H.J. Schelhaas, M.D. Ph.D.
J.H. Veldink, M.D.
Disease progression is often unexpectedly rapid for the patient and his relatives. Difficulties with activities of daily living (ADL) and ambulation arise and increase quickly and adjustments in the living environment may come too late. The rehabilitation physician and the occupational therapist will have to search for ways to minimise the disabilities of a patient that are due to progressive deterioration of neurological function. Adjustments in and around the house must be made and devices that help a patient to stay independent longer must be sought.
Dysphagia arises from weakness of the bulbar muscles. To prevent choking patients eat more slowly and carefully, which could lead to suboptimal caloric and fluid intake. Survival is worse in malnourished patients, independent of neurological functioning, but malnutrition will also negatively influence general loss of strength and fatigue. Adequate nutrition is therefore of importance. The expertise of a speech therapist and nutritionist must be sought to advise patients on swallowing techniques and diets. Patients often change their eating patterns to accommodate advancing bulbar weakness. Because these strategies are generally effective in preventing choking, patients do not spontaneously admit to eating difficulties. Ultimately enteral nutrition via percutaneous endoscopically placed gastrostomy (PEG) may be necessary, although in some this need may come in an earlier stage. It is preferred that the PEG tube is inserted before a patient's vital capacity falls below 50% of predicted, as sedation is often used and oxygen saturation may fall during the procedure. Another reason not to insert a PEG when respiratory function is low is that sudden deaths sometimes occur in patients with diaphragmatic weakness. In a supine position, the abdominal content is pushed upwards as the stomach is filled through a recently inserted PEG and acute respiratory insufficiency may ensue. Several studies suggest that in general, survival of patients with a PEG increased an average of 1 to 4 months as compared to patients without a PEG.
Weakening of the facial musculature may lead to drooling, which often causes significant social stress. This is the consequence of poor handling of saliva rather than of increased production. Amitriptyline (10 mg 1-3/day) reduces the production of saliva but also causes a decrease of gastrointestinal motility, which may result in constipation. A maintenance dose of a laxative (e.g. lactulose) can help. Irradiation of the parotid gland (3-30 Gy, 3-10 fractions) or treatment of the parotid and submandibular gland with botuline toxine may also reduce sialorrhea. After irradiation, the production of saliva will immediately fall. This effect will last for 4-6 months.
Approximately 70% to 80% of patients with ALS will develop some form of dysarthria in the course of their disease: usually a mixed, spastic and bulbar, type. A speech therapist can help to maximise residual verbal communicative potential and possibly create new ways such as communication with the aid of computer programmes.
Pathologic crying and laughing, pseudobulbar affect, is thought to occur in 30% to 50% of patients. Amitriptyline (10mg 2-3/day) may reduce this abnormal display of affect but no randomized, controlled trials in patients with ALS have been done as yet.
As mentioned before, the cause of death in ALS is usually respiratory insufficiency due to weakness of the respiratory muscles. In our study, 24% of deceased ALS patients had received opiates in doses with a probable life-shortening effect, and one in five patients with ALS died as a result of euthanasia (17 percent) or physician-assisted suicide (3 percent). Physicians in 90 percent of patients classified deaths as peaceful. Early symptoms of weakness of respiratory muscles include dyspnea on exertion, fatigue and sleeping disturbances. Physiological respiration is least efficient at night and respiratory insufficiency will firstly occur during sleeping hours. Patients complain of restlessness, frequent awakenings, morning headaches and daytime sleepiness. By then vital capacity (VC) has usually fallen below 50%. As weakness of the respiratory muscles progresses and VC decreases, the risk of acute respiratory failure becomes greater. VC should therefore be monitored and it is wise to anticipate decisions concerning chronic non-invasive ventilatory support already in patients in whom the VC becomes less than 80 percent of the expected value. Invasive mechanical ventilation, through a tracheostomy, can keep patients alive virtually without limitations. However, in the end, total paralysis of all skeletal muscles will result and the patient will be completely dependent upon caregivers and will not be able to communicate. In a small minority of cases respiratory insufficiency may be the presenting symptom. In these patients, diaphragmatic weakness is disproportionately severe compared with limb involvement. Selective degeneration of the phrenic motor neurons in the cervical cord is thought to be the cause of this very rare presentation. In this situation, (temporary) invasive mechanical ventilation may be recommended. Most patients are informed about the possibility of respiratory support. Less than 1 % of patients chose for invasive mechanical ventilation, and usually do so for a limited period of time.
In the early stage of respiratory insufficiency, continuous invasive ventilation may not be necessary. Nocturnal non-invasive ventilatory support is usually sufficient to prevent sleeping disturbances, daytime sleepiness and morning headaches. Positive pressure ventilation is possible using a nasal mask that can be applied and removed easily. Studies indicate an improvement of the quality of life and an increase of survival. Eventually, a progressive loss of bulbar muscle tone will increase the risk of aspiration, weakness of facial musculature may cause air that is blown into the nose to escape via the mouth without having entered the lungs, and difficulties clearing secretions will start to emerge. In this stage non-invasive ventilatory support will no more be sufficient and tracheostomy can be considered.
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