Temporary unilateral amaurosis with pneumosinus dilatans of the sphenoid sinus.

Pneumosinus dilatans (PSD), first described by Meyes in 1898, is an abnormal dilatation of one or more of the paranasal sinuses without bony erosion. The term sinus pneumocele indicates the presence of bony erosion. Review of the literature from 1968 to 1992 revealed 24 cases of idiopathic PSD and 17 cases of pneumocele of various paranasal sinuses. PSD occurred most commonly in the frontal sinus. Males were more often affected than females. The average age for males ranged from 16.5 for the maxillary sinus to 35.5 years for the sphenoid sinus. Pneumoceles occurred most commonly in the maxillary sinus. The average age for males ranged from 29 years for the frontal sinus and 47 years for the ethmoid sinus. Two patients (1 pneumocele and 1 PSD) had a temporary loss of vision. We report the case of a 37-year-old mountain climber who experienced temporary loss of vision in his left eye above 3000 m. Vision returned below 2000 m. High resolution computed tomography scan revealed pneumosinus dilatans of the sphenoid sinus with dehiscence of the optic canal on the left side. Endonasal microendoscopic resection of the anterior wall of the left sphenoid sinus was performed. The patient has remained symptom-free after 2 years of follow-up. Pneumosinus dilatans should always be considered in the differential diagnosis of sudden visual loss associated with atmospheric pressure changes.