Post-Polio Syndrome: Pathophysiology and Clinical Management
Anne Carrington Gawne and Lauro S. Halstead
X. EVALUATION OF THE POST-POLIO PATIENT.
Proper assessment of post-polio patients presents both a challenge and a dilemma: a challenge because of the diversity and nonspecific nature of the problems they may present with, and a dilemma because of the absence of specific diagnostic tests, the continuing uncertainty of the underlying cause or causes, and the lack of any curative therapeutic intervention. Our approach to the assessment of post-polio patients is based on a number of assumptions concerning their past health experience and present needs. These assumptions guide the format and content of our evaluation. They are based on the experience gained in assessing and managing over 1000 patients over nearly a decade and the lessons learned in organizing and running two major polio programs in two different institutional settings. Clearly, these assumptions represent a particular bias and we recognize that other professionals, with a different perspective or with different resources available to them, may want to use a modification of the approach outlined here. We believe it is essential that the evaluation includes the following elements:
A. Comprehensive and Interdisciplinary Evaluation.
Because of the number, diversity, and complexity of the problems presented by these patients, a comprehensive, coordinated assessment is required. For many of these patients the evaluation in the post-polio clinic may be one of the first examinations done by a group of specialists that are familiar with the features of PPS. The best way to provide a comprehensive, coordinated evaluation that looks at the medical, functional, and psychosocial and vocational issues of this population is to use an interdisciplinary rehabilitation team including the physician and nurse and physical and occupational therapists. A social worker or psychologist, orthotist, and respiratory therapist may complete this team.
B. Diagnosis by Exclusion.
Because post-polio syndrome is a diagnosis by exclusion, it is essential that every patient receive a careful history and physical examination, along with appropriate laboratory, radiological, and diagnostic studies to rule out other medical, orthopedic, or neurologic conditions that might be causing or aggravating the symptoms. A psychosocial evaluation is often helpful, along with an assessment of function, gait, and orthotic needs. In addition, a baseline measure of strength and endurance in key muscle groups is essential to observe for the appearance of new weakness. Because manual muscle testing alone is not a reliable and valid measure of strength over time in post-polio patients in comparison to more quantitative measurements, we recommend objective testing of key muscle groups in the good to normal range with a myometer or isokinetic test.[91,92,93] For virtually every patient, we feel a standard electromyogram/nerve conduction study (EMG/NCS) of all four extremities and appropriate paraspinals is essential. We have found that this test is invaluable in confirming the presence of an old anterior horn cell disease (AHCD), identifying major muscle groups with subclinical involvement, establishing a baseline and helping exclude certain other neurologic and myopathic conditions, and in detecting additional diagnoses, including carpal tunnel syndrome (CTS), ulnar neuropathy, and radiculopathy. A summary of our experience with 100 consecutive patients is shown in Table 6. We do not believe more sophisticated studies with single fiber EMU or macro-EMG are indicated in the routine clinical setting because they have not helped separate the symptomatic from the asymptomatic patient or proven useful in guiding clinical management.
Additional Electrodiagnostic Findings in 100 Consecutive Post-Polio Patients (Ref. 94.)
|Carpal Tunnel Syndrome (CTS)||35||35
|Ulnar Neuropathy at the Wrist||2||2
|CTS and Ulnar Neuropathy||3||3
A standard battery of screening tests such as an electrolyte panel, fasting glucose, etc. used on a routine basis are generally not helpful; however, when indicated we may obtain a hematocrit, blood glucose, creatine phosphokinase (CPK), or thyroid function tests. Whether it is useful to monitor CPK levels on a regular basis to assist in determining long-term prognosis or as an aid in clinical management is still not clear.
Patients who had respiratory involvement initially and have a history of pulmonary disease or scoliosis should have a screening vital capacity (VC) and functional expiratory volume (FEV1) measured along with their other vital signs. If the vital capacity is less than 50% of predicted or the history and clinical situation warrant, further pulmonary function tests (PETs) are obtained. If the patient has significant spinal curvature, a 36-in gravity loaded scoliosis film is obtained to provide a baseline for follow up exams. If degenerative joint disease (DJD) or other skeletal abnormalities are suspected, appropriate radiographs are obtained.
