Diagnosis of motor neuron disease by neurologists: a study in three countries

Time to diagnosis and factors affecting diagnostic delay in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive, degenerative neuromuscular disease with limited treatment options. The diagnosis of ALS can be challenging for numerous reasons, resulting in delays that may compromise optimal management and enrollment into clinical trials. Several studies have examined the process and challenges regarding the clinical diagnosis of ALS. Twenty-one studies that were almost exclusively from the English literature published between 1990 and 2020 were identified via PubMed using relevant search terms and included patient populations from the United States, Canada, Japan, Egypt, and several countries in South America and Europe. Probable or definitive ALS patients were identified using El Escorial or revised El Escorial/Airlie House Criteria. Time to diagnosis or diagnostic delay was defined as mean or median time from patient-reported first symptom onset to formal diagnosis by a physician, as recorded in medical records. The typical time to diagnosis was 10-16 months from symptom onset. Several points of delay in the diagnosis course were identified, including specialist referrals and misdiagnoses, often resulting in unnecessary procedures and surgeries. Bulbar onset was noted to significantly reduce time to ALS diagnosis. Future interventions and potential research opportunities were reviewed.

Pathogenic Mechanisms in Sporadic Amyotrophic Lateral Sclerosis

In recognition of the 100th anniversary of Charcot’s death we have reviewed possible pathogenic mechanisms in amyotrophic lateral sclerosis (ALS). Advances in the last 5 years in molecular biology and genetics have identified mutations in the cytosolic dismutase (SODI) gene in some patients with familial ALS raising the possibility that oxidative stress may be involved in the pathogenesis. An excitotoxic pathogenesis has been implicated based on elevated plasma and CSF levels of amino acids and altered contents of amino acids in the nervous system of ALS patients and changes in the number of excitatory amino acid receptors. ALS sera containing antibodies to L-type calcium channels and the development of immune mediated lower and upper and lower motor neuron models have revitalized research efforts focusing on an immune basis for ALS. Other pathogenic mechanisms which have been the subject of recent research include elemental toxicity, apoptosis and programmed cell death and possibly a deficiency or abnormality in growth factors. Pathogenic processes for ALS must account for an increasing incidence of ALS, male preponderance, and the selective vulnerability of the corticomotoneuronal system.

Young-onset amyotrophic lateral sclerosis: historical and other observations

There is a wide range of age at initial symptom onset in amyotrophic lateral sclerosis despite a mean age of 65 years in population-based studies. 'Young-onset' amyotrophic lateral sclerosis typically refers to patients younger than ∼45 years and accounts for about 10% of cases in contemporary series. A review of published cases of amyotrophic lateral sclerosis from 1850 to 1950 revealed a far higher proportion of cases with young onset (>50%), with a steady decline to the contemporary figure. It is possible that this is not solely explained by increases in life expectancy. While there is still a rich variation in phenotypes among cases of young-onset amyotrophic lateral sclerosis, bulbar onset was found to be significantly under-represented in analysis of a large patient database, with implications for age-related vulnerabilities pertaining to focality of symptom onset. The timing of initiating pathological processes in relation to the emergence of symptoms is discussed, including the potential role of very early development and the interaction of epigenetic and environmental factors.

Electrodiagnostic criteria for diagnosis of ALS

A consensus meeting was held to determine the best use and interpretation of electrophysiological data in the diagnosis of ALS. The utility of needle EMG and nerve conduction studies was affirmed. It is recommended that electrophysiological evidence for chronic neurogenic change should be taken as equivalent to clinical information in the recognition of involvement of individual muscles in a limb. In addition, in the context of a suspected clinical diagnosis of ALS, fasciculation potentials should be taken as equivalent to fibrillation potentials and positive sharp waves in recognising denervation. The importance of searching for instability in fasciculation potentials and in motor unit potentials in ALS is stressed. These changes in the interpretation of electrophysiological data render obsolete the category Probable Laboratory-Supported ALS in the modified El Escorial diagnostic criteria for ALS. Methods for detection of upper motor neuron abnormality appear sensitive but require further study, particularly regarding their value when clinical signs of upper motor neuron lesion are uncertain.

ISIS Survey: an international study on the diagnostic process and its implications in amyotrophic lateral sclerosis

In a number of ALS patients, a long delay between onset of symptoms and diagnosis is reported. In this international study (ISIS Survey) we have identified the pathway followed by ALS patients from first symptoms to diagnosis confirmation. Diagnostic data from a total of 201 patients with definite ALS from 6 countries (Argentina, Brazil, Germany, Italy, Spain and the USA) were analyzed. The median time needed to confirm diagnosis was found to be 14 months; time to first consultation took 2 months, time to consultation with a neurologist took 8 months, and time for observation and diagnostic assessment by the neurologist took 4 months. This time delay was shorter when presentation was at bulbar level and when fasciculations were present. The major causes of diagnostic delay were unfamiliarity of the physician with the disease, unusual clinical presentation, coexistence of other diseases to which clinical symptomatology was attributed, misleading findings or misinterpretation of neuro-radiological or neurophysiological findings. The diagnostic delay has several implications for patients and their families, including mismanagement, delay in establishing appropriate and individualized pharmacological and symptomatic therapies, and difficulty in planning personal and familiar future.

