Post-polio syndrome
Post-polio syndrome | |
---|---|
Other names | Post-poliomyelitis syndrome, Post-polio sequelae |
Science fiction writer Arthur C. Clarke developed post-polio syndrome in 1988 after initially contracting polio in 1962.[1] | |
Specialty | Infectious diseases |
Post-polio syndrome (PPS, poliomyelitis sequelae) is a group of
The precise mechanism that causes PPS is unknown. It shares many features with
Signs and symptoms
After a period of prolonged stability, individuals who had been infected and recovered from polio begin to experience new signs and symptoms, characterised by
Increased activity during healthy years between the original infection and onset of PPS can amplify the symptoms. Thus, contracting polio at a young age can result in particularly disabling PPS symptoms.[5]
A possible early occurring and long-lasting sign is a slight jitter exhibited in handwriting.[citation needed]
Mechanism
Numerous theories have been proposed to explain post-polio syndrome. Despite this, no absolutely defined causes of PPS are known. The most widely accepted theory of the mechanism behind the disorder is "neural fatigue". A motor unit is a nerve cell (or neuron) and the muscle fibers it activates.
The neural fatigue theory proposes that the enlargement of the motor neuron fibers places added metabolic stress on the nerve cell body to nourish the additional fibers. After years of use, this stress may be more than the neuron can handle, leading to the gradual deterioration of the sprouted fibers, and eventually, the neuron itself. This causes muscle weakness and paralysis. Restoration of nerve function may occur in some fibers a second time, but eventually, nerve terminals malfunction and permanent weakness occurs.[3] When these neurons no longer carry on sprouting, fatigue occurs due to the increasing metabolic demand of the nervous system.[6] The normal aging process also may play a role. Denervation and reinnervation are going on, but the reinnervation process has an upper limit where the reinnervation cannot compensate for the ongoing denervation, and loss of motor units takes place.[7] What disturbs the denervation-reinnervation equilibrium and causes peripheral denervation, though, is still unclear. With age, most people experience a decrease in the number of spinal motor neurons. Because polio survivors have already lost a considerable number of motor neurons, further age-related loss of neurons may contribute substantially to new muscle weakness. The overuse and underuse of muscles also may contribute to muscle weakness.[8]
Another theory is that people who have recovered from polio lose remaining healthy neurons at a faster rate than normal. However, little evidence exists to support this idea.
Diagnosis
Diagnosis of PPS can be difficult, since the symptoms are hard to separate from complications due to the original polio infection, and from the normal infirmities of aging. No laboratory test for post-polio syndrome is known, nor are any other specific diagnostic criteria. Three important criteria are recognized, including previous diagnosis of polio, long interval after recovery, and gradual onset of weakness.[10]
In general, PPS is a diagnosis of exclusion whereby other possible causes of the symptoms are eliminated.
Management
PPS treatment concerns comfort (relieving pain via
Medications for fatigue, such as amantadine and pyridostigmine, are ineffective in the management of PPS.[12] Muscle strength and endurance training are more important in managing the symptoms of PPS than the ability to perform enduring aerobic activity. Management should focus on treatments such as hydrotherapy and developing other routines that encourage strength, but do not affect fatigue levels.[6] A recent trend toward use of intravenous immunoglobulin, which had yielded promising albeit modest results,[13] but as of 2010[update] proves insufficient to recommend as a treatment.[12]
PPS increasingly stresses the musculoskeletal system from progressive muscular atrophy. In a review of 539 PPS patients, 80% reported pain in muscles and joints and 87% had fatigue.[14] Joint instability can cause appreciable pain and should be adequately treated with painkillers. Directed activity, such as decreasing mechanical stress with braces and adaptive equipment, is recommended.[4][6]
Because PPS can fatigue facial muscles, as well as cause
Prognosis
In general, PPS is not life-threatening. The major exception is patients left with severe residual respiratory difficulties, who may experience new severe respiratory impairment. Compared to control populations, PPS patients lack any elevation of
No sufficient longitudinal studies have been conducted on the prognosis of PPS, but speculations have been made by several physicians based on experience. Fatigue and mobility usually return to normal over a long period of time. The prognosis also differs depending upon different causes and factors affecting the individual.[5] An overall mortality rate of 25% exists due to possible respiratory paralysis of persons with PPS; otherwise, it is usually not lethal.[16]
Prognosis can be abruptly changed for the worse by the use of anesthesia, such as during surgery.[17]
Epidemiology
Old data show PPS occurs in roughly 25 to 50% of people who survive a polio infection.[18] However, newer data from countries that have contacted their polio survivors have shown 85% of their polio survivors to have symptoms of post polio syndrome.[19] Typically, it occurs 30–35 years afterwards, but delays between 8 and 71 years have been recorded.[20][21] The disease occurs sooner in persons with more severe initial infections.[21] Other factors that increase the risk of PPS include increasing length of time since acute poliovirus infection, presence of permanent residual impairment after recovery from the acute illness,[20][21] and being female.[22] PPS is documented to occur in cases of nonparalytic polio (NPP). One review states late-onset weakness and fatigue occur in 14–42% of NPP patients.[23]
See also
References
- New York Times. Retrieved 19 March 2008.
