what internists need to know about postpolio syndrome

704 CLEVELAND CL IN IC JOURNAL OF MEDICINE VOLUME 69 • NUMBER 9 SEPTEMBER 2002

HEN A POLIO SURVIVOR presents withnonspecific symptoms such as weakness

and fatigue, how do you determine whetherthey are due to postpolio syndrome or to anunrelated problem?

Postpolio syndrome is a neurologic disorderdefined by a collection of symptoms occurringdecades after a patient has recovered from aninitial infection with the poliovirus. New mus-cle weakness is the hallmark, but breathing orswallowing problems, fatigue, myalgias, andcold intolerance are frequently also present.

In this review, we discuss the criteria fordiagnosing postpolio syndrome, guidelines forruling out other conditions, and treatmentstrategies to optimize function in postpoliopatients.

■ 1 MILLION POLIO SURVIVORS

There are probably at least 1 million polio sur-vivors in the United States, though not allhave residual effects. Worldwide, there aremillions more. Polio eradication is ongoing,and it is hoped that new cases will be com-pletely eliminated over the next few years.

■ ACUTE POLIOMYELITISMAY BE SUBCLINICAL

Historically and even recently, acutepoliomyelitis has been thought of as havingdistinct presentations:

Abortive polio, which presents as a minorillness of fever, malaise, sore throat, anorexia,myalgias, and headache

Nonparalytic polio, which presents asaseptic meningitis

Paralytic polio, which presents as severeback, neck, and muscle pain, with the rapid or

JULIE K. SILVER, MDMedical Director, Spaulding-Framingham OutpatientCenter, Framingham, Mass; Assistant professor,Department of Physical Medicine and Rehabilitation,Harvard Medical School, Boston, Mass

DOROTHY D. AIELLO, PTSenior physical therapist, Spaulding-FraminghamOutpatient Center, Framingham, Mass

What internists need to knowabout postpolio syndrome

REVIEW

■ ABSTRACT

Decades after recovery from polio, many patients developnew muscle weakness and other symptoms that can lead toincreased debility. Treatment is aimed at the mostprominent symptoms. Medications may help, as well asphysical therapy and a carefully paced exercise program.Screening for osteopenia and osteoporosis isrecommended.

■ KEY POINTS

Postpolio syndrome affects an estimated 60% of“paralytic” polio survivors, plus unknown numbers ofpatients who had subclinical polio.

Postpolio syndrome is a diagnosis of exclusion. Symptomsare related to new muscle weakness and may includemuscle atrophy, myalgias, fatigue, and problems withswallowing and breathing.

No drugs specifically address postpolio syndrome.Pyridostigmine has had mixed results for treating weaknessand fatigue, as have methylphenidate and bromocriptine.Modafinil may be helpful for fatigue. Nonsteroidal anti-inflammatory drugs are used to treat pain.

Rehabilitation professionals who have expertise in treatingpolio survivors can be valuable resources in preservingfunction and preventing deconditioning.

W

CLEVELAND CL IN IC JOURNAL OF MEDICINE VOLUME 69 • NUMBER 9 SEPTEMBER 2002 705

gradual development of paralysis.1In fact, however, the acute viral illness is

probably more of a spectrum, in which thereare subclinical cases of paralysis that in thepast would have been classified as nonparalyt-ic.2 This concept is important becausealthough most patients who are at risk for post-polio syndrome had well-recognized “paralyt-ic” polio, others who were never diagnosedwith polio or were thought to have had “non-paralytic” polio may also be at risk for postpo-lio syndrome.

An estimated 60% of “paralytic” polio sur-vivors are affected by postpolio syndrome.3The prevalence in those who had subclinicalillness is unknown.

■ WHAT CAUSES THE LATE SYMPTOMS?

Postpolio syndrome occurs in polio survivorswho had injury to their central nervous sys-tem, generally the anterior horn cells in thespinal cord, during the initial infection. Thecause of the late symptoms is not well under-stood but is believed to involve attrition ofmotor neurons during aging.4 Other theoriesabound, however, and the etiology is likelymultifactorial.

When motor neurons are lost in acutepolio, the surviving motor neurons sprout col-lateral fibers that reinnervate the denervatedmuscle fibers (FIGURE 1). The resulting motorunits are larger than normal, and there arefewer of them than before. Therefore, the bur-den on each of these remaining motor neuronsis higher than under normal conditions.

