We injected wheat germ agglutinin conjugated to horseradish peroxidase into different segments of the spinal cord in order to examine the topographic organization of corticospinal projections from the medial wall of the hemisphere. We observed that substantial projections to the spinal cord originate not only from the supplementary motor area (SMA) in area 6, but also from 2 regions within the cingulate sulcus. The distribution of labeled neurons following tracer injections into different spinal cord segments indicates that corticospinal projections from the SMA and from the 2 cingulate regions are somatotopically organized. These findings together with other recent anatomical observations suggest that the corticospinal projections from the medial wall of the hemisphere provide the basal ganglia and limbic system with a somatotopically organized access to spinal cord mechanisms.

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During this last decade, nonlinear analyses have been used to characterize the irregularity that exists in the neuronal data stream of the basal ganglia. In comparison to linear parameters for disparity (i.e., rate, standard deviation, and oscillatory activities), nonlinear analyses focus on complex patterns that are composed of groups of interspike intervals with matching lengths but not necessarily contiguous in the data stream. In light of recent animal and clinical studies, we present a review and commentary on the basal ganglia neuronal entropy in the context of movement disorders.

Over the last 30 years, the functions (and dysfunctions) of the sensory-motor circuitry have been mostly conceptualized using linear modelizations which have resulted in two main models: the “rate hypothesis” and the “oscillatory hypothesis.” In these two models, the basal ganglia data stream is envisaged as a random temporal combination of independent simple patterns issued from its probability distribution of interval interspikes or its spectrum of frequencies respectively. More recently, non-linear analyses have been introduced in the modelization of motor circuitry activities, and they have provided evidences that complex temporal organizations exist in basal ganglia neuronal activities. Regarding movement disorders, these complex temporal organizations in the basal ganglia data stream differ between conditions (i.e., parkinsonism, dyskinesia, healthy control) and are responsive to treatments (i.e., l-DOPA, deep brain stimulation). A body of evidence has reported that basal ganglia neuronal entropy (a marker for complexity/irregularity in time series) is higher in hypokinetic state. In line with these findings, an entropy-based model has been recently formulated to introduce basal ganglia entropy as a marker for the alteration of motor processing and a factor of motor inhibition. Importantly, non-linear features have also been identified as a marker of condition and/or treatment effects in brain global signals (EEG), muscular activities (EMG), or kinetic of motor symptoms (tremor, gait) of patients with movement disorders. It is therefore warranted that the non-linear dynamics of motor circuitry will contribute to a better understanding of the neuronal dysfunctions underlying the spectrum of parkinsonian motor symptoms including tremor, rigidity, and hypokinesia.

The objective of the investigation was to determine what effect intracranial pathology has on alterations of superior sagittal sinus blood flow, and to determine the role of color flow Doppler imaging of the superior sagittal sinus in the diagnosis of intracranial pathology in the neonate and infant. One hundred examinations were performed prospectively in 96 patients. The velocity was determined with an angle correction at 30-60 degrees and was obtained with and without gentle transducer compression. Superior sagittal sinus thrombosis was identified in two patients by the absence of flow. Multiple t-tests for independent measures showed no clinically significant differences between flow velocities with regard to intracranial hemorrhage, ventriculomegaly, extracorporeal membrane oxygenation therapy or prematurity. The authors conclude that color flow Doppler can accurately diagnose superior sagittal sinus thrombosis and may be used to screen high risk neonates such as those with thrombosis elsewhere or those treated with extracorporeal membrane oxygenation. No clinically significant associations were found between superior sagittal sinus flow velocity and any of the parameters evaluated in this study.

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Intracerebral hematomas following evacuation of a subdural hematoma have been described in adults resulting from sudden decompression during the drainage of the hematoma. In infants an open fontanelle and patent sutures are expected to offer protection against sudden decompression. We report the occurrence of intracerebral hematoma in an infant following evacuation of a subdural hematoma. The multiplicity and centripetal spread of the postoperative hematomas suggested that they had resulted from sudden decompression.

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