The roentgenographic finding of enlarged internal auditory canal with flaring of the porus acusticus is highly suggestive of acoustic neurinoma. Despite the occurrence of this finding in a patient with neurofibromatosis, a complete evaluation led to exclusion of a diagnosis of cerebellopontine angle tumor.
REPORT OF A CASE
A 45-year-old man with long-standing neurofibromatosis was admitted to the Tampa Veterans Administration Hospital, University of South Florida College of Medicine, with a 2.5-year history of decreased hearing in both ears, worse on the left. On physical examination, numerous subcutaneous nodules were noted on the face and body and hearing was markedly decreased in both ears, more so on the left than the right.Towne's projection of the skull (Figure) showed widening of both internal auditory canals with flaring of the porus acusticus bilaterally and erosion of the petrous tip on the left, highly suggestive of masses in the cerebellopontine angles.
Murtagh FR, Boyd RE, Okulski TA. Internal Auditory Canal Flaring in Neurofibromatosis Without Acoustic Neuroma. Arch Neurol. 1980;37(12):785. doi:10.1001/archneur.1980.00500610065013