- ^ a b "Post-polio syndrome: Symptoms". MayoClinic.com. Retrieved 23 February 2009.
- ^ a b c "Post-Polio Syndrome Fact Sheet: National Institute of Neurological Disorders and Stroke (NINDS)". Archived from the original on 29 July 2011. Retrieved 30 December 2008.
- ^ PMID 10904484.
- ^ PMID 15933355.
- ^ PMID 15373379. Archived from the original(PDF) on 7 November 2014. Retrieved 24 December 2008.
- PMID 3007983.
- ^ "Post-polio syndrome: Causes". MayoClinic.com. Retrieved 23 February 2009.
- ^ PMID 16084828.
- ^ "Post-polio syndrome: Tests and diagnosis". MayoClinic.com. Retrieved 23 February 2009.
- ^ ISBN 978-1-56053-606-2.[page needed]
- ^ PMID 25984923.
- PMID 20668713.
- S2CID 23276693.
- S2CID 33885580.
- ISBN 978-0-443-04345-1.
- S2CID 3056696.
- ^ Jubelt, B; J Drucket (1999). Poliomyelitis and the Post-Polio Syndrome in Motor Disorders. Philadelphia: Lippincott Williams and Wilkins. p. 381.
- PMID 15074431.
- ^ PMID 3315237.
- ^ PMID 1442743.
- ^ Atkinson W, Hamborsky J, McIntyre L, Wolfe S (eds.) (2012). "11. Poliomyelitis". Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book) (12th ed.). Washington DC: Public Health Foundation.
{{cite book}}
:|author=
has generic name (help)CS1 maint: multiple names: authors list (link) - PMID 10678596.
Further reading
- Bruno, Richard L. (2002). The Polio Paradox. New York: Warner Books. ISBN 978-0-446-52907-5.
- Maynard, F.M., & Headley, J.H. (Eds.) (1999). Handbook on the Late Effects of Poliomyelitis for Physicians and Survivors. Saint Louis, MO: GINI (now Post-Polio Health International). Information on 90 post-polio topics; a compilation of the research and experience of over 40 experts.
- March of Dimes Birth Defects Foundation. (1999). Identifying Best Practices in Diagnosis & Care. Warm Springs, GA: March of Dimes International Conference on Post-Polio Syndrome
- Nollet F. "Perceived health and physical functioning in postpoliomyelitis syndrome". Vrije Universiteit Amsterdam, 2002.
- Nollet, F. "Post-polio syndrome". Orphanet Ecyclopaedia, 2003
- Silver, Julie K. (2001). Post-Polio Syndrome: A Guide for Polio Survivors and Their Families. New Haven: Yale University Press. (Dr. Silver is medical director, Spaulding-Framingham Outpatient Center; Assistant Professor, Department of Physical Medicine and Rehabilitation, Harvard Medical School.)