863: GBS

Definition of GBS

Acute, autoimmune neuro disorder chracracterized by demyelination and/or axonal damage to peripheral nerves and roots leading to motor neuropathy and flaccid paralysis

GBS risk factors

• 2/3 pts had illness 2 months preceding onset

  • Viral and bacterial

• Surgery and vaccinations also associated w/ onset

Etiology of GBS

• circulating antibodies bind to antigen on surface of myelin and activate macrophages

• Generalized inflamm response in PNS → T cells and macrophages dyemyelinate at nodes of ranvier → followed by repair process

• Lesions occur throughout PNS, spinal nerve roots > distal termination of sensory and motor nerves

• Axonal damage also occurs in most cases

Clinical findings required for diagnosis

• progressive symmetric weakness of > 1 limb

• Areflexia or hyporeflexia

Clinical findings supportive of diagnosis

• <4 weeks progression of symptoms

• Mild sensory dysfunction

• CN involvement

• Impaired autonomic function

• Recovery of S+S

Medical diagnosis

• lumbar puncture CSF: elevated protein

• Electrophysiologic test: dyemyelination seen on EMG

• Tests to rule out other causes of peripheral neuropathy

Differential diagnoses: acute peripheral neuropathies

• toxic

• Drugs

• Alcohol

• Porphyria

• Systemic vasculitis

• Poliomyelitis

• Diphtheria

• Tick paralysis

• Critical illness polyneuropathy

Differential diagnoses: disorder of NM transmission

• botulism

• MG

• CNS disorders

• Basilar artery occulision

• Acute cervical transverse myelitis

Symptoms/ course of disease

• ascending symmetric flaccid paralysis

• Distal sensory symptoms: parenthesis often first symptom

• 50% have CN involvement

• 50% have ANS involvement: tachycardia, cardiac arrhythmia, BP changes, bowel/bladder dysfunction

• 4 weeks for 90% of pts to peak impairment

Factors associated with less favorable prognosis

• older age

• Severe disease indicated by outcome measures

• Rapid disease progress

• On improvement after 3 weeks of plateau

• Preceding diarrheal illness

• Average distal motor response amplitude reduction to 20%

• Need for ventilator support

Factors associated with prolonged length of stay

• lower strength

• Baseline FM

• Muscle belly tenderness

• Axonal damage

Compound motor action potential

Predictor of prognosis

If amplitude <20% of normal limits at 3-5 weeks predicts a prolonged or poor outcome

Medical management: plasmapharesis

• removal of plasma from circulation, filter to remove or dilute circulating antibodies, shown to improve time to independent ambulation

• Treatment effect shown to be more affective within first week

• Dosage

  • 4-6 treatments over 8-10 days, starts working in 2-3 days, takes 3-4 weeks for max result, works better within 7 days of onset

High dose intravenous immunoglobulins

• daily infusions administered within first 2 weeks has been shown to be as affective as plamapharesis with less complications

• Dosage: 5 days

• Side effects: nausea, aseptic meningitis, rash, acute renal failure, hypo viscosity causing stroke

Treatment of symptoms and prevention of complications

DVT, respiratory, dysautonomia, fatigue, pain

Ventilation needed when pulmonary function is compromised by

• loss of respiratory skeletal muscle control

• Coughing and clearing of tracheal secretions becomes difficult

• Weakness of laryngeal and pharyngeal muscles making swallowing difficult and increasing risk of aspiration

Indications of respiratory fatigue

Shallow breathing, staccato speech, dysautonomia, tachycardia/brow sweating, inward abdominal movement with inspiration

Early PT focus is on prevention of complications of immobilization

• position changes

• Skin checks

• Encourage coughing and deep breathing

• Maintenance of PROM vs AAROM vs splinting to prevent contractures/heterotopic ossification

Parenthesia,hyperesthesia may make WB hard

• desensitization

• Gradual WB: tilt table, TENS

Chronic inflammatory demyelinating polyradiculoneuropathy, CIDP

• chronic variant of GBS, tends to develop over course of months but variable course

• Characterized by progressive weakness and impaired sensory function in legs and arms

Etiology of CIDP

• caused by damage to myelin sheath by the pts immune system

• Classic this is idiopathic, but variants can be caused by HIV, diabetes, and neoplastic processes

Diagnosis of CIDP

• electrodiagnostic studies find demyelinating neuropathy affecting multiple nerve segments

• Lumbar puncture shows albuminocytologic dissociation

• MRI may show enlargement of the brachial or lumbosacral plexus and cauda equine nerves

Symptoms/course of CIDP

• typically starts insidiously and evolves slowly or relapsing with partial or complete recovery between recurrences

• Symmetric LE and UE involvement, motor predominant, and affects proximal and distal muscle groups

• Sensory symptoms are usually less severe

• Periods of worsening and improvement

• Duration of symptoms > 8 weeks required for diagnosis

Prognosis of CIDP

• variable some with spontaneous recovery, others with many bouts with partial recovery in between relapses

• Early treatment intervention with improved outcomes