A computer-assisted diagnostic and treatment concept to increase accuracy and safety in the extracranial correction of cranial vault asymmetries.

PURPOSE: Proteus syndrome is described as a progressive, asymmetric, disproportional overgrowth of various parts of the body. The theory of somatic mosaicism is widely accepted to be the cause of this disease. Affected patients present very heterogeneous symptoms, but in about 30% craniofacial deformities are the leading clinical features. Because no causal therapy exists, treatment options are limited to surgical improvement of functional constraints. MATERIALS AND METHODS: A computer-assisted method was used to increase the accuracy and safety of bone removal in the extracranial correction of cranial vault asymmetries. Descriptions of the diagnosis, preoperative planning, and intraoperative management of craniofacial dysmorphia caused by Proteus syndrome in a 6-year-old boy are presented. After computed tomography-based generation of a virtual 3-dimensional (3D) model of the patient and a haptic stereolithographic model to display the special pathology, flow-sensitized 4-dimensional magnetic resonance imaging was performed to clarify the properties of vascular formation inside the hyperostosis. To transfer the mathematically optimized preoperative planning of a new skull shape to the patient, a surgical guide was fabricated by rapid manufacturing. Intraoperative 3D real-time navigation was installed as an additional visualization and security feature. RESULTS: The surgery could be performed safely and quickly. Postoperative imaging showed that the surgical plan was realized with high accuracy. CONCLUSION: This newly developed and validated method can be successfully implemented in the operating room environment.

Enabling an unimpeded surgical approach to the skull base in patients with cranial hyperostosis, exemplarily demonstrated for craniometaphyseal dysplasia.

Craniometaphyseal dysplasia is an extremely rare, genetic bone-remodeling disorder. Comparable to osteopetrosis, fibrous dysplasia, and other infrequent conditions, craniometaphyseal dysplasia is characterized by progressive diffuse hyperostosis of the neuro- and viscerocranium. Affected patients present with a pathognomonic dysmorphia: macrocephalus, hypertelorism, bulky facial skeleton, and a prominent mandible. Progressive thickening and petrification of the craniofacial bones can continue throughout life, often resulting in neurological symptoms due to obstruction of the cranial nerves in the foramina and therefore immediately requiring neurosurgical interventions to avoid persistent symptoms with severe impairment of function. Treatment is largely infeasible given the lack of suitable tools to perform a craniotomy through the gross calvarial bone. In this paper, the authors present a complete process chain from the CT-based generation of an individual patient's model displaying his pathology to optimized preoperative planning of the skull's shape with a thickness of about 6-7 mm. For concise verification of the surgical plan in an operating room environment, a 3D real-time navigation prototype system was utilized. To guarantee realization of the surgery in a reasonable time frame, the mechanical tools were preoperatively selected for optimizing the ablation rate in porcine and bovine bone, which were comparable to that in the patient. This process chain was developed in a modular way, so that it could be easily adopted completely or partially for other surgical indications. A 21-year-old man was treated according to this sophisticated concept. Skull bone more than 50 mm thick in some regions was reduced to physiological thickness. The patient was thus in a stage that neurosurgical interventions could be performed with a regular risk within a reasonable time of treatment.

[Problems in the development of a comprehensive three-dimensional databank of the human skull for the preoperative preparation of an exact implant for the treatment of bone defects]. / Problematik des Aufbaus einer Datenbank dreidimensional erfasster menschlicher Schädel als Voraussetzung für eine präoperative Anfertigung passgenauer Implantate zum Ausgleich von Knochendefekten.

Various human skulls were scanned with a laser scanner. Impressive Landmarks of the skull were determined and tested to be comparable stored in a uniform coordinate system for subsequent 3-d reconstruction. The Rhinion, the Nasion, the Spina nasalis anterior, the Prosthion, and the Opisthokranion were found to be very qualified for the adjustment in the median plane. The frontal plane was defined by the Rhinion and the Spina nasalis anterior. The Mastoidealia, the Zygomaxillaria and the Orbitalia were used to align the skull in the horizontal plane. The qualification of the database as a fundamental part for the comparison of human skulls and for the discovery of similarities to patient skulls with bone defects is demonstrated by means of 2 clinical cases. A subsequent result is the application to manufacture fitting implants of biocompatible materials for covering huge side-overlapping bone destructions.