Gross enophthalmos after cerebrospinal fluid shunting for childhood hydrocephalus: the "silent brain syndrome".

PURPOSE To describe the clinical characteristics and ophthalmic management of 2 patients who developed gross enophthalmos after ventriculo-peritoneal shunting performed in their teenage years. A key radiologic feature is presented, and a conjectural mechanism is proposed for this disfiguring condition. METHODS Retrospective case note review for 2 patients requiring ophthalmic care for gross enophthalmos after prior ventriculo-peritoneal shunting. RESULTS Two patients, aged 24 and 25 years, presented with severe bilateral enophthalmos, bridging of all the tarsal plates off the ocular surface with secondary upper eyelid entropion, and significant lagophthalmos, associated with diffuse keratopathy. Both patients were of normal body weight, and neither had a history of anorexia nervosa. CT of the orbit revealed gross enophthalmos, with air entrapment between the globe and upper eyelids, together with a marked upward bowing of the orbital roof in the anterior cranial fossa, a newly recorded sign in this condition. One patient underwent bilateral orbital roof implants, and the other had bilateral upper eyelid entropion repair. CONCLUSIONS Progressive, severe, bilateral, symmetrical enophthalmos with bridging of the eyelids across the ocular surface due to upward bowing of the orbital roof many years after venticulo-peritoneal shunt in the absence of symptomatic intracranial disease are pathognomonic features of the "silent brain syndrome." A common feature was shunting in the early teenage years; although the enophthalmos had been noted for several years before presentation, the corneal symptoms had only become troublesome enough to seek ophthalmic care in their third decade, and the speed of development for this condition remains unclear. The authors suggest that a sudden reduction of raised intracranial pressure causes an "implosion" of the only available thin cranial bone-namely, the frontal plate of the orbit. Such remodeling might be greater if the bone was still relatively unmineralized, because of youth or preceding hydrocephalus. The expansion of orbital volume is responsible for the characteristic clinical features and symptoms and can be treated with placement of appropriately sized orbital roof implants or, if this is not desired, by upper eyelid entropion repair.