C. Expectation of Improvement.
We believe that everyone who comes to the clinic can be helped, regardless of the etiology or severity of disability. As a result, our goal is that everyone, even if they can implement only some of the recommendations and interventions, will feel better physically and emotionally and achieve an improved level of function.
D. Convenience and Efficiency.
Because of the comprehensive, interdisciplinary nature of our evaluation, and frequently the decreased stamina these patients may have, we attempt to complete the evaluation in 1 or 2 days, having team members come to the patient in a central location rather than having the patient come for a series of single service outpatient evaluations. All laboratory, radiological, and electrodiagnostic procedures are performed on location the day of the evaluations.
A typical evaluation in the NRH Post-polio Clinic extends over 2 days, with the first day reserved for evaluations by team members, including a rehabilitation nurse, physician, physical therapist, occupational therapist, social worker, and, if needed, an orthotist.
The patient is seen initially by the nurse, who makes a brief assessment of the past and current health status, clarifies the patient's goals for the clinic visit, coordinates the evaluations by the team members, schedules diagnostic tests, and assists with patient and family education. The medical evaluation consists of a comprehensive history and physical exam, with special attention to the history of the details of the initial illness with acute polio and its management and a special focus during the physical exam on neurologic and musculoskeletal findings. There is also an analysis of station and gait to determine the need for orthoses and other durable medical equipment. In addition, the physician determines the need for X-ray, laboratory and electrodiagnostic studies, and initiates referrals to other rehabilitation disciplines, such as a nutritionist, vocational counselor, speech language pathologist, or psychologist, as well as other medical and/or surgical specialists if needed.
The physical therapist's evaluation is based on a protocol outlined by Smith and includes a baseline manual test of major muscle groups, measurement of major joint range of motion and leg length, and an evaluation of habitual postures during standing, sitting, lying down, and walking. It also includes an analysis of activities and positions that provoke or relieve muscle and joint pains. The occupational therapist's assessment is based on a format described by Young and includes an evaluation of activities that produce pain, weakness, or fatigue; when they occur; and how these problems interfere with the person's activities of daily living (ADL). Special attention is paid to the frequency and intensity of activities in the home, at work, in the community and during travel, and to the use or need for adaptive aids.
The social work evaluation focuses on how new health problems and functional loss impact on the patient, the family, significant others, and colleagues at work, school, or elsewhere outside the home. There is also an effort to identify coping strategies used by, and available to, the individual and assess the emotional impact of the original polio experience and relate it to current feelings of having a second disability.[97,98] In addition, the social worker facilitates referrals and access to community resources and services, including the local post-polio support group. In the afternoon, we obtain any necessary diagnostic tests to help rule out other medical, orthopedic, or neurologic conditions that might be causing or aggravating the patients presenting symptoms.
Finally, the morning of the second day is used to complete any unfinished evaluations and to hold a team conference with the patient and his/her family. This conference is used to review the results of diagnostic tests and discuss our impressions and recommendations for interventions. Patients are given a written copy of recommendations and then seen in follow-up 6 to 8 weeks later to evaluate the effectiveness of the interventions and make any modifications or additional suggestions for management. Thereafter, patients are seen as needed and at annual intervals for a repeat functional evaluation and manual muscle test as well as an interim history and a physical.
In summary, the assessments provided by special diagnostic testing are generally more fruitful in excluding certain conditions than in assisting either with the diagnosis or management of post-polio syndrome. Despite the growing body of evidence that suggests that the major pathologic process is motor unit dysfunction, there is still no objective method to predict who might develop new weakness in the future or to monitor the progress of the underlying pathology in the subject who has already becoming weaker. Specifically, no serologic, enzymatic, electrodiagnostic, or muscle biopsy test can diagnose PPS. In general, we rely on a careful patient history to distinguish between those patients who have no new weakness (clinically stable) and those who are experiencing new weakness (clinically unstable).
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Created: 5th June 2000
Last modification: 24th January 2010.