Poliomyelitis
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Definition
An Acute viral infectious disease.
Transmitted by person to person contact through faeco-oral route or oro-oral route.
Incubation period-6 to 20 days.
Infectious 7-10 days before appearance of symptoms and as long as virus is in saliva or faeces.
Factors that increase the risk and severity of the infection disease:
Immune deficiency
Malnutrition
Tonsillectomy
Physical activity immediately following the onset of paralysis
Skeletal muscle injury due to injection ofvaccines or therapeutic agents
Pregnancy
Outcomes of poliovirus infection
Asymptomatic
Minor illness
Non-paralytic aseptic meningitis
Paralytic poliomyelitis
Spinal polio 79%
Bulbospinal polio
Bulbar polio
Minor Illness
Upper respiratory tract infection.
Gastro-intestinal disturbances.
Influenza like illness.
CNS Involvement
Non paralytic Aseptic Meningitis
Paralytic
Encephalitis -confusion,headache,fever,fits,
spastic paralysis.
Pathophysiology
Through Mouth to pharynx and intestinal mucosa. Replication in intestinal lymphoid cells-- deep cervical and mesentericlymph nodes.
Sustained replication in Reticulo Endothelial System, muscle ,fat → Major viremia.
CNS invasion---local inflammatory response.
Poliovirus spreads along nerve fibers
Viral invasion of the motor neurons of the anterior horn cells, or the ventral gray matter section in the spinal column, which are responsible for movement of the muscles, including those of the trunk, limbs and the intercostal muscles.
Destroys motor neurones within spinal cord, brainstem or motor cortex.
Lesions in spinal ganglia, also vestibular nuclei, cerebellar vermis, deep cerebellar nuclei, hypothalamus and thalamus.
Early symptoms
High fever, headache, stiffness in the back and neck
Asymmetrical weakness of various muscles
Sensitivity to touch
Difficulty in swallowing
Muscle pain
Loss of superficial and deep reflexes
Paraesthesia (pins andneedles)
Irritability
constipation
Difficulty urinating.
Paralytic polio
Incidence and extent increase with age of the child
Non-paralytic meningitis most likely
Consequent paralysis - only 1 in 1000 cases.
In adults, paralysis -1 in 75 cases .
In children < 5yrs, paralysis of one leg is most common; in adults, extensive paralysis of the chest and abdomen and quadriplegia is more likely.
Highest rates of paralysis (1 in 200) associated with poliovirus type 1, the lowest rates (1 in 2,000) associated with type 2.
The muscles atrophy (weak, floppy and poorlycontrolled)
Progression to maximum paralysis rapid(2 to 4 days),
Associated with fever and muscle pain
Deep tendon reflexes -usually absent or diminished
Sensation -not affected .
Asymmetrical paralysis -Any limb or combination of limbs may be affected
Bulbar polio
The bulbar region is a white matter pathway that connects the cerebral cortex to the brain stem
Destruction of the neurones there affects the muscles supplied by the cranial nerves
Encephalitis symptoms: difficulty in breathing, speaking and swallowing .
Nerves affected in bulbar polio : Glossopharyngeal nerve,Vagus nerve,Accessory nerve
Trigeminal nerve and facial nerve -the cheeks, tear ducts, gums,
and muscles of the face, double vision; difficulty in chewing;
abnormal respiratory rate, depth, and rhythm--respiratory arrest.
Pulmonary edema and shock also possible, and may be fatal .
Bulbospinal polio
Cervical spinal cord(C3-C5) - paralysis of the diaphragm occurs. Nerves affected are the phrenic nerve, - Breathing Affected-ventilator needed.
Paralysis of the arms and legs and heart functions
Complications
Skeletal Deformities-Equinus Foot,
Scoliosis .Osteoporesis ,Increased bone fractures.
Neuropathy.
Pulmonary edema, Aspiration pneumonia,
UTI, Renal stones,
Paralytic ileus
Myocarditis, Cor pulmonale.
Treatment
NO CURE
SUPPORTIVE MEASURES ONLY
1. Relief of symptoms-Analgesics,Antibiotics
2. Speeding recovery by rest
3. Prevent complications-
4. Nutritious diet.
5. Prevention by OPV (oral polio vaccine)
Prognosis
Minor illness - complete recovery
Aseptic meningitis -2-10 days
Spinal paralysis-rarely fatal.
Recovery - 4-6 weeks up to 6-8 months.
After 1year-Permanent paralysis.
50% complete recovery, 25% mild
