This is a progressive disease of unknown origin in which there is degeneration of motor neurons of the spinal cord and cranial nerve nuclei and of pyramidal neurons in the motor cortex.
👉 95% of the cases – Viral infection, trauma, exposure to toxins and electric shock. (Though no Strong evidence exists)
👉 5% of the cases – Familial showing autosomal dominant inheritance. Defect lies in Chromosome 21 on the enzyme SOD1 (Superoxide dismutase)
👩⚕️ Usually affects people above 50 years of age. Very uncommon before 30.
👨⚕️ Male predominance.
👩⚕️ Dysarthria and Dysphagia.
👨⚕️ Wasting and fasciculation of muscles.
👩⚕️ Weakness of tongue, face, palate and limb muscles.
👨⚕️ Spasticity, extensor plantar reflexes and excessive tendon reflexes are seen in case of pyramidal tract involvement.
👩⚕️ External ocular muscles and sphincters usually remain intact.
👨⚕️ No sensory deficit objectively seen.
👩⚕️ Intellectual impairment is not seen in most cases.
🧐 Differential diagnosis: diabetic amyotrophy, multifocal neuron disease, spinal disorders should be excluded.
🧐 Electromyography – helps confirm fasciculation and denervation.
🧐 Spinal imaging and brain scanning – to exclude focal spinal or cerebral disease.
🧐 A slightly elevated protein concentration is seen in the CSF examination sometimes.
💊 Riluzole 100 Mg per day appears to be modestly effective in prolonging the life of the patient.
💊 Helps the Quality of life of patients: Psychological and physical support, speech therapist, physiotherapist.
💊 Mechanical aids: Splints, wheelchairs, walking aids, communication devices.
⚠️ Motor Neuron Disease is progressive; the mean time from diagnosis to death is 1 year.
⚠️ Most patients die within 3-5 years after the onset of symptoms.
⚠️ Death is usually from respiratory infection and failure, and the complications of immobility.
SOURCE: Davidson’s Principles and Practice of Medicine (19th edition)