Signs and symptoms of Parkinson's disease are varied. Parkinson's disease affects movement, producing motor symptoms. Non-motor symptoms, which include dysautonomia, cognitive and neurobehavioral problems, and sensory and sleep difficulties, are also common. When other diseases mimic Parkinson's disease, they are categorized as parkinsonism.
Motor
Four motor symptoms are considered cardinal signs in PD: slowness of movement (bradykinesia), tremor, rigidity, and postural instability. Typical for PD is an initial asymmetric distribution of these symptoms, where in the course of the disease, a gradual progression to bilateral symptoms develops, although some asymmetry usually persists. Other motor symptoms include gait and posture disturbances such as decreased arm swing, a forward-flexed posture, and the use of small steps when walking; speech and swallowing disturbances; and other symptoms such as a mask-like facial expression or small handwriting are examples of the range of common motor problems that can appear.
Cardinal signs Four motor signs are considered cardinal in PD: tremor, rigidity, bradykinesia, and postural instability (also referred to as parkinsonism).
Tremor is the most apparent and well-known sign. It is also the most common; though around 30% of individuals with PD do not have tremor at disease onset, most develop it as the disease progresses. It is usually a rest tremor, maximal when the limb is at rest and disappearing with voluntary movement and sleep. It affects to a greater extent the most distal part of the limb, and at onset typically appears in only a single arm or leg, becoming bilateral later during the course of the disease. Frequency of PD tremor is between 4 and 6 hertz (cycles per second). It is a pronation–supination tremor that is described as "pill-rolling"; that is, the index finger of the hand tends to get into contact with the thumb, and they perform a circular movement together. Such term was given due to the similarity of the movement in PD patients with the former pharmaceutical technique of manually making pills. PD tremor is not improved with alcohol intake, as opposed to essential tremor. Rigidity is characterized by an increased muscle tone (an excessive and continuous contraction of the muscles) which produces stiffness and resistance to movement in joints. Rigidity may be associated with joint pain, with such pain being a frequent initial manifestation of the disease. When limbs of the person with PD are passively moved by others, a "cogwheel rigidity" is commonly seen. Cogwheel-like or ratchety jerks are characterized by the articulation moving as opposed to the normal fluid movement; when a muscle is externally tried to move, it resists at first, but with enough force, it is partially moved until it resists again, and only with further force, will it be moved. The combination of tremor and increased tone is considered to be at the origin of cogwheel rigidity. Bradykinesia and akinesia: the former is slowness of movement, while the latter is the absence of it. It is the most characteristic clinical feature of PD, and is associated with difficulties along the whole course of the movement process, from planning to initiation and finally execution of a movement. The performance of sequential and simultaneous movements is also hindered. Bradykinesia is the most disabling symptom in the early stages of the disease. Initial manifestations of bradykinesia are problems when performing daily life tasks requiring fine motor control such as writing, sewing, or getting dressed. Clinical evaluation is based in similar tasks consisting such as alternating movements between both hands or feet. Bradykinesia is not equal for all movements or times. It is modified by the activity or emotional state of the subject to the point of some patients who are barely able to walk being capable of riding a bicycle. Generally, patients have less difficulties when some sort of external cue is provided. ... immobile patients who become excited may be able to make quick movements such as catching a ball (or may be able to suddenly run if someone screams "fire"). This phenomenon (kinesia paradoxica) suggests that patients with PD have intact motor programmes, but have difficulties accessing them without an external trigger, such as a loud noise, marching music, or a visual cue requiring them to step over an obstacle. Postural instability: In the late stages, postural instability is typical, which leads to impaired balance and frequent falls, and secondarily to bone fractures. Instability is often absent in the initial stages, especially in younger people. Up to 40% of the patients may experience falls and around 10% may have falls weekly, with the number of falls being related to the severity of PD. It is produced by a failure of postural reflexes, along other disease-related factors such as orthostatic hypotension or cognitive and sensory changes.
Other motor symptoms
Other motor symptoms include:
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