Mucocele generally exists in the nasal and orbital cavities of extracranial space . Some of them, however, extend intracranially resulting in compression of the brain and cranial nerves . The authors encountered a very rare case of ethomoid sinus pyocele extending not only intracranially but also into the intradural space. The patient was a 34-old-year male who had a sinusitis 24 years ago . In addition, he suffered severe head injury with fracture of the frontal base of the skull when 15 years

more »

... old . He was admitted to our hospital on February 7, 1978, with chief complaints of severe headache and vomiting . Neurological examina tions on admission revealed left hyposmia and meningeal irritation but no occular signs . Plain and tomogram X-ray films of the skull showed cloudy shadow in the left ethmoid sinus and destruction of the roof of the same sinus . The left common carotid angiogram demonstrated no remarkable changes . CT-scan (axial and coronal sections) showed enhanced dumbbell like mass lesion, due to expansion of the ethmoid sinus mucocele into the intradural space through bone defect at the left frontal base. Removal of the intracranial portion was performed by bifrontal craniotomy on February 22, 1978, and defects of the dura mater and bone of the frontal base were confirmed . The postoperative course was uneventful and he became free from headache and vomiting . The patient is now wait ing for otological radical residual extracranial lesion operation. It is assumed that the ethmoid sinus mucocele extended into the intradural space which was less resistant than the extradural space because of defects of the dura mater and bone of the left frontal base affected by basis fracture . We could not find reports of any other case like this in Japan .