MOTOR NEURON DISEASE

Prognostic factors in ALS: A critical review

We have performed a systematic review to summarize current knowledge concerning factors related to survival in ALS and to evaluate the implications of these data for clinical trials design. The median survival time from onset to death ranges from 20 to 48 months, but 10-20% of ALS patients have a survival longer than 10 years. Older age and bulbar onset are consistently reported to have a worse outcome. There are conflicting data on gender, diagnostic delay and El Escorial criteria. The rate of symptom progression was revealed to be an independent prognostic factor. Psychosocial factors, FTD, nutritional status, and respiratory function are also related to ALS outcome. The effect of enteral nutrition on survival is still unclear, while NIPPV has been found to improve survival. There are no well established biological markers of progression, although some are likely to emerge in the near future. These findings have relevant implications for the design of future trials. Randomization, besides the type of onset, should take into account age, respiratory status at entry, and a measure of disease progression pre-entry. Alternative trial designs can include the use of natural history controls, the so-called minimization method for treatment allocation, and the futility approach.

SEROTONERGIC MECHANISMS IN AMYOTROPHIC LATERAL SCLEROSIS

Serotonin (5-HT) has been intimately linked with global regulation of motor behavior, local control of motoneuron excitability, functional recovery of spinal motoneurons as well as neuronal maturation and aging. Selective degeneration of motoneurons is the pathological hallmark of amyotrophic lateral sclerosis (ALS). Motoneurons that are preferentially affected in ALS are also densely innervated by 5-HT neurons (e.g., trigeminal, facial, ambiguus, and hypoglossal brainstem nuclei as well as ventral horn and motor cortex). Conversely, motoneuron groups that appear more resistant to the process of neurodegeneration in ALS (e.g., oculomotor, trochlear, and abducens nuclei) as well as the cerebellum receive only sparse 5-HT input. The glutamate excitotoxicity theory maintains that in ALS degeneration of motoneurons is caused by excessive glutamate neurotransmission, which is neurotoxic. Because of its facilitatory effects on glutaminergic motoneuron excitation, 5-HT may be pivotal to the pathogenesis and therapy of ALS. 5-HT levels as well as the concentrations 5-hydroxyindole acetic acid (5-HIAA), the major metabolite of 5-HT, are reduced in postmortem spinal cord tissue of ALS patients indicating decreased 5-HT release. Furthermore, cerebrospinal fluid levels of tryptophan, a precursor of 5-HT, are decreased in patients with ALS and plasma concentrations of tryptophan are also decreased with the lowest levels found in the most severely affected patients. In ALS progressive degeneration of 5-HT neurons would result in a compensatory increase in glutamate excitation of motoneurons. Additionally, because 5-HT, acting through presynaptic 5-HT1B receptors, inhibits glutamatergic synaptic transmission, lowered 5-HT activity would lead to increased synaptic glutamate release. Furthermore, 5-HT is a precursor of melatonin, which inhibits glutamate release and glutamate-induced neurotoxicity. Thus, progressive degeneration of 5-HT neurons affecting motoneuron activity constitutes the prime mover of the disease and its progression and treatment of ALS needs to be focused primarily on boosting 5-HT functions (e.g., pharmacologically via its precursors, reuptake inhibitors, selective 5-HT1A receptor agonists/5-HT2 receptor antagonists, and electrically through transcranial administration of AC pulsed picotesla electromagnetic fields) to prevent excessive glutamate activity in the motoneurons. In fact, 5HT1A and 5HT2 receptor agonists have been shown to prevent glutamate-induced neurotoxicity in primary cortical cell cultures and the 5-HT precursor 5-hydroxytryptophan (5-HTP) improved locomotor function and survival of transgenic SOD1 G93A mice, an animal model of ALS.

Survival of Patients with Amyotrophic Lateral Sclerosis in a Population-Based Registry

OBJECTIVE

To evaluate the survival of patients with amyotrophic lateral sclerosis (ALS) in an Italian population and to assess the effects of selected prognostic indicators on survival.