Diagnostic dilemmas in amyotrophic lateral sclerosis

The El Escorial criteria for the diagnosis of amyotrophic lateral sclerosis (ALS) were introduced in 1990 to provide a standardised and diagnostically reliable approach to the early recognition of this disease. It is still unclear, however, whether these are the best criteria available for the early diagnosis of ALS. We applied these criteria retrospectively to clinical material available from 34 cases of autopsy proven ALS in an attempt to validate their usefulness in a pathological series. The clinical material was reviewed and specific clinical signs and anatomical levels of involvement recorded. Only signs listed in the criteria were included in the analysis. The El Escorial criteria for clinically definite ALS demonstrated high sensitivity and accuracy when validated in this clinicopathological study. Neuroimaging and electromyography were important in shortening the time in which patients were given a diagnosis of clinically definite ALS. Other diagnostic dilemmas in ALS and the role of early diagnosis of this disease are discussed.

Early diagnosis of ALS/MND

With the advent of a specific biological therapy for ALS there is an increasing imperative for early diagnosis. As new, more effective therapies become available, this will become more important. It is intuitively probable that early therapy will prevent disability in this otherwise relentlessly progressive disorder. The difficulties posed by this need for early diagnosis in clinical practice are discussed.

Diagnosis of amyotrophic lateral sclerosis

This review of the differential diagnosis of amyotrophic lateral sclerosis focuses on two themes. The first is practical, how to establish the diagnosis based primarily on clinical findings buttressed by electrodiagnosis. The main considerations are multifocal motor neuropathy and cervical spondylotic myelopathy. The second theme is the relationship of motor neuron disease to other conditions, including benign fasciculation (Denny-Brown, Foley syndrome), paraneoplastic syndromes, lymphoproliferative disease, radiation damage, monomelic amyotrophy (Hirayama syndrome), as well as an association with parkinsonism, dementia and multisystem disorders of the central nervous system.

Clinical epidemiology of amyotrophic lateral sclerosis

The introduction of palliative therapies in amyotrophic lateral sclerosis (ALS) will alter the epidemiology of ALS as it is known now. Although incidence rates will remain unchanged in the near future, prevalence rates will likely increase dramatically. Better understanding of the age-specific presentation of motor neuron diseases worldwide will shed light on the vexing questions concerning the variable incidence rates in some countries and apparent incidence gradients in North America and Europe.

Eyelid "apraxia" in patients with motor neuron disease

Three patients with motor neuron disease had eyelid "apraxia" with impaired voluntary but preserved involuntary eyelid movements. Attempts were made to localise the lesions responsible with neuroimaging and neuropathological examination.

Reduced isotope uptake restricted to the motor area in patients with amyotrophic lateral sclerosis

To study degeneration in the central nervous system in amyotrophic lateral sclerosis (ALS), we studied four patients using single photon emission tomography (SPECT) and magnetic resonance imaging (MRI). MRI demonstrated high intensity along the pyramidal tract on T2-weighted images in two. SPECT demonstrated reduced isotope uptake restricted to the motor area. While the cause of degeneration of the cortical neurons in the motor area is unknown, SPECT is useful for detecting the degeneration in patients with ALS.

Adult onset motor neuron disease: worldwide mortality, incidence and distribution since 1950

This review examines the commonly held premise that, apart from the Western Pacific forms, motor neuron disease (MND), has a uniform worldwide distribution in space and time; the methodological problems in studies of MND incidence; and directions for future epidemiological research. MND is more common in men at all ages. Age-specific incidence rises steeply into the seventh decade but the incidence in the very elderly is uncertain. A rise in mortality from MND over recent decades has been demonstrated wherever this has been examined and may be real rather than due to improved case ascertainment. Comparison of incidence studies in different places is complicated by non-standardised methods of case ascertainment and diagnosis but there appear to be differences between well studied populations. In developed countries in the northern hemisphere there is a weak positive correlation between standardised, age-specific incidence and distance from the equator. There is now strong evidence for an environmental factor as the cause of the Western Pacific forms of MND. A number of clusters of sporadic MND have been reported from developed countries, but no single agent identified as responsible.

Criteria for Diagnosis of Familial Amyotrophic Lateral Sclerosis

Clinical criteria for the diagnosis of motor neuron disease, agreed at the inaugural meeting of the European Familial Amyotrophic Lateral Sclerosis Collaborative Group, are described. The criteria are derived from those developed for the study of sporadic amyotrophic lateral sclerosis, and allow the inclusion of certain recognized clinical sub-types of familial amyotrophic lateral sclerosis. They will require testing for consistency and sensitivity.