Motor unit changes in thoracic paraspinal muscles in amyotrophic lateral sclerosis

Prognostic models based on patient snapshots and time windows: Predicting disease progression to assisted ventilation in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a devastating disease and the most common neurodegenerative disorder of young adults. ALS patients present a rapidly progressive motor weakness. This usually leads to death in a few years by respiratory failure. The correct prediction of respiratory insufficiency is thus key for patient management. In this context, we propose an innovative approach for prognostic prediction based on patient snapshots and time windows. We first cluster temporally-related tests to obtain snapshots of the patient's condition at a given time (patient snapshots). Then we use the snapshots to predict the probability of an ALS patient to require assisted ventilation after k days from the time of clinical evaluation (time window). This probability is based on the patient's current condition, evaluated using clinical features, including functional impairment assessments and a complete set of respiratory tests. The prognostic models include three temporal windows allowing to perform short, medium and long term prognosis regarding progression to assisted ventilation. Experimental results show an area under the receiver operating characteristics curve (AUC) in the test set of approximately 79% for time windows of 90, 180 and 365 days. Creating patient snapshots using hierarchical clustering with constraints outperforms the state of the art, and the proposed prognostic model becomes the first non population-based approach for prognostic prediction in ALS. The results are promising and should enhance the current clinical practice, largely supported by non-standardized tests and clinicians' experience.

Integrative biomarker discovery in neurodegenerative diseases

Data mining has been widely applied in biomarker discovery resulting in significant findings of different clinical and biological biomarkers. With developments in technology, from genomics to proteomics analysis, a deluge of data has become available, as well as standardized data repositories. Nonetheless, researchers are still facing important challenges in analyzing the data, especially when considering the complexity of pathways involved in biological processes and diseases. Data from single sources appear unable to explain complex processes, such as those involved in brain-related disorders, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, thus raising the need for a more comprehensive perspective. A possible solution relies on data and model integration, where several data types are combined to provide complementary views. This in turn can result in the discovery of previously unknown biomarkers by unraveling otherwise hidden relationships between data from different sources, and/or validate such composite biomarkers in more powerful predictive models.

Clinical and laboratory findings of 21 patients with radiation-induced myopathy

BACKGROUND

Limited data are available on radiation-induced myopathy (RIM) in adult cancer survivors.

METHODS

We retrospectively reviewed the clinical, electrophysiological, serological, radiological and pathological findings of patients with RIM seen in the neurology clinic over a 11-year period (2002-2013).

RESULTS

Out of 251 patients with radiotherapy-induced neuromuscular complications, 21 had RIM (11 men and 10 women). Cancers included: Hodgkin's lymphoma (13), non-Hodgkin's lymphoma (one), pinealoblastoma (one), tongue (two), nasopharyngeal (one), thyroid (one) and testicular cancer (two). Various radiotherapy protocols were used but all patients received neck and upper torso radiation. The mean latency between radiation exposure and onset of RIM was 15 years (range 2-45 years). The most common presentation was head drop (43%) followed by neck pain (38%). Axial (86%) and periscapular (81%) muscle weakness and atrophy were frequent findings. Two patients died in follow-up from hypercapnic respiratory failure secondary to neuromuscular weakness. Serum creatine kinase values were usually normal or slightly elevated. EMG revealed predominantly myopathic changes in the axial and periscapular muscles. Half of the muscle biopsies (6/12) showed myopathic changes; increased connective tissue elements were observed in seven of eight muscle biopsies performed in the irradiated field; and mitochondrial dysfunction in two.

CONCLUSIONS

RIM is a potential long-term neuromuscular adverse effect of radiation exposure in Hodgkin's disease and other types of cancer manifesting predominantly as head drop and can be fatal due to neuromuscular respiratory failure. Improved radiotherapy protocols might reduce the risk of RIM and other radiation-induced neuromuscular complications.

Changes in motor unit properties in SOD1 (G93A) rats

INTRODUCTION

In amyotrophic lateral sclerosis (ALS), progressive death of motor neurons results in denervation and reinnervation of muscles. It is not clear how ALS affects the properties of motor units (MUs).

METHODS

Properties of single MUs in the medial gastrocnemius (MG) muscle of rats bearing the human mutated superoxide dismutase gene type 1 (SOD1) were determined at 3 stages: asymptomatic (ALS I); early symptomatic (ALS II); and terminal (ALS III).

RESULTS

In ALS II, higher proportions of FF (fast fatigable) and S (slow) MUs were observed, whereas in ALS III higher percentages of S and lower percentages of FF MUs were noted compared with controls. S motor neurons reinnervated fast muscle fibers, and those MUs gained some properties of fast MUs, including lower fatigue resistance, greater force generation, and higher action potential amplitudes.

CONCLUSION

Changes in MU properties of SOD1 rats have progressive and multidirectional character and speed depending on the MU type.

Electrodiagnosis in persons with amyotrophic lateral sclerosis

Electrophysiology remains an important tool in the evaluation of patients presenting with signs and symptoms of motor neuron disease. The electrodiagnostic study should include peripheral nerve conduction studies and needle electromyography to both exclude treatable disease and gather evidence regarding a diagnosis of amyotrophic lateral sclerosis (ALS). The recent changes in the revised El Escorial criteria, recommended by the Awaji-shima consensus group, have increased the diagnostic significance of fasciculation potentials to equal that of fibrillation and positive sharp-wave potentials in the needle electromyography examination of patients suspected of having ALS. In addition, electrophysiologic evidence is now considered equivalent to clinical signs and symptoms in reaching a diagnostic certainty of ALS. These changes, strategies for the design, and implementation of an effective electrodiagnostic evaluation, in addition to electrophysiologic techniques and their relationship to the evaluation of a patient with ALS, are reviewed and discussed.