With age, we all gradually lose some motorneurons.5 Polio survivors may be more affectedby this loss of motor neurons because theyhave fewer to begin with.

Another theory is that insufficient levelsof acetylcholine are released at the neuromus-cular junction, resulting in diminished musclecontraction.5

Maselli et al6 noted reduced amplitudes ofminiature end plate potentials and structuralabnormalities of the neuromuscular junction,such as reduced diameter of nerve terminals,but these changes were not noted in all post-polio syndrome patients.

Some have found ongoing immune activa-tion and defective viral particles in the spinal

CCF©2002

FIGURE 1

■ What causes postpoliosyndrome? One theory

In acute polio, someneurons die, while others survive

In the stable postpolio period,the surviving neurons cover moreterritory than they did before thepolio by sprouting collateral fibers

In postpolio syndrome, moreneurons are lost by normal attrition,leading to muscle weakness


fluid,7 although the significance of these isunclear.

General fatigue may also have a centralcause—an abnormality in the reticular acti-vating system in the brain that occurred dur-ing the acute polio episode.5,7

■ HALLMARK IS NEW WEAKNESS

The hallmark symptom of postpolio syndromeis new weakness, which may occur in musclesknown to be previously affected or in musclesthat were thought to be normal.3 The patientmay report difficulty with walking or liftingitems, falls, needing more assistance withtransfers (eg, moving from the bed or com-mode to the wheelchair), and being less ableto do functional tasks. The weakness charac-teristically worsens with increased activityand is most pronounced at the end of the day.

Symptoms may also include dyspnea onexertion due to respiratory muscle weakness,other breathing or swallowing problems, pain(myalgias), cold intolerance, and unaccus-tomed fatigue. New muscle atrophy may alsobe present.8

Pain can be due to factors related to thehistory of polio, but which are not classifiableas postpolio syndrome. For example, a patient

may present with left leg paralysis due to theinitial polio and report increased limping andpain in the right hip (ie, the “good” leg). Thenew symptoms may be due to osteoarthritis ofthe hip, which is more likely to occur in apolio survivor without good muscular supportaround the hip and after years of additionalwear and tear.

Postpolio muscle pain classically occurs inthe muscles rather than in the joints. Thepain is often described as aching, cramping,burning, or a “tired” feeling. It frequentlyoccurs at night or after the person has beenvery active.8

Numbness or paresthesias are not typicalsymptoms of postpolio syndrome.

■ DIAGNOSING POSTPOLIO SYNDROME

Postpolio syndrome is a diagnosis of exclusionand should fit specific criteria (TABLE 1).Screening for other possible diagnoses isessential.

Evaluating weaknessIn postpolio syndrome, weakness progressesgradually over months to years. This musclefatigue is associated with overuse and worsenswith increased activity. Rapid loss of strength

Postpoliomuscle painclassicallyoccurs inmuscles ratherthan joints

Criteria for diagnosing postpolio syndromeHistory of old polio, preferably with recent electrodiagnostic findings consistentwith remote anterior horn cell diseaseA period of at least partial recovery from the initial illness and then a long stable period(10–20 years or more)New symptoms consistent with postpolio syndrome that are not attributable to any other medicalcondition; these may include weakness, myalgias, fatigue, swallowing problems, breathing problems,cold intolerance, and muscle atrophy

T A B L E 1

POSTPOLIO SYNDROME SILVER AND AIELLO

Not available for online publication.See print version of the

Cleveland Clinic Journal of Medicine

T A B L E 2


over weeks to months should suggest anotherdiagnosis (TABLE 2).

Evaluating fatigueGeneralized fatigue has many possible causes(TABLE 3) that should be ruled out with screen-ing tests (TABLE 4).

Since sleep disorders are common in poliosurvivors,9,10 referral to a sleep clinic shouldbe considered. In our practice, we often seepatients who feel tired but say they have notrouble sleeping. However, many of them testpositive for sleep disturbances, includingobstructive sleep apnea (characterized bymorning fatigue, snoring, and difficulty sleep-ing supine) and random limb movement dis-order (characterized by morning muscle painand overall fatigue).

