The diagnosis of parkinson’s disease is based on the identification of a parkinsonian syndrome associated with at least two “supporting” criteria.
Parkinsonian Syndrome and these symptoms
This parkinsonian syndrome is evoked when at least 2 of the following 3 symptoms of parkinson’s disease are observed: akinesia, muscle hypertonia, tremor.
Akinesia is defined as slowness, delay, or difficulty in initiating movement. Patients are no longer able to perform fine, repetitive, rapid movements such as handwriting.
Patients express the sensation that their limbs respond long after they intend to make a movement, as if the command takes longer to reach the muscles. This sensation is indeed true since at 50% loss of dopaminergic neurons, there is no longer enough dopamine for the neurons to communicate effectively with each other and with the muscles.
Hypertonia is defined as a permanent increase in muscle tone. The patient has a feeling of stiffness and a special posture due to a permanent contraction of the muscles that allow the limbs to flex. Abnormal flexion of the neck, trunk, arms and legs may occur over time. Face expression is affected with a very low frequency of blinking. The voice can also be modified, less loud and with less intonation (monochord voice)
However, tremor, the most well-known symptom of the disease, is present in only 30-40% of cases of Parkinson’s disease. It is a resting tremor that affects the extremities of the arms, legs or jaw. This tremor disappears during sleep and during voluntary movements.
