Parkinson’s disease: a difficult diagnosis

At the beginning of the disease, the diagnosis of Parkinson’s disease is difficult because symptoms may go unnoticed. Nevertheless several criteria now allow to carry a reliable diagnosis… If not early.

The symptoms of Parkinson’s disease are progressive and little specific: fatigue, pain, rheumatism, depression… This is why the national agency of Accreditation and assessment in health (predecessor of the high authority of health) listed specifically in 2000 the criteria according to which the parkinsonian diagnosis could and should be established.


The clinical criteria of Parkinson’s disease
The diagnosis of Parkinson’s disease is based on the review and examination of the patient, looking for symptoms previously observed.

Three cardinal signs of Parkinson’s disease more often successful are: The resting tremor:It is slow and repetitive but disappear during voluntary movement or during sleep. It is usually this symptom that causes the patient to consult. But some Parkinson’s disease patients do not shake and tremble ever;
Bradykinesia:It’s a difficulty initiating movements, which will be slow and difficult;
Muscle rigidity:It is due to hypertension of the set of muscles that can give the impression of a rigid body.
Other clinical signs may be observed and facilitate the diagnosis of Parkinson’s disease:
The asymmetry of symptoms: one side of the body is more affected than the other.
A significant response to L-dopa.

The resting tremor, bradykinesia and asymmetry of symptoms have the best positive predictive values (PPV). A VPP is the probability that the symptom is observed when the disease is diagnosed. In other words, more PPV is high, most disease is likely if the symptom is present.

Diagnosis of Parkinson’s disease
The combination of three cardinal signs associated with the asymmetry give a VPP of 90% for the diagnosis of Parkinson’s disease. But the criteria stipulate that the diagnosis must be called into question at any time and must adapt to the evolutionary characteristics of the pathology:

Early symptoms:should be given to the clinical criteria having a strong VPP. Any other unusual symptom must be studied in order to exclude the diagnosis of another disease. At this stage, the response to L-dopa is not significant in the development of diagnosis;

After a period of 3 to 5 years, the pharmacological response is a usable criterion if there is a 50% improvement of symptoms, response to dopaminergic treatment, according to the scale UPDRS Unifed Parkinson’s Disease Rating Scale ();
After a decade:the pharmacological response is confirmed and is accompanied by frequently uncontrolled and involuntary movements (dyskinesias).

Diagnosis is only based on the identification and association of clinical signs. It will be confirmed by the efficiency of the dopaminergic treatment.

The importance of the early diagnosis of Parkinson’s disease
Other exams, neurological agenda or imagery, are not essential to diagnose Parkinson’s disease, but they can intervene when there is a doubt.

In general, at less than 40-year-old patient, an MRI (Magnetic Resonance Imaging), neuropsychological and/or electrophysiological, explorations urodynamic tests and some biological tests may be carried out. A determination of copper can be requested to exclude the Wilson’s disease, which she also reaches the nervous system.

The early diagnosis of Parkinson’s disease is based on the observation of clinical symptoms (or in default on their description) and allows a faster charge with a significant improvement of the quality of life of patients.