Continuing Education Activity
Poliomyelitis (polio) is a viral disease that can range in severity from self-limiting disease to meningitis. In its most severe form, it may present as acute flaccid paralysis. Polio has the potential to severely damage motor neurons leading to a lifetime of muscular dysfunction or even death if the respiratory function is affected. To avoid such a disability, the vaccine must be administered as primary prevention. This activity reviews the diagnosis, prevention, treatment, and complications associated with this condition and the care of the interprofessional team.
- Summarize the epidemiology of poliomyelitis.
- Explain the common physical exam findings of those with poliomyelitis.
- Identify complications of poliomyelitis.
- Explain the importance of improving care coordination amongst the interprofessional team to improve outcomes for patients with poliomyelitis and post-polio syndrome.
Poliomyelitis is an infectious disease transmitted by fecal-oral contamination with lymphatic replication. Before global health efforts, polio caused widespread morbidity and mortality in children during multiple epidemics between 1900-1950. Due to worldwide vaccination efforts that began in the 1980s, poliomyelitis is now considered almost completely eradicated. This disease primarily impacts developing countries with poor sanitation. Healthcare providers in endemic regions should have a high suspicion of polio in patients with viral prodrome symptoms and new-onset paralysis. Consider early serologic testing because this disease can cause static flaccid paralysis in a minority of those infected if undetected. Post-polio syndrome (PPS) is a progressive syndrome of muscular weakness that may occur later in life. In light of the recent increase in polio-like illnesses in the US, it is important to correctly differentiate between poliomyelitis and other viruses such as Enterovirus D68.
Poliovirus, the virus causing both acute polio and PPS, is a member of the Picornaviridae family and species Enterovirus C. There are three serotypes of wild Poliovirus: Poliovirus 1, 2, and 3. Wild type 1 poliovirus was the primary cause of the majority of the world’s paralytic polio cases until vaccines became widespread. Wild types 2 and 3 are considered eradicated as of 2015.
There are cases of paralytic poliomyelitis due to a loss of viral attenuation in the oral polio vaccine (OPV), known as vaccine-associated paralytic poliovirus (VAPP). VAPP is extremely rare, occurring approximately 3.8 times per million cases in countries using the oral poliovirus vaccine. It is associated with serotype 3 and patient immunodeficiency. It is theorized that circulating maternal antibodies and the timing of the first OPV dose affect the risk of developing VAPP.
Another potential paralytic poliomyelitis is known as vaccine-derived poliomyelitis. This is caused by mutations of the attenuated virus within the OPV, which can lead to increased virulence and allow for naturally selective proliferation in populations with low herd immunity. Due to this risk, there has been a worldwide movement to increase the use of inactivated polio vaccine (IPV) and remove attenuated type 2 Polio within the OPV formulation to create a bivalent OPV (containing only types 1 and 3). In the United States, IPV is the only vaccine available, with the CDC recommending a 4-dose schedule. (see Treatment/Management)
Before global health initiatives, nearly 1 in 200 with poliomyelitis developed permanent paralysis. There were 350,000 cases of endemic poliomyelitis spread across 125 countries in 1988. However, in that same year, the World Health Assembly set goals for the complete eradication of wild-type polio. Since then, type 1 is the only wild type still circulating and is endemic only in Pakistan and Afghanistan. There are recent cases of type 2 polioviruses derived from oral vaccines that are also increasing in sub-Saharan Africa and parts of Asia. Some barriers to complete eradication include poor program compliance and access to healthcare in remote endemic areas. Routine childhood vaccine administration has been successful against the spread of the disease on a global scale, with a 99% reduction in cases from the earlier stated 350,000 in 1988, to just 33 in 2018.
Poliovirus is primarily spread via fecal-oral contamination, but oral-oral spread is also possible. Primary infection can lead to viral replication in oropharyngeal and gastrointestinal lymphatic tissues. Maximum viral excretion begins 2 to 3 days before symptoms start and continue for an additional one week. In up to 95% of cases, infections are non-paralytic, presenting as a flu-like illness. In approximately 5% of cases, pure motor paralysis can occur.
