Disorders of neuromuscular function Flashcards
Muscle Tone Terminology
- Hypotonia
- Diminished resistance to passive movement
- Soft muscles on palpation
- Diminished deep tendon reflexes - Hypertonia
- Hyperexcitable stretch reflex causing rigidity & spasticity - Clonus
- Involuntary rhythmic muscular contractions and relaxations
Motor Dysfunction Terminology
Plegia = stroke or paralysis Paralysis = loss of movement Paresis = weakness Mono- = one limb Hemi- = both limbs on one side Di- or para- = both upper limbs or both lower limbs
Quadri- or tetra- = all four limbs
Upper Motor Neuron Damage
> Weakness and loss of voluntary motion > Spinal reflexes remain intact but cannot be modulated by the brain - Increased muscle tone - Hypertonia/Hyperreflexia - Spasticity
Lower Motor Neuron Damage (where it connects to the muscle)
> Neurons directly innervating muscles are affected
Irritated neurons
- Involuntary muscle contractions called fasciculation (small/local)
Death of neurons
- Spinal reflexes are lost
- Flaccid paralysis
- Denervation atrophy of muscles
Skeletal Muscle Disorders: muscle atrophy & muscular dystrophy
- Muscle Atrophy
- Disuse
- Denervation - Muscular Dystrophy
- Contractile proteins not properly attached to cytoskeleton of muscle cell (muscle issue, not nerve)
Muscular Dystrophy
- Genetic (inherited X-linked recessive trait)
- Primarily males
- 9 major types - Progressive degeneration (protein breakdown) and necrosis of skeletal muscle fibers & tissues
- Sarcoma do not attach properly
- Fat and connective tissue replace it
Note: muscles, not nerves are affected
Muscular Dystrophy: Duchene MD & Becker
- Duchene MD (most common form)
- Recessive X-linked
- Affects 1:3500 male births
- Females usually asymptomatic if carrier (or milder symptoms) - Becker MD
- slower, less severe
- Later in childhood than DMD
MD Presentation
- Boys asymptomatic at birth
- Hips/shoulder muscles often affected first
- Calf muscles hypertrophy (fat/tissue)
- By 2-3 years, abnormal posture, falls, contractures, joint immobility, scoliosis
- Wheelchair by teen years
- Incontinence
Resp: weak cough = resp infections
CVS: cardiomyopathy
MD Diagnosis
- Family history
- Observation of voluntary movement
- Elevated creatine kinase (CK-MM)
- Muscle biopsy
- Echo, ECG
MD Treatment
- Maintain ambulation
- Prevent deformities
- Prevent respiratory infections
- Death in young adulthood common
Disorders of Neuromuscular Junction
- Decreased acetylcholine release
- Decreased acetylcholine effects on muscle cell (receptors are lost)
- Myasthenia Gravis
- Decreased acetylcholinesterase activity resulting too much acetylcholine at neuromuscular junction, also interfering with nerve impulse
Myasthenia Gravis Risk Factors
- Women > Men
- Early adulthood (women)
- 50 years of age for men - Placental transfer from Mom
- 10-15% only, and often spontaneous resolution within months - Thymus tumor or hyperplasia in 75% of cases (unclear connection)
Myasthenia Gravis: autoimmune
- Decreased motor response d/t loss of functional acetylcholine receptors
- Autoimmune
- Gradual destruction of acetylcholine receptors in neuromuscular junction
- Injury to postsynaptic muscle membrane
- Receptor sites degraded and blocked d/t antibody response
MG Manifestations
> Initial: progressive throughout day
- Muscle weakness (periorbital muscles: ptosis, diplopia)
- Fatigue
Progression
- Respiratory muscle weakness, difficulty speaking/chewing/swallowing, weak limbs
> Myasthenia Crisis
- d/t stress, infection, emotional upset, pregnancy, alcohol, cold, surgery, etc.
MG Diagnosis
- History, physical exam
- Acetylcholine receptor blood test
- Electrophysiologic studies to assess stage
MG Treatment
- Corticosteroid (immunosuppressant)
- Thymectomy (if thymoma)
- Plasmapheresis (remove antibodies from the blood)
- IgG IV
Carpal Tunnel Syndrome Causes
- Mononeuropathy
- Compression of median nerve passing through carpal bones and ligaments
> Causes: - Inflammation of tendons, synovial swelling, tumor, RA, DM
- Repetitive flexion-extension movements
Carpal Tunnel Manifestations
- Pain, patesthesis
- Numbness of thumb, 1st, 2nd, 3rd, and part of 4th digit
Wrist and hand pain, worse at night (unable to clench effectively) - Atrophy of abductor pollicus muscle
Carpal Tunnel Syndrome Diagnosis & Treatment
Diagnosis Tinel sign Light percussion over median nerve at wrist Tingling sensation into palm = positive Phalen maneuver Complete flexion x 1 minute Paresthesia = positive Treatment Anti-inflammatories, immobilization
Peripheral Nerve Disorders: Guillain-Barre Syndrome
- Demyelinating polyneuropathy
- Acute onset… Life-threatening!
