M O T O R N E U R O N D I S E A S E S

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M O T O R N E U R O N D I S E A S E S

  1. 1. MOTOR NEURON DISEASES<br />
  2. 2. DR.PRAVEEN NAGULA<br />MOTOR NEURON DISEASES<br />
  3. 3. Each single motor neuron and the muscle fibers it innervates constitute a MOTOR UNIT.<br />No .of muscle fibers in a motor unit varies.<br />HAND,MOTION OF EYE – 3-6 muscle fibers.<br />LEG MUSCLES – 600 muscle fibers.<br />Group of muscle fibers (forming a motor unit ) can be intermixed in a muscle.<br />ALL THE MUSCLE FIBERS IN A MOTOR UNIT ARE OF SAME TYPE. <br />MOTOR UNIT<br />
  4. 4. Based on type of muscle fibers innervated ,duration of twitch contraction<br />Motor units are divided into<br />S- slow -- small units<br />FR – fast resistant to fatigue<br />FF fast fatiguable --- large units<br />RECRUITMENT of motor units follows size principle:<br />S muscle units – relatively slow contraction,controlled contraction ---FR more powerful response –FF muscle units most demanding tasks..<br />
  5. 5.
  6. 6.
  7. 7.
  8. 8. By example<br />
  9. 9. Differ by activity<br />Increased activity – muscle hypertrophy –type IIa ,IIb fibers<br />Inactivity –atrophy – type I fibers are susceptible<br />MUSCLE UNITS<br />
  10. 10. Muscle fibers<br />
  11. 11. Original delineation of ALS – charcot – CHARCOT’S disease.<br />Pathological apsects of disease – Joffroy,gambault<br />Labioglossolaryngealparalysis – progressive bulbar palsy<br />"Lou Gehrig's disease".<br />HISTORY<br />
  12. 12. STEPHEN HAWKING<br />
  13. 13. Amyotrophic comes from the greek language: <br /> A- means "no", myo refers to "muscle", and trophic means "nourishment"; amyotrophic therefore means "no muscle nourishment," which describes the characteristic atrophication of the sufferer's disused muscle tissue. <br />Lateral identifies the areas in a person's spinal cord where portions of the nerve cells that are affected are located. <br />As this area degenerates it leads to scarring or hardening (“sclerosis") in the region.<br />TERMS<br />
  14. 14. Introduction<br />Heterogenous group of neurodegenerative disorders.<br />Unknown etiology<br />Selective loss of motor neurons controlling voluntary movements.<br />
  15. 15. Essentials for diagnosis<br />Weakness<br />No sensory loss<br />No sphincter disturbances<br />Progressive course<br />No identifiable underlying cause<br />
  16. 16. Spectrum of MND<br />
  17. 17. AMYOTROPHIC LATERAL SCLEROSIS<br />
  18. 18. AMYOTROPHIC LATERAL SCLEROSIS<br />M.C form of progressive motor neuron disease.<br />Prime ex. of neurodegenerative disease.<br />Most devastating of the neurodegenerative disorders.<br />
  19. 19. Epidemiology<br />Prevalence 4-6/100,000<br />Incidence-1-3/100,000<br />Equal presentation in all racial groups<br />20-90 years of age<br />Peak between 50-70 years<br />M:F—1.5:1<br />Relentlessly progressive<br />Death from resp. paralysis<br />Survival 3-5 years<br />Risk factors-pesticides,smoking.<br />
  20. 20. familial<br /><ul><li>5-10%
  21. 21. 20%--SOD1 gene mutation
  22. 22. 21q chromosome
  23. 23. Copper , zinc dependent superoxide dismutase gene
  24. 24. Autosomal dominant
  25. 25. Indistinguishable from sporadic
  26. 26. Dynactin,senataxin
  27. 27. Alsin –AR
  28. 28. DYNACTIN </li></li></ul><li>Pathology<br />HALLMARK-death of LMN ,.UMN<br />LMN-ant.horn cells of spinal cord,bulbar muscles<br />UMN—layer 5 of motor cortex,descending via pyramidal tracts.<br />Other motor neuron disease involves only subset of motor neurons.<br />
  29. 29.
  30. 30. BETZ CELLS<br />
  31. 31.
  32. 32. Onset-----UMN or LMN-----Involves both---absence of them ?diagnosis.<br />Acc of lipid pigmented—LIPOFUSCHIN.<br />Normally seen in aged cells.<br />Focal enlargements are frequent –SPHEROID—acc of neurofilament proteins.<br />Proliferation of astrocytes,microglia.<br />Combined grey and white matter disease.<br />Motor cells and motor fibre tracts.<br />ATROPHY,DEGENERATION.LOSS OF MOTOR NEURONS OF CN.. <br />
  33. 33. Death of the peripheral motor neurons in brainstem,spinal cord.<br />Denervation<br />Consequent atrophy of the muscle fibres<br />Histochemical,electrophysiological<br />Early stages<br />Reinnervation<br />Less than poliomyelitis.peripheral neuropathy<br />
  34. 34. Atrophy,wasting<br />
  35. 35. Progressive degeneration –muscle atrophy is readily recognised in muscle biopsies and on clinical exam,---AMYOTROPHY.<br />Thinning of corticospinal tracts<br />Loss of fibers in the Lateral columns—fibrillarygliosis-LATERAL SCLEROSIS.<br />SELECTIVITY OF NEURONAL CELL DEATH.<br />
