The diagnosis of Parkinson's disease is based first of all on a neurological examination, which includes past and present medical history and history, as well as a neurological examination and assessment of the response to dopaminergic replacement therapy.
The clinical picture, on the other hand, is based on international assessment scales, evaluated by expert doctors. For example, one of the most used is UPDRS (Unified Parkinson's Disease Rating Scale) consisting of 4 parts in sequence. Part I is found which provides for the evaluation of the mental state of the patient, of his mood and behavior; in part II there is a sort of self-evaluation of daily activities; Part III consists of a clinical evaluation regarding the motor skills of the individual affected by Parkinson's, while Part IV, which is also the last, takes into consideration the possible motor complications.
Each part is given a value that varies between 0, which means absent, and 4, which instead means serious; in the end a numerical score is obtained which indicates the progression of the disease and the clinical efficacy of treatment with anti-parkinson drugs.
Following the neurological examination, pharmacological tests, instrumental and functional tests follow one another. It is important to remember that pharmacological tests are often necessary for the diagnosis of Parkinson's disease, although generally what is significant is a good response to L-dopa therapy. To perform these tests, apomorphine, dispersible L-dopa and L-dopa methyl ester are generally used. Generally, when apomorphine is used, there is a good indication regarding the activity of dopaminergic receptors in the striatum. In fact apomorphine is able to stimulate these receptors directly; after 15 minutes from its subcutaneous administration, the first detection is performed. This test is defined as positive when there is a 20% greater improvement on the motor tests performed with the UPDRS international rating scale.
With the L-dopa test, intestinal absorption, the ability of residual neurons to convert L-dopa into dopamine and the efficiency of receptors is observed. Also for this test, the same protocol as the test described above is performed.
As for the doubtful cases, in which the diagnosis of Parkinson's disease is complicated by the presence of atypical clinical signs, instrumental examinations such as CT and MRI (magnetic resonance) are very useful, and functional tests such as PET ( positron emission tomography) and SPECT (single photon emission tomography) which, by offering neuroimaging, allow diagnostic confirmation.
On the basis of various international assessment scales, such as the aforementioned UPDRS or the Hohen and Yahr scale, the different degrees of disability and motor-postural impairment of Parkinson's disease are established. In these scales of assessment are also considered the mental capacity, the activity of daily life and the complications arising from the therapy. These parameters allow specialists to better quantify the disorders of the Parkinson's patient.
