Motor Neuron Diseases- أ.د. عمرو حسن الحسني أستاذ المخ و الأعصاب

Definition:
A group of purely motor degenerative disorders that involve selective loss of the function of upper and/or lower motor neurons innervating the voluntary musculature of the limb and bulbar regions.


Pathogenesis:
Oxidative stress theory: Disruption of cell detoxification mechanismsoxidative stress on neurons  neuronal degeneration.
Loss of certain neurotrphic factors: These factors are responsible for maintenance and survival of neurons.


Classification :

Combined LMN and UMN involovement
Amyotrophic lateral sclerosis
Pure UMN involovement
Primary lateral sclerosis
Hereditary spastic paraplegia
Pure LMN involovement =Spinal muscular atrophy (SMA)
Acute infantile SMA (Werdnig-Hoffmann syndrome).
Bulbo-SMA (Kennedy's syndrome)
Chronic childhood SMA (Kugelberg-Welander syndrome).
Distal SMA

Diagnosis: can be made on clinical bases.
Electrophysiological studies:
Nerve conduction studies are also required to exclude motor neuropathy & to provide evidence of chronic denervation.
Neuroimaging studies: to exclude conditions which may cause UMN and/or LMN signs that may simulate ALS e.g. focal quadriparesis due to cervical cause.


Treatment:
A) Non -Pharmacological:
Speech therapy. d) Physiotherapy.
Nutritional support. e) Occupational therapy.
Respiratory therapy. f) Mental health care.
B) Pharmacological:
1. Symptomatic treatment: e.g. muscle relaxant for treatment of stiffness.
2. Potentially disease modifying drugs:
Glutamate antagonists: Riluzole: 50-200 mg / d, EDARAVONE
Antioxidant drugs : e.g. Vitamin E.
Neurotrphic factors: e.g. Nerve growth factor.
Other lines of treatment:e.g. Stem cell therapy, gene therapy.