Which is pathgnomonic for motor neuron disease

Ans. is 'a' ie Fasciculations Among the given options, only fasciculation is seen in MND (Motor neuron disease).There is no bladder bowel involvement in MNDIn MND the neurological deficit is purely motor (there is no sensory involvement).There is no pseudohypertrophy of muscles rather progressive muscular atrophy is seen.Motor Neuron diseaseIn Motor Neuron disease there is degeneration of motor Neurons either upper motor neuron or lower motor Neuron or both. The severity of involvement of upper and lower motor neuron is variable.When there is loss of upper motor neuron (corticospinal tract) + lower motor neuron (Ant. horn of spinal cord) it is called Amyotrophic lateral sclerosis.When there is predominantly upper motor Neuron (Corticospinal tract)--Primary lateral sclerosis.When there is predominantly lower motor Neuron involvement due to Ant Horn involvement- Progressive muscular atrophy.When there is lower motor neuron involvement due to cranial nerve nuclei involvement - Progressive bulbar palsy.Most common* type of MND - Amyotrophic lateral sclerosis.Clinical manifestationManifestation are variable depending upon the predominant involvement of various neurons:-With predominant lower motor neuron (consisting of Ant. cells or their brainstem homologues)