[Changes in the sensitivity of the cornea in patients with intracerebral tumors. Studies of patients with meningioma of the cranial base and neurinoma of the trigeminal nerve and the vestibulocochlear nerve using the Draeger esthesiometer].

The center of the cornea was measured preoperatively in 29 patients suffering from intracranial tumors (acoustic neuroma, trigeminus neuroma, basal meningioma). These measurements were made with the Draeger electronic-optical esthesiometer; the results were supplemented by an analysis of tumor diameters determined by computer tomography. In each case one-half of the patients with acoustic neuromas and medial meningiomas of the wing of the sphenoid bone manifested a reduction in sensitivity at the center of the ipsilateral cornea (normal: 0.8 to 1.7 x 10(-5) N). The diameters of the sensitivity-reducing acoustic neuromas ranged from 15 mm to 45 mm. It may be deduced both from the topographic conditions at the skull base in the vicinity of the porus acusticus internus and from the conditions associated with a pressure-induced lesion of a peripheral nerve that medial acoustic neuromas as small as 10.1 mm in diameter can lead to a reduction in the conductivity of the ipsilateral trigeminal nerve. Only when they attain a diameter of 28.4 mm and when the proportions of the skull base are equally spacious do the acoustic neuromas regularly cause an ipsilateral corneal hypesthesia.