Improving the Diagnostic Accuracy in Parkinsonism
Improving the Diagnostic Accuracy in Parkinsonism
Disturbed gait can develop in all patients with parkinsonism, especially late in the disease course, but the pattern varies between different diseases. Early gait abnormalities in PD include slowing of gait and an asymmetrically reduced arm swing. With disease progression, step height and length become smaller, and many patients develop start hesitation, festination (defined as taking increasingly rapid and small sequential steps during walking) and freezing (defined as debilitating episodes during which they are unable to start walking or, while walking, suddenly fail to continue moving forward). Importantly, gait remains narrow-based in PD, even until late in the disease, but is usually broad-based in patients with the various forms of AP, even early on in the disease. Freezing tends to occur much earlier and more severely in patients with AP, and unlike in PD, responds less well (or not at all) to external cueing. The exception is drug-induced parkinsonism, where freezing seems very rare. Ataxic gait is a key symptom in MSA-C. Gait in CBD is typically affected by asymmetrical and usually fixed foot dystonia.
Balance is generally not disturbed in early PD, unlike most forms of AP. Early falls (within the first year) are a hallmark of PSP, and result from a combination of gait and balance problems. Most falls are backwards (for reasons unknown), whereas PD patients mostly fall forwards (due to freezing of gait). Unlike PD, falls in PSP often cause serious injuries – fractures of long bones and head injury – because many patients are also reckless, and because protective responses during falls are absent. Although characteristic, falls within the first year of disease are not exclusive for PSP, can also occur in MSA, CBD, DLB and other forms of parkinsonism. Typical for MSA is the presence of vertical ('drop down') falls due to preceding syncope (orthostatic hypotension), while this is rare in PD. Patients with AP often require walking aids, and may become fully wheelchair-bound within the first 3 years of the disease. This 'wheelchair sign' would be very unusual for PD.
Gait and balance are best assessed using a combination of tests, including a proper gait analysis and a retropulsion test (incorporated in UPDRS III) Another good test is tandem gait (performed by instructing patients to walk 10 consecutive steps along a thin line); the test is usually normal in PD, and taking even a single corrective side step points towards AP. A related test is asking whether patients are still able to ride their bicycle: cycling is usually preserved in early PD, but inability to cycle early in the disease course suggest AP.
Eye Movement Disorders Examination of the eye movements is crucial for the clinical diagnostic process, as PD and the different forms of AP can show different abnormalities (although these can be subtle). A thorough examination of eye movements involves observing fixation, voluntary eye movements in all directions, smooth pursuit, and saccades in both the horizontal and vertical direction. If there is a vertical gaze palsy, it is important to investigate the doll-eye-phenomenon to localise the disorder as being either supra- or (infra-)nuclear. An upward vertical gaze palsy can develop in the healthy older patients, albeit with preserved velocity of the residual saccade. Also, in PSP, downgaze is usually impaired before upgaze. Supranuclear vertical gaze palsy is characteristic for PSP when present, but a considerable proportion of patients never develop this. Overt supranuclear vertical gaze palsy can be preceded by slowing of vertical saccades and, even more subtle, the 'round-the-house' phenomenon (abnormal trajectory with subtle deviation from the straight line upon attempted vertical saccades, presumably the first stage of saccadic slowing) Cerebellar eye movements, including square wave jerks, can also occur in PSP patients.
MSA patients can show cerebellar eye movements, with nystagmus, square-wave jerks and dysmetria, but often also hypometric saccades, reflecting concurrent parkinsonism. In CBD, the initiation – but not the execution – of saccades can be slowed in both the horizontal and vertical plane, whereas PD patients show limited spontaneous blinking and hypometric eye movements, but a preserved velocity of the saccades.
Autonomic Dysfunction Symptoms of autonomic dysfunction, mostly in the form of orthostatic hypotension, erectile dysfunction and urge incontinence, are commonly early symptoms of MSA, usually even preceding other symptoms. The presence of cold, discoloured hands also frequently develops in MSA. Autonomic dysfunction also occurs in DLB, including orthostatic hypotension and carotid sinus hypersensitivity, causing syncope and transient loss of consciousness. Urinary incontinence may also occur early in the course of the disease. Urinary incontinence also occurs in PSP patients, although generally not as an early feature. In contrast, symptoms of dysautonomia in PD are generally mild and are usually absent in the first years of the disease.
