[Nutritional approach for patients with amyotrophic lateral sclerosis]

Abstract

Prevalence of malnutrition in ALS ranges between 16 and 53 p. 100. The percentage of loss of weight greater than 10 p. 100 or, in a more inconstant way, body mass index lower than 18.5, are relevant criteria of malnutrition because predictive of survival. Arm muscle circumference and bioelectrical impedance analysis can assess body composition, but their impact on disease progression has not been evaluated. Measurement of serum albumin levels is of no interest. NUTRITIONAL REQUIREMENTS: Considering that energy expenditure is increased 10 to 20 p. cent in the majority of patients, energy needs can be estimated to be approximately 35 kcal/kg/d. In order to limit the accumulation of fat mass in the sub-group of patients with decreased energy expenditure, monitoring of triceps skin fold or impedance could be proposed, but their interest remains to be evaluated. In the absence of available data on protein requirements in ALS, an intake ranging between 1 and 1,5 g/kg/d seems reasonable, knowing that there is a risk of deficiency when intake is less than 1 g/kg/d and that an increase to 1,5 g/kg/d, considered as harmless, could be useful in the event of hypercatabolism. Supplementation with creatine, antioxidants or amino acids has not proven to be effective. These nutrients being provided by a balanced diet, specific supplementations have no proven utility provided that the patient receives sufficient proteins and energy. Systematic supplementation with vitamin D is however warranted to prevent osteoporosis due to the known risk related to a common state of deficiency. RELEVANCE OF GASTROSTOMY: Studies with good methodological quality evaluating percutaneous endoscopic gastrostomy (PEG) in ALS are not available. Because of the impact of malnutrition on survival, PEG must be considered when oral intake becomes insufficient. Retrospective studies suggest that the PEG tube is usually inserted too late during the disease course, minimizing expected benefits. Criteria useful for making the decision to installation a PEG tube should be the subject of randomized controlled studies. Mortality in the month which follows PEG, approximately 10 p. cent, is primarily due to respiratory failure. It occurs more frequently among patients having a forced vital capacity<50 p. cent. To avoid a degradation of pulmonary function in this sub-group of patients, several approaches are suggested in the literature: earlier PEG, peri-operative noninvasive ventilation, and radiological gastrostomy which does not require a general anesthesia. Whatever the technique used for gastrostomy, it should be carried out in an expert centre, because patients with ALS are more exposed to complications than others.