Neuromuscular Disorders GuillainBarr Syndrome Chapter 30 Myasthenia Gravis

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

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

Guillain-Barré Syndrome

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

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.

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

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.

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.

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.

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

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

Ventilatory Failure • • Mucous Accumulation Airway Obstruction Alveolar Consolidation Atelectasis

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.

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

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

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

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

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

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).

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.

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

Prognosis • Spontaneous recovery is expected in 8595% of cases. • Improvement may take weeks or months. • 30% of adults have residual weakness at 3 years.

Myasthenia Gravis

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.

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.

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.

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

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.

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.

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.

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

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.

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

ABG • Acute ventilatory failure with hypoxemia • Decreased p. H • Increased Pa. CO 2, • Decreased Pa. O 2 • Hypoxemia secondary to hypoventilation

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

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.

Thymus Gland • Manufacture Tlymphocytes.

Management • Patients may live a normal life span. • Exacerbation: • • • Oxygen Frequent monitoring of VC and NIF. Frequent monitoring of BP and Sp. O 2. Frequent monitoring of ABG. Mechanical ventilation.

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

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

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

SPINAL CORD INJURY

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

Spinal Cord Injury • High neck fractures (above C 3). • Apnea. • All respiratory muscles are affected. • Mechanical ventilation/Tracheostomy. • Injury to C 3 -C 8 is a quadriplegic but retains some use of respiratory muscles. • Night-time mechanical ventilation. • Injury below C 8. • Cough weak and ineffective secretion removal. • Loss of function of abdominal muscles.

Amyotrophic Lateral Sclerosis

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.

• 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/