ABSENCE OF THE SEPTUM-PELLUCIDUM AND RELATED DISORDERS

We present an illustration of the spectrum of intracranial abnormaliti es associated with absence of the septum pellucidum to better define a nd illustrate this disorder. CT and 1.5 Tesla MRI examinations of fift een Patients with absence of the septum pellucidum were meticulously a nalyzed and correlated with clinical and laboratory studies. The findi ngs were compiled and categorized based upon the presence and type of associated radiologic abnormalities. Absence of the septum pellucidum may occur as an isolated abnormality (n = 3). In most patients (n = 12 ), associated complex developmental abnormalities are present which in clude heterotopias, hypoplastic falx, ventricular clefts, encephalocel e, small pituitary gland, small optic nerves and chiasm, and corpus ca llosal dysgenesis. Inferior pointing and a squared-off appearance of t he frontal horns are frequently noted. These, or other, more severe ve ntricular configuration deformities are present in all patients. We ha ve portrayed the complete range of findings associated with absence of the septum pellucidum using an illustrative approach to clarify the d ifferent patterns of radiologic abnormalities which may be seen with t his complex entity.