GBS is an autoimmune attack on the peripheral nerve myelin, resulting in acute, rapid segmental demyelination of peripheral nerves and some cranial nerves, producing symmetrical ascending weakness (classical) with dyskinesia, hyporeflexia, and paresthesias. An antecedent event, most commonly from viral infection, result in the clinical presentation of 60% to 70% of GBS cases.
- Campylobacter jejuni is implicated in 40% of cases. Cytomegalovirus, Epstein-Barr virus, Mycoplasma pneumoniae, H. influenzae
- Men and women are equally affected at around 1 to 2 in 100,000 people.
- 70% of patients recover, with the remaining 30% becoming disabled to varying degrees. 5% to 10% of cases result in death due to respiratory failure, autonomic dysfunction, sepsis, or pulmonary embolism.
There are various subtypes (clinical presentations) of GBS:
- Ascending GBS: the most common and well known presentation, where patients experience weakness in the legs which progresses upwards and has the potential for respiratory failure.
- Motor GBS: only motor control is lost; sensation is intact.
- Descending GBS: a subtype that mainly affects the head and neck muscles
Pathophysiology
- GBS is the result of cell-mediated humoral immune response that attacks peripheral nerve myelin proteins, which results in inflammatory demyelination.
- The best accepted theory is molecular mimicry, where infectious agents appear as myelin proteins, which the immune system attempts to destroy, which results in an autoimmune disorder.
- The exact location of the peripheral nervous system attacked is the ganglioside GM1b. Macrophages and other immune agents attack myelin and cause inflammation, destruction, and resultant interruption of nerve conduction and axonal loss.
- Recovery after GBS can occur as Schwann cells (myelin producers) and damaged axon bodies can be restored. If axons are damaged, recovery may take months to years, and is often incomplete.
Clinical Manifestations
Demyelination often occurs 1 to 3 weeks before symptoms begin.
- Muscle Weakness, Diminished Reflexes of the Lower Extremities, which may progress to Tetraplegia. This may ascend upwards and plateau (at varying lengths) at respiratory failure. Peak severity takes from 2 weeks to no longer than 4 weeks. If the progress lengthens past 4 weeks, the patient is classified as having chronic inflammatory demyelinating polyneuropathy.
- Neuromuscular Respiratory Failure and Bulbar Weakness may result from damage to the myelin sheath for nerves that innervate the diaphragm and intercostal muscles.
- Sensory Impairment: paresthesias, pain related to demyelination of sensory fibers
- Cranial Nerve Demyelination:
- Cranial Nerve II (Optic): blindness
- Cranial Nerve IX, X (Glossopharyngeal, Vagus): swallowing and clearing secretions is impaired.
- Cranial Nerve X (Vagus): instability of the cardiovascular system; tachycardia, bradycardia, hypertension, orthostatic hypotension.
GBS may be staged according to progression of disease:
- Stage I: lymphocytes migrate through endoneural vessels and surround nerve fibers, but have not done any damage.
- Stage II: segmental demyelination begins.
- Stage III: central chromatolysis of the nerve cell body occurs, muscle begins to develop denervation atrophy.
- Stage IV: extensive axonal destruction, with irreversible damage.
Clinical Presentation is divided between three phases:
- Phase 1: paresthesia
- Phase 2: difficulty in arising from chair
- Phase 3: areflexia, weakness, distal sensory loss
Diagnostic Examination
Diagnosis of GBS is mainly symptomatic.
- Symmetric weakness, diminished reflexes, and history of upward progression of muscle weakness.
- History of viral illness in the previous weeks (1 to 3).
- Changes in vital capacity and negative inspiratory force is during impending neuromuscular respiratory failure.
- CSF Evaluation shows elevated proteins.
- Electrophysiology shows progressive loss of nerve conduction velocity.
Medical Management
- ICU care is required due to rapid progression and risk for neuromuscular respiratory failure. Baseline values are identified and changes in muscle strength and respiratory function can alert the clinician to the needs of the patient.
- Respiratory therapy or mechanical ventilation may be necessary for supporting pulmonary function and oxygenation. These may be weaned off when spontaneous respiration becomes effective.
- Elective intubation may be done prior to extreme respiratory muscle fatigue, as emergent intubation can result in autonomic dysfunction.
- Preventing immobility complications: the use of anticoagulants or sequential compression boots avoid DVTs, VTEs, and PEs.
