Dying back neuropathy is seen in all except :

Answer is D (CBS) The two basic pathological processes of pathogenesis in neuropathy include Axonal degenetration and Demyelination. Neuropathy associated with Axonal degeneration is often called 'dying back neuropathy' as degeneration usually proceeds from distal to proximal. Neuropathy associated with Diabetes mellitus, Porphyria and Arsenic are primarily caused by axonal degeneration and represent examples of dying back neuropathy. GBS is primarily a demyelinating neuropathy and is the single best answer of choice. Pathology of Ncuropathy Axonal Degeneration (Retrograde) (Dying Back Neuropathy) Retrograde Axonal Degeneration is one type of classical response of nerve to an insult and consists of degeneration of axon from distal to proximal (Referred to as 'Dying back neuropathy) This type of degeneration is most commonly seen after toxic and metabolic injuries (Since the distal axon is the poion fahest from the cell body it is most vulnerable to toxic and metabolic derangements) Neuropathies resulting from Toxins (eg Arsenic) and.Metabolic derrangements (Diabetes, Porphyria) are pathologically caused by axonal degeneration (Refer Harrison 16th/2504, 2505) and may hence be grouped as dying back neuropathies. Demyelination Demyelination is another type of response of nerve to an insult Such demyelination is associated with a' ' conduction block' which results from failure of nerve conduction across the demyelinated segment and results in a rapid onset type neuropathy (weakness) Neuropathies resulting from demyelination do not have a distal to proximal progression and may occur either distally The primary pathological process in GBS is demyelination (although associated axonal degeneration may he present) and hence it represents an example of Demyelinating neuropathies and not a type of dying back neuropathy