Hemiparkinsonism with infarction of the ipsilateral substantia nigra

Substantia nigra micro-haemorrhage causing ipsilateral unilateral Parkinsonism and abnormal dopamine transporter scan uptake

Parkinsonism is a commonly seen movement disorder syndrome with neurodegenerative and non-neurodegenerative causes. Presynaptic dopamine transporter (DaT) single-photon emission computed tomography (SPECT) imaging is the most commonly used imaging technique in clinical practice to differentiate degenerative Parkinson's disease (PD) and PD plus syndromes from other causes such as essential tremor and drug-induced parkinsonism. This can help identify the patients who would benefit from medical therapy due to underlying pre-synaptic dopaminergic deficits. We report a case of unilateral parkinsonism caused by ipsilateral substantia nigra micro-haemorrhage resulting in disruption of the nigrostriatal pathway. This is an unusual case of a 55-year-old male patient who presented with unilateral Parkinsonism a decade after significant head trauma where MRI plays a critical and complementary role in diagnosing complete interruption of the nigrostriatal pathway due to cerebral micro-haemorrhage. The case also beautifully demonstrates the anatomy of the nigrostriatal pathway where a small lesion in the substantia nigra caused complete loss of radioligand uptake in the ipsilateral corpus striatum. Physicians should be aware of the importance of structural imaging in atypical movement disorder cases and, in particular, the routine use of susceptibility-weighted sequences (SWI).

Pure Hemiparkinsonism Secondary to Contralateral Lacunar Stroke in the Substantia Nigra

There are different etiologies of hemiparkinsonism. A few patients with hemiparkinsonism secondary to infarction in the contralateral substantia nigra have been reported in the literature, and only one of these patients presented with pure hemiparkinsonism. This paper reports the unusual case of a patient presenting with pure hemiparkinsonism secondary to a lacunar stroke in the substania nigra. A 66-year-old man who presented with a 5-year history of left-sided hemiparkinsonism manifested by tremor, rigidity, and bradykinesia located mainly on the upper extremity. Magnetic resonance imaging of the brain revealed a lacunar infarct located in the right substantia nigra. Patients experiencing sudden hemiparkinsonism should be investigated to rule out any abnormality in the contralateral substantia nigra. This case points to the significance of neuroimaging in the evaluation of unilateral parkinsonism.

Vascular parkinsonism--characteristics, pathogenesis and treatment

Parkinson disease is a primary degenerative disease of the brain, but parkinsonism can also result from a variety of vascular disorders. Vascular parkinsonism (VP) most frequently presents as lower body parkinsonism, a condition that is accompanied by the development of white matter lesions (WMLs) and lacunes in the brain. Patients with lower body parkinsonism exhibit gait impairment and go on to develop urinary incontinence, abnormal pyramidal responses and cognitive decline. However, WMLs and lacunes are also common observations among elderly individuals who do not have parkinsonism, which causes difficulty in determining the pathogenetic mechanisms that lead to VP. In addition, imaging studies suggest that many pathological and clinical features are common to VP and Binswanger disease, a type of small vessel vascular dementia. This Review summarizes current understanding of the clinical characteristics of VP, as well as knowledge gained from neuroimaging and nuclear imaging of the pathological features of VP. The lack of current treatment options, and the emergence of new therapies such as cerebrospinal fluid drainage, are also discussed. Finally, consideration is given to whether the overlap between VP and Binswanger disease means that these two disorders should be considered as part of the same disease entity.

