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Hypokinetic Movement Disorders.

Abstract: Hypokinesis is the term used to refer to slow or reduced movement. Hypokinetic movement disorders are often referred to as parkinsonisms because they display clinical features of idiopathic Parkinson's disease (IPD). As a result, distinguishing other parkinsonian syndromes from IPD is difficult, and it is often not until post mortem that a misdiagnosis is realized. Conditions displaying features of parkinsonism are extensive. The more commonly encountered are IPD, multiple system atrophy, and progressive supranuclear palsy.

The purpose of this paper is to identify the main differences between three of the more commonly encountered hypokinetic movement disorders. First described by James Parkinson in 1817 in "An Essay on the Shaking Palsy," Parkinson's disease has been widely written about since then. However, recent years have seen the emergence of other parkinsonian conditions. Nursing care and medical treatment differ for each group of patients and can greatly affect their quality of life. Therefore clinicians should be aware of the subtle differences between the various movement disorders.

Idiopathic Parkinson's Disease

Idiopathic Parkinson's disease (IPD) is a chronic degenerative disease of the basal ganglia.[7] Parkinsonism in IPD is a result of neuronal loss and Lewy body formation in the substantia nigra.[1] As the cells die, there is a depletion of dopamine concentration in the substantia nigra. Dopamine is the major neurotransmitter regulating subconscious movements of the skeletal muscle.[3] When dopamine production is reduced, a chemical imbalance occurs, affecting movement, balance, and gait. It is clear from the pathology that definitive diagnosis can be reached only after death.[4] Therefore, clinicians must be aware of specific signs and symptoms that can provide a diagnosis of IPD.

Akinesia is a symptom pertaining to bradykinesia (slowness of movement) and muscle stiffness or rigidity.[4] The classic pill-rolling rest tremor associated with IPD is noted when the hand is motionless. Characteristically in IPD, the rest tremor disappears or is diminished on movement of the limbs.[7] This symptom, although classically associated with IPD, does not affect all patients. The phenomenon of cogwheeling in the upper limbs is a result of rigidity and superimposed rhythmic contractions on passive stretching of the muscles.[7] Rigidity of the facial muscles gives the face a mask-like expression typical of IPD. Such rigidity is a common characteristic of IPD but is not always present.[2] Postural instability occurs late in IPD. Therefore, a patient presenting with frequent falls may be suffering from another form of parkinsonism.

Multiple System Atrophy

Multiple system atrophy (MSA) is a sporadic, degenerative neurological disorder of sudden onset. A definitive diagnosis of MSA can be reached only at post mortem and is characterized microscopically by the appearance of glial intrascopic inclusions. Atrophy is widespread, leading to the term multiple system, suggesting that signs and symptoms can vary considerably.[5] The three major features of MSA are parkinsonism, cerebellar dysfunction, and autonomic dysfunction.[6] Pyramidal and extrapyramidal signs are often also present, whereas in IPD, pyramidal tracts are not affected. In addition, cerebellar or autonomic dysfunction is rarely seen in IPD. Bradykinesia with rigidity or tremor may be evident. The asymmetric parkinsonism with tremor can appear on first examination to mimic the symptoms of IPD. However, the movement disorder in MSA has specific differences. One difference is that these symptoms rarely occur singularly and are often accompanied by autonomic involvement, such as orthostatic hypotension, or cerebellar involvement, such as ataxic gait. Further, the classic pill-rolling rest tremor is rarely present in MSA.

Also, patients with MSA have poor responses to levodopa even at maximum tolerated doses.[6] This is an important diagnostic tool used to differentiate between IPD and MSA. Although a subgroup of patients with MSA has been identified to have a good response to levodopa, this response is relatively short-lived. Levodopa is known to exacerbate other symptoms, particularly postural hypotension. This contrasts with IPD, in which levodopa therapy is used as a first-line treatment resulting in significant clinical improvement.