- Immune-mediated
- Linked to Campylobacter jejuni, cytomegalobvirua, - - Epstein-Barr virus: as influenza like illness often before onset
GB Manifestations
- Progressive/variable
- Ascending muscle weakness/paralysis
(respiratory muscle involvement) - Paresthesia, numbness
- Loss of tendon reflexes
- ANS involvement = postural, hypotension, arrhythmias, flushing, sweating, urinary retention
- Pain common in shoulder, back, posterior thighs
GB Treatment
- Support of ventilation
- Prevent complications
- Plasmapheresis
- IV immunoglobulin
80-90% have full recovery in 6-12 months
Disorders of the Cerebellum & Basal Ganglia
- Tourette’s Syndrome
- Parkinson Disease
Movement disorders (no paralyisis involved)
- Tremors, tics
- Hyperkinesia
Choreiform (jerks)
Athetoid (twisting movement)
Ballismus (violent flingling movements)
Dystonia (rigidity)
Tourette’s Syndrome
- Dysfunction in cortical and subcortical regions (thalamus, basal ganglia, frontal cortex)
- Inherited
- Onset in childhood
- Multiple physical tics and phonic tics (coprolalia- small % excessive swearing)
- Limited treatment options
Parkinson Disease
- Progressive disorder of basal ganglia and substantia nigral pathway resulting in depletion of dopamine
- 2nd most common neurogenerative disorders after Alzheimer’s
- Usually occurs after 50 years of age
Parkinson: Risk Factors
- Post encephalitic syndrome
- Antipsychotic drug s/e (block dopamine receptors and output)
- Toxins
- Carbon monoxide poisoning
- Genetics
- Brain tumors, CVA, head trauma, degenerative neurological diseases
Parkinson Manifestations
- Unilateral at first, then bilateral
- Rhythmic tremor of distal limbs
- Ceases with purposeful movement/sleep - Rigidity
- Passive joint movement causes jerks - Bradykinesis
- Slow to move; difficulty stopping voluntary movements
- Shuffling when walking, freeze, lean forward to keep moving
Parkinson Manifestations: Late
- Difficulty planning, starting or carrying out tasks
- Dementia/cognitive dysfunction (20-30%)
> Motor function abnormalities - Falls
- Voluntary facial movements become limited and slow = stiff, masklike expression
- Tongue, palate, throat muscles become rigid
- Slow speech, poor articulation
Parkinson Manifestations: Late Cont.
Sleep disorders
Neuropsychiatric disorders
- Unable to express emotions
ANS: lacrimation, sweating, dysphagia, orthostatic hypotension, thermal regulation, constipation, impotence, incontinence
Parkinson Treatment
- Individualized
> Nonpharmacologic: - Group support, education, exercise, nutrition guidance
- Botulinum toxin injections for dystonias for those people not responding to traditional treatments
Parkinson Treatment: Pharmacologic
- Increase dopamine levels
- Levodopa - Stimulate dopamine receptors
- Bromocriptine, Pramipexole, Amantadine - Slow breakdown of dopamine
- Selegiline, Rasagiline
Amyotrophic Lateral Sclerosis (Low Gehrig Disease)
> Lou Gehrig Disease - Etiology unclear - 5-10% familial; SOD 1 gene Mapped genetically Middle to late adulthood, male 80% die within 2-5 years of diagnosis Amyotrophy = denervation/shrinkage of muscle fibers = atrophy Lateral sclerosis = sliosis (scarring) of lateral columns of white matter 3000 affected currently in Canada
ALS (genetic mutation)
Genetic mutation
Glutamate (neurotransmitter) accumulation
- Opens calcium channels > normal
Damages both upper & lower neurons controlling voluntary movement
Distal affected first in lower spinal cord, then disease moves toward parent nerve
ALS affect on motor neurons
Affects motor neurons in
Anterior horn of SC: decreased motor neuron firing = irritation, weakness, denervation atrophy, hyperflexia
Motor nuclei of brain stem
Cerebral cortex (weakness, lack of motor control, stiffness, spasticity)
ALS Does not affect…
Does not affect, in most cases:
Entire sensory system
Intellect
Ocular motility
ALS Manifestations: Early
- Muscle cramps
- One extremity progressively weakness and atrophies
- Generalized weakness
- Hyporeflexia
- Fasciculations
- Impaired fine motor control
ALS Manifestations: Late
- Progressive
- Limbs, head weakness
- Weakness of palate, pharynx, tongue
- Speech disorders, dysphagia - Neck, shoulders, respiratory muscles
