Concerning the late diagnosis of certain cerebellopontine angle tumors.

The sensitivity of diagnostic methods for cerebellopontine angle lesions (auditory nerve electrophysiology, computed tomography scanning, magnetic resonance imaging) has increased in recent years. Paradoxically, in our experience this has not led to an increased percentage of tumors detected at an early stage. In 1975 20% of tumors were confined to the internal auditory canal, whereas only 6.6% were intercanalicular in 1988. A detailed analysis of 120 recent cases included first symptoms, time between first symptoms and diagnosis, symptoms at diagnosis, and size of tumor. We conclude the low percentage of intracanalicular tumors in the recent series results from: (1) rapid growth in some cases; (2) slow enlargement of the tumor over a long time without compression of adjacent cranial nerves leading to a paucity of symptoms; (3) misleading clinical pictures, including sudden hearing loss and hydrops; and (4) tumor symptoms masked by unrelated pathologic processes (otosclerosis, presbyacusis, trauma).