Depression, thyroid dysfunction, or bothmay be present as coexisting conditions andalso contribute to fatigue.

Evaluating painPain related to postpolio syndrome is due tomuscle overuse or biomechanical problems, orboth. Treatment of coexisting orthopedicproblems is vital to alleviate pain and improvefunction (TABLE 5).

Evaluating respiratory problemsDifficulty breathing can be life-threatening.Conditions other than postpolio syndromeshould be considered (TABLE 6).

Polio survivors with a weakened dia-phragm breathe shallowly and experience dys-pnea on exertion. New respiratory muscleweakness causes restrictive lung disease, whichis associated with chronic alveolar hypoventi-lation. In obese patients, excess weight overthe thoracic cage and abdominal cavity wors-ens the condition.

Pulmonary function tests can be used fordiagnosis and to determine if supplementaloxygen is necessary. Arterial blood gas mea-surements and pulse oximetry can also helpwith the diagnosis. Referral to a pulmonologistis indicated if a patient requires a respirator.

All polio survivors who undergo surgeryneed special precautions beforehand to avoidpotential problems with respiratory sequelaeand ventilator weaning. These include pul-monary function testing and consideration of





T A B L E 3

T A B L E 4


alternatives to general anesthesia wheneverpossible. Even well-appearing polio survivorscan have significant restrictive lung diseasedue to paralysis of respiratory muscles.

Evaluating swallowing difficultiesSwallowing problems can also be life-threaten-ing. In view of the risk of choking, family mem-bers should be educated in the Heimlichmaneuver. Patients presenting with difficultyswallowing may require specific testing, such asa modified barium swallow, or referral to a spe-cialist for further evaluation and intervention.

■ TREATMENT RECOMMENDATIONS

Treatment of postpolio syndrome should focuson the most prominent symptoms and caninclude:• Medications• Supplemental oxygen

• Physical, occupational, and speech therapy• An exercise program to preserve mobility

and prevent deconditioning.

MedicationsDrug therapy for postpolio syndrome has beengenerally disappointing. No medicationsspecifically address postpolio syndrome. Thatsaid, many medications may play an impor-tant role in alleviating symptoms.

For weakness and fatigue, pyridostig-mine (Mestinon), usually given as an oraldose of 60 mg three times a day, has had some-what mixed results. One study of postpoliosyndrome patients found that it improvedupper extremity subjective strength andfatigue.11 Another found no significant differ-ence between patients taking pyridostigmineand placebo, except that very weak muscles(25% or less of baseline) were minimallystronger with pyridostigmine.12

Methylphenidate hydrochloride (Ritalin)and bromocriptine (Parlodel) have been triedfor postpolio patients with chronic debilitat-ing fatigue, also with mixed results.7,13

Modafinil (Provigil) has been used to treatfatigue14,15 and may be useful in polio survivors.The starting dose is usually 200 mg orally in themorning and may be increased to 400 mg eachmorning or given in divided doses.

Side effects can be a problem with thesemedications. Pyridostigmine’s side effects aregenerally dose-related and can be recalled bythe acronym SLUD (increased salivation,lacrimation, urination, and defecation).Respiratory secretions may also be increasedwith this medication. Modafinil’s side effectsinclude headache, nausea, and nervousness,and modafinil may increase circulating levelsof diazepam, phenytoin, and propranolol.

Respiratory problems often improve withcontinuous positive airway pressure or bilevelpositive airway pressure at night. Oxygen canexacerbate chronic alveolar hypoventilationand should be used with caution. A physicaltherapist or occupational therapist skilled intreating respiratory disorders may be helpful inteaching the patient breathing and posturaltechniques and help the patient conserveenergy to decrease respiratory demands.

Pain can be treated with traditional non-steroidal anti-inflammatory drugs, cyclo-oxy-

Differential diagnosisfor respiratory problems

Cardiac diseaseChronic obstructive pulmonary diseaseAsthmaAnemiaDeconditioning

T A B L E 6


Even well-appearing poliosurvivors canhave restrictivelung disease

Not available for onlinepublication.

See print version of theCleveland Clinic

Journal of Medicine

T A B L E 5


genase-2 inhibitors (particularly in elderlypatients or those with a history of gastroin-testinal problems), and nonnarcotic anal-gesics. Tramadol (Ultram) may be helpful insome patients but should be avoided in thosewith a history of seizures.

