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L Swan, PT, NCS, is Assistant Professor, Program in Physical Therapy, Department of Health Promotion and Rehabilitation, Central Michigan University, Pearce Hall 134, Mount Pleasant, MI 48859 (USA) (laurie.l.swan{at}cmich.edu). Address all correspondence to Ms Swan
J Dupont, PhD, is Visiting Professor, Department of Psychology, Central Michigan University
Key Words: Multiple system atrophy Olivopontocerebellar atrophy Orthostatic hypotension Parkinson disease Shy-Drager syndrome Striatonigral degeneration
| Introduction |
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| The History and Nomenclature of MSA |
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The term"multiple system atrophy"has been used interchangeably with Shy-Drager syndrome, striatonigral degeneration, and olivopontocerebellar atrophy.2 In 1995, a consensus statement was approved by the American Autonomic Society and the American Academy of Neurology to clarify the definitions of MSA, pure autonomic failure (PAF), and orthostatic hypotension.9 Multiple system atrophy is now defined as"a sporadic, progressive, adult-onset disorder characterized by autonomic dysfunction, parkinsonism, and ataxia in any combination."9(p125) Autonomic dysfunction commonly appears as postural hypotension, bowel and bladder incontinence, and impotence.10 Characteristics of parkinsonism include bilateral involvement, bradykinesia, impaired writing, slurred speech, and rigidity.10 The cerebellar component of MSA should not be confused with inherited cerebellar disorders. Inherited disorders usually present at an earlier age and have a different cytological picture and a longer rate of survival.2 Cerebellar features that are characteristic of MSA have their initial manifestations in the trunk and lower extremities, leading to disturbances in gait.10 In MSA, patients often have symptoms that are characteristic of autonomic dysfunction, parkinsonism, or cerebellar dysfunction. As the disease progresses, additional symptoms emerge (Fig. 1).
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| Incidence |
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| Neuropathology |
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Based on postmortem examination of the brains of 20 patients with MSA, Wenning et al16 found that all patients had cell loss and gliosis of the striatonigral system and that 17 patients had olivopontocerebellar atrophy. Eleven of these 17 patients had no signs of cerebellar dysfunction in life. The researchers concluded that the relationship between cell loss in the olivopontocerebellar system and the presence or absence of cerebellar signs was unclear.
Cytoplasmic inclusions are pathological features found at the subcellular level in both IPD and MSA. In IPD, the inclusions are Lewy bodies, and they are found primarily in the substantia nigra.17 In MSA, argyrophilic cellular inclusions can be found in oligodendrocytes throughout the damaged structures of the central nervous system,4 whereas Lewy bodies are more often absent.1 Postmortem studies18,19 have shown degeneration of the striatal and nigral efferent pathways. The loss of postsynaptic dopamine receptors in these pathways may account for the poor or absent response to levodopa treatment.18 Studies of the spinal cords of patients who had MSA have revealed a loss of the intermediolateral column cells,20,21 which are the preganglionic component of the sympathetic nervous system. The smaller-diameter fibers of the autonomic nervous system appear to be affected first, followed by the gamma fibers and finally the alpha fibers.21 The losses are initially caudal and ascend as the disease progresses.21
Imaging techniques have been used in an attempt to elucidate the disease process of MSA. Schulz et al22 used magnetic resonance imaging (MRI) and single-photon emission computed tomography to examine patients with the cerebellar and parkinsonian forms of MSA. Sixty-three percent of the patients in this study had loss of striatal dopamine receptors, which was equally distributed among the 2 forms.22 In addition, there was atrophy of the cerebellum and the brain stem, which was more prominent in the patients with the cerebellar type of MSA.22 These neuroanatomical changes are typical of the neuropathology of olivopontocerebellar atrophy but can also be found in other types of cerebellar pathology.22 The researchers used a quantitative approach to document signal intensity measured on the MRI images of patients with MSA.22 The images on the radiographic film were independently rated on the degree of cortical atrophy and the signal intensities of the putamen.22 Analysis showed a decrease of the signal intensity extending through part of the body of the putamen (median putamenal hypointensity equal to 2 on a scale ranging from 0 to 3) compared with controls.22 In addition, these putamenal hypointensities were more severe in patients with the predominantly parkinsonian type of MSA.22 The researchers also found that the signal intensity measured within the pons and middle cerebellar peduncles was higher than for controls, and these hyperintensities were more pronounced for patients with the cerebellar types of MSA.22
