Traumatic rupture of an intracranial dermoid cyst: Case report and literature review
A 47-year-old healthy female struck the back of her head on a shelf in a closet at her home and suffered a transient loss of consciousness. She had a headache immediately thereafter and this progressively worsened over the next 2 days. She also developed nausea and vomiting and photophobia over this time interval. On physical examination at initial presentation to our hospital, she was found to have nuchal rigidity, but otherwise her neurological examination was unremarkable. A noncontrast computer tomography (CT) scan revealed a heterogeneous very low attenuation lesion extending from the floor of the anterior cranial fossa superiorly along the falx, with diffuse scattered areas of low-attenuation throughout the subarachnoid space and lateral ventricles. These areas of low attenuation resembled the appearance of pneumocephalus. Magnetic resonance imaging (MRI) scans revealed a large multi-lobulated lesion extending along the floor of the left anterior and middle cranial fossae that was hyperintense on T1 weighted sequences at all locations except at the skull base attachment at the planum sphenoidale, where it was hypointense. Droplets of T1 hyperintense material were present throughout the subarachnoid space, including the sylvian fissures bilaterally, the quadrigeminal cistern, the ambient cisterns, and sulci over the frontal convexity. Fat-fluid levels were present throughout the ventricular system, with evidence of obstructive hydrocephalus [Figures and ].\nThe patient was immediately started on high dose intravenous (IV) steroids and monitored in the intensive care unit. Two days after admission, her symptoms of headaches and nausea had resolved. The patient was taken to the operating room on hospital day three. The tumor was removed via a left fronto-temporal craniotomy and orbital osteotomy with combined transsylvian, sub-frontal, and transcortical-transventricular approaches. The sylvian fissure was opened widely, and large amounts of fat globules as well as some hair fragments were found within the fissure. The ventricular contents of the ruptured cyst were approached through a small corticectomy in the middle frontal gyrus. The frontal horn of the lateral ventricle was entered, where a large amount of fatty material expressed itself under pressure. Sebaceous material and hair were removed from a contained cyst that was dissected away from the surrounding ependyma. The sub-frontal exposure allowed access to the remainder of the cyst at the skull base, where it was dissected away from the optic nerve and the carotid artery in a piecemeal fashion and away from the dura of the skull base. During the dissection, and at the conclusion of the case, the ventricular system and subarachnoid space were thoroughly irrigated with saline solution.\nOnce a gross total removal of the cyst was achieved, communication between the basal-frontal and the intraventricular approaches was accomplished and a septostomy was performed. A ventricular catheter was placed and externalized to allow residual fat droplets and sebaceous material in the ventricular system a path to exit the cranium []. The postoperative course was uneventful; the ventriculostomy catheter was removed successfully 3 days after surgical intervention, and the patient was discharged home on postoperative day 4 on a tapering dosage of steroids. Histo-pathologic examination of the surgical specimens showed the wall of a ruptured dermoid cyst, with the typical squamous epithelial lining, and dispersed pilosebaceous units (hair follicles and associated sebaceous glands) with some focal calcification [].\nTwo weeks after discharge the patient was seen in clinic with worsening headaches and a subgaleal fluid accumulation. Repeat head CT showed evidence of dilatation of the ventricular system consistent with communicating hydrocephalus. The patient underwent placement of a right frontal ventriculo-peritoneal shunt.