<prompt> Neuronal degeneration is seen in all of the following except:Crush nerve injuryFetal development.SenescenceNeuropraxia  <response>: D i.e. Neuropraxia Neuropraxia refers to physiological disruption of conduction only, no structural changes or degeneration occur. Neuronal degeneration is seen inQ - Crush nerve injury, Fetal development, Senescence Seddons Classification of Nerve Injury Features Neuropraxia Axontemesis Neurontemesis Pathology - No anatomical disruption Axons myelin sheath disrupted but - Complete division of nerve - Both axon sheath intact - Physiological disruption of endoneural perineurium and epineurium sheath neural tube is - Axon neural tube i.e. perineurium, epineurium, endoneural sheath conduction only intactQ both are divided. Degeneration No degeneration Q Degeneration present proximal distal Degeneration present proximal Distal Wallerian Wallerian Neuroma No In continuity End or side neuroma Tinels sign12 Absent Advancing present Static Motor march Prognosis - Excellent - Good fair poor Poor - Recovery is complete usually with in 6 weeks - Occurs as regenerating axons grow into intact sheath - Electrodiagnostic studies like nerve conduction study EMG are used to distinguish between paial complete lesionQ and to establish a baseline for monitoring subsequent functional recoveryQ. However, these are not helpful until 2-3 weeks after an acute injury. - If a muscle lose its nerve supply dt nerve injury, EMG shows denervation potential at 3rd week; which exludes neuropraxia but however does not differentiate between axontmesis and neu rontemesis. All types of injuries may cause sensory, motor or both loss depending on type of nerve damaged. Each axon is covered by myelin sheath in myelinated nerve only or neurilemma Schwann sheath. Each nerve fiber containing many axons is covered by endoneurium. Each fasciculus containing many nerve fibres is covered by perineurium. And each nerve containing mamy fasciculus is covered by epineurium. 