Reduction cranioplasty for macrocephaly with long-standing hydrocephalus and non-fused fontanelle in Chiari malformation type I

Jong-Il Choi 0 Eun Sang Dhong 0 Dong-Jun Lim 0 Sang-Dae Kim 0 0 E. S. Dhong Department of Plastic surgery, Korea University Guro Hospital , Seoul, Korea 1 ) Department of Neurosurgery, Korea University Ansan Hospital , Ansan, Korea Introduction Because hydrocephalus is diagnosed and treated at an early stage in pediatric patients, pediatric neurosurgeons rarely encounter patients with hydrocephalic macrocephaly. There are even fewer cases of infants with long-standing hydrocephalus in whom macrocephaly progresses and is accompanied by skull defect due to malunion of suture lines despite long-term CSF diversion treatment. Case report We report the case of a male infant with Chiari malformation type I who presented with congenital hydrocephalus and occipital encephalocele that progressed to hydrocephalic macrocephaly with frontal skull defect, despite numerous cerebrospinal fluid diversion operations. The patient eventually recovered successfully after reduction cranioplasty. - Fontanelle bulging and macrocephaly with bony defect due to persistent hydrocephalus despite adequate choice and timing of treatment options is extremely rare. Macrocephaly refers to a condition where the circumference of the head is greater than two standard deviations above the mean circumference for a given age. A massive head size may lead to difficulties with head positioning and movement control in a child. If this condition persists, complications like developmental disruption, kyphosis, or scoliosis may occur. When the cranium remains unclosed, facial deformities, vulnerability to trauma, and cosmetic issues may arise. In addition, a massive head size that results in significant deformity may lead to psychosocial problems [1]. Therefore, macrocephaly with skull defect needs to be corrected at an appropriate time. Macrocephaly most commonly results from untreated or inadequately treated hydrocephalus [13] or from expanding chronic subdural hematomas [4, 5]. Various kinds of congenital anomalies may also be responsible for postnatal hydrocephalus. The treatment options and prognosis for an infant with Chiari I malformation secondary to hydrocephalus from an occipital encephalocele are less well known due to its low prevalence. The treatment of hydrocephalic macrocephaly with frontal skull defect is an uncommon circumstance, rarely faced by pediatric neurosurgeons. There are few reported cases of longstanding hydrocephalus in Chiari malformation type III that progress to macrocephaly with skull defect due to suture malunion despite various cerebrospinal fluid (CSF) diversion treatments. Therefore, we herein describe a case of hydrocephalic macrocephaly with bony defect in Chiari malformation type I, and its treatment with reduction cranioplasty, which markedly improved the quality of life of the patient and achieved good cosmetic results. A male baby with low body weight (2,530 g) was born at full term by cesarean section, while his twin brother was born with normal birth weight and no specific complications. An antenatal ultrasound investigation had already revealed an occipital encephalocele in the affected child. After birth, this was clinically confirmed, as the newborn presented with an encephalocele that measured 22.5 cm in size and was entirely covered with meninges. Magnetic resonance imaging (MRI) was performed the day after delivery and showed severe hydrocephalus and an occipital encephalocele. The cerebral aqueduct and fourth ventricle were collapsed, and consequent dilatation of the lateral and third ventricles were noted, along with the herniation of the lower brainstem and cerebellum into the cervical defect (Fig. 1). In order to prevent infection or rupture of the encephalocele sack, surgical closure of the defect was performed and was successful. Postoperatively, the hydrocephalus worsened, so a ventriculo-peritoneal (V-P) shunt was placed. On physical examination after the V-P shunt operation, the patients head circumference continued to increase gradually with massive frontal bossing, and the function of the shunt was not satisfactory. On the follow-up MRI scan, dilatation of the lateral and third ventricles, slight dilatation of the fourth ventricle, and evidence of tonsillar descent below the rim of the foramen magnum were noted (Fig. 2). Foramen magnum decompression and endoscopic third ventriculostomy (ETV) were performed to correct the associated obstructive hydrocephalus. However, ventriculomegaly persisted even after the ETV, and shunt infection had developed. The shunt device was removed. Extra-ventricular drainage (EVD) and antibiotic therapy took place multiple times, and a shunt reoperation was performed. A follow-up brain CT scan was done after the shunt reoperation, and there was an improvement in the long-standing hydrocephalus. However, macrocephaly was still evident and the anterior fontanelle still bulged open 32 months postnatally. Fig. 2 Preoperative MRI scan (T1-weighted mid-sagittal scan) demonstrating tonsillar herniation in the upper cervical level. Dilated lateral, third ventricle, and slightly dilated fourth ventricle are seen The defect measured 5761 mm in size along the anterior fontanelle. The skull was boat shaped; the anterior-posterior diameter was 168 mm and the bi-temporal width measured 120 mm. The cranial index was 0.71 (Fig. 4a). The patient underwent modified pi-procedure of reduction cranioplasty for cranial vault reshaping (Fig. 3). The coronal bone flap was advanced to the midline to cover the bone defect and two paired sagittal-parietal bone flaps were removed and grafted at the anterior fontanelle. Multiple barrel stave osteotomy at the level of the squamosal suture was performed, allowing the brain to expand laterally on both sides during intraoperative skull shortening. Postoperatively, the non-fused fontanelle with skull defect was occluded. The operative time (defined as the beginning of anesthesia until the end of anesthesia) was 6.5 h, and the blood loss associated with the surgery was 300 ml. After the successful correction of macrocephaly, the skull vault circumference decreased from 58 to 53 cm. The cranial index had changed to 0.75 (Fig. 4b). There were no postoperative complications. Early in infancy, the patient showed substantial developmental delays, manifested by failure to meet routine Fig. 1 Preoperative MRI scan (T1-weighted mid-sagittal scan) clearly demonstrating an occipito-cervical meningoencephalocele, sized approximately 22.5 cm with hypoplastic cerebellar structures jutting into the malformed sac. Cerebellar tonsillar herniation below the fourth ventricle, together with collapsed cerebral aqueduct and fourth ventricle are seen Fig. 3 Intraoperative view demonstrating macrocephaly with bony defect due to non-fused fontanelle Fig. 4 Pre- (a) and postoperative (b) 3D skull CT scans after successful correction of macrocephaly and occlusion of frontal bony defect with the described technique develop (...truncated)