The diagnosis of Parkinson disease (PD; sometimes termed idiopathic Parkinson disease, to distinguish it from symptomatic forms of parkinsonism, and from other primary forms) is mainly based on the typical neurological findings, their evolution over the course of the disease, and their responsiveness to levodopa (l-dopa). Longitudinal observation may be necessary before a definitive diagnosis of PD can be given. PD is characterized by a number of disturbances of motor function (cardinal manifestations) and by other accompanying manifestations of different kinds and variable severity.
Bradykinesia, hypokinesia, and akinesia. Motor disturbances include slow initiation of movement (akinesia), sluggishness of movement (bradykinesia) and diminished spontaneous movement (hypokinesia); these terms are often used nearly interchangeably, as these disturbances all tend to occur together. Spontaneous fluctuations of mobility are not uncommon. The motor disturbances are often more pronounced on one side of the body, especially in the early stages of disease. They affect the craniofacial musculature to produce a masklike facies (hy-pomimia), defective mouth closure, reduced blinking, dysphagia, salivation (drooling), and speech that is diminished in volume (hypo-phonia), hoarse, poorly enunciated, and monotonous in pitch (dysarthrophonia). The patient may find it hard to initiate speech, or may repeat syllables; there may be an involuntary acceleration of speech toward the end of a sentence (festination). Postural changes include stooped posture, a mildly flexed and adducted posture of the arms, and postural instability. Gait disturbances appear in the early stages of disease and typically consist of a small-stepped gait, shuffling, and limping, with reduced arm swing. Difficulty initiating gait comes about in the later stages of disease, along with episodes of "freez-ing"—complete arrest of gait when the patient is confronted by doorway or a narrow path between pieces of furniture. It becomes difficult for the patient to stand up from a seated position, or to turn over in bed. Impairment of fine motor control impairs activities of daily living such as fastening buttons, writing (micro-
graphia), eating with knife and fork, shaving, and hair-combing. It becomes difficult to perform two activities simultaneously, such as walking and talking.
Tremor. Only about half of all PD patients have tremor early in the course of the disease; the rest usually develop it as the disease progresses. It is typically most pronounced in the hands (pill-rolling tremor) and is seen mainly when the affected limbs are at rest, improving or disappearing with voluntary movement. Its frequency is ca. 5 Hz, it is often asymmetrical, and it can be exacerbated by even mild stress (mental calculations, etc.). Rigidity. Elevated muscle tone is felt by the patient as muscle tension or spasm and by the examiner as increased resistance to passive movement across the joints. Examination may reveal cogwheel rigidity, i.e., repeated, ratchetlike oscillations of resistance to passive movement across the wrist, elbow, or other joints, which may be brought out by alternating passive flexion and extension. Postural instability (loss of balance). Propulsion and retropulsion arise in the early stages of Parkinson disease because of generalized impairment of the postural reflexes that maintain the bipedal stance. Related phenomena include involuntary acceleration of the gait (festination), difficulty in stopping walking, gait instability, and frequent falls.
■ Behavioral Changes
Depression. The range of depressive manifestations includes worry, anxiety, avoidance of social contact, general unhappiness, listlessness, querulousness, brooding, somatoform disturbances, and (rarely) suicidal ideation. Anxiety. Tension, worry, mental agitation, lack of concentration, and dizziness are relatively common complaints.
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