Wakai et al,23 using MRI, found no relationship between the decrease in size of the pars compacta of the substantia nigra and the hypointensity of the putamen of patients with MSA. This finding did not match the clinical observations of the severity of parkinsonism23 and led to 2 main conclusions. First, there is no relationship between degeneration of the pars compacta and the putamen, and second, the degeneration of the putamen could be used as a biological marker for the parkinsonian form of MSA.23 The loss of dopamine receptors in the striatum may be a separate phenomenon rather than a consequence of degeneration of the nigral projections.23
Otsuka et al24 used positron emission tomography (PET) to compare patients with MSA, patients with IPD, and a control group. Markers were used to visualize the uptake of dopamine (DA-PET) and the uptake of glucose (glucose-PET). The results of the DA-PET studies revealed that patients with MSA had a decreased uptake in the putamen and caudate and that patients with IPD had a decreased uptake in the putamen and a much smaller decrease of uptake in the caudate.24 The researchers were able to use these ratios to formulate a caudate-putamen index that could potentially be used to discriminate between diagnoses of MSA and IPD.24 The glucose-PET studies showed no difference between the patients with IPD and the control subjects.24 The patients with MSA had a decreased uptake of the glucose marker in the frontal and temporal cortices, the caudate and putamen, and the cerebellum and brain stem.24
The normal response to maintaining appropriate blood pressure with postural changes is dependent on an intact baroreflex arc. Damage to the autonomic nervous system interrupts this reflex arc in patients with MSA.25 Patients with MSA do not demonstrate the normal rise in plasma norepinephrine levels when coming to a standing position.25 The loss of this mechanism results in vasodilation rather than vasoconstriction of the large vascular beds of the skeletal muscle and splanchnic regions.25 The lack of vasoconstriction results in the decreased blood pressure.25
| Symptoms of MSA |
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A complex relationship among exercise, blood pressure, and orthostatic hypotension has been demonstrated in patients with MSA. Smith et al28 had patients with MSA complete supine exercise by pedaling a cycle ergometer. The patients' cardiac output was similar to that of a control group, but their blood pressure was lowered and remained low 10 minutes after exercise. The low blood pressure appeared to be a result of vasodilation within skeletal muscle without a compensatory vasoconstriction in other large vascular beds. In another study,29 blood pressure response to exercise was compared between patients with the predominantly striatonigral form of MSA and patients with a predominantly olivopontocerebellar form of MSA. A fall in blood pressure was seen with the patients with the olivopontocerebellar form of MSA during supine exercise, whereas patients with the striatonigral form of MSA showed no fall in blood pressure with supine exercise or in a supine position following exercise. Both groups, however, demonstrated a fall in blood pressure when coming to a standing position following the supine exercise. The investigators theorized that patients with the olivopontocerebellar form had more difficulty with blood pressure regulation due to greater damage to the cardiovascular control structures of the brain stem.29
Genitourinary dysfunctions are common symptoms of MSA. Urinary bladder dysfunction may include frequency, urgency, incontinence, and retention.10 Men may experience erectile difficulties early in the course of the disease.10
Patients with MSA frequently have motor symptoms that initially mirror those of IPD. Signs that should raise suspicion for a diagnosis of MSA over IPD include a symmetrical onset of movement disorders, lack of tremor at onset, lack of response or poor response to levodopa, and a rapid progression of symptoms.13 In addition, there may be signs of early instability and falling.1 Rivest et al30 reviewed the case report literature to determine the prevalence of dystonia in patients with MSA. Although there appear to be some reported incidents of dystonic posturing, the literature was inconclusive as to the evidence of their occurrence.30 Antecollis has been observed in some patients with MSA.30 It is unclear whether this antecollis is true dystonia or an imbalance of muscular forces resulting in a sustained posture.30
Patients with the olivopontocerebellar presentation of MSA have an atypical form of ataxia.31 Their gait is narrow based and unsteady.31 Wenning et al31 theorized that patients with the olivopontocerebellar type of MSA also have an impairment of postural reflexes leading to their narrow base of support and early history of frequent falls.
