Pituitary and Parapituitary Tumours. Value of Perimetry in Diagnosis.

THE occurrence of pallor of the optic discs and bitemporal field defects suggests to every ophthalmologist the possibility of a pituitary tumour. This diagnosis is usually confirmed by x-ray examination of the skull, when the classical signs of ballooning of the sella turcica with backward displacement or erosion of the posterior clinoid processes and, in more advanced cases, gross enlargement of the pituitary fossa may be found. The significance of optic atrophy and bitemporal field defects when the sella turcica seemed normal in the roentgenogram was first emphasized by Cushing (1930) as suggestive of other tumours in this region, such as suprasellar meningiomata, craniopharyngiomata, gliomata, and aneurysms, and also of pituitary adenomata which may fail to enlarge the sella but spread upwards to involve the chiasm. McConnell and Mooney (1938) pointed out that, when a tumour is postchiasmal in situation, the optic discs may remain normal for a very long time, and Walsh (1957) mentions that normal discs may be seen in such circumstances even after the onset of complete blindness. The significance of scotomatous field defects, unilateral in some cases, as a presenting sign of pituitary tumours has been re-emphasized by Kelly (1962). The typical progression of the field defect from the early loss in the upper temporal quadrants is clockwise in the right field and anti-clockwise in the left. When, however, a tumour spreads forwards to involve one optic nerve, there is often a temporal or nasal hemianopia in one field (depending upon whether the anterior angle of the chiasm is involved from the medial or lateral side) followed by blindness in the eye on this side, and the simultaneous or later appearance of a temporal field defect in the other (Scott, 1957); this was the position in both the patients mentioned below. Negative plain x-ray findings, therefore, in suspected cases of pituitary tumour should not dissuade the ophthalmologist from this diagnosis, particularly in the presence of such suggestive perimetric evidence. Investigations by the neurologist and endocrinologist may be helpful but, unfortunately, are often unrevealing and, in such circumstances, more elaborate x-ray examinations such as angiography and air studies are needed to establish the diagnosis. Alfano, Almeida, and Whitworth (1963) reported two cases of far-advanced tumours, one a craniopharyngioma and the other a suprasellar meningioma, presenting with optic atrophy and irregular bitemporal field defects, where both plain skull x rays and neurological examinations were normal. When, however, angiography was performed, there was shown to be unmistakable evidence of a space-occupying lesion in the region of the optic chiasm and, as a result, craniotomy was undertaken with gratifying results.