The onset of Parkinson’s disease is slow and the initial symptoms often go unnoticed. There are individual differences in the first symptoms of Parkinson’s disease, which appear in the following order: tremor > muscle rigidity or bradykinesia > inflexibility and/or difficulty writing > gait disturbance > myalgia, spasticity, pain > speech disturbance > generalized weakness, muscle weakness > drooling and reduced facial expressions. Some patients with Parkinson’s disease may also present early with only mood disorders such as decreased sense of smell, sleep disturbances, constipation, idiopathic tremor, anxiety, and depression.
1. Resting tremor
Tremor is the most common first symptom of Parkinson’s disease, with approximately 70% of patients first experiencing the symptom. In the early stages of the disease, tremor often occurs when the fingers or limbs are in a particular position, and disappears when the position is changed. Later, the tremor develops only when the limb is at rest, for example, when watching TV or talking with others, the limb suddenly appears to tremble involuntarily, and the tremor decreases or stops when changing position or movement, so it is called resting tremor, which is the main characteristic of tremor in Parkinson’s disease.
The tremor intensifies when the patient is emotional or nervous, and can disappear completely during sleep. Another characteristic of tremor is its rhythmical nature, where the frequency of the vibrations is 4-6 times per second. Limb tremors are not necessarily Parkinson’s disease. There are two classifications according to the behavior of tremor as a state of limb activity: motor tremor and primary tremor. There are symptoms such as rapid heart rate, fatigue and weakness, excessive food and easy hunger, wasting, and excessive sweating and fear of heat. In Parkinson’s disease, the tremor mostly starts on one side of the body and usually the other side is affected after a few years, while tremor caused by other diseases mostly starts bilaterally and simultaneously.
2. Muscle stiffness
The early stage of the disease usually starts from one limb. At the beginning, one limb feels inflexible and stiff, and it gradually worsens, resulting in motor retardation and even difficulty in doing some movements of daily life. In the early stage of the disease, sometimes muscle stiffness is not easy to detect, so the patient can actively move one limb, and the dystonia of the affected limb will be increased by passive movement. Rigidity can involve the extremities, trunk, neck, and head and face muscles to present a specific posture.
Mental pillow: Rigidity is often preferred in the posterior cervical muscles and shoulders. When the patient is lying on his back, the head may remain in forward flexion for several minutes, leaving a space between the head and the mattress, and a “mental pillow.
Signpost phenomenon: Most patients have more rigidity in the upper extremities than in the lower extremities. Let the patient rest both elbows on the table, so that the forearms are perpendicular to the table, and both arms and wrist muscles are relaxed.
Mask face: Rigidity of the facial muscles can appear as a “mask face” with reduced facial expressions as well as reduced movement.
Ape posture: The limbs, trunk and neck muscles are involved at the same time, and muscle tone is increased, but the flexor muscle tone is higher than the extensor muscle at rest. The hip and knee joints are slightly flexed, showing an “ape posture”.
Patients with severe muscle stiffness can cause pain in the limbs, which can be easily misdiagnosed as frozen shoulder or rheumatism, and should be distinguished. The degree of stiffness in any stable patient is not fixed, the movement, stress and anxiety of one limb can increase the stiffness of the opposite limb, and the enhancement effect is also affected by the patient’s posture, which is more obvious when standing than sitting.
3.Sluggish movement
Bradykinesia refers to the slowing of movement, difficulty in initiation, and loss of active movement. The patient’s range of motion is reduced, especially during repetitive movements. Depending on the site of involvement, bradykinesia can be manifested in several ways.