The spread of the virus to the CNS is poorly understood. If this does occur, the virus may cause anterior horn neuronal death resulting in a physical exam consistent with intact sensation and pure motor deficits.
Enlarged motor neurons are characteristic but not pathognomonic of poliovirus. In the muscle fibers affected by acute poliomyelitis, the original innervating neurons are destroyed. Neighboring neurons attempt to reinnervate the denervated tissue. This leaves the surrounding motor units innervating more muscle fibers than intended, enlargement of the affected neuron, and is suspected to be part of the fatigue associated with PPS later in life.
History and Physical
On patient evaluation, a pure motor deficit (sensation intact) alongside a viral prodrome is potential evidence of paralytic poliomyelitis. Clinically, the prodrome may consist of headaches, myalgias, fatigue, nausea, neck stiffness, or pharyngitis. Up to 95% of poliovirus infections present as this constellation of symptoms and remain non-paralytic. In infections that progress into the spinal cord, severe muscle spasms with myalgias typically present before an asymmetrical flaccid paralysis. The paralysis tends to have a lower limb predominance. Acute flaccid myelitis (AFM) with viral prodrome can also be caused by other viral infections (see differential diagnosis). It is important to note that most other enterovirus-related AFMs have an upper extremity predilection.
Poliomyelitis can present in stages, such as the acute stage, recovery stage, and residual-paralysis stage. The acute stage is mainly comprised of features, such as fever, neck stiffness, profound muscular weakness, paraparesis, and autonomic dysfunction. In the convalescent or recovery stage, the acute features disappear, and the recovery of paralyzed muscles begins. This stage can last up to two years. In the last stage, the patient is left with residual paralysis, imbalance of muscle power, and poor posture.
Providers should have a high suspicion of viral meningitis when acute flaccid paralysis is present. Testing should include blood, CSF, respiratory, stool tests, EMG, and brain/spinal cord MRI to rule out other pathologies. Regarding Post-Polio Syndrome, there are no definitive biomarkers widely accepted; thus, diagnosis is made by exclusion. There is currently early research of potential biomarkers of PPS in the CSF using PCR.
Treatment / Management
Supportive care is the mainstay of treatment since there are no approved antiviral medications for poliomyelitis. In patients affected by paralytic polio, most do not regain full strength. The more severe the acute disease is, the greater the likelihood of residual deficits and the development of PPS in the future.
Polio immunity is likely accomplished with the administration of inactivated polio vaccine (IPV) or live-attenuated oral polio vaccine (OPV, Sabin). In developing countries, the OPV is still used primarily because of cost. However, due to the increased possibility of Vaccine-Associated Paralytic Poliovirus (VAPP) with its use, IPV is preferred in most vaccination schedules. The OPV formulation is changing to remove type 2 to reduce the chance of strain mutations, as type 2 is the most common strain of VAPP. Type 2 is being phased out because its wild type has been eradicated as of 1999, yet it continues to cause outbreaks in countries previously completely free of polio. In the United States, IPV is the only vaccine available. Children typically receive 4 doses of IPV at 2 and 4 months, then between 6 and 18 months, followed by a booster between 4 and 6 years of age. This vaccine schedule confers greater than 95% efficacy.
The release of joint contractures is also an important management step. Many surgical interventions can be taken into account to reestablish balance in the muscles around the joint to prevent deformities. Surgical management aims to get the patient walking and correct factors that will lead to deformity with age.
In the acute stage, treatment involves general supportive measures for fever and irritation, preventing respiratory tract infections, and managing any respiratory paralysis. The paralyzed legs are supported by splints to relieve pain and spasm. It also plays an imperative role in the prevention of the development of deformities.
In the convalescent stage, the goal should be to achieve an acceptable physical status for the patients to be integrated into their communities. Nonfatiguing exercise programs are the most appropriate to deal with muscle overuse weakness.
Orthoses are helpful in the conservative and definitive treatment of many deformities, and they are available for all parts of the body.
Other enteroviruses can cause acute flaccid paralysis, including enterovirus A71, D68, and coxsackievirus A. Other viruses that may present similarly are West Nile, Herpes Zoster, Japanese Encephalitis, and Rabies. Syndromes such as Guillain-Barré should also be ruled out.