Gait and Balance Disorders
Disturbed gait can develop in all patients with parkinsonism, especially late in the disease course, but the pattern varies between different diseases. Early gait abnormalities in PD include slowing of gait and an asymmetrically reduced arm swing. With disease progression, step height and length become smaller, and many patients develop start hesitation, festination (defined as taking increasingly rapid and small sequential steps during walking) and freezing (defined as debilitating episodes during which they are unable to start walking or, while walking, suddenly fail to continue moving forward). Importantly, gait remains narrow-based in PD, even until late in the disease, but is usually broad-based in patients with the various forms of AP, even early on in the disease. Freezing tends to occur much earlier and more severely in patients with AP, and unlike in PD, responds less well (or not at all) to external cueing. The exception is drug-induced parkinsonism, where freezing seems very rare. Ataxic gait is a key symptom in MSA-C. Gait in CBD is typically affected by asymmetrical and usually fixed foot dystonia.
Balance is generally not disturbed in early PD, unlike most forms of AP. Early falls (within the first year) are a hallmark of PSP, and result from a combination of gait and balance problems. Most falls are backwards (for reasons unknown), whereas PD patients mostly fall forwards (due to freezing of gait). Unlike PD, falls in PSP often cause serious injuries – fractures of long bones and head injury – because many patients are also reckless, and because protective responses during falls are absent. Although characteristic, falls within the first year of disease are not exclusive for PSP, can also occur in MSA, CBD, DLB and other forms of parkinsonism. Typical for MSA is the presence of vertical ('drop down') falls due to preceding syncope (orthostatic hypotension), while this is rare in PD. Patients with AP often require walking aids, and may become fully wheelchair-bound within the first 3 years of the disease. This 'wheelchair sign' would be very unusual for PD.
Gait and balance are best assessed using a combination of tests, including a proper gait analysis and a retropulsion test (incorporated in UPDRS III) Another good test is tandem gait (performed by instructing patients to walk 10 consecutive steps along a thin line); the test is usually normal in PD, and taking even a single corrective side step points towards AP. A related test is asking whether patients are still able to ride their bicycle: cycling is usually preserved in early PD, but inability to cycle early in the disease course suggest AP.
Eye Movement Disorders Examination of the eye movements is crucial for the clinical diagnostic process, as PD and the different forms of AP can show different abnormalities (although these can be subtle). A thorough examination of eye movements involves observing fixation, voluntary eye movements in all directions, smooth pursuit, and saccades in both the horizontal and vertical direction. If there is a vertical gaze palsy, it is important to investigate the doll-eye-phenomenon to localise the disorder as being either supra- or (infra-)nuclear. An upward vertical gaze palsy can develop in the healthy older patients, albeit with preserved velocity of the residual saccade. Also, in PSP, downgaze is usually impaired before upgaze. Supranuclear vertical gaze palsy is characteristic for PSP when present, but a considerable proportion of patients never develop this. Overt supranuclear vertical gaze palsy can be preceded by slowing of vertical saccades and, even more subtle, the 'round-the-house' phenomenon (abnormal trajectory with subtle deviation from the straight line upon attempted vertical saccades, presumably the first stage of saccadic slowing) Cerebellar eye movements, including square wave jerks, can also occur in PSP patients.
MSA patients can show cerebellar eye movements, with nystagmus, square-wave jerks and dysmetria, but often also hypometric saccades, reflecting concurrent parkinsonism. In CBD, the initiation – but not the execution – of saccades can be slowed in both the horizontal and vertical plane, whereas PD patients show limited spontaneous blinking and hypometric eye movements, but a preserved velocity of the saccades.
Autonomic Dysfunction Symptoms of autonomic dysfunction, mostly in the form of orthostatic hypotension, erectile dysfunction and urge incontinence, are commonly early symptoms of MSA, usually even preceding other symptoms. The presence of cold, discoloured hands also frequently develops in MSA. Autonomic dysfunction also occurs in DLB, including orthostatic hypotension and carotid sinus hypersensitivity, causing syncope and transient loss of consciousness. Urinary incontinence may also occur early in the course of the disease. Urinary incontinence also occurs in PSP patients, although generally not as an early feature. In contrast, symptoms of dysautonomia in PD are generally mild and are usually absent in the first years of the disease.
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