Neuromuscular Disorders

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Neuromuscular Disorders

• Guillain-Barré Syndrome - Chapter 30
• Myasthenia Gravis Chapter 31

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Neuromuscular Diseases

• Guillain-Barré Syndrome
• Myasthenia Gravis
• Amyotrophic Lateral Sclerosis (ALS)
• Muscular Dystrophy
• Multiple Sclerosis
• Cerebral Palsy
• Spinal cord injury

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Guillain-Barré Syndrome
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Definition

• An acute, usually rapidly progressive form of
  inflammatory polyneuropathy characterized by
  muscular weakness and mild distal sensory loss,
  which in about 2/3 of cases, begins 5 days to 3
  weeks after a banal infectious disorder, surgery,
  or an immunization.
• Disorder of the peripheral nervous system.
• Also known as
• Landry's Ascending Paralysis
• Acute Inflammatory Demyelinating
  Polyradiculoneuropathy
• Post-infectious polyneuritis
• Acute post-infection polyneuropathy

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Etiology

• Cause is unknown.
• Autoimmune?
• Follows a febrile infection by 1-4 weeks
• Upper Respiratory Tract
• GI illness
• Viruses and bacteria
• Infectious mononucleosis is associated with 25
  of cases.
• Followed the swine flu influenza vaccination in
  1976.
• 500 cases of Guillain-Barré and 25 deaths.

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Etiology

• Parainfluenza 2
• Variola
• Measles
• Mumps
• Hepatitis A and B
• Mycoplasma Pneumoniae
• Salmonella typhi

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Etiology

• All age groups
• Greater incidence in age group gt 45 years age.
• Either sex
• Greater incidence in males.
• Greater incident in white population.
• No seasonal clustering.

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Pathophysiology

• Most common acquired demyelinating neuropathy.
• Inflammation and deterioration of peripheral
  nervous system.
• Decreased ability of the neurons to transmit
  impulses to the muscles.
• Paralysis.

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Neurilemma

• The outer membrane of the Schwann cells is called
  the neurilemma.
• Neurilemma is essential for regeneration of cut
  and injured axons.
• Axons in the brain and spinal cord have no
  neurilemma and therefore cannot regenerate.

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Clinical Manifestations

• Progressive ascending skeletal muscle paralysis.
  
• Ground to brain (G-B).
• Tingling sensation and numbness.
• Paresthesia
• Loss of deep tendon reflexes.
• Sensory nerve impairment.
• Peripheral facial weakness.
• Decreased gag reflex.
• Decreased ability to swallow.
• Dysphagia

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Symptoms

• Fever
• Malaise
• Nausea prostration.
• Tingling or numbness in extremities.
• Feet/legs affected first.
• Paralysis and loss of reflexes.

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Ventilatory Failure

• Mucous Accumulation
• Airway Obstruction
• Alveolar Consolidation
• Atelectasis

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Progression of the Disease

• Paralysis peaks in less than 10 days.
• Progression of the paralysis may stop at any
  point.
• As paralysis reaches its maximum, it usually
  remains unchanged for a few days to weeks.

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Clinical Manifestations

• ABG
• Acute ventilatory failure with hypoxemia.
• Cyanosis
• PFT
• Restrictive lung disease.
• Decreased volumes.
• Breath Sounds decreased.

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Diagnosis

• Neurological symptoms.
• Cerebral Spinal Fluid.
• Increased protein and normal cell count.
• Electro-diagnostic studies.

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X-ray

• Normal.
• If atelectasis is present
• Radiopaque or radiodense (white).

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Autonomic Nervous System Dysfunction

• Develops in 50 of cases
• Sympathetic
• Parasympathetic
• Loss of bowel and bladder sphincter control may
  occur

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Management

• Oxygen
• Frequent monitoring of pulmonary function
  parameters.
• Vital capacity
• NIF or MIP MEP
• Frequent monitoring of PO and ABG.
• Mechanical ventilation
• Ventilatory Respiratory Failure.
• Tracheostomy

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Management

• Hyperinflation Protocol.
• Bronchial Hygiene Protocol.
• Risk of thromboembolic events
• Subcutaneous heparin.
• Elastic stockings.
• Passive range of motion exercises.
• Management of bedsores
• Frequent turning.
• Monitor for Pneumonia (infection).

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Management

• Urinary catheterization.
• Treat cardiac dysrhythmias.
• Plasmapheresis
• Withdraw blood.
• Separate out the plasma discard.
• Re-infuse the cells with fresh frozen plasma.
• Decreases the antibodies.
• Total of five exchanges of 3 L each over 8-10
  days.
• Steroid Therapy is controversial.

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Pulmonary Function Monitoring

• Mechanical Ventilation is indicated if
• If VC decreases to 10 - 15 cc/kg or less.
• NIF (MIP) is 20 cm H20 or lower.
• f increases above 30/min.

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Prognosis

• Spontaneous recovery is expected in 85-95 of
  cases.
• Improvement may take weeks or months.
• 30 of adults have residual weakness at 3 years.

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Myasthenia Gravis
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Definition

• A disease characterized by episodic muscle
  weakness caused by loss or dysfunction of
  acetylcholine receptors.
• Chronic disorder.
• Axon and receptor site of the voluntary muscle.
• Periods of fatigue with improvement following
  rest.