  36. 36. UBIQUITIN-marker for degeneration is seen.<br />Nucleus of Onuf –innervates bowel ,bladder is not involved.<br />Max involvement in cervical spinal cord<br />Loss of large pyramidal cells BETZ cells in motor ,premotor cerebral cortex.<br />Gliosis of lateral cords<br />NONE ARE PATHOGNOMONIC.<br />
  37. 37. Pathogenesis<br />Cause not well defined..<br />Excitatory neurotransmitters.<br />Glutamate participate in death of motor neurons in ALS.<br />EAAT2.<br />SOD1—cellular defense against excitotoxicity<br />When mutated—catalytic.<br />Non neuronal cells –influences the disease course.<br />
  38. 38. CLINICAL MANIFESTATIONS<br />Variable on motor neurons involved.<br />Asymmetric weakness ,usually distally in one of the limbs.<br />Insidious onset<br />Development of cramps with volitional movements in early hours of morning.<br />Weakness<br />Wasting<br /> Atrophy<br />
  39. 39. Cont..<br /><ul><li>Spontaneus twitching of motor units or fasciculation
  40. 40. EXTENSORS >FLEXORS in upper limbs
  41. 41. Difficulty in chewing ,swallowing,movements of face and tongue.
  42. 42. Early involvement of resp.muscles—death
  43. 43. Hyperactivity of muscle stretch reflexes
  44. 44. Spastic response to passive movements
  45. 45. Muscle stiffness out of proportion
  46. 46. Exaggeration of motor expression of emotion—weeping,laughing—pseudobulbar effect </li></li></ul><li>Cont…<br />Asymmetric—symmetric<br />Whether UMN or LMN at onset—both later<br />Sensory,bowel,bladder –not involved.<br />Cognitive function,ocular motility –preserved<br />Dementia is not a component of sporadic ALS<br />Familial—ALS+ FRONTO TEMPORAL DEMENTIA.<br />
  47. 47. Cont…<br /><ul><li>Fatigue
  48. 48. Weight loss
  49. 49. Wide spread muscle pains
  50. 50. Experience fear,anxiety,depression
  51. 51. Limb symptoms>bulbar
  52. 52. Proximal weakness—limbs,trunks,neck
  53. 53. Hemiplegia
  54. 54. Spastic paraparesis
  55. 55. Foot drop
  56. 56. Pescavus</li></li></ul><li>Cont..<br />Upper limb> lower limb<br />Distal> proximal<br />Extensor>flexor<br />Clawing of hands<br />Asymmetric at onset<br />
  57. 57. Cont..<br />Spontaneus clonus<br />DTR—inc<br />Babinski—postive<br />Abd. Reflexes –preserved<br />Bed sores are uncommon—collagen<br />Dysphagia worse for liquids > solids<br />Choking <br />Flaccid dysarthria<br />Inability to purse lips<br />
  58. 58. COMPLETELY SPARED<br />THE ENTIRE SENSORY APPARATUS<br />REG. MECH. FOR CONTROL AND COORDINATION OF MOVEMENTS<br />COGNITION<br />SEXUAL FUNCTION<br />OCULAR MUSCLES<br />
  59. 59. Diagnosis<br /><ul><li>WORLD FEDERATION OF NEUROLOGY
  60. 60. Simultaneous inv. Of UMN,LMN
  61. 61. PROGRESSIVE WEAKNESS
  62. 62. EXCLUSION OF ALTERNATE DIAGNOSIS
  63. 63. DEFINITE ALS-3 or 4 ---bulbar,cervical,thoracic,lumbosacral
  64. 64. 2sites—probable
  65. 65. 1 site-possible
  66. 66. exception –mutation in gene encoding SOD1-21q</li></li></ul><li>INVESTIGATIONS<br />MUSCLE BIOPSY<br />ELECTROMYOGRAPHY<br />NERVE CONDUCTION STUDIES<br />MRI<br />OTHER ROUTINE INVESTIGATIONS<br />
  67. 67. D.D<br />ATYPICAL—only UMN or LMN<br />Inv. of neurons other than motor neurons<br />Motor neuronal conduction block<br />1.cervical<br />2.MFMN CB<br />3.lead poisoning<br />4.thyrotoxicosis<br />5.recovery from poliomyelitis<br />6. parkinsonism<br />
  68. 68. TREATMENT<br />No treatment arrests the progression.<br />RILUZOLE—100mg/day<br />Increases survival,18 months<br />M.O.A- not known<br />Decreases glutamate release<br /> well tolerated <br />IGF –1<br />Ceftriaxone—anti excitotoxic<br />Inhibitory RNA<br />
  69. 69. REHABILITATION<br />Foot drop splints<br />Finger extension splints<br />Respiratory support<br />Respiratory devices<br />Cough assist devices<br />Gastrostomy<br />Speech synthesizers<br />
  70. 70. LMN disorders<br />1.KENNEDY DISEASE—X LINKED SPINOBULBAR MUSCLE ATROPHY<br />Males<br />Androgen receptor insensitivity<br />Gynaecomastia<br />Absence of pyramidal tract signs<br />Sensory symptoms present<br />CAG<br />
  71. 71. 2.TAY SACHS—hexosaminidase<br />Cerebellar atrophy<br />Absent spasticity<br />Dysarthria<br />3.SMA-5q<br />Floppy infant<br />Infantile—werdinghoffman disease<br />4.MMNCB—<br />Improved on immunoglobulins,chemotherapy.<br />
  72. 72. UMN<br />1.primary lateral sclerosis<br />Sporadic<br />No fasciculations<br />No denervation<br />Selective l oss of pyramidal cells<br />2.familial spastic paraplegia<br />AD<br />Respiratory function spared <br />
  73. 73. miscellaneous<br />
  74. 74. 1.what is a motor unit?differentiate UMN and LMN signs? Add a note on ALS ?<br />questions<br />
  75. 75. Thank you<br />
  76. 76.
  77. 77. Thank you<br />

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