiting spasticity (Bobath 1990) to improve function, however there is no experimental evidence to support this. Carr and Shepherd (1995) believe the focus of treatment should be on training the individual to gain control over the muscles required for essential tasks of daily living and preventing secondary and adaptive soft tissue changes.
Carr and Shepherd (1995) divided the symptoms into negative and positive features. The negative features include muscle weakness, loss of dexterity, and fatiguability. This is thought to be caused by insufficient descending fibres converging onto lower motor neurones to shape complex movements and insufficient frequency discharge resulting in weakness. The positive features result from hyperreflexia, including the claspknife phenomenon, exaggerated tendon jerks and clonus.