The most common motor symptoms of PD include tremor (occurring at rest), slowness of movements (bradykinesia), rigidity of movements in the limbs, trunk, and neck, and reduced balance. PD is a progressive neurological condition so symptoms, including motor symptoms, worsen over time.
Tremor – Around 80% of PD patients have a tremor or will develop one. Some patients may also feel an internal tremor which is not visible to others. The tremor will typically start on one side of the body, usually in the hand, and spread throughout the affected limb and the other limb on the same side of the body before progressing to the other side of the body. The tremor typically appears during rest, but may also appear while engaged in another activity such as eating, walking, etc. Tremors may be exacerbated by stressful situations or strong emotions such as anger or excitement.
Bradykinesia – Bradykinesia is characterized by decreased spontaneous movement, unusually slow movement, and a slow reaction time. Bradykinesia affects all PD patients and often interferes with activities of daily living such as walking, cooking, cleaning, dressing, and other daily chores. Slower movements can also cause a reduction in communication through reduced gesturing and a reduction in facial expressions (commonly referred to as masked face). This may cause PD patients to appear as uninterested or having reduced emotions.
Rigidity – Rigidity is stiffness of part of the body resulting in increased resistance to passive movement by an examiner. Patients can also feel rigidity as aches and pains in different joints, with the most common being shoulder pain.
Reduced Balance (Postural Instability) – Reduced balance usually develops later in the course of PD. Decrease in balance can also lead to falls, exposing PD patients to a significant risk of serious injuries. Medications used for PD typically help balance less than tremor and bradykinesia. Poor or hunched posture often accompanies reduced balance. This problems can cause an altered gait, and eventually lead to PD patients being unable to walk independently.
Freezing of Gait- Another issue commonly affecting gait is freezing, which is the phenomenon described as the feet seeming to stick to the floor. Freezing causes difficulties for PD patients to initiate or continue with their gait. Freezing commonly occurs while turning, going through smaller spaces (i.e. a doorway), or walking after arising from a sitting position.
Other motor symptoms that may arise include:
- difficulty swallowing
- shuffling gait
- micrographia (small handwriting)
- soft speech
- dystonia (cramping of muscles)
Dyskinesia – Dyskinesia arises as a side effect from PD medications (usually levodopa, but dopamine agonists, COMT inhibitors and MAO-B inhibitors can worsen dyskinesia in patients on levodopa). Dyskinesias are involuntary overflow movements of various body parts that are usually induced or worsened during volutary movement. The movements are usually rocking or wiggling movements which can sometimes be reduced by adjusting PD medications or with surgical interventions such as deep brain stimulation.