Non-infectious considerations include spinal cord infarctions, acquired axonal neuropathies, myasthenia gravis, Lambert-Eaton myasthenic syndrome, or rhabdomyolysis. Clinical clues such as injury to an affected limb compared to prodromal illness will help to differentiate between diagnoses.
The presentation of polio is highly variable, ranging from viral symptoms without paralysis to quadriplegia and even respiratory failure. Polio patients who present with only viral prodromes are likely to see complete resolution of symptoms. For those that experience acute paralysis, the degree of paralysis often remains static. Approximately 30% to 40% of polio patients will develop post-polio syndrome decades after the primary infection. This progression is multifactorial and depends on factors like severity of acute paralysis, age of onset, and even socioeconomic status.
The greatest complications of polio infection include paralysis with bulbar involvement, fatal respiratory, cardiovascular collapse, and PPS. PPS is characterized by new-onset or progressive muscle weakness in a patient previously diagnosed with poliomyelitis. Conservative estimates are that up to 30 to 40% of the 15 to 20 million known polio survivors worldwide develop some form of PPS. The classic symptom is new or progressive muscle weakness decades after the acute infection. Other symptoms include myalgias, respiratory distress, joint pain, atrophy, dysphagia, and generalized fatigue. The exact pathophysiology of PPS is unknown. It is believed to result from the overuse of remaining motor units, inflammatory changes in CNS, or deteriorating neuromuscular junctions. Complications of this syndrome include respiratory failure, fractures, or failure to thrive.
Postoperative and Rehabilitation Care
With 60-80% of patients with a past diagnosis of polio reporting at least 1 fall in the past year, rehabilitation and a strong interdisciplinary team are integral. Tailored physical therapy, aquatic therapy, endurance training, and pain control are priorities of PPS treatment. Fitted orthoses can mitigate gait disturbances. Potential orthopedic surgery may be warranted to correct deformities and muscle imbalances. Tricyclic antidepressants are effective against fatigue associated with PPS. There is high variability in the PPS presentation, and each must be carefully considered when beginning treatment plans.
Deterrence and Patient Education
Patients must be educated on how to avoid transmission with proper hygiene and prevention through vaccination efforts. As more communities worldwide oppose vaccinations, informing the public on the potentially deadly and disabling side effects of not receiving the polio vaccine can make an impact. The Global Polio Eradication Initiative partners with the World Health Organization, US Centers for Disease Control, Rotary International, United Nations Children’s Fund, and the Bill & Melinda Gates Foundation to work for a polio-free world. They have laid out a Polio Endgame Strategy with the following key components:
- Routine immunization
- Goal of >80% vaccination of all children in the first year of life
- At least three doses of OPV (or IPV per current CDC recommendations) as part of the national immunization schedule
- Supplementary immunization
- Mass immunization campaigns are known as National Immunization Days
- 2 rounds, 1 month apart from each other
- Immunize all children under 5 regardless of immunization status with two doses of OPV
- Finding all cases of children with acute flaccid paralysis
- Stool sample analysis transport
- Isolating the virus in laboratories
- Mapping the virus/tracking outbreaks
- Targeted “mop-up” campaigns
- Door-to-door campaigns in targeted areas of known polio infections or suspected areas.
Enhancing Healthcare Team Outcomes
With an effective vaccine schedule in place, poliomyelitis is often a forgotten-about disease, but we must recognize that polio is still endemic in Pakistan and Afghanistan. With the growing number of communities against vaccinations in developed countries, there is still a great deal of patient education to complete. Furthermore, the recognition and treatment of post-polio syndrome will need further discussion with improved testing capabilities in the future.
Therefore, a comprehensive interprofessional approach to polio prevention and management is necessary, utilizing an interprofessional team approach that involves clinicians, mid-level practitioners, nurses, and pharmacists, all working collaboratively and delivering a consistent message to the patient/patient's parents regarding vaccination schedules, the importance fo hygiene, and working to treat the disease when it makes an appearance in accordance with best practices. This interprofessional approach to managing polio vaccine scheduling and preventing this disease will result in individual patients and provide societal health benefits. [Level 5]