- Therapeutic Plasma Exchange (Plasmapheresis) and IVIG help reduce peripheral nerve myelin antibody levels, reducing the amount of time the patient remains immobilized and dependent on MV.
- Cardiovascular risks: ECG monitoring is required because of autonomic dysfunction.
- Tachycardia and hypertension are treated with short-acting medications e.g. alpha-adrenergic blocking agents, propranolol. Only short-acting medications are used due to the lability of autonomic dysfunction.
- Hypotension is treated by increasing the volume of IV fluid administration. Bradycardia is treated with atropine.
Nursing Process
Assessment
On-going assessment for disease progression is critical. Life-threatening conditions such as respiratory failure, cardiac arrhythmias, and VTE/DVT/PEs are checked so intervention may be initiated.
- Check individual muscle groups every 2 hours in the acute phase.
- Observe for autonomic dysreflexia.
- Assess for cranial nerve function
- Because of the sudden nature of the disease and its life-threatening complications, assess the patient and family’s coping ability.
Diagnosis
- Impaired breathing associated with rapidly progressive weakness and impending respiratory failure
- Impaired mobility associated with paralysis
- Impaired nutritional intake associated with inability to swallow
- Impaired verbal communication associated with cranial nerve dysfunction
- Anxiety associated with loss of control and paralysis
- Fatigue associated with physical deconditioning and stressors
- (Collaborative) Respiratory Failure
- (Collaborative) Autonomic Dysfunction
Planning, Goals, and Intervention
- Maintaining Respiratory Function: incentive spirometry and CPT; monitor changes in vital capacity and negative inspiratory force. Prepare for MV if vital capacity falls.
- The possible need for an MV should be discussed with the family on admission to give adequate time for decision making and decreasing anxiety. Intubation may be elective when weakness is marked. Read Also: Airway and Ventilatory Management (Burns).
- Bulbar weakness results in impaired airway clearance, which contributes to hypoperfusion. Assess the patient regularly and maintain a clear airway with suctioning if necessary.
- Autonomic Dysfunction may require short-acting medications or a temporary pacemaker for clinically significant bradycardia.
- Enhancing Physical Mobility: prevention of the complications of immobility.
- Paralyzed extremities are supported in functional positions, and passive ROM exercises are performed at least twice a day.
- ROM, Position Changes, Anticoagulation, Antiembolism Stockings, and Sequential Compression Boots, and Adequate Hydration
- Pressure injuries can be prevented by padding bony prominences and frequent repositioning. Adequate nutrition and hydration also help avoid pressure injuries. Check the patient’s laboratory results to identify malnutrition or dehydration.
- Providing Adequate Nutrition: a paralytic ileus may result from inadequate parasympathetic activity. IV fluids and parenteral nutrition may be used until bowel sounds return. Bulbar paralysis may result in an inability to swallow, requiring a gastrotomy tube to be put in place. Oral nutrition is continued once the gag reflex and bowel sounds are back to normal.
- Improving Communication: cognition remains complete intact, but the patient is unable to speak, laugh, or cry. An alternative method for communication needs to be established e.g. the use of picture cards or blinking. Collaboration with a speech therapist may be helpful.
- Decreasing Anxiety: provide education, emphasize positive appraisal, and information about relaxation exercises and distraction techniques. A positive atmosphere from the healthcare team is beneficial. Visitors reduce isolation and loneliness.
- Reducing Fatigue: aid the patient (especially recovering patients) in pacing activities and to incorporate periods of physical and mental rest. Assess the patient’s exertion, sleep quality and duration, and ensure time for self-care and an appropriate diet.
- Monitoring and Managing Potential Complications: regular and thorough respiratory and cardiac assessment, monitoring for embolisms, urinary retention, and other threats to immobilized and paralyzed patients.
Evaluation
- Maintains effective respirations and airway clearance: clear BS, gradual improvement in respiratory function, spontaneous breathing, normal vital capacity, and normal ABG readings.
- Shows increasing mobility: regains the use of extremities, participates in rehabilitation, demonstrates no contractures and minimal muscle atrophy
- Receives adequate nutrition and hydration: consumes diet adequate to meet nutritional needs, and swallows without aspiration.
- Demonstrates recovery of speech: communicates needs, practices exercises recommended by speech therapist
- Shows less anxiety
- Experiences fewer episodes of fatigue: verbalizes plan to reduce fatigue and increase energy, takes rest periods, and identifies priority activities when energy is high.
- Has absence of complications: maintains skin integrity, free from embolus, and voids without difficulty.