Other medications typically used forchronic pain may also be tried, such as tri-cyclic antidepressants and anticonvulsants.Tricyclic antidepressants have cholinergicside effects; the most serious is the possibili-ty of acute urinary retention in men, espe-cially if underlying prostate problems arepresent.

Injections with local anesthetics or corti-costeroids or both may be effective for specificconditions that are often associated with post-polio syndrome, such as myofascial pain,trochanteric bursitis, carpal tunnel syndrome,lateral epicondylitis, or rotator cuff tendonitis.

Physical and occupational therapyFrom a quality-of-life perspective, perhaps themost important thing a physician can do is tohelp patients preserve mobility and avoid fallsand resultant injuries.

Physical and occupational therapists canbe extremely helpful in treating patients withmusculoskeletal pain, weakness, decreasedendurance, impaired balance, and difficultywalking. They can recommend appropriateadaptive equipment, such as shower grab bars,a raised toilet seat, sturdy and lightweightbraces, assistive devices such as canes andcrutches, and footwear modifications such asheel lifts and lateral wedges. Therapists canalso advise patients on how to pace them-selves, which is especially important for poliosurvivors. Home safety, work simplification,falls prevention, and proper exercise are alsostrategies that can enhance function.

ExerciseOne of the most common questions polio sur-vivors ask is, “How should I exercise?” Thishas been much debated. General guidelinesfor patients:• Maintain an active exercise program to

avoid deconditioning and cardiovascularsequelae

• Avoid overly aggressive exercise (fatigu-ing)

• Resist the impulse to exercise throughpain.Muscle fibers of polio survivors have very

limited endurance because of the loss of aero-bic enzyme activity and greater reliance onanaerobic metabolic capacity.16 Cross-trainingprograms, such as alternating cycling withswimming and walking, are a good way toinvolve different muscle groups, but such pro-grams should be consistent in terms of repeti-tions, resistance, and time. For most people,using daily activities as a primary way to exer-cise is too erratic and may lead to overuse,fatigue, and further weakness.

Is a wheelchair needed?For patients who are having difficulty withwalking or who may be at risk for falls, amotorized wheelchair or scooter can be useful,either full-time or part-time. Such vehiclescan improve functional mobility, decrease riskof falls, and help conserve energy.

Manual wheelchairs have the advantageover motorized wheelchairs of being lighterand easily folded for transport. However, man-ual wheelchairs tend to promote overuse syn-dromes in the arms and are generally recom-mended only when another person will pushthe patient.

Ancillary health careReferral to other appropriate health careproviders can markedly improve the quality oflife for polio survivors. For example, speechand language pathologists can be extremelyhelpful in teaching patients compensatorymechanisms for swallowing. Referral to a men-tal health counselor, with pharmacologicintervention if needed, should be consideredfor patients who are depressed or have otherpsychological sequelae.

■ AVOIDING COMPLICATIONS

Osteoporosis. Patients with significantparalysis often have associated loss of bonedensity. Recent studies indicate that malepolio survivors are at risk for osteopenia andosteoporosis, and may be at higher risk forfracture.8,16,17 We recommend that all poliosurvivors be screened for bone density loss andbe appropriately treated.

Screen allpolio survivorsfor bonedensity loss

Falls. Polio survivors are also at greaterrisk of tripping and falling due to poor bal-ance and weak arms or legs, and are less like-ly to be able to protect themselves as theyfall.18–21 Since the complications of a fallcan be serious, interventions for fall preven-tion are crucial. Both physical and occupa-

tional therapists typically address fall pre-vention.

Upper extremity injuries. Because poliosurvivors tend to overuse their arms, they arealso at risk for upper extremity injuries,including carpal tunnel syndrome and ulnarneuropathy.8,22–24

■ REFERENCES1. Cohen JI. Poliovirus. In: Fauci AS, Braunwald E, Isselbacher

KJ, et al, editors. Harrison’s Principles of InternalMedicine. 14th ed. New York: McGraw-Hill,1998:1120–1121.

2. Halstead LS, Silver JK. Nonparalytic polio and postpoliosyndrome. Am J Phys Med Rehabil 2000; 79:13–18.

3. Gawne AC, Halstead LS. Post-polio syndrome: pathophysi-ology and clinical management. Crit Rev Phys RehabilMed 1995; 7:147–188.

