Vault reduction cranioplasty for extreme hydrocephalic macrocephaly

Modified Bilateral Pi Craniectomy Technique for Reduction Cranioplasty: Novel Technique

OBJECTIVE

Severe hydrocephalic macrocephaly can cause significant morbidity in infants due to positioning difficulties, skin breakdown, and poor cosmesis. Many surgeons over the past decades have described a variety of surgical techniques of reduction cranioplasty. In this article, the authors describe a novel technique for skull reduction cranioplasty with modified bilateral Pi craniectomy.

METHODS

Anterior coronal and posterior lambdoid bone cuts are performed to extend inferiorly toward the sqamous bone. Last bone cuts are made connecting the parasagittal burr holes bilaterally, thus isolating and de-roofing of the sagittal suture. Bilateral peninsular bone flaps are reduced medially aiming to approximate the upper borders of both flaps. Edges of frontal and occipital bone can be resected and shaved to achieve smooth round contour of the reconstruct. The final reconstruct can be fixated with metal meshes.

RESULTS

In our technique, modified bilateral Pi craniectomy is simple and effective reduction cranioplasty technique, as the technique does not require bone graft resection and reconstruction of the grafts making the time of the surgery short with decreased possible complications. Also, the amount of bone resection, bone bending, and shaving of the bone edges can be controlled and adjusted during the. An important issue is that this technique avoids posterior skull reconstruction which is more risky, as many patients are bed ridden with secondary compressed and flat occiput.

CONCLUSIONS

Modified bilateral Pi craniectomy is a simple and effective technique for cranial vault reduction, especially in flat-occiput cases. Good understanding of the structural abnormality and the pathophysiological mechanisms of the possible complications is very important for performing proper surgical reconstruction.

Reverse Distraction for Treatment of Hydrocephalic Macrocephaly in Late Childhood

Macrocephaly diminishes quality of life for children whose head size inhibits independent mobility and appropriate interaction with caregivers. Cranial reduction is a method of addressing these issues, historically with a high morbidity due most commonly to bleeding and shunt complications. The authors present a 9-year-old girl with holoprosencephaly and severe macrocephaly from progressive hydrocephalus who underwent cranial reduction via reverse distraction osteogenesis, a method to slowly reduce the skull volume. The patient underwent circumferential occipital temporoparietal frontal craniotomy with placement of 4 cranial distractors, followed approximately 1 month later by removal of the distractors and cranioplasty with resorbable fixation devices. The patient demonstrated significant postoperative improvement in head control and interaction in school activities. This is the oldest patient with macrocephaly treated with reverse distraction in the literature to date. The slow contraction of the cranial vault with limited bony surgery at the time of initial reduction provides an additional safety margin, and should be considered in older children presenting with profound macrocephaly.

Early postnatal cranial vault reduction and fixation surgery for severe hydrocephalic macrocephaly

OBJECTIVE Infants with severe hydrocephalus and extreme macrocephaly typically undergo CSF diversion early in life, which can result in significant cranial deformity due to CSF overdrainage. In this scenario, overlap of the cranial plates can precede the development of secondary synostosis and/or severe, permanent cranial deformity. As a result, extensive cranial vault remodeling is sometimes undertaken later in life, which is often challenging and has been associated with mortality and a high morbidity rate. The authors have previously described a technique for early postnatal cranial vault reduction and fixation (CVRF), in which the calvarial bones are stabilized using absorbable fixation plates in the neonatal period, in an attempt to facilitate patient positioning, simplify hydrocephalus management, and improve cosmesis. Here, the authors describe their institutional experience managing patients with extreme neonatal hydrocephalus with CSF diversion, with and without CVRF, over the past 12 years. METHODS The authors retrospectively reviewed the charts of infants with extreme hydrocephalus (head circumference > 49 cm) treated at their children's hospital with ventriculoperitoneal shunting, with or without CVRF, between 2005 and 2017. Data collected included age, sex, etiology of hydrocephalus, type of CVRF performed (anterior, posterior, or combined), follow-up duration, orbitofrontal circumference, craniometric measurements, intraoperative blood loss, operative duration, and postoperative complications. Developmental data were collected using the third edition of the Ages and Stages Questionnaire. Photographic imaging was used to demonstrate esthetic outcomes, and family questionnaires were used to evaluate satisfaction with the esthetic outcome. RESULTS Eleven patients with extreme neonatal hydrocephalus underwent CSF shunting; 5 underwent shunting alone and 6 patients underwent shunting and CVRF. For patients who underwent shunting and CVRF, the median age at CVRF was 6 days and the median interval between shunt placement and CVRF was 2.5 days. The mean extent of calvarial vault volume reduction was 44.5% (± 3.9%). The mean duration of the CVRF procedure was 108 minutes, and 5 of 6 patients required intraoperative transfusion. Of the 5 patients who underwent shunting alone, 3 developed severe cranial deformities. Of 6 patients who underwent shunting and CVRF, 1 had a poor cosmetic outcome. In the shunting-alone group, 2 patients died and 1 required extensive cranial vault correction at 10 years of age. One patient in the shunting and CVRF group also died. CONCLUSIONS CVRF in combination with CSF shunting in the neonatal period can simplify the treatment of the rare case of severe hydrocephalic macrocephaly and leads to cosmetic outcomes that are considered good by their families.

