  Segmental demyelination  Dysfunction of the Schwann cell or damage to the myelin sheath  Axonal degeneration and reinnervation of muscle  Wallerian degeneration  Denervation atrophy  Reactions of the Muscle fiber  Segmental necrosis  Vacuolation, alterations in structural proteins or organelles, and accumulation of intracytoplasmic deposits  Regeneration  Fiber hypertrophy General Reactions of the Motor unit

  Inflammatory neuropathies  Infectious polyneuropathies  Hereditary neuropathies  Acquired metabolic and toxic neuropathies  Traumatic neuropathies  Tumors of peripheral nerve – chapter 28 Diseases of Peripheral Nerve

  Immune-mediated neuropathies  Guillain-Barre syndrome (acute inflammatory demyelinating polyradiculoneuropathy)  2/3 preceded by a flu-like illness  Infections or prior vaccination  Ascending paralysis  Chronic inflammatory demyelinating polyradiculoneuropathy Inflammatory Neuropathies

  Leprosy ( Hansen Disease)  Diphtheria  Varicella-Zoster Virus Infectious Polyneuropathies

  Hereditary motor and sensory neuropathies  HMSN I – charcot-Marie-Tooth disease, peroneal muscular atrophy, hypertrophic neuropathy  HMSN II  HMSN III – Dejerine-Sottas neuropathy  Hereditary sensory and autonomic neuropathies – Table 27-2  Familial amyloid polyneuropathies – transthyretin gene  Peripheral neuropathy accompanying inherited metabolic disorders – Table 27-3 Hereditary Neuropathies

  Peripheral neuropathy in Adult-Onset DM  Distal symmetric sensory or sensorimotor neuropathy, autonomic neuropathy, focal or multifocal asymmetric neuropathy  Metabolic and nutritional peripheral neuropathies  Uremic  Thiamine – neuropathic beriberi  Vitamin B12, B6, E  Alcoholism  Neuropathies associated with malignancy  Brachial plexopathy, obturator palsy, cranial nerve palsies, polyradiculopathy, paraneoplastic  Toxic neuropathies  Industrial or environmental chemicals, biologic toxins, therapeutic drugs, organic compounds Acquired Metabolic and Toxic Neuropathies

  Laerations  Avulsions  Traumatic neuroma  Compression neuropathy ( entrapment)  Carpal tunnel syndrome  “Saturday night palsy Traumatic Neuropathies

  Degeneration atrophy – Spinal muscular atrophy, panfascicular atrophy, Werdnig-Hoffmann – floppy infant  Muscular dystrophies  Ion channel myopathies (Channelopathies)  Hyperkalemic, hypokalemic, normokalemic periodic paralysis  Malignant hyperpyrexia (hyperthermia)  Congenital myopathies – Table 27-6  Myopathies associated with inborn errors of metabolism  Lipid and mitochondrial ( ragged red fibers and parking lot inclusions)  Inflammatory myopathies – dermatomyositis, polymyositis, inclusion body myositis  Toxic myopathies – Thyrotoxic, ethanol, drug-induced  Diseases of the neuromuscular junction – myasthenia gravis, Lambert- Eaton  Tumors of skeletal muscle – chapter 26 Diseases of Skeletal Muscle

  X-linked MD  Duchenne – more severe  Becker  Dystrophin mutations  Variations in fiber size, increased number of internalized nuclei, degeneration, necrosis, and phagocytosis of muscle fibers, regeneration of muscle fibers, proliferation of endomysial connective tissue, muscle s eventually totally replaced by fat and CT  Other = Limb girdle MD  Myotonic dystrophy Muscular Dystrophies