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Etiology

• Circulating anti-ACh receptor antibodies disrupt
  the chemical transmission of ACh.
• Blocking the ACh from the receptor site.
• Accelerating the breakdown of ACh.
• Destroying the receptor sites.
• Thymus gland is abnormal
• Antibodies thought to come from the thymus gland.

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Etiology

• Twice as common in women.
• Peak age of onset for females is 15 to 35 years.
• Peak age of onset for males is 40 to 70 yrs.
• Signs/symptoms are provoked by
• Emotional upset.
• Physical stress.
• Exposure to extreme temperature changes.
• Febrile illness.
• Pregnancy.
• Death is possible but incidence of deaths decline
  after 10 years.

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Anatomic Alterations

• Isolated groups of muscles (eyelids).
• Generalized muscle weakness
• May include the diaphragm.
• Ventilatory Failure.

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Clinical Findings

• Weakness of striated muscle
• Eye muscles (ptosis).
• Extraocular muscles (diplopia).
• Muscles of the lower portion of the face (speech
  impairment).
• Chewing and swallowing muscles (dysphagia).
• Muscles of the arms and legs.

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Clinical Findings

• Descending paralysis.
• Mind to Ground (MG)
• Gradual onset.
• First symptoms.
• Drooping of the eyelids.
• If only the eyes are involved than it is referred
  to as Ocular Myasthenia.

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Clinical Findings

• Generalized skeletal muscle disorder
• Muscles of neck and face.
• Unable to chew and swallow.
• Aspiration
• Unable to speak clearly.
• Weakness of neck muscles causes the patients head
  to fall forward.

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Clinical Findings

• Weakness of arms and legs results in difficulty
  in
• Climbing stairs.
• Lifting objects.
• Maintaining balance.
• Walking.
• Hand cannot lift to the mouth.

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Clinical Findings

• Pain is rare.
• Tendon reflexes remain intact.
• Patient may demonstrate normal health for weeks
  and months at a time.
• May only show signs of weakness late in the day
  or at night (exhaustion).
• Develop a sudden and transient generalized muscle
  weakness that includes the diaphragm.

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Clinical Findings

• If ventilatory failure is handled properly the
  chest x-ray findings should be normal.
• If improperly managed
• Alveolar consolidation
• Atelectasis
• Excessive secretions

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ABG

• Acute ventilatory failure with hypoxemia
• Decreased pH
• Increased PaCO2,
• Decreased PaO2
• Hypoxemia secondary to hypoventilation

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Clinical Findings

• Pulmonary Functions
• Decreased volumes.
• Cyanosis
• Diminished BS
• X-ray
• Normal or radiopaque (white) if atelectasis is
  present.

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Diagnosis

• Clinical history.
• Clinical response to an IV injection of
  edrophonium chloride (Tensilon).
• Tensilon Test
• Tensilon is an anticholinesterase.
• Electrophysiological tests (EMG).
• Circulating antibody levels in the blood.
• Enlarged Thymus gland.

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Thymus Gland

• Manufacture T-lymphocytes.

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Management

• Patients may live a normal life span.
• Exacerbation
• Oxygen
• Frequent monitoring of VC and NIF.
• Frequent monitoring of BP and SpO2.
• Frequent monitoring of ABG.
• Mechanical ventilation.

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Management of MG

• Anticholinesterase Drugs
• Edrophonium Chloride (Tensilon)
• Neostigmine (Prostigmine)
• Pyridostigmine (Mestinon)
• Steroid Therapy
• Prednisone
• ACTH therapy

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Management of MG

• Thymectomy
• Useful in young adult females
• Plasmapheresis
• Bronchial hygiene
• Hyperinflation protocol
• Atelectasis

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Myasthenia Crisis vs.Cholinergic Crisis

• Myasthenia Crisis
• Exacerbation of the disease.
• Muscle strength improves after Tensilon Test.
• Increase dosage of anticholinesterase agents.
• Cholinergic Crisis
• Too much anticholinesterase drugs.
• No muscle strength noted after Tensilon.
• Stop or decrease dosage of anticholinesterase
  agents and give atropine.
• MEDICAL EMERGENCY

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SPINAL CORD INJURY
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Spinal Nerves

• 31 Pair
• 8 Cervical
• 12 Thoracic
• 5 Lumbar
• 5 Sacrospinal
• 1 Coccygeal

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Spinal Cord Injury

• High neck fractures (above C3).
• Apnea.
• All respiratory muscles are affected.
• Mechanical ventilation/Tracheostomy.
• Injury to C3-C8 is a quadriplegic but retains
  some use of respiratory muscles.
• Night-time mechanical ventilation.
• Injury below C8.
• Cough weak and ineffective secretion removal .
• Loss of function of abdominal muscles.

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Amyotrophic Lateral Sclerosis
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Lou Gehrigs Disease

• Anterior Horn Cells.
• Weakness of hands and less often in the feet.
• The site of onset is random, and progression is
  asymmetric.
• Dysarthria and dysphagia are due to involvement
  of brain stem nuclei and pathways.
• Sensory systems, voluntary eye movements, and
  urinary sphincters are spared.
• Rarely, a patient survives 30 years
• 50 die within 3 years of onset.
• 20 live 5 years.
• 10 live 10 years.

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• ALS can strike anyone.
• Male or female
• Any ethnic origin
• At any age
• Some have been diagnosed as teens
• Usual onset is in middle age
• http//www.alsa.org/