Important in the management of ALS is periodic monitoring of respiratory function. We have typically performed pulmonary function tests every few months after the first year or so of illness. Our experience has been that the vital capacity in cubic centimeters can be estimated by multiplying the highest number to which a patient can count with 1 deep breath by 100. Thus, the ability to count to 25 with a full effort in a single breath corresponds to a vital capacity of approximately 2.5 L. Significant practical advances have been made in the respiratory management of ALS. The introduction of bilevel positive airway pressure (BiPAP) has allowed patients to sleep better and reduce daytime somnolence. Many patients do not initially tolerate the device, usually because of maladjusted face masks or excessive applied airway pressures. Almost always, a seasoned pulmonary technologist can find solutions to these problems. It is appropriate to begin BiPAP at (or before) the earliest sign of carbon dioxide retention, a state that is heralded by disruption of sleep, nightmares, early morning headaches, and daytime drowsiness. With noninvasive respiratory assistance, it may be possible to defer tracheostomy for months or years. Ultimately, as the diaphragm fails, BiPAP is needed not only at night but also during the day. As BiPAP use approaches 20 to 24 h per day, patients must usually address the difficult question of tracheostomy and mechanical ventilation. We broach this subject early enough in the course of the disease to allow ample time for discussion and reflection. In practice, most patients elect not to undergo tracheostomy and full ventilation.
Another important issue regards nutrition. As oropharyngeal palsy progresses, food should be cut into small pieces and dry foods, such as toast should be avoided; milk shakes and preparations of the same consistency are ideal at this stage. Speech therapists are capable of teaching patients methods to adapt to declining bulbar function and at the same time minimizing aspiration. Ultimately, in our experience, most ALS patients will need a feeding tube to maintain normal hydration and caloric intake. Although we adopt a neutral position in discussions with patients regarding mechanical ventilation, we tend to urge patients to undergo placement of a feeding tube at the appropriate time. This presumably increases survival and improves quality of life by preventing dehydration and recurrent aspiration. Laparoscopic and radiologic technologies for the placement of a gastrostomy tube render the procedure swift and nearly painless. Some patients have tubes inserted as outpatients and then start gastric feeding within 1 or 2 days.
Other devices, often guided by the physical and occupational therapist, may be of great assistance to the patient and family as the disease progresses. These include a mechanized bed and structural accommodations in the home that facilitate entry of a wheelchair and the safe use of the bath or shower as well as thick-handled utensils. Ambulation aids, beginning with simple canes (first 1, then 2) followed by a walker (preferably with basket and seat) and then a wheelchair (manual or electric) are of value in maintaining a sense of independence and ensuring safety.
The American Academy of Neurology has published guidelines for management that have been of aid to patients and physicians; they emphasize the complex and multidisciplinary needs of ALS patients (see Miller et al 2009a and 2009b).
Genetic Forms of Progressive Muscular Atrophy
These diverse diseases have a clear heredofamilial nature, usually monogenic, unlike ALS, in which there is an inherited factor in only some cases. They are mostly the concern of pediatric neurology but some have later onset and are mistaken for acquired neuromuscular disorders.
Spinal Muscular Atrophy (Werdnig-Hoffman Disease, SMN Mutation)