Diagnosis of Parkinson’s disease in most cases remains purely clinical. However, sometimes certain instrumental methods can be used to slightly increase the degree of confidence in the diagnosis.
This is about a simple and accessible method for visualizing the substantia nigra of the brain. Let us recall that this is the very area of the brain whose gradual atrophy causes the main motor symptoms of Parkinson’s disease—slowness of all movements (hypokinesia), muscle stiffness (rigidity), and trembling of the limbs (often resting tremor)
The technique is an ultrasound examination of brain structures conducted transcranially (through the open temporal window of the skull bones) and is called transcranial sonography (TCS).
In more than 90% of patients with Parkinson’s disease, a specific biomarker is identified using TCSG – an increased area of hyperechogenicity signal in the substantia nigra, or hyperechogenicity of the substantia nigra. The method is included in all expert recommendations for the diagnosis of PD – according to the recommendations of the International Parkinson and Movement Disorder Society (European Section) EFNS/MDS-ES MRS has an evidence level A in differentiating PD from atypical and secondary parkinsonism
For the hyperechogenicity of SN to be considered a sign of PD, the area must be more than 0.20 cm. The method has almost 90% specificity and almost 90% sensitivity. However, false-negative results may occur—most often observed in genetic forms of Parkinson’s disease caused by gene mutations PARK2 (parkin). Research has shown that the detection rate of this marker in parkin-associated genetic cases is no more than 50%
At the same time, the severity of SN hyperechogenicity is not a marker of the severity and progression of PD, nor does this indicator change depending on the stage. This means that TCS can be used for the diagnosis of PD at any stage—even in healthy individuals, to identify predisposition to the development of the disease.
The method is available at our Center (V.S. Buzaev International Medical Centre). We conduct this research together with the functional diagnostics physician Karina Fanilevna Valeeva.
Neurologist specializing in Parkinson’s disease at the V.S. Buzaev International Medical Centre, PhD, Gulnara Nailevna Akhmadeeva
Doctor - Obstetrician-Gynecologist, Ultrasound Diagnostics Doctor