Vascular parkinsonism--an update.

Vascular parkinsonism (VP) is a heterogeneous clinical entity. The idea of a relationship between cerebral vascular disease and parkinsonism may be traced back to the 1920s, when the diagnostic unit called "arteriosclerotic parkinsonism", a predecessor of VP, was established. This review is concerned with historical and contemporary views regarding the possible vascular genesis of parkinsonism. Confusion persists as a result of vaguely defined diagnostic criteria. The following types of simultaneous occurrence of parkinsonism and cerebral vascular disease (CVD) may be recognised: 1. gait disorders of the lower body parkinsonism type are caused mostly by white matter lesions in the frontal lobes; such disorders may require a diagnosis of vascular origin. We suggest replacing the term "lower body parkinsonism" with a more appropriate term not including the word "parkinsonism": an alternative term could be "cerebrovascular gait disorder"; 2. if the signs and symptoms are typical for idiopathic Parkinson's disease (IPD), the coincidence of IPD and CVD should be considered; 3. if the symptoms of parkinsonism are neither typical for IPD nor for VP, and there are clinical or MR signs of CVD, VP should be regarded as possible when alternative causes are excluded; 4. if the symptoms of parkinsonism and clinical and MR signs are typical for VP, VP should be regarded as probable; 5. if a stroke affecting the contralateral basal ganglia is followed by the occurrence of hemiparkinsonism, the diagnosis of VP is unambiguous. Vascular parkinsonism (VP) is probably one of the most frequently erroneous neurological diagnoses. The reason for this misdiagnosis is that both cerebral vascular disease (CVD) and parkinsonism usually occur at the same age. Due to the high incidence of CVD, it is possible for CVD and idiopathic Parkinson's disease (IPD) to coincide in some cases. Another reason for the misdiagnosis is that the concept of VP lacks clarity. This review aims to contribute to an improved understanding of VP in clinical practice. In this context, the term "CVD" is understood in the broad sense of a brain impairment caused by cerebral vessel pathology. It covers various concepts, as some authors use the term CVD to mean a manifestation of vascular lesions in pathologico-anatomical material or in the imaging techniques; others mean the history and clinical manifestation of cerebral ischaemia, or, more rarely, haemorrhage. The term CVD may cover large vessel disease as well as small vessel disease. This means that territorial and lacunar infarcts and white matter lesions (WML) are all considered as CVD.

Cognitive- and movement-related potentials recorded in the human basal ganglia.

Sources of potentials evoked by cognitive processing of sensory and motor activities were studied in 9 epilepsy surgery candidates with electrodes implanted in the basal ganglia (BG), mostly in the putamen. Several contacts were also located in the pallidum and the caudate. The recorded potentials were related to a variety of cognitive and motor activities (attentional, decisional, time estimation, sensory processing, motor preparation, and so on). In five different tests, we recorded P3-like potentials evoked by auditory and visual stimuli and sustained potential shifts in the Bereitschaftspotential and Contingent Negative Variation protocols. All of the studied potentials were generated in the BG. They were recorded from all over the putamen. Various potentials on the same lead or nearby contacts were recorded. A functional topography in the BG was not displayed. We presume that the cognitive processes we studied were produced in clusters of neurons that are organized in the basal ganglia differently than the known functional organization, e.g., of motor functions. The basal ganglia, specifically the striatum, may play an integrative role in cognitive information processing, in motor as well as in nonmotor tasks. This role seems to be nonspecific in terms of stimulus modality and in terms of the cognitive context of the task.

Cognitive potentials in the basal ganglia-frontocortical circuits. An intracerebral recording study.

We studied cognitive functions related to processing sensory and motor activities in the basal ganglia (BG), specifically in the putamen and in cortical structures forming the BG-frontocortical circuits. Intracerebral recordings were made from 160 brain sites in 32 epilepsy surgery candidates. We studied P3-like potentials in five different tests evoked by auditory and visual stimuli, and two sustained potentials that are related to cognitive activities linked with movement preparation: BP (Bereitschaftspotential) and CNV (contingent negative variation). We compared the presence of a potential with a phase reversal or an amplitude gradient to the absence of a generator. All of the studied cognitive potentials were generated in the BG; the occurrence in frontal cortical areas was more selective. The frequency of all but one potential was significantly higher in the BG than in the prefrontal and in the cingulate cortices. The P3-like potentials elicited in the oddball paradigm were also more frequent in the BG than in the motor/premotor cortex, while the occurrence of potentials elicited in motor tasks (BP, CNV, and P3-like potentials in the CNV paradigm) in the motor cortex did not significantly differ from the occurrence in the BG. The processing of motor tasks fits with the model by Alexander et al. of segregated information processing in the motor loop. A variable and task-dependent internal organisation is more probable in cognitive sensory information processing. Cognitive potentials were recorded from all over the putamen. The BG may play an integrative role in cognitive information processing.

Levodopa-induced dyskinesias and continuous subcutaneous infusions of apomorphine: results of a two-year, prospective follow-up.

Twelve patients with levodopa-induced dyskinesias were treated with continuous subcutaneous apomorphine. A markedly significant reduction in peak dose dyskinesias occurred over a two-year follow-up.