Occipital Intradiploic CSF Pseudocyst: An Unusual Complication of a Ventriculoperitoneal Shunt Malfunction

Abstract

SUMMARY: We report a rare and unique complication of ventriculoperitoneal (VP) shunt malfunction. A progressively expansile, CSF-containing occipital intradiploic cyst developed in a 15-year-old boy at the site of cystoperitoneal shunt draining a Dandy-Walker cyst; the shunt was placed when the boy was 4 years old. A proposed pathogenesis of the lesion is discussed. Many complications of ventriculoperitoneal (VP) shunts have been previously described from common complications (eg, tube disconnection/obstruction, infection, and intraperitoneal CSF pseudocyst) to more esoteric ones (eg, bowel perforations, pleural effusions, shunt migration to the heart, and extrusion into or through the anus/vagina/scrotum).1,2 We report the case of a 15-year-old boy with a previous medical history including a diagnosis of a Dandy-Walker cyst with hydrocephalus, which required a VP shunt at age 6 months and a posterior fossa Dandy-Walker cystoperitoneal shunt connecting to the VP shunt through a Y connector at age 4 years. At 15 years old, the boy had an asymptomatic large, expansile, intradiploic occipital cyst containing CSF as a result of a disconnected VP shunt tube in the chest wall and an occluded intracranial catheter of the posterior fossa cystoperitoneal shunt. Case ReportThe reported patient is a 15-year-old boy who presented for a VP shunt evaluation before trying out for a football team. At age 6 months, the patient was diagnosed with a Dandy-Walker cyst and had a VP shunt placed for relief of his hydrocephalus. At age 4 years, the patient experienced progressive headaches and projectile vomiting and was found to have a disconnected shunt. MR imaging examination showed an enlarging Dandy-Walker cyst with compression of the brain stem and cerebellum. A cystoperitoneal shunt was placed, which was connected to the repaired VP shunt via a Y connector (Fig 1). At the time of surgery, it was found that the Dandy-Walker cyst was under pressure.When the patient presented for a football pregame check-up at age 15 years, he was asymptomatic and denied any signs or symptoms of shunt malfunction. Plain radiographs revealed a break in the shunt catheter at the level of the right upper chest. Skull radiographs showed a cystic expansion of the occipital diploic space measuring 10 ϫ 10 ϫ 5 cm in the transverse, superoinferior, and anteroposterior dimensions, respectively (Fig 2). The reservoir of the posterior fossa cystoperitoneal shunt had migrated into the enlarged diploic space. Head CT examination confirmed the intradiploic location of the reservoir and the expansion of the diploic space extending from the supraoccipital into the basioccipital part of the occipital bone, including the occipital condyle and lower clivus (Fig 3).The patient was taken to the operating room, where it was found that the protruded occipital outer table was paper thin and the expanded diploic space contained CSF under pressure. The intracranial

A systematic approach in the diagnosis of paediatric skull lesions: what radiologists need to know

“…They are characterised by a breach of the inner table with a tear of dura mater, with intradiploic accumulation of CSF in a sac with a covering lined by arachnoid membrane. The time interval between trauma and diagnosis of post-traumatic intradiploic pseudomeningocele is variable, ranging from 10 months to 50 years [140-142], with the occipital region being the most common location.…”

Posttraumatic Intradiploic Leptomeningeal Cyst: A Rare Complication of Head Trauma

“…These cysts are characterized by fracture of inner table and laceration/tear of dura mater with accumulation of CSF in a sac with a covering lined by arachnoid membrane and situated within the diplopic space. Almost all patients give previous history of head trauma with the time interval between trauma and diagnosis of posttraumatic intradiploic leptomeningeal cyst being extremely variable, ranging from 10 months to even 50 years [ 7 – 9 ]. While occipital region is the most common location, PTIDLCs have also been reported in other regions of the skull [ 7 ].…”

“…The thickness of the occipital bone and the thick muscle cover buttressing its outer table explain the predilection of this entity to occur in the occipital region. Other contributory factors in this regard may include the more capacious diploic space as well as cartilaginous origin of occipital bone compared to the membranous origin of the rest of the calvaria [ 9 , 11 ].…”

Intradiploic occipital pseudomeningocele in a patient with remote history of surgical treatment of Chiari malformation

“…Intradiploic cysts (leptomeningeal cyst or arachnoid cyst) involving the cranial hemispheric convexities, the skull base, and the posterior fossa have been reported. [2][3][4][5]11,13,17,18 We report a case of a delayed finding of a posterior fossa intradiploic CSF collection related to remote treatment of Chiari malformation with associated occipitocervical bony fusion in a patient originally treated as a young child.…”