Phenotypic variability in amyotrophic lateral sclerosis

Clinically, ALS phenotypes depend on the areas of the body that are affected, the different degrees of involvement of upper and lower motor neurons, the degrees of involvement of other systems, particularly cognition and behavior, and rates of progression. Phenotypic variability of ALS is characteristic and can be declined on the distribution of motor manifestations but also on the presence of extra-motor signs present in a variable manner in ALS patients. Neuropathologically, ALS is defined by the loss of UMN and LMN and the presence of two representative motor neuronal cytoplasmic inclusions, Bunina bodies and 43kDa Transactivation Response DNA Binding Protein (TDP-43) - positive cytoplasmic inclusions. The distribution of cytopathology and neuronal loss in patients is variable and this variability is directly related to phenotypic variability. Key regulators of phenotypic variability in ALS have not been determined. The functional decrement of TDP-43, and region-specific neuronal susceptibility to ALS, may be involved. Due to the selective vulnerability among different neuronal systems, lesions are multicentric, region-oriented, and progress at different rates. They may vary from patient to patient, which may be linked to the clinicopathological variability across patients.

Staging amyotrophic lateral sclerosis: A new focus on progression

Amyotrophic lateral sclerosis (ALS) is a heterogenous motoneuronal neurodegenerative condition with a panel of phenotypes exhibiting different clinical patterns. Two compounds are currently available for the treatment of ALS but the majority of trials have failed to show a positive effect on prognosis. One of the explanations which could be put forward involves the way efficacy is evaluated: clinicians agree that the ALSFRS-revised scale used in all trials does not fit with highlighting a positive effect. So, the development and validation of new tools allowing a reliable assessment of ALS has become a key issue in clinical research. Over the last three years, two functional scales (the King's College and MiToS staging systems) have been proposed. These scales rely on two different approaches to ALS: an anatomical and prognostic concept, and loss of autonomy. Both scales propose five stages. We will discuss below the contribution of these two scales to clinical evaluation and the questions which remain to be resolved in the future.

Hypermetabolism is a deleterious prognostic factor in patients with amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

The aim of this study was to investigate patients with amyotrophic lateral sclerosis in order to determine their nutritional, neurological and respiratory parameters, and survival according to metabolic level.

METHODS

Nutritional assessment included resting energy expenditure (REE) measured by indirect calorimetry [hypermetabolism if REE variation (ΔREE) > 10%] and fat mass (FM) using impedancemetry. Neurological assessment included the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised score. Survival analysis used the Kaplan-Meier method and multivariate Cox model.

RESULTS

A total of 315 patients were analysed. Median age at diagnosis was 65.9 years and 55.2% of patients were hypermetabolic. With regard to the metabolic level (ΔREE: < 10%, 10-20% and >20%), patients with ΔREE > 20% initially had a lower FM(29.7% vs. 32.1% in those with ΔREE ≤10%; P = 0.0054). During follow-up, the median slope of Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised tended to worsen more in patients with ΔREE > 20% (-1.4 vs. -1.0 points/month in those with ΔREE ≤10%; P = 0.07). Overall median survival since diagnosis was 18.4 months. ΔREE > 20% tended to increase the risk of dying compared with ΔREE ≤10% (hazard ratio, 1.33; P = 0.055). In multivariate analysis, an increased REE:FM ratio was independently associated with death (hazard ratio, 1.005; P = 0.001).

CONCLUSIONS

Hypermetabolism is present in more than half of patients with amyotrophic lateral sclerosis. It modifies the body composition at diagnosis, and patients with hypermetabolism >20% have a worse prognosis than those without hypermetabolism.

Epidemiology of amyotrophic lateral sclerosis: A review of literature

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons, resulting in worsening weakness of voluntary muscles until death occurs from respiratory failure. The incidence of ALS in European populations is two to three people per year per 100,000 of the general population. In Europe, crude prevalences range from 1.1/100,000 population in Yugoslavia to 8.2/100,000 in the Faroe Islands. Major advances have been made in our understanding of the genetic causes of ALS, whereas the contribution of environmental factors has been more difficult to assess and large-scale studies have not yet revealed a replicable, definitive environmental risk factor. The only established risk factors to date are older age, male gender and a family history of ALS. Median survival time from onset to death is usually 3 years from the first appearance of symptoms. Older age and bulbar onset are consistently reported to have poorer outcomes. However, there are conflicting data regarding gender, diagnostic delay and El Escorial criteria. The rate of symptom progression has been revealed to be an independent prognostic factor. Psychosocial factors and impaired cognitive function are negatively related to ALS outcome, while nutritional status and respiratory function are also related to ALS prognosis. The effect of enteral nutrition on survival is still unclear, although noninvasive positive pressure ventilation (NIPPV) has been found to improve survival. These findings have relevant implications for the design of future trials.

Population-based epidemiology of amyotrophic lateral sclerosis (ALS) in an ageing Europe--the French register of ALS in Limousin (FRALim register)

BACKGROUND AND PURPOSE

The main objective of establishing the French register of amyotrophic lateral sclerosis (ALS) in the Limousin region (FRALim), was to assess the incidence of ALS, in this ageing region of Europe, over a 12-year period (2000-2011).

METHODS

Patients were included if they lived in Limousin at the time of diagnosis of ALS according to El Escorial revised criteria and were identified by at least one of the following sources: (i) the French national body coordinating ALS referral centres; (ii) public and private hospitals in the region; (iii) health insurance data related to long-term diseases.

RESULTS

The FRALim register identified 279 incident cases (2000-2011). The crude and European population standardized incidences of ALS were as high as 3.19/100,000 person-years of follow-up (95% CI 2.81-3.56) and 2.58/100,000 person-years of follow-up (95% CI 2.27-2.89) respectively. Median age at onset was 70.8 years (interquartile range 63.1-77.1). The standardized sex incidence ratio (male/female) was 1.3 overall, but 1.1 under the age of 65 years, 1.7 between 65 and 75 years and 1.9 above 75 years. The exhaustiveness of the register has been estimated at 98.4% (95% CI 95.6-99.4) by capture-recapture analysis.

CONCLUSION

It was possible for the first time in France to monitor accurately the incidence of ALS over a long time period. It appears to be in the upper range of data reported in western countries. Patterns displayed here might anticipate the epidemiology of ALS in ageing western countries.