Poliomyelitis
(Redirected from Poliovirus)
Background
- Neurotropic enterovirus
- Extremely rare in developed world, targeted for global eradication by WHO
- Still endemic in Pakistan, Afghanistan, and Nigeria
- Fecal-oral transmission, virus enters through GI tract then reproduces in GI lymphoid tissues
- If virus reaches critical concentration, can spread to motor nuclei of spinal cord, brainstem, and reticular formation → loss of infected neurons→ cycle of muscle denervation/reinnervation→ loss of muscle function
Clinical Features
- >90% of infections are asymptomatic
- Minor (abortive) polio:
- Non-paralytic polio:
- Paralytic (spinal) polio (~1-2% of polio infections)
- Neuro symptoms may manifest after resolution of initial febrile illness
- Maximal paralysis at around 5 days, muscle wasting after several weeks, with most patients' paralysis resolving after about 1 year
- Flaccid muscle weakness/paralysis
- Fasciculations
- Absent or decreased reflexes
- Autonomic dysfunction (e.g. sweating disturbances, urinary retention, constipation
- Neuropathic pain, paresthesias, though usually no sensory deficits on exam
- Bulbar dysfunction in about 20% of spinal polio (dysphagia, dysarthria, facial weakness)
- Encephalitis: can cause reticular formation disturbances, resulting in dysrhythmias, BP lability, hypoxia, and hypercarbia
- Post-polio syndrome
- Occurs sometime after complete resolution of initial acute symptoms
- Can involve same muscle groups affected during patient's acute illness, as well as those not affected during initial viral infection
- Symptoms include muscle weakness, atrophy, fasciculations, fatigue, insomnia, joint pain, bulbar dysfunction, respiratory dysfunction
Differential Diagnosis
Weakness
- Neuromuscular weakness
- Upper motor neuron:
- CVA
- Hemorrhagic stroke
- Multiple sclerosis
- Amyotrophic Lateral Sclerosis (ALS) (upper and lower motor neuron)
- Lower motor neuron:
- Spinal and bulbar muscular atrophy (Kennedy's syndrome)
- Spinal cord disease:
- Infection (Epidural abscess)
- Infarction/ischemia
- Trauma (Spinal Cord Syndromes)
- Inflammation (Transverse Myelitis)
- Degenerative (Spinal muscular atrophy)
- Tumor
- Peripheral nerve disease:
- Neuromuscular junction disease:
- Muscle disease:
- Rhabdomyolysis
- Dermatomyositis
- Polymyositis
- Alcoholic myopathy
- Upper motor neuron:
- Non-neuromuscular weakness
- Can't miss diagnoses:
- ACS
- Arrhythmia/Syncope
- Severe infection/Sepsis
- Hypoglycemia
- Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
- Respiratory failure
- Emergent Diagnoses:
- Symptomatic Anemia
- Severe dehydration
- Hypothyroidism
- Polypharmacy
- Malignancy
- Aortic disease - occlusion, stenosis, dissection
- Other causes of weakness and paralysis
- Acute intermittent porphyria (ascending weakness)
- Can't miss diagnoses:
Evaluation
- Evaluate for other causes of symptoms
- PCR: virus can be identified in throat washings (early), CSF (early), and stool/rectal swab (highest yield)
- CSF: Pleocytosis (PMN predominance initially, then mostly lymphocytes), usually ~normal opening pressure, protein, and glucose.
Management
- Protect airway, support respiration if bulbar or respiratory muscle weakness
- Supportive care, symptomatic treatment
Disposition
- Admit