Non contrast CT Brain
Corpus callosal Agenesis evident by widely separated non converging lateral ventricles.
An associated heterotrophic grey matter seen as a mass iso dense to cortical grey matter and deep grey nuclei in right frontal lobe, a congenital malformation characterized by focal clumps of grey matter at abnormal location.
A congenital disorder of abnormal neuronal migration.
Gray matter stuck at wrong place.
Can be inherited or acquired (from maternal trauma, infection or toxin)
Normally sub ependymal germinal zone proliferates and form neuroblasts and glial cells which then migrates outwards towards cerebral convexity forming an outer cortical grey matter and inner white matter. Any interruption or arrest in the normal course of this neuronal migration leaves heterotrophic neuronal deposits. These being gray matter deposits follow same density and signal intensity as that of cortical gray matter, non enhancing.
Sub ependymal nodular heterotrophia – a focal or multi focal subependymal nodules.
Band heterotrophia – alternate band of gray and white matter , ‘ double cortex’.
Clinical presentation :
Seizures is most common, delayed milestones.
Closest differential is subependymal nodules of Tuberous sclerosis which often shows an associated calcification.
Surgery reserved for intractable Sz.
Resect small accessible Epileptogenic nodules.
Corpus Callosotomy if bilateral or diffuse unresectable lesions.