Motor Neuron Diseases

The motor neuron disorders are a clinically diverse group of diseases that share a pathologic loss of the motor neurons. The most common adult-onset disorder is amyotrophic lateral sclerosis (ALS). Other forms include the spinal muscular atrophies, infectious motor neuronopathies, and rare focal forms of anterior horn cell loss.Overall, the incidence rate of ALS is believed to be 1.5 to 2.0 cases per 100,000 person-years, and the prevalence rate is 4 to 6 cases per 100,000 population. Other than in sparsely populated geographic clusters (eg, Guam and the Kii Peninsula of Japan), the incidence rate seems consistent across ethnic and geographic boundaries.

Infectious Myelopathies

In the setting of both globalization and increasing use of immunosuppressive therapy, infectious myelopathies are an important cause of morbidity worldwide. Clinical spinal cord syndromes related to infection are varied, including transverse myelitis, acute flaccid paralysis related to anterior horn cell involvement, spinal cord compression, chronic spastic paraparesis, and myeloradiculitis. Causative pathogens include viruses, parasites, pyogenic and atypical bacteria, and fungi. The epidemiology, clinical characteristics, diagnosis, and treatment of selected organisms will be discussed in this article.

Mixed Upper and Lower Motor Neuron Damage in Japanese Encephalitis Virus Infection

Cerebral manifestations in Japanese B encephalitis are well known. However, there are very few studies focusing on extra-cerebral manifestations, among which focal anterior horn cell involvement is exceedingly rare. We herein report a case of Japanese B encephalitis with focal anterior horn cell involvement and unfurl how stepwise clinical approach and targeted investigations helped to solve the diagnostic conundrum. A 27-year-old female was admitted with fever, headache, altered sensorium, and convulsions. She tested positive for Japanese B encephalitis-IgM. Following conservative management, she regained consciousness after 5 days when neurological examination revealed marked cognitive impairment, medial convergence of eyeballs, upward gaze restriction, upper limbs dystonia with brisk tendon jerks, and flaccid paraparesis. A repeat neurological examination, on day 15 of admission, showed marked wasting and intermittent fasciculation in both lower limbs. Brain magnetic resonance imaging showed asymmetrical (right > left) bilateral thalamic and midbrain lesions, hyperintense on T2 and T2-fluid-attenuated inversion recovery (FLAIR)-weighted imaging with mild diffusion restriction on diffusion-weighted imaging and apparent diffusion coefficient map, suggestive of encephalitis . Nerve conduction study revealed decreased compound muscle action potentials exclusively in lower limbs with intact sensory nerve action potentials. Electromyogram showed chronic denervation potentials and presence of spontaneous activity in lower limbs, but not in upper limbs, indicative of focal anterior horn cell involvement. Prognosis of Japanese B encephalitis does not only depend on cerebral sequelae. Anterior horn cell involvement can dictate poor outcome and can easily be missed if not carefully dealt with.

New Therapeutics Options for Pediatric Neuromuscular Disorders

Neuromuscular disorders (NMDs) of Childhood onset are a genetically heterogeneous group of diseases affecting the anterior horn cell, the peripheral nerve, the neuromuscular junction, or the muscle. For many decades, treatment of NMDs has been exclusively symptomatic. But this has changed fundamentally in recent years due to the development of new drugs attempting either to ameliorate secondary pathophysiologic consequences or to modify the underlying genetic defect itself. While the effects on the course of disease are still modest in some NMDs (e.g., Duchenne muscular dystrophy), new therapies have substantially prolonged life expectancy and improved motor function in others (e.g., spinal muscular atrophy and infantile onset Pompe disease). This review summarizes recently approved medicaments and provides an outlook for new therapies that are on the horizon in this field.