Mucocoele of the sphenoidal sinus eroding the petrous temporal bone

As mucocoeles of the air sinuses enlarge they produce pressure atrophy and expansion of the sinus walls, and tend to extend along the line of least resistance. The lesion is usually diagnosed initially as a neoplasm. Sphenoidal sinus mucocoeles are rare, about 60 cases having been reported. Only in a few of these was the correct diagnosis made on clinical and radiological findings. The common path of expansion is forwards into the orbit and posterior ethmoidal sinuses, and this produces ocular defects such as muscle paralysis, exophthalmos and visual disturbances from pressure on the optic nerve. The patient frequently complains of headache which is frontal or parietal and often unilateral. Other less common features include endocrine disturbance, 5th nerve pain and bulging of the posterior nasopharyngeal wall. Nasal symptoms and signs were present in only one third of the cases reported by Lundgren and Olin (1961). A 50-year-old labourer gave a history of headache in the left parietal region and left-sided deafness for two-and-a-half months. Prior to admission he had become generally unwell and noticed some diplopia and also unsteadiness in walking. There was no history of sinus disease. He was found to have decreased visual acuity in the left eye, although the visual fields were full and the fundi normal. There was also a mild left proptosis, small pupil and 6th nerve palsy. The deafness was sensori-neural, of moderate severity, and associated with a diminished left caloric response.