13 - Neuromuscular Dysfunction

respiratory complications of neuromuscular diseases (NMDs)

• ineffective cough

• recurrent pulmonary infections

• ventilatory insufficiency in advanced disease

impact of NMDs on respiratory function

• control of breathing

• respiratory muscle function

• lung and chest wall mechanics

• gas exchange

• sleep

• upper respiratory function (bulbar muscles)

evaluation of respiratory function for NMDs

• clinical history

• physical exam

• ABGs

• PFTs

• radiology: sniff test

assessment of respiratory muscle function

• MIP/MEP

• VC

• maximum voluntary ventilation (MVV)

• transdiaphragmatic pressure

  • gastric pressure − esophageal pressure = diaphragm pressure

upper motor neuron disorders

• stroke

• cervical spinal cord injury

  • C1-C3: paralysis of all respiratory muscles

  • C3-C5: paralysis of diaphragm

  • C5-C6: paralysis of intercostal and abdominal muscles

• Parkinson

• MS

lower motor neuron disorders

• amyotrophic lateral sclerosis (ALS)

  • 20% 5-year survival

• poliomyelitis and post-poliomyelitis muscular dystrophy

• acute flaccid myelitis

peripheral nerve disorders

• phrenic nerve injury

• (poly)neuropathy

• Guillain-Barre syndrome

Guillain-Barre syndrome

autoimmune disease of peripheral nerves

• flaccid paralysis

• ↑immunoglobulins

• demyelination

  • inflammation

  • edema

  • ↓nerve impulse

Guillain-Barre syndrome

• respiratory complications

• possible ventilatory failure

• mucus accumulation

• airway obstruction

• atelectasis

Guillain-Barre syndrome

• risk factors

• viral illness (cytomegalovirus, Epstein-Barr)

• Mycoplasma pneumoniae infection

• flu vaccine

• cancer

• recent surgery

• 12-18 y.o. or > 45 y.o.

• male, white

Guillain-Barre syndrome

• mortality

4-6%

Guillain-Barre syndrome

• morbidity (permanent condition)

5-10%

Guillain-Barre syndrome

• length of recovery

up to 3 years

Guillain-Barre syndrome

• presentation

• symmetrical weakness in lower limbs

• pain in low back, buttocks, legs

• ascending paralysis

• usually peaks in 2 weeks

• absent tendon reflexes

• dysphagia

• 10-30% diaphragmatic paralysis

Guillain-Barre syndrome

• manifestations

• RR varies

• cyanosis

• chest exam

  • diminished breath sounds, crackles, wheezing

• ANS dysfunction

  • BP, HR variable

Guillain-Barre syndrome

• diagnosis

• history, CSF (↑protein), EMG

• PFT

  • restriction, ↓MIP

• ABG

  • acute respiratory failure with hypoxemia

• radiology

  • normal or reduced volumes

Guillain-Barre syndrome

• management

• support vitals

• frequent VC and MIP

  • ventilation when impending failure

    • VC < 20 mL/kg IBW

    • MIP < −25 cmH₂O

    • pH < 7.35 or P_aCO₂ > 45

• prevent DVT

• skin care

• RT protocols

  • O₂, lung expansion, bronchial hygiene

• immune modulation

• steroids

• PT and rehab

disorders of neuromuscular junction

• Lamber-Eaton syndrome (similar to myasthenia gravis)

• botulism (Clostridium botulinum)

• myasthenia gravis

myasthenia gravis

chronic NM junction disorder

• affects acetylcholine receptors (voluntary muscles)

• fatigue and weakness

• no loss of sensory function

myasthenia gravis

• respiratory pathophysiology

• respiratory failure

• mucus accumulation

• airway obstruction

• alveolar consolidation

• atelectasis

myasthenia gravis

• demographics

• young women

• older men

myasthenia gravis

• diagnosis

• history

• neuro exam

• EMG

• blood analysis

• tensilon (edrophonium) test

• ice pack test

• sleep test

• CT/MRI of thymus

myasthenia gravis

• manifestations

• chronic muscle fatigue

  • usually with activity

  • can have remission

• facial weakness (ptosis, diplopia)

• dyspnea, dysphonia, dysphagia

• RR variable

• severe: cyanosis

myasthenia gravis

• clinical findings: chest exam

• diminished breath sounds

• crackles

• wheezing

myasthenia gravis

• PFT

• restrictive pattern

• ↓MIP

myasthenia gravis

• ABG

ventilatory failure with hypoxemia

myasthenia gravis

• radiology

normal or increased opacities

myasthenia gravis

• management

• monitor ventilation, vitals

• anticholinesterase

  • pyridostigmine (Mestion)

• immunosuppressants

• corticosteroids

• thymectomy

• plasmapheresis

myasthenia gravis

• RT protocol

• O₂

• bronchial hygiene

• lung expansion

• MV if severe

inherited myopathies

• Duchenne/Becker muscular dystrophy

  • gender-linked

  • Becker is milder

• myotonic dystrophy (common)

• acid maltase deficiency

  • defect in metabolism

• fascioscapulohumeral muscular dystrophy

• limb-girdle muscular dystrophy

• mitochondrial myopathy

acquired inflammatory myopathies

• systemic lupus erythematosus

• steroid myopathy

goals of NMD treatment

• maintain lung function

• restore independence

• prevent infection

• ensure nutrition

treatment of NMDs

• respiratory muscle training

  • exercise

  • resistance devices

• assisted cough

  • peak cough flow should be < 160 L/min

  • in-/exsufflation

  • quad cough

• glossopharyngeal breathing (frog breathing)

• NIV/MV

  • start early with signs of impending failure

• diaphragmatic pacemaker