Dysphagia and dysarthria are symptoms that occur later in the disease.10 Sudden death may occur due to abnormal patterns of respiration during sleep.32 Stridor during sleep results from unilateral or bilateral vocal cord adduction due to paresis of cord abductors.32 Damage to the respiratory control centers of the brain stem may lead to a lethal desaturation of oxygen during sleep.32
Tison et al33 followed 100 patients with MSA over a 1-year period and found that 47% of the patients had complaints of pain that seemed to be associated with disease progression. The majority of these patients reported a rheumatic type of pain that affected the extremities more often than the neck and spine.33 The next most common type of pain was associated with sensory symptoms such as cold or burning sensations, paresthesia, or numbness.33 Dystonic pain was also reported, although this pain may have been related to levodopa therapy in some cases.33
Patients with MSA often demonstrate difficulty with thermoregulation.34 The presence of cold hands, with a poor circulatory return after removal of pressure, may be another factor that points to a diagnosis of MSA.34 Klein et al34 found the mean (±SD) baseline temperature to be 29.5°±3.9°C for patients with MSA, 32.6°±0.9°C for patients with IPD, and 32.2°±1.1°C for a control group. The baseline temperature for the patients with MSA was statistically significantly lower than that of the patients with IPD or the control group.34 When the hands were cooled by placing them between cold packs for 5 minutes, the patients with MSA showed the greatest reduction in skin temperature (to a mean of 59.5% of initial baseline temperature) than either the patients with IPD (mean of 77.4% of initial baseline temperature) or the control group (mean of 71.6% of initial baseline temperature).34 The mean skin temperatures of the patients with IPD and the control group had returned to their initial baseline measurements 10 minutes after removing the cold packs.34 In contrast, the mean skin temperature of the patients with MSA was at 87.4% of their initial baseline measurement 10 minutes after removal of the cold packs.34
Although intellectual function and mental state have been reported as intact in patients with MSA,1,10 extensive neuropsychological testing has uncovered some problems with cognition. Meco et al38 compared patients with the striatonigral degeneration form of MSA and patients who had IPD. The 2 groups performed similarly on memory, speech, and conceptual thinking tasks but differed on tasks of executive functioning.35 The patients with MSA had great difficulty switching attention from one stimulus to another.35 The authors theorized that patients with MSA may show a greater attentional deficit than patients with IPD due to the loss of input to the frontal lobe by the damaged striatal region.35
The many potential forms of MSA have led to difficulty in diagnosis. Quinn and Wenning4 have proposed diagnostic criteria that are continually being updated to classify patients as possibly having MSA, probably having MSA, or definitely having MSA (Fig. 2).
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| Treatment Strategies |
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Patients with parkinsonism are often started on levodopa. Early in the course of the disease, some patients show clinical improvement on levodopa.36 Unfortunately, the beneficial effects are seldom sustained.36 This poor response may correlate with the decreasing numbers of dopaminergic receptors during the course of the disease and was illustrated in the study by Wenning et al,15 who followed 33 patients with MSA who were given levodopa. The initial clinical response was excellent in 13% of the patients, good in 25%, and poor in 62%.15 The last recorded response was good in 7% of the patients and poor in 93%.15
The majority of current treatment strategies for MSA focus on the control of orthostatic hypotension. Robertson and Davis37 advocated measuring progress through functional goals rather than achieving a target blood pressure. Medication can be used to control orthostatic hypotension by increasing the total plasma volume or through vasoconstriction.38 Nonpharmacological interventions include increasing the consumption of caffeine, salt, and fluids while decreasing alcohol intake and eating smaller, more frequent meals throughout the day.38 Mechanical interventions include elevating the head of the bed up to 20.3 cm (8 in) for sleeping37 and use of elastic garments.38 Further patient education should include advising the patient to refrain from quick postural changes, especially on awakening38; scheduling activities for later in the day37; and avoiding motionless standing activities.37 Warm environmental temperatures and activities that invoke the Valsalva maneuver should also be avoided.37 Concerns about orthostatic hypotension should not preclude patients from the long-term benefits of a reasonable exercise regimen. Robertson and Davis37 suggested that swimming may be an ideal exercise, as the hydrostatic pressure of the water counteracts the hypotension.
As MSA progresses, patients and families are faced with the difficult decisions of undergoing possible tracheotomy secondary to respiratory stridor and gastrostomy due to dysphagia.1
Physical therapists need to be aware of clinical distinctions between IPD and MSA. A patient with parkinsonism who has difficulty with postural hypotension and/or a poor response to levodopa treatment should be referred back to the physician with a suspicion of MSA.
Quinn1 has clearly described the need for the services of physical therapists, occupational therapists, speech-language pathologists, and social workers in the treatment of patients with MSA. The expertise of these professionals in the numerous practical difficulties encountered by patients with MSA may positively affect the patients' status.1 In particular, physical therapists can be instrumental in monitoring and making adjustments for blood pressure within the context of activities of daily living and exercise programs. Additionally, they can guide motor control activities for patients with parkinsonism and ataxia, provide modalities for pain relief, and facilitate education of the patient and family.
| Summary |
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| References |
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