BACKGROUND

Median survival of ALS patients has been reported to range between 12 and 23 months from diagnosis and between 23 and 36 months from onset of symptoms. Although several negative prognostic factors have been identified, the overall picture still needs clarification.

METHODS

We included patients enrolled in an Italian ALS Regional Register (population 4,529,003) during the calendar year 1998. The diagnosis was confirmed by an ad hoc committee using the original El Escorial criteria. Each case was regularly followed up until death or December 31, 2002, whichever came first. Survival was assessed with the Kaplan-Meier method in the whole sample, by level of diagnostic certainty, and by selected prognostic indicators (age, sex, bulbar or spinal onset, and disease duration). Multivariate analysis was done with the Cox proportional hazard function.

RESULTS

The sample comprised 79 patients (33 female; 46 male) aged 28-85 years (mean age 64.4 years). Onset of symptoms was bulbar in 30% of cases. Mean symptom duration at diagnosis was 13.3 months. ALS was definite in 43%, probable in 29%, possible in 6%, and suspected in 22%. By December 31, 2002, 56 cases (71%) had died. The cumulative probability of surviving after diagnosis was 78% at 12 months, 56% at 24 months, and 32% at 48 months. Median survival from onset was 39.2 months and from diagnosis 30.6 months. Multivariate analysis confirmed definite ALS at diagnosis and older age as adverse prognostic factors.

CONCLUSIONS

Survival of ALS patients in the present sample was slightly longer than previously reported. Better palliative care and supportive treatment may explain the difference. Older age and the presence of definite ALS at diagnosis are poor prognostic predictors.

[Progressive muscular atrophy: clinical and laboratory study in eleven patients]

Progressive muscular atrophy (PMA), an infrequent type of motor neuron disease (MND), is a predominantly lower motor neuron degeneration, causing muscle wasting and weakness with loss of weight and fasciculations. The diagnosis is based on rigid criteria, considering clinical aspects and eletroneuromyography findings. Blood tests and radiological investigation are necessary to look for other diagnosis mimicking PMA. We herein present 11 patients with PMA (5.9% of all our MND patients), 9 men and 2 women, which onset of symptoms occurred mainly under de age of 50, with a mean of 45.5 years. Cramp was the most frequent symptom preceding muscular weakness. Muscle pain, fatigue and fasciculations were also cited as starting symptoms. Asymmetric weakness of the arms was the most frequent pattern of onset of the disease. Bulbar muscular weakness developed in all patients during the course of the disease. Predisposing factors and distinctive clinical outcome was not observed in any of the patients. Ophthalmoparesis and sphincter dysfunction were seen in two patients who had a prolonged time in artificial respiratory assistance. Immunosuppressive therapy was ineffective in all patients. Progressive course was seen in all cases and the mean survival time was 44 months.

The basic aspects of therapeutics in amyotrophic lateral sclerosis

Once thought to be a single pathological disease state, amyotrophic lateral sclerosis (ALS) is now recognized to be the limited phenotypic expression of a complex, heterogeneous group of biological processes, resulting in an unrelenting loss of motor neurons. On average, individuals affected with the disease live <5 years. In this article, the complex nature of the pathogenesis of ALS, including features of age dependency, environmental associations, and genetics, is reviewed. Once held to be uncommon, it is now clear that ALS is associated with a frontotemporal dementia and that this process may reflect disturbances in the microtubule-associated tau protein metabolism. The motor neuron ultimately succumbs in a state where significant disruptions in neurofilament metabolism, mitochondrial function, and management of oxidative stress exist. The microenvironment of the neuron becomes a complex milieu in which high levels of glutamate provide a source of chronic excitatory neurotoxicity, and the contributions of activated microglial cells lead to further cascades of motor neuron death, perhaps serving to propagate the disease once established. The final process of motor neuron death encompasses many features of apoptosis, but it is clear that this alone cannot account for all features of motor neuron loss and that aspects of a necrosis-apoptosis continuum are at play. Designing pharmacological strategies to mitigate against this process thus becomes an increasingly complex issue, which is reviewed in this article.

