Interactive MR-guided biopsies of maxillary and skull-base lesions in an open-MR system: first clinical results.

The purpose of this study was to explore the potential of interactive MR-guided biopsies in the maxillary and skull base region using a 0.5-T open-configuration scanner in patients with tumours affecting the maxilla or skull base. Ten patients with cystic or solid tumours affecting the maxillary and skull base regions underwent MR-guided biopsy in a superconducting, open 0.5-T MR system equipped with an optical frameless stereotaxic system. T2-weighted spin-echo images were acquired prior to and following biopsy, which was performed with 18- or 22-G needles using an enoral or percutaneous approach following infiltration of the skin, mucosa and periosteum with local anaesthetics. The position of the needle tip was continuously updated on fast T1-weighted gradient-recalled-echo images (TR 19 ms, TE 7.1 ms, flip angle 30 degrees, slice thickness 1 cm, field of view 24 x 24 cm) using the frameless stereotaxic system. In addition, the needle was identified based on the associated susceptibility artefact in all three planes. Once the target lesion had been reached, cytology material was aspirated. All ten patients tolerated the interactive MR-guided biopsies well without complications. Vital structures, including the brain, neurovascular bundles, vessels and eyes, were visualized on MR imaging and could be spared. There was no difference in the use of 18- or 22-G non-ferromagnetic needles concerning the susceptibility artefact. Sufficient material for cytological analysis was obtained in nine of ten cases. The mean biopsy time was 15 min. Interactive MR-guided biopsies of the head and neck in an open system are technically feasible and safe. Monitoring of the needle path in multiple planes permits the interactive adjustment of the needle course in near real time. Interactive MR-guided biopsies may well replace open surgical procedures in the maxillary region in selected patients.

The value of stereolithographic models for preoperative diagnosis of craniofacial deformities and planning of surgical corrections.

The purpose of this study was to assess the importance of stereolithographic models (SLMs) for preoperative diagnosis and planning in craniofacial surgery and to examine whether these models offer valuable additional information as compared to normal CT scans and 3D CT images. Craniofacial SLMs of 20 patients with craniomaxillofacial pathology were made. A helical volume CT scan of the anatomic area involved delivered the necessary data for their construction. These were built with an SLA 250 stereolithography apparatus (3D-Systems, Valencia, CA, USA), steered by FORM-IT/DCS software (University of Zurich, Switzerland). The stereolithography models were classified according to pathology, type of surgery and their relevance for surgical planning. Though not objectively measurable, it was beyond doubt that relevant additional information for the surgeon was obtained in cases of hypertelorism, severe asymmetries of the neuro- and viscerocranium, complex cranial synostoses and large skull defects. The value of these models as realistic "duplicates" of complex or rare dysmorphic craniofacial pathology for the purpose of creating a didactic collection should also be emphasized. The models proved to be less useful in cases of consolidated fractures of the periorbital and naso-ethmoidal complex, except where there was major dislocation.

Seven years clinical experience with mandibular distraction in children.

Mandibular distraction was performed on 14 children, between September 1991 and December 1997. Their average age was 6.9 years, ranging from 1.5 to 13.5 years. All patients had severe hypoplastic mandibles with retromandibulism. Seven of the children (50%) had respiratory distress due to obstruction of the upper airway before distraction. This resolved in every case. Five patients underwent unilateral and nine bilateral distraction. A total of 23 distractors were used, 15 were applied extraorally and 8 endorally. The average latency time after operation was 2.8 days, but for the past 2 years, distraction was started beginning with the operation. The distraction was increased twice daily for an average of 5.5 weeks, by 0.4 or 0.5 mm each time, depending on the distractor. Computed tomography and ultrasound were used to follow the ossification process in the distraction gap and to measure the lengthening achieved. Subsequent retention time averaged 2.4 weeks. The mandibles were elongated by up to 18 mm (average 9.3 mm) and the respiratory distress symptoms resolved in all patients. Several minor complications which are reported occurred. Six patients were followed up for periods between 3 and 7 years. During this time further growth of the distracted mandibles was recorded.

Development of the frontal sinus following bilateral fronto-orbital osteotomies.

The presence of frontal sinuses following bilateral fronto-orbital advancement is discussed controversially in the literature. In a retrospective study, 33 patients (18 male and 15 female) were operated on between 1982 and 1993, with at least one year postoperative follow-up and with a minimum age of 6 years at the end of the follow-up period following bilateral fronto-orbital remodelling, were included. The average age at which the procedure was performed was 29 months with a minimum of 3 months and a maximum of 7.8 years. The study presented shows a pneumatization of the frontal sinus in 72.7% of 33 patients following bilateral fronto-orbital advancement. The first radiographic signs of sinus development were detected between the ages of 4 and 11, average 8.3 years. There were no statistically proven correlations between frontal sinus pneumatization and age at operation or the amount of advancement or sex of the patients. Surgical enlargement of the cranium by frontal advancement with adequate stabilization results in an enlargement of the neurocranium, thereby decreasing pressure on the inner frontal cortex and allowing frontal sinus pneumatization to proceed normally. Hence, the development of a frontal sinus may be a reflection of the effectiveness of the surgical therapy.