- Death d/t cerebral and respiratory complications
ALS Treatment
- Riluzole (antiglutamate) decreases glutamate accumulation and slows progression
- Support of ADLs
- Nutrition
- Psychological assistance
Demyelination Disorders of the Central Nervous System: Multiple sclerosis
Multiple sclerosis
- Inflammation & destruction of CNS myelin
- Usually 20-40 year of age, women
- Immune-mediated
- Genetically susceptible
15x more likely if immediate relative has
MS: patho
> Demyelination of nerve fibers of white matter in brain, spinal cord and optic nerve
- Either increased or decreased condction
Plaques: hard, sharp-edged, sclerotic, patchy
- Lack oligodendrocytes
1st stage: sequential development of small inflammatory lesions
2nd stage: lesions extend & consolidate, demyelination and gliosis occurs
MS: Manifestations
> Unpredictable/dependent on location/extent
- If healthy, symptoms occur, last for days or weeks, then resolve (next occurrence differs)
- Paresthesia (mild to severe)
(Numbness, tingling, burning, pressure)
- Sexual & bladder dysfunction
- Fatigue, speech disturbances, mood swings
- Optic nerve and muscle abnormalities (neuritis, diplopia, gaze paralysis, nystagmus, vertigo)
MS: Manifestations (cont)
- Lhermitte sign
flex neck = shock-like response down back/legs - Muscle spasticity
- Corticobulbar tracts (speech/swallowing)
- Corticospinal tracts (muscle strength)
- Cerebellar tracts (gait, coordination)
- Spinocerebrellar tracts (balance)
- Posterior cell columns of spinal cord (position, vibratory sensation)
Fatigue with depression
MS Stages
A) Relapsing-remitting - Acute worsening episodes, stabilizing between episodes B) Secondary progressive - Gradual worsening with episodes of improvement, previously had relapses-remittent C) Primary progressive - Continuous deterioration D) Progressive relapsing - Gradual but with superimposed relapses
MS Diagnosis: Lesions
Evidence of CNS lesions occurring in different parts at least 3 months apart
MRI – lesions (CT can be normal)
CSF: elevated IgG, elevated lymphocytes possible
MS Treatment
- Manage symptoms
- Healthy lifestyle
- Physiotherapy
- Corticosteriods
- Adrenocorticotropic hormone (ACTH)
- Plasmapheresis
- Interferon (enhances immune system)
- Glatiramer acetate (decoys t-cells)
- Mitroxantrone (suppresses leukocytes)
Vertebral and Spinal Cord Injury
- Primary young people
- MVA, fall, violence, gun shot wounds
- Most involve vertebral columns or supporting ligaments and the spinal cord
- Life expectancy has increased with recent treatment advances
Acute Spinal Cord Injury
> Direct trauma to cord (penetrating wound) or indirect (vertebral fracture, dislocation, subluxation of spine)
Spinal Cord Shock
- Complete loss of motor, sensory, reflex and autonomic function below level of injury
- Muscles, bowels, bladder, vasomotor tone
- May recover in hours or days
Conus Medullaris Syndrome & Manifestations
Damage/compression to conus medullaris > Manifestations -Low back pain -Sciatica (usually bilateral) -Flaccid bowel/bladder -Sexual dysfunction -Possible motor/sensory loss to legs/feet
SCI: Primary injuries
- Gray matter hemorrhages
- White matter edematous
- Necrosis of neural tissue
SCI: Secondary injuries
- Neurons and white matter damage d/t
- Blood vessel damage
- Decreased vasomotor tone
- Local release of vasospastic substances
- Release of enzymes from damaged cells
SCI Management
- Reduce neurological deficit & limit additional loss
- Immobilization, traction, alignment
- Decompression
- Surgery: internal skeletal stabilization to enable early ambulation
Classifications of SCI
- Tetraplegia/quadraplegia
- Cervical damage = loss of sensory motor or both - Paraplegia
- Thoracic, lumbar, sacral damage
- Arm function spared, trunk/legs/pelvis involvement varies
Muscle Grading
0 = total paralysis 5 = full movement
Impairment Scale
A = complete m/s loss E = normal
Complication of SCI: Autonomic Dysreflexia
- Post SCI above T6
- Unpredictable, exaggerated ANS response
Triggers - Pain, full/spasm bladder, dressing change, uterine contraction, ejaculation, wrinkled sheets
Manifestations – sudden onset - Vasospasm, HTN, bradycardia, diaphoresis, h/a.
Treatment: - Remove cause, support