Etiologies of Parkinsonism in a century-long autopsy-based cohort

We investigated the distribution of different etiologies underlying Parkinsonism in a hospital-based autopsy collection, studied the demographic data and evaluated diagnostic accuracy using histopathological examination as the gold standard. Out of a total of 9359 consecutive autopsy cases collected between 1914 and 2010, we identified 261 individuals who carried a clinical diagnosis of a Parkinsonian syndrome at death. A detailed neuropathological examination revealed idiopathic Parkinson's disease (PD) in 62.2%, progressive supranuclear palsy (PSP) in 4.2%, multiple system atrophy (MSA) in 2.3%, corticobasal degeneration (CBD) in 1.2%, postencephalitic Parkinsonism (PEP) in 2.7%, vascular Parkinsonism (VaP) in 8.8% and Alzheimer-type pathology (ATP) of the substantia nigra in 8%. The diagnostic accuracy of PD in our cohort was lower (71.2%) than those reported in previous studies, although it tended to increase during the last decades up to 85.7%. Of particular interest, we found that PD, while being the most frequent cause of Parkinsonism, was greatly overdiagnosed, with VaP and ATP being the most frequent confounding conditions.

Vascular parkinsonism

PURPOSE OF REVIEW

Vascular parkinsonism is a highly controversial concept since its first description by Critchley in 1929. There is no doubt that cerebrovascular disease can cause elements of parkinsonism. However, the extent of the spectrum of vascular parkinsonism remains quite imprecise. Here we review recent epidemiological, clinical, electrophysiological, morphological and functional brain imaging and pathological studies on 'vascular parkinsonism'.

RECENT FINDINGS

Epidemiological studies have demonstrated that vascular parkinsonism represents 3-5% of all cases of parkinsonism. The more specific clinical features are a history of stroke, lower body parkinsonism and poor levodopa response. Vascular risk factors are dominated by arterial hypertension, whereas others have been less evaluated. Vascular lesions within or outside the basal ganglia, unique and multiple, lacunae or territorial infarcts can be demonstrated by magnetic resonance imaging. Functional imaging of the dopaminergic pathway helps to differentiate vascular parkinsonism from idiopathic Parkinson's disease. However, none of these clinical or imaging criteria taken alone are specific for the diagnosis. A combination of convergent clinical and imaging clues are therefore necessary to improve the accuracy of the diagnosis, which is only certain when the pathology excludes underlying idiopathic Parkinson's disease.

SUMMARY

At present it remains unexplained why some patients develop vascular parkinsonism and others do not with the same apparent vascular lesion load. This will need further research along with the need to develop criteria to improve the accuracy of diagnosis of vascular parkinsonism. Vascular parkinsonism is also a research field on the relationships between vascular brain lesions and neurodegenerative disorders.

Secondary parkinsonism due to focal substantia nigra lesions: a PET study with [18F]FDG and [18F]fluorodopa

We present a 71 year old woman with predominantly right sided parkinsonism of sudden onset, but without tremor. Magnetic resonance imaging (MRI) depicted lesions affecting the substantia nigra (SN) bilaterally, but more pronounced on the left side. There were no other discernible structural lesions. Using positron emission tomography (PET), we investigated regional cerebral metabolic rate of glucose (rCMRG) using the tracer [18F]-fluorodeoxyglucose (FDG), and striatal dopa decarboxylase capacity using the tracer [18F]-L-6-fluorodopa (FDOPA). The degree and pattern of distribution of FDOPA uptake reductions (putamen > caudate nuclei) were similar to those in idiopathic Parkinson's disease (PD). FDG uptake also revealed similar changes (reductions in frontal cortex and cerebellum, but increases in thalamus), except for putamen which showed reduced rCMRG. In conclusion, the absence of tremor at rest accords with experimental SN lesions. The PET findings in this atypical condition are explained in terms of deafferentation of various brain regions involved in motor control. Furthermore, they illustrate the metabolic effects related to acute focal lesions of the SN as opposed to the progressive degeneration in idiopathic PD and may serve to help unravel the complicated pathophysiology underlying these conditions.

Hemiparkinsonism following haemorrhage in the contralateral substantia nigra

We report a patient with right hemiparkinsonism following haemorrhage in the left substantia nigra. The hemiparkinsonism responded to treatment with trihexyphenidyl hydrochloride and deteriorated after temporary discontinuation of the drug. Single photon emission computed tomography using technetium 99m d, l-hexamethylpropyleneamine oxide showed reduced uptake in the left putamen, globus pallidus and thalamus.