Vault reduction cranioplasty for extreme hydrocephalic macrocephaly

Reduction Cranioplasty in Cases of Hydrocephalic Macrocephaly: Pearls and Pitfalls of Computer-Assisted Surgery

Reduction cranioplasty may be indicated to address functional or cosmetic sequelae of hydrocephalic macrocephaly. With the advent of CAD/CAM digital workflow, surgeons can design and fabricate craniotomy guides, templates, and models that allow for precise cranial reconstruction. Although there are several advantages of virtual planning, pre-determined surgical plans may limit intraoperative flexibility, requiring surgeons to troubleshoot errors in pre-operative planning or model design. The purpose of this report is to present a series of cases demonstrating our institution's technique for single-stage reduction cranioplasty using a CAD/CAM workflow. This report will highlight the benefits and challenges associated with a contemporary digital workflow for reduction cranioplasty.

[Reduction cranioplasty for hydrocephalic macrocephaly: clinical observations and literature review]

Reduction cranioplasty for extreme hydrocephalic macrocephaly is performed for acquiring motor skills (head holding, sitting, moving), aesthetic correction and social adaptation of children. The authors analyze literature data and describe 2 patients with congenital hydrocephalic macrocephaly who underwent shunting surgery followed by reduction cranioplasty in early age using resorbable mini-plates. Reduction cranioplasty decreased skull volume, improved social adaptation of children and ensured favorable aesthetic outcome.

Case Report: Cranial Vault Reduction Cranioplasty for Severe Hydrocephalus

Extreme hydrocephalic macrocephaly is still encountered in developing countries due to delayed treatment, rapidly progressing hydrocephalus and family socioeconomic problems. Reduction cranioplasty was used with several techniques to address the issue. The study aimed to determine the safety and feasibility of barrel-stave technique for reducing the size of extreme hydrocephalic macrocephaly. Three post-diversion patients underwent surgical reconstruction. Children with head circumference more or equal to two standard deviation above mean on given age, no active wound at the area of surgery, presentation of sufficient “potential removable fluid” that allows dura reduction and no active shunt infection were eligible. The surgical procedure includes modified pi, barrel-stave technique, and diversion of the cerebrospinal fluid and subdural collection. Clinical data were recorded. Three patients with age range of 2 month to 2 years old underwent the surgery. Two patients had shunt implanted at least 1 month before the surgery and 1 patient had an ETV procedure 3 months before the reduction. The frontal-occipital circumference before surgery ranged from 50 to 63 cm. The maximum reduction that could be achieved was 15 cm. One patient (2 months old) died within 24 hour due to failure to cope with excessive blood loss. Two patients were followed up for 3 months and 6 months without complications. Reduction cranioplasty using barrel-stave techniques is an option for children with extreme large head that poses a mechanical or cosmetic problem. Risk and pitfalls should be considered and taken care meticulously, especially the age and blood loss.

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.