In the early stages of the disease, fine movements of the upper extremity become slower and the range of motion narrower due to stiffness of the fingers and forearm. The patient’s fine movements of the upper extremities become much slower than before, or cannot be performed smoothly at all. The writing becomes smaller and smaller, which is known medically as “microtia”. In the early stages of the disease, joint motor function is also affected, and the back and forth swing of both upper limbs is reduced or lost when walking; the patient cannot answer questions and button clothes at the same time. As the disease progresses, clumsy and uncoordinated movements appear, and fine motor movements are affected, so that people cannot take care of themselves in daily life, such as washing their faces, brushing their teeth, putting on clothes and tying their shoes.
”Mask face”, “poker face”
The facial muscle movement is reduced, the patient seldom blinks, the eyes turn less, often stares at one place, the expression is dull, the previous amiable face disappears, as if wearing a mask, the medical term is “mask face”, or “poker face”. The medical term is “mask face” or “poker face”.
The disease affects the movement of the muscles of the mouth, tongue, jaw and pharynx, leading to swallowing disorders, which manifest as salivation, difficulty in eating and choking. The patient is unable to swallow saliva naturally, resulting in salivation, which occurs early at night, with traces of saliva on the pillow early in the morning, and later during the day, with heavy salivation, requiring frequent wiping with tissues and handkerchiefs. Due to choking on food and water, only semi-liquid diet can be taken, and in the late stage, even no food can be taken, requiring nasal feeding or intravenous nutrition. Aspiration pneumonia, asphyxia, and cachexia due to swallowing dysfunction are the primary causes of death in PD patients, and neither pharmacological nor surgical treatment is effective; early rehabilitation exercises should be performed to delay the appearance as well as the severity.
”Panic gait”
When Parkinson’s disease affects the lower extremities, gait disorders are more prominent, manifested as a small fragmented gait, forward gait, panic gait or unilateral lower extremity dragging. With the development of the disease, when walking, it is difficult to start, can not take a step, the feet are like sticking to the ground; once the step is opened, the body leans forward, the weight shifts forward, and rushes forward with a very fast pace, the pace is small but faster and faster, can not stop in time or turn difficult, which is called “panic gait”.
4.Posture and balance disorder
Postural reflexes and balance disorders can occur when the trunk muscles are involved, mostly in patients with middle to late stage Parkinson’s disease, which has serious impact on life. Postural reflexes can be detected by a backward pull test: the examiner stands behind the patient and asks the patient to get ready and then pulls his or her shoulders. A normal person can return to normal uprightness within one step of stepping back, while a patient with absent postural reflexes often has to take more than three steps back or requires assistance to stand upright, i.e., balance disorder, when Parkinson’s disease has entered the middle stage of development. Because of the balance disorder, patients must take continuous small steps when turning backward, so that the trunk and head turn together, and they are prone to fall forward when walking, and hip fractures often occur. At this time, rehabilitation and daily life guidance are very important.
5.Frozen gait
”Freezing’ manifests itself as a sudden inability to move, a difficulty with the start of movement or continuous rhythmic repetitive movements (speech, walking, writing, etc.). Freezing gait manifests itself as hesitation in starting, with the feet seemingly stuck to the ground, or a sudden and brief inability to take a step while walking, requiring a pause of several seconds before continuing to move forward or being unable to start again. Freezing is common at the start of walking (difficulty starting to move), when turning around, when approaching a target, or when worrying about not being able to cross a known obstacle, such as crossing a threshold, going through a revolving door, etc. The freezing phenomenon is related to the duration and severity of the disease and is commonly seen in the middle to late stages of Parkinson’s disease. If it appears early in the disease and is the main symptom, consider whether it is a Parkinson’s syndrome such as progressive supranuclear palsy or multiple system atrophy.
Clinically, freezing phenomenon is not consistent with hypokinesia, which responds well to dopamine treatment, while freezing phenomenon responds poorly to levodopa treatment. Patients can improve by silent mnemonics, visual cues, walking to music or a metronome, and if necessary, using a walker or even a wheelchair for protection. Because freezing gait occurs mostly suddenly and unpredictably, it is an important cause of patient injury and falls, and is an important independent risk factor for patient quality of life decline.