Genetics of sporadic ALS

The only known gene to be involved in ALS is the CuZn-superoxide dismutase (CuZn-SOD) gene. Since 1993, 89 disease-associated mutations have been found in this gene, 14 of them in cases with apparently sporadic ALS. Most frequent are the D90A (most often with recessive inheritance, but a few with dominant inheritance) and the I113T (dominant inheritance with variable penetrance). Statistical and genealogical evidence suggest that quite a number of diagnosed sporadic cases may in fact be familial cases in pedigrees with very low disease penetrance.

Electrodiagnostic studies in amyotrophic lateral sclerosis and other motor neuron disorders

The clinical electrodiagnostic medicine (EDX) consultant asked to assess patients with suspected amyotrophic lateral sclerosis (ALS) has a number of responsibilities. Among the most important is to provide a clinical assessment in conjunction with the EDX study. The seriousness of the diagnoses and their enormous personal and economic impact require a high-quality EDX study based on a thorough knowledge of and experience with motor neuron diseases (MNDs) and related disorders. Clinical evaluation will help determine which of the EDX tools available to the EDX consultant should be applied in individual patients. Although electromyography (EMG) and nerve conduction study are the most valuable, each of the following may be helpful in the assessment of selected patients based on their clinical findings: repetitive nerve stimulation, motor unit number estimate, single-fiber EMG, somatosensory evoked potential, autonomic function test, and polysomnography. The pertinent literature on these is reviewed in this monograph. The selection and application of these EDX tools depend on a thorough knowledge of the MNDs and related disorders.

The prognosis of adult-onset motor neuron disease: a prospective study based on the Scottish Motor Neuron Disease Register

The Scottish Motor Neuron Disease Register (SMNDR) is a prospective, collaborative, population-based project which has been collecting data on incident patients since 1989. In this report we present the clinical features of 229 patients with motor neuron disease (218 sporadic and 11 familial) diagnosed in 1989 and 1990 and compare their prognosis with previous studies of survival. The overall 50% survival from symptom onset was 2.5 years (95% CI, 2.2-3.0) and 5-year survival 28% (95% CI, 20-36%). The presence of progressive bulbar palsy (PBP), either at presentation or developing during the course of the illness, significantly reduced survival and was the most important prognostic indicator. Patients who survived longer than 5 years from symptom onset did not have PBP as part of their presenting illness. The prognosis was worse for women, and this was in part related to the higher frequency of PBP in older women, but age was also an independent adverse risk factor. Differences in survival between this and previous series can probably be explained on the basis of variation in case definition and ascertainment methods.

Epidemiology of amyotrophic lateral sclerosis in Hordaland county, western Norway

The incidence, prevalence and prognosis of amyotrophic lateral sclerosis (ALS) in the county of Hordaland, western Norway were determined for the years 1978 through 1988. The average annual incidence rate was 1.60 per 100,000 population with a male to female ratio of 1.26 (95% confidence interval: 0.76-2.09). The maximal age-specific annual incidence was 8.12 per 100,000 and occurred in the age-group between 61 and 65 years. The prevalence of ALS was 3.67 per 100,000 on December 31, 1988. The average age at the onset of the disease was 60.9 years ranging from 34 to 82 years of age. Survival was studied with life table techniques. Median survival from the onset of symptoms was 28.0 months overall. In patients with bulbar onset the median survival was 24.0 months whereas it was 40 months in patients with spinal onset of disease (log rank test, P = 0.0004). The difference in survival between ALS with bulbar or spinal onset was not explained by age or sex differences in the two groups.

Population frequencies of neuromuscular diseases--II. Amyotrophic lateral sclerosis (motor neurone disease)

A summary of the world literature on the prevalence of amyotrophic lateral sclerosis (motor neurone disease) has been carried out. Excluding those particular isolates with especially high prevalences (e.g. Guam and the Kii Peninsula of Japan), the mean prevalence among both sexes in other populations is around 41.6 x 10(-6) or 1 in 24,000.

Survival prediction in amyotrophic lateral sclerosis

This longitudinal study of 194 patients with sporadic ALS demonstrated that it is possible for physicians to predict the approximate survival time for an individual ALS patient given: (1) the age of the patient, (2) the duration of his weakness and (3) an estimate of his clinical disability (ALS Score). This information is of value in the clinical management of ALS patients, and it should facilitate construction of experimental therapeutic trials in ALS.