Reduction cranioplasty with the aid of simulated computer imaging for the treatment of hydrocephalic macrocephaly

OBJECT

The occurrence of hydrocephalic macrocephaly is uncommon. When the condition does occur, it is usually seen in infants and young children. Patients with this disorder have an excessively enlarged head and weak physical conditions. Various surgical techniques of reduction cranioplasty for the treatment of these patients have been reported. In this study, a revised surgical procedure with the aid of simulated computer imaging for the treatment of hydrocephalic macrocephaly is presented.

METHODS

Five cases of hydrocephalic macrocephaly in children ranging in age from 16 to 97 months were reviewed. These patients underwent surgical treatment at The First Affiliated Hospital of Xiamen University over a period of 4 years from January 2007 to January 2011. After physical examination, a 3D computer imaging system to simulate the patient's postoperative head appearance and bone reconstruction was established. Afterward, for each case an appropriate surgical plan was designed to select the best remodeling method and cranial shape. Then, prior to performing reduction remodeling surgery in the patient according to the computer-simulated procedures, the surgeon practiced the bone reconstruction technique on a plaster head model made in proportion to the patient's head. In addition, a sagittal bandeau was used to achieve stability and bilateral symmetry of the remodeled cranial vault. Each patient underwent follow-up for 6-32 months.

RESULTS

Medium-pressure ventriculoperitoneal shunt surgery or shunt revision procedures were performed in each patient for treating hydrocephalus, and all patients underwent total cranial vault remodeling to reduce the cranial cavity space. Three of the 5 patients underwent a single-stage surgery, while the other 2 patients underwent total cranial vault remodeling in the first stage and the ventriculoperitoneal shunt operation 2 weeks later because of unrecovered hydrocephalus. All patients had good outcome with regard to hydrocephalus and macrocephaly.

CONCLUSIONS

There are still no standard surgical strategies for the treatment of hydrocephalic macrocephaly. Based on their experience, the authors suggest using a computer imaging system to simulate a patient's postoperative head appearance and bone reconstruction together with total cranial vault remodeling with shunt surgery in a single-stage or 2-stage procedure for the successful treatment of hydrocephalic macrocephaly.

Cranial reduction and fixation with a resorbable plate combined with cerebrospinal fluid shunting for difficult-to-manage macrocephaly related to hydrocephalus

The management of newborns with extreme macrocephaly related to hydrocephalus can be difficult; balancing the treatment of severe cranial deformity with optimal hydrocephalus management can be complicated. Excessive CSF drainage can result in significant suture overlap that leads to difficulties in patient positioning, secondary synostosis, and long-term aesthetic complications. Delayed cranial reduction and remodeling procedures carry significant risk, and the aesthetic outcomes have sometimes been poor. The authors describe a newborn with severe macrocephaly who underwent shunt placement followed by a limited cranial reduction and fixation procedure using an absorbable plate within the 1st week of life. The procedure produced an immediate intracranial volume reduction of 49%. This novel management strategy facilitated patient positioning, simplified hydrocephalus management, and provided an excellent aesthetic outcome.

The developmental trajectory of brain-scalp distance from birth through childhood: implications for functional neuroimaging

Measurements of human brain function in children are of increasing interest in cognitive neuroscience. Many techniques for brain mapping used in children, including functional near-infrared spectroscopy (fNIRS), electroencephalography (EEG), magnetoencephalography (MEG) and transcranial magnetic stimulation (TMS), use probes placed on or near the scalp. The distance between the scalp and the brain is a key variable for these techniques because optical, electrical and magnetic signals are attenuated by distance. However, little is known about how scalp-brain distance differs between different cortical regions in children or how it changes with development. We investigated scalp-brain distance in 71 children, from newborn to age 12 years, using structural T1-weighted MRI scans of the whole head. Three-dimensional reconstructions were created from the scalp surface to allow for accurate calculation of brain-scalp distance. Nine brain landmarks in different cortical regions were manually selected in each subject based on the published fNIRS literature. Significant effects were found for age, cortical region and hemisphere. Brain-scalp distances were lowest in young children, and increased with age to up to double the newborn distance. There were also dramatic differences between brain regions, with up to 50% differences between landmarks. In frontal and temporal regions, scalp-brain distances were significantly greater in the right hemisphere than in the left hemisphere. The largest contributors to developmental changes in brain-scalp distance were increases in the corticospinal fluid (CSF) and inner table of the cranium. These results have important implications for functional imaging studies of children: age and brain-region related differences in fNIRS signals could be due to the confounding factor of brain-scalp distance and not true differences in brain activity.