4. Dalakas MC. Pathogenetic mechanisms of post-polio syn-drome: morphological, electrophysiological, virological,and immunological correlations. Ann NY Acad Sci 1995;753:167–185.

5. Halstead LS. Managing Post-Polio: A Guide to Living Wellwith Post-polio Syndrome. Washington, DC: NRH Press,1998.

6. Maselli RA, Wollmann R, Roos R. Function and ultra-struc-ture of the neuromuscular junction in post-polio syn-drome. Ann NY Acad Sci 1995; 753:129–137.

7. Dalakas MC. Pathogenetic mechanisms of post-polio syn-drome: morphological, electrophysiological, virological,and immunological correlations. Ann NY Acad Sci 1995;753:167–185.

8. Silver JK. Post-polio Syndrome: a Guide for Polio Survivorsand their Families. New Haven: Yale University Press,2001.

9. Bruno RL. Abnormal movements in sleep as post-poliosequelae. Am J Phys Med Rehabil 1998; 77:339–343.

10. Dean AC, Graham BA, Dalakas M, Sato S. Sleep apnea inpatients with postpolio syndrome. Ann Neurol 1998;43:661–664.

11. Seivert BP, Speier JL, Canine JK. Pyridostigmine effect onstrength, endurance and fatigue in post-polio patients[abstract]. Arch Phys Med Rehabil 1994; 75:1049.

12. Trojan DA, Collet JP, Shapiro S, et al. A multicenter, ran-domized, double-blind trial of pyridostigmine in postpo-lio syndrome. Neurology 1999; 53:1225–1233.

13. Bruno RL, Zimmerman JR, Creange SJ, Lewis T, Molzen T,Frick NM. Bromocriptine in the treatment of post-polio

fatigue: a pilot study with implications for the pathophys-iology of fatigue. Am J Phys Med Rehabil 1996;75:340–347.

14. Kingshott RN, Vennelle M, Coleman EL, Engleman HM,Mackay TW, Douglas NJ. Randomized, double-blind,placebo-controlled crossover trial of modafinil in thetreatment of residual excessive daytime sleepiness in thesleep apnea/hypopnea syndrome. Am J Respir Crit CareMed 2001; 163:918–923.

15. Mitler MM, Harsh J, Hiroshkowitz M, Guilleminault C.Long-term efficacy and safety of modafinil (PROVIGIL) forthe treatment of excessive daytime sleepiness associatedwith narcolepsy. Sleep Med 2000; 1:231–243.

16. Silver JK, Aiello DD. Bone density and fracture risk inmale polio survivors [abstract]. Arch Phys Med Rehabil2001; 82:1329.

17. Silver JK, MacNeil JR, Aiello DD. Effect of Fosamax onbone density in a male polio survivor: a case report[abstract]. Arch Phys Med Rehabil 2001; 82:1329.

18. Silver JK, Aiello DD. Fall prevention strategies in a poliosurvivor: a case report [abstract]. Arch Phys Med Rehabil2000; 81:1309.

19. Silver JK, Aiello DD. Polio survivors’ attitudes regardingfalls [abstract]. Arch Phys Med Rehabil 2000; 81:1296.

20. Silver JK, Aiello DD. Risk of falls in polio survivors[abstract]. Arch Phys Med Rehabil 2000; 81:1272.

21. Silver JK, Aiello DD. Polio survivors: falls and subsequentinjuries. Am J Phys Med Rehabil. In press 2002.

22. Veerendrakumar M, Taly AB, Nagaraja D. Ulnar nervepalsy due to axillary crutch. Neurol India 2001; 49:67–70.

23. Waring WP, Werner RA. Clinical management of carpaltunnel syndrome in patients with long term sequelae ofpoliomyelitis. J Hand Surg 1989; 14:865–869.

24. Slowman LS, Silver JK. Prevalence of median and ulnarneuropathy in post-polio patients [abstract]. Arch PhysMed Rehabil 2001; 82:1312–1313.

ADDRESS: Julie K. Silver, MD, Spaulding-FraminghamOutpatient Center, 570 Worcester Road, Framingham, MA01702; e-mail [email protected].


what internists need to know about postpolio syndrome

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