Correlation Between Substantia Nigra Features Detected by Sonography and Parkinson Disease Symptoms

Abstract

Objective. The aim of this study was to assess the correlation between substantia nigra (SN) echogenic features and area and the clinical symptoms in patients with Parkinson disease (PD). Methods. Clinical examinations and transcranial sonographic evaluations of the SN were performed in 115 consecutive patients with PD. The presence of tremors, rigidity, bradykinesia, gait disorders, speech disorders, and hypomimia was evaluated according to the motor portion of the Unified Parkinson Disease Rating Scale. The Mann-Whitney U test, the Kruskal-Wallis test, analysis of variance, and multivariate analysis were applied when assessing statistical significance. Results. An enlarged and hyperechoic SN existed in 84.0% of patients with bilateral rigidity but in only 70.6% of patients with unilateral rigidity (P < .05). Similarly, 85.0% of patients with bilateral bradykinesia in comparison with 65.7% of patients with unilateral bradykinesia had an enlarged and hyperechoic SN (P < .05). A significant correlation was shown between the SN echogenicity and area (r = 0.705; P < .01). Conclusions. An enlarged and hyper echoic SN seems to be a marker of structural involvement of the SN in patients with PD. This structural involvement is expressed more in patients with bilateral rigidity and bradykinesia. Key words: bradykinesia; Parkinson disease; substantia nigra; transcranial sonography; tremor. Moreover, studies published so far have shown that TCS-detectable changes of SN echogenicity are not strictly specific only for PD, but they are also more frequent in other movement disorders than in the healthy population. [2][3][4]7,11 An enlarged and hyperechoic SN can be detected in 9% to 50% of patients with multiple system atrophy, [12][13][14] in 20% to 40% of patients with vascular parkinsonism, 15,16 in 90% of patients with corticobasal degeneration, 12,17 and in up to 97% of patients with Lewy body dementia.

Specificity of transcranial sonography in parkinson spectrum disorders in comparison to degenerative cognitive syndromes

“…This feature is in parallel with the results, where the SN+ correlated with the bilateral bradykinesia and rigidity [35]. The SN+ on the right side was larger to the contralateral clinical symptoms on disease presentation ( p = 0.021), but was not replicated on the left side to the contralateral clinical symptoms ( p = 0.055).…”

“…Grade I of the SN echogenicity was defined as the same echogenicity as the brainstem, grade II - when clearly detectable from the brainstem, grade III- lower signal intensity when comparing to perimesencephalic cisterns, grade IV - the same to perimesencephalic cisterns, grade V - higher than perimesencephalic cisterns [35]. …”

Light pigmentation phenotype is correlated with increased substantia nigra echogenicity

“…Although we 16 and others [17][18][19] have shown that echogenic SN area is sensitive to ongoing degeneration of dopaminergic neurons in manifest PD, other reports did not find enlargement of echogenic SN area to be related to the stage of PD. 20,21 Increased prevalence of SN1 in cohorts with malignant melanoma, 15,22 prodromal PD symptoms (eg, hyposmia, 23 rapid eye movement sleep behavior disorder, 24 depression 25 ) or asymptomatic parkin and LRRK2 mutation carriers 26,27 appear to indicate that SN1 at least in some circumstances represents a risk marker of PD rather Correlation between mean echogenic SN size and phenotypical traits as well as odds ratio for detection of echogenic enlarged SN area when presenting with specific characteristics.…”

Transcranial sonography in Parkinson's disease

“…It is not known, however, whether this increased amount of iron in this region is a primary cause of PD, which would cause oxidative stress and injury of dopaminergic neurons, or is a secondary phenomenon in the development of disease. In general, the SN hyperechogenicity is present bilaterally in PD, is more extensive (in terms of echogenic area) on the side contralateral to the more symptomatic side, is stable during the course of the disease, and is clinically associated with rigidity and bradykinesia (19,20) . Despite the controversies, some studies suggest that the larger the echogenic area of the SN, the earlier the onset of PD and the slower the progression of the disease (21,22) .…”