Neurosurgery and the glymphatic system.

The discovery of the glymphatic system has fundamentally altered our comprehension of cerebrospinal fluid transport and the removal of waste from brain metabolism. In the past decade, since its initial characterization, research on the glymphatic system has surged exponentially. Its potential implications for central nervous system disorders have sparked significant interest in the field of neurosurgery. Nonetheless, ongoing discussions and debates persist regarding the concept of the glymphatic system, and our current understanding largely relies on findings from experimental animal studies. This review aims to address several key inquiries: What methodologies exist for evaluating glymphatic function in humans today? What is the current evidence supporting the existence of a human glymphatic system? Can the glymphatic system be considered distinct from the meningeal-lymphatic system? What is the human evidence for glymphatic-meningeal lymphatic system failure in neurosurgical diseases? Existing literature indicates a paucity of techniques available for assessing glymphatic function in humans. Thus far, intrathecal contrast-enhanced magnetic resonance imaging (MRI) has shown the most promising results and have provided evidence for the presence of a glymphatic system in humans, albeit with limitations. It is, however, essential to recognize the interconnection between the glymphatic and meningeal lymphatic systems, as they operate in tandem. There are some human studies demonstrating deteriorations in glymphatic function associated with neurosurgical disorders, enriching our understanding of their pathophysiology. However, the translation of this knowledge into clinical practice is hindered by the constraints of current glymphatic imaging modalities.

Atypical Virchow-Robin SpacesMimicking Cystic Primary Brain Tumor ­ Clinical Report and Literature Review

The Virchow-Robin spaces (VRSs), which are often incidentally observed in modern structural neuroimaging examinations, are small cystic cavities that usually surround the small arteries and arterioles at the level of basal ganglia, the anterior perforated substance and the thalamic-mesencephalic junction. Typically, they have similar physicochemical characteristics to cerebral spinal fluid (CSF) and there is no contrast enhancement on brain CT andMRI images. Its real meaning is unknown, although some contemporary studies have suggested that it might be related to certain traumatic brain injury or several other central nervous system (CNS) disorders, as degenerative diseases. Occasionally, some wide and atypical VRS may be mistaken for primary cystic brain tumors, especially in the context of large and symptomatic lesions, multiple clustered cysts, cortical lesions and if there is adjacent reactive gliosis. The present paper reports four patients who were affected by atypical VRS mimicking brain tumors that required imaging follow-up or even a biopsy to confirm the diagnosis or to indicate the correct approach. Although it is not so unusual, one of them occurred concomitantly and adjacent to a diffuse glioma (co-deleted 1p19q, WHO-GII).

Reversible Focal Dystonia Secondary to Giant Perivascular Spaces.

Giant perivascular spaces (PVS) are rare, CSF-filled, dilated cavities lined by the pia mater that are most often asymptomatic radiological findings but can sometimes cause neurological symptoms. We present two exceptional cases of secondary focal dystonia induced by the mass effect on the basal ganglia caused by giant diencephalic PVSs. In both cases, we chose a surgical stereotactic drainage approach as a treatment strategy that allowed controlling the movement disorders. The beneficial therapeutic effect was sustained at long-term follow-up. We believe that similar cases could be addressed successfully with this method.

Cerebrospinal fluid leakage after posterior fossa surgery may impair brain metabolite clearance.

The discovery of the important role of cerebrospinal fluid (CSF) drainage of cerebral metabolite waste, known as the glymphatic system, has changed our view of brain waste clearance. We recently performed experiments to evaluate the glymphatic system in non-human primates (NHP). Here, we report the case of an NHP with iatrogenic CSF leakage. In this animal, solute transport through the brain, assessed by gadolinium injection in the CSF, was severely impaired by iatrogenic pseudomeningocele. This observation raises an important question: does brain surgery, and particularly posterior fossa surgery, lead to chronic impairment of parenchymal CSF circulation and solute transport?