Cerebrovascular lesions in parkinsonian patients: when do they really matter?
Arquivos de Neuro-Psiquiatria
C erebrovascular disorder is a relatively uncommon cause of parkinsonism but its recognition is important since it may be confounded with many other etiologies. The classical clinical features of vascular parkinsonism (VP) includes dementia, urinary incontinence, impairment of stance, freezing of gait, rigidity and bradicinesia mainly of lower limbs 1 . Clinicians have significant difficulties when facing patients with parkinsonism with early onset of axial symptoms and problems with balance
... gait since multiple systems atrophy, progressive supranuclear palsy, normal pressure hydrocephalus or VP are plausible diagnoses for this condition. Zijlmans et al. studied the brains of 17 patients who died with a parkinsonian syndrome without evidence of Lewy body pathology at the mesencephalon and with cerebrovascular abnormalities such as small vessel disease and macroscopic infarcts 2 . They confirmed the tendency of VP to affect the lower limbs and to have a more severe course as compared to Parkinson's disease (PD). They also describe four patients who had a somewhat different clini cal course resulting from "strategic" lesions of the contralateral thalamocortical pathway. These patients had asymmetric symptomatology and an acute or delayed progressive onset. Glass et al from the same group later described the clinical correlates of 28 patients (inclu ding those first 17 patients) and found that falls, lower body predominance, pyramidal signs are highly prevalent on VP while visual hallucinations are virtually absent in all these patients 3 . The presence of visual hallucinations would be decisive to diagnose PD or dementia with Lewy bodies instead of VP as the cause of the symptoms even in symmetric and axial predominant parkinsonian syndrome. On this issue of the Arquivos de NeuroPsiquiatria Vale et al. 4 present the clinical correlates of 17 Brazilian patients fulfilling the criteria for VP of Zijlmans et al. 2 . They found roughly the same characteristics of other series with lower limbs motor predominance, falls and freezing of gait, urinary incontinence and dementia. A poor response to levodopa was also frequently seen in the patients. Although the clinical characteristics are important to define VP we need laboratorial or radiological data to support the clinical diagnoses. It is not uncommon that typical or atypical parkinsonian patients present cerebrovascular abnormalities on imaging studies of the brain. Are these cerebrovascular abnormalities really meaningful for a given patient? Magnetic resonance imaging (MRI) of the brain is the technique of choice to diagnose VP due to its greater sensitivity to detect small lesions, mainly in subcortical white matter and deep gray nuclei. FLAIR and conventional T2(T) SE weighted images are preferred. The main abnormalities are multiple territory infarcts (96% in VP versus 22% in PD), periventricular and subcortical white matter lesions (7590% in VP versus 716% in PD), and basal ganglia is chaemic lesions (38-44% in VP versus 4.6-8.0% in PD) 5 . White matter lesions are also frequently found in watershed areas and patients with acute onset of symptoms also tend to have gray nuclei lesions (putamen or thalamus alone or in one of these nuclei along with globus pallidus or caudate nucleus). T2 * and recent susceptibility weighted image techniques are best for detecting hemorrhagic foci 1 . Diffusion tensor techniques diffusion measures ( fractional anisotropy and mean diffusivity) can show disruption of the microstructural organization of frontal lobe which is associated