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

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

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