Motor neuron disease in Cantabria

Sixty-two patients with motor neuron disease (MND), encompassing amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP) and progressive muscular atrophy (PMA), were selected from within a defined area (Cantabria) in northern Spain, from 1974 to 1985. The annual incidence of MND was 1.01 per 100,000 inhabitants and the prevalence rate was 3.52 per 100,000. The male to female ratio was 1.78:1. Age-specific incidence rates increased with advanced age, with a maximum between 60 and 69 years for males and over 70 years for females. The median age at onset was 60.5 years. The average interval between the onset symptoms and diagnosis was 11 months. Fifty-three per cent of the patients had conventional or pseudopolyneuritic ALS, 36% had PBP and 11% had PMA. There were three familial cases. Two PMA patients had had acute poliomyelitis. The mean duration of the disease was 26.6 months and was significantly longer in males aged under 60 years. The survival rates in 50 patients with adequate follow-up were 18% after 5 years from onset and 6% after 10 years.

A survival analysis of 155 cases of progressive muscular atrophy

We performed a survival analysis of 155 cases of progressive muscular atrophy (PMA). In about half the cases, hands were involved first, the lower limbs in 30% and the shoulder girdle in 23%. The lifetables of PMA, adjusted to the expected mortality, showed a survival rate of 61.3% and 56.4% at three and five years, respectively. The location of onset symptoms did not modify the life expectancy, whereas the age of the patients at the moment of first diagnosis had a great influence on the course of the disease. The patients were further subdivided in two groups on the basis of the diffusion of the neuromuscular damage at the moment of the diagnosis. The course of the patients with a localized disease was markedly better than that of subjects with widespread disease. Some hypotheses are made about the latter group of cases.

Motor neuron disease in the province of Turin, Italy, 1966-1980. Survival analysis in an unselected population

We performed a population based survival analysis of all incident cases (220) of motor neuron disease (MND) in the province of Turin, Italy, during the period 1966-1980. 175 cases were diagnosed as amyotrophic lateral sclerosis (ALS), 43 as progressive muscular atrophy (PMA) and 2 as progressive bulbar palsy (PBP). The life-tables of MND, adjusted as to the "expected" mortality, showed a survival rate of 27.8% and 22.0% at 5 and 10 years, respectively. The course of PMA and ALS cases was different, with a 5-year survival rate of 66.8% and 17.7%, respectively. Nevertheless both life-tables showed a similar pattern with a rapidly fatal outcome in the first 3 years after diagnosis and a slower death rate in the following years. In each curve, the slopes suggested the presence of 2 subgroups with different prognosis. It is to be stressed that a percentage of PMA patients (25.7%) showed a rapidly fatal outcome and that a subgroup of ALS patients (26.6%) showed a relatively benign course. This might suggest a different individual susceptibility to the disease.

Epidemiology of motor neuron disease in northern Sweden

All cases of motor neuron disease (MND), encompassing amyotrophic lateral sclerosis (ALS), progressive bulbar paralysis (PBP) and progressive spinal muscular atrophy (PSMA), in northern Sweden, diagnosed between 1969-1980 have been analysed. 128 cases were found, corresponding to an average annual incidence rate of 1.67 per 100,000. The prevalence on December 31, 1980 was 4.8 per 100,000. Age-specific incidence rates were higher in the high age groups with a maximum at 60-64 years for males, at 70-74 years for females and at 65-69 years for the sexes combined. The median age at onset was 61 years. Clustering was not found in mining districts and overrepresentation of miners and stone treaters was not observed. Minor differences in incidence rates, as measured by the standardized morbidity ratio, SMR, were found between the inland, coastal and mountain areas. The median survival time after onset of disease was 32 months for ALS, 30 months for PBP and 70 months for PSMA. The combined survival rate for all MND cases was 28% after 5 years and 15% after 10 years. The male to female ratio was 1.1:1, and 4.7% were familial cases.