In contrast to other tumors of the CNS, IGs demonstrate a particular propensity to infiltrate along preexisting structures, including white matter tracts, perivascular spaces, and subventricular and subpial
compartments, conforming to and exploiting a terrain that is ostensibly familiar to the neoplastic cell type.
4,5,6,7) There is differing opinion as to whether GMH can also form due to neurons losing their way during migration, migrating in the wrong direction or migrating too far (into the subpial
space), and as to whether these heterotopic nests establish abnormal interconnections and exert abnormal trophic influences on surrounding tissue or whether only a limited number of axons exit these nests resulting in limited connectivity with other areas of the brain.
resection technique is employed during all the phases of this procedure (8,21,58).
Lesions are disseminated throughout the CNS, but have a predilection for optic nerves, subpial
spinal cord, brain stem, cerebellum, juxtacortical and periventricular white matter regions.
In eloquent areas the surgeon uses a subpial
dissection technique, where the pial bank is preserved against blood vessels and nerves, while the grey matter is dissected out and away from the white matter tracts, often using an ultrasonic aspirating device on very low suction and fractionation settings.
W Stewart Alexander an Australian pathologist, as a fatal infantile leukodystrophy that is characterized by astrocytic eosinophilic inclusions containing Rosenthal fibers, mainly located in the perivascular periventricular and subpial
spaces of the cerebral hemispheres, cerebellum, and brainstem (l,2).
Although CNS involvement by tuberculosis is seen in all age groups, there is a predilection for younger patients, with 60-70% of cases occurring in patients younger than 20 years of age 2 Haematogeneous spread from the lungs or gastrointestinal tract is most common, leading to small subpial
or subependymal infective foci.
Leptomeningeal involvement results from either hematogenous spread or rupture of subpial
or subependymal foci (known as Rich foci) into the subarachnoid space .
38,39) Of these, precursors of the granule cells and cerebellar nuclei cells, after leaving the upper rhombic lip, migrate tangentially through a subpial
stream, (9,38-40) while unipolar brush cells appear to migrate through the white matter (41) before settling in the inner granule cell layer of the cerebellar cortex (Fig.
Other modalities like immunosuppression and neurosurgical techniques like subpial
resections, hemispherectomy may warrant trial in extreme cases.
Therefore, an alternative surgical technique, termed multiple subpial
transection (MST), was developed to extend surgery to an epileptic focus located in highly functional cortical areas without inducing significant functional deficits.
Three types of lesions are found in the cerebral cortex, namely cortical-subcortical lesions involving the white and grey matter, small perivascular demyelinating intracortical lesions, and extensive subpial
demyelination bands that cover several gyri and three or four layers (Rudick & Trapp, 2009).