DIOPATHIC orbital inflammation is a clinical and patho- logical condition usually seen by the ophthalmologist, but when it extends intracranially the patient is re- ferred to a neurosurgeon. It is composed of a nonspecific inflammatory infiltrate of the fatty tissue within the orbit. Occasionally, the disease may extend into tissues outside the orbit. We present a case with intracranial extension that occurred in the youngest patient reported to date and having the broadest and most diffuse intracranial ex- tension. Case Report This 16-year-old girl complained of blurred vision in the left eye and vertical diplopia in August 1993. By De- cember 1993, she had marked visual loss with left eye pto- sis. Her extraocular movements were intact. Examination. She was first seen by the neurosurgical service in February 1994 and was unable to count fingers using her left eye. Examination revealed ptosis and pro- ptosis in the left eye with only light perception; the right eye had normal visual acuity. There was no restriction in the extraocular movements. Her left pupil was amaurotic. Funduscopic examination showed a pale left disc with blurred margins. The remainder of the neurological exam- ination was normal. Blood tests, including antinuclear antibody, Complement 3, Complement 4, venereal dis- ease, lupus erythematosus, hepatitis profile, cytomegalo- virus and herpes titers, and serum electrophoresis, were normal. The erythrocyte sedimentation rate was slightly elevated. Chest x-ray films, purified protein derivative test, and cerebrospinal fluid analysis were unremarkable. A computerized tomography (CT) scan of the head showed a soft-tissue mass inside the left orbit. The intra- cranial anatomy was unremarkable. Magnetic resonance (MR) imaging of the head showed thickened and diffuse contrast enhancement of the meninges in the left cerebral J Neurosurg 85:510–513, 1996 510 Idiopathic orbital inflammation with intracranial extension Case report ORLANDO DE JESÚS, M.D., JAIME A. INSERNI, M.D., ANARDA GONZALEZ, M.D., F.C.A.P., AND LILLIAN E. COLÓN, M.D. Section of Neurosurgery and Department of Pathology, University of Puerto Rico, San Juan, Puerto Rico U Idiopathic orbital inflammation or orbital pseudotumor with intracranial extension is a rare condition. It consists of a nonspecific infiltrate of the fatty tissue of the orbit that extends through one or more foramina into the adjacent intracra- nial tissue. The lesion mimics an infectious or neoplastic lesion. The authors present a case involving the youngest patient yet reported, with the broadest intracranial extension. Only 17 previous cases have been reported. The principal symptoms include decreased visual acuity and proptosis. Extension commonly develops through the superior orbital fissure into the middle cranial fossa and the cavernous sinus. The initial treatment is a regimen of high-dose steroids, with radiotherapy given in unresponsive cases. KEY WORDS • idiopathic orbital inflammation • orbital pseudotumor • intracranial extension I J. Neurosurg. / Volume 85 / September, 1996 FIG. 1. Coronal T 1 -weighted magnetic resonance image after gadolinium administration showing thickened and marked en- hancement of the left temporoparietal dura and the tentorium.