Neuromuscular Disorders

1. Neuromuscular Disorders Guillain-Barré Syndrome - Chapter 30 Myasthenia Gravis – Chapter 31

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

3. Guillain-Barré Syndrome

4. 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

5. 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.

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

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

8. 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.

12. 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.

13. 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

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

15. Ventilatory Failure • Mucous Accumulation • Airway Obstruction • Alveolar Consolidation • Atelectasis

16. 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.

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

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

19. X-ray • Normal. • If atelectasis is present: • Radiopaque or radiodense (white).

20. Autonomic Nervous System Dysfunction • Develops in 50% of cases • Sympathetic • Parasympathetic • Loss of bowel and bladder sphincter control may occur

21. 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

22. 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).

23. 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.

24. 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.

25. 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.

26. Myasthenia Gravis

27. 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.

28. 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.

29. 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.

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

32. 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.

33. 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.

34. 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.

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

36. 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.

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

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

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

40. 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.

41. Thymus Gland • Manufacture T-lymphocytes.

42. 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.

43. Management of MG • Anticholinesterase Drugs • Edrophonium Chloride (Tensilon) • Neostigmine (Prostigmine) • Pyridostigmine (Mestinon) • Steroid Therapy • Prednisone • ACTH therapy

44. Management of MG • Thymectomy • Useful in young adult females • Plasmapheresis • Bronchial hygiene • Hyperinflation protocol • Atelectasis

45. 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

46. SPINAL CORD INJURY

47. Spinal Nerves • 31 Pair • 8 Cervical • 12 Thoracic • 5 Lumbar • 5 Sacrospinal • 1 Coccygeal

48. 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.

49. Amyotrophic Lateral Sclerosis

50. Lou Gehrig’s 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.