Postural instability is often an early feature in MSA, and although it can occur in IPD, it usually develops later in the disease. In patients with cerebellar dysfunction, gait ataxia, ataxic dysarthria, and nystagmus may be observed. Impaired up gaze and mild impairment of down gaze may be seen as in progressive supranuclear palsy (PSP). However, in PSP, supranuclear down gaze palsy is much more prominent. Lewy bodies have been identified in the pigmented brainstem nuclei of patients with striatal pathology in MSA, whereas Lewy bodies were once thought to be absent in MSA.[4] This has led clinicians to appreciate that the identification of Lewy bodies in neural tissue in IPD is not sufficient to lead to definitive diagnosis unless the striatum is examined.

Progressive Supranuclear Palsy

PSP is classically marked by a supranuclear gaze palsy along with rigidity. Cognitive problems are a prominent feature, whereas in IPD and MSA cognition remains largely intact. In PSP the speed of mental processing is slowed, and deficits in memory, attention, and problem solving have been noted. Patients with IPD can experience depression and cognitive decline in later stages of the disease, but this is thought to be due to drug side effects rather than to disease pathology. In MSA, cognition is unaffected, and depression is rare. In PSP the neck is affected more prominently, and posture tends to be erect rather than the typical stooped appearance of a patient with IPD. Facial expression in PSP is usually described as grimacing more than mask-like. Early symptoms in PSP include falling, imbalance, and a general slowness of movement, typical of all hypokinetic movement disorders. Typically, initial presentation o:f PSP is similar to that of IPD; however, prognosis is worse and treatment options are limited. Neuropathology of PSP and IPD does overlap, but important differences have been identified. On post-mortem examination, neurofibrilliary tangles are a characteristic of PSP in contrast to the Lewy bodies of IPD.[1] In addition, in PSP there is a greater loss of dopamine in the caudate than the putamen, the reverse being true in IPD. The clinical diagnosis of PSP identifies a gradual progressive disorder with onset in middle age, supranuclear limitation of vertical gaze, prominent instability, and falls in the first year of onset. Dysphagia and swallowing abnormalities on functional testing are common in PSP. Therefore, progressive dysphagia has been regarded as more characteristic of PSP than IPD and is thought to represent a manifestation of brainstem involvement.

Summary

On initial examination, definitive diagnosis could be wrongly assumed because of close similarities of the parkinsonian diseases. However, on closer examination subtle differences can be identified. MSA may present with rigidity and tremor, but the presence of autonomic signs and pyramidal signs such as postural hypotension distinguish MSA from IPD. The tremor, although evident, rarely resembles that of the classic pill-rolling rest tremor seen in IPD, nor does it present independently of cerebellar or autonomic features.

Immediate presentation of PSP is similar to that of IPD with small but distinct differences. Classically with PSP supranuclear down gaze palsy is present along with rigidity. Problems with cognition are evident in PSP, whereas they are absent in MSA and early IPD. In addition, deterioration is often more marked and prognosis is worse.

Through clinical experience and further research we can become familiar with the differences between IPD and other parkinsonisms and thus provide more effective treatment and a better quality of life for our patients.

References

[1.] Hardman CD, Halliday GM: The external globus pallidus in patients with Parkinson's disease and progressive supranuclear palsy. Mov Disord 1999; 14(4): 626-633.

[2.] Hickey J: The Clinical Pratice of Neurological and Neurosurgical Nursing, 4th ed. JB Lippincott Company, 1997.

[3.] Lusis SA: Pathophysiology and management of idiopathic Parkinson's disease. J Neurosci Nurs 1997; 29(1): 24-31.

[4.] Quinn N: Parkinsonism--recognition and differential diagnosis. Brit Med J 1995; 310: 447-452.

[5.] Quinn N: Multiple system atrophy--the nature of the beast. J Neurol Neurosurg Psychiatry 1989; (Special Suppl): 78-89.

[6.] Quinn N, Wenning G: Multiple system atrophy. Curr Opin Neurol 1995; 8: 323-326.

[7.] Youdirn MBK, Riederer P: Understanding Parkinson's disease. Sci Am 1997; 276(1): 38-45.

Questions or comments about this article may be directed to: Ellie Borrell, The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG. She is a clinical practice facilitator in neurology.
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Author:Borrell, Ellie
Publication:Journal of Neuroscience Nursing
Geographic Code:1USA
Date:Oct 1, 2000
Words:1379
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