[Preoperative diagnosis of complex craniofacial syndromes]. / Präoperative Diagnostik komplexer kraniofazialer Syndrome.

The aim of this study was to evaluate stereolithography as a tool in craniofacial surgery. The indications were classified according to the usefulness of stereolithography for different craniofacial pathologies. Stereolithography models of 21 patients were built; in three cases two models were made. The age of the 7 male and 14 female patients was 17 years on average (range: 15 months-44 years). First a helical volume CT scan of the anatomical region was performed. After transformation of the data set, the models were built by an SLA 250 stereolithography apparatus (3D-Systems, Valencia, Calif., USA), steered by FORM-IT/DCS-Software (University of Zurich, Switzerland). The stereolithography models were constructed by superposition of epoxy resin slices of 0.05 mm thickness, which were polymerized by a helium-cadmium laser. These models were classified according to the indication for stereolithography, the operation performed, the relevance for surgical planning and the usefulness for the fabrication of implants and protheses. In craniofacial syndromes, severe asymmetries of the viscerocranium, large skull defects and before surgical correction of hypertelorism these models provided important additional information for the surgeon. Before complex interventions in these fields the construction of a stereolithography model should be considered. In multiple fractures consolidated in dislocation, the models proved to be less useful.

[Fronto-orbital corrections and development of the frontal sinus]. / Frontoorbitale Korrekturen und Stirnhöhlenentwicklung.

The development of frontal sinuses following bilateral fronto-orbital advancement is a topic of controversial discussion in the literature. In a retrospective study on 33 patients (15 girls and 18 boys) the development of the frontal sinus was examined radiologically. Only patients with a minimum age of 6 years and with at least 1 year of postoperative follow-up were included. The radiological reference for the frontal sinus development consisted of pneumatisation at or above the level of the supraorbital rims, as projected din postero-anterior cephalograms. According to these criteria a frontal sinus development was seen in 72.7% of our patients. There was no statistically proven correlation between sinus development and the sex of the patient, age at surgery or the amount of advancement. With the exception of severe cases of Crouzon's disease we usually expect normal development of the frontal sinus following bilateral fronto-orbital correction.

[Cranial development after corrective skull surgery in craniosynostosis]. / Wachstumsverhalten nach Schädelkorrekturen bei Kraniosynostosen.

Craniofacial development may be potentially implicated after vault corrections in cases of craniosynostosis. The aim of this prospective study was the investigation of the surgical effect on calvaria growth, correlating the percentiles of a group of patients before and after craniosynostosis correction in relation to the normal percentiles of growth. The patient population consisted of 71 children; the postoperative follow-up time in 57 patients was more than 12 months. Of the children followed up, 36 were male and 21 female. Thirty-six cases involved untreated non-syndromic craniosynostosis; the remaining 21 were syndrome cases. The patient ages ranged from 16 to 27 months. In 11 cases correction of an occipital craniosynostosis was carried out. The fronto-occipital circumference was registered in accordance with Prader's percentile table. The operative method included a fronto-parietal craniotomy, the temporary removal and shaping of the fronto-orbital band and a vault cranioplasty. During follow-up 13 patients treated with fronto-orbital advancement in cases of isolated craniosynostosis remained in the registered percentile curve. In 13 patients a change to a lower percentile curve was confirmed; 1 patient changed to a higher curve. In cases of syndromic craniosynostosis 10 patients remained in the post-operatively registered percentile curve; 8 patients changed to a lower and 1 patient to a higher percentile curve. No growth restriction of the reshaped calvaria after surgical correction of craniosynostosis was observed. No significant difference was found in the potential calvaria growth between syndromic and isolated craniosynostosis.

[Occipital correction in scapho- and plagiocephaly]. / Okzipitale Korrektur bei Skapho- und Plagiozephalie.

The operation technique and the results after occipital correction in children with plagiocephaly and scaphocephaly are reported. The indication for the intervention is provided by aesthetic and functional considerations. The outcome is very good; the growth of the skull follows the same range of percentiles as preoperatively and normal mental development is seen.

[A new device for reproducible computerized tomography in improved diagnosis of surgical maxillofacial conditions]. / Ein neues Gerät für reproduzierbare Computertomographie zur verbesserten Diagnostik kieferchirurgischer pathologischer Befunde.

The aim of this study was the evaluation of a newly developed radiotranslucent headholder (craniostat) in order to improve diagnosis of maxillofacial pathology. In this prospective study, 103 patients with maxillofacial pathology were examined preoperatively with a Philips SR 7000 computed tomograph using this craniostat. The apparatus was applied fixing the patient's head at three points (meatus acusticus externus on both sides and the glabella). The control group consisted of 106 patients with similar pathology who were examined by computed tomography without a headholder. The application of the craniostat resulted in the following advantageous findings: (1) reproducible CT scans, therefore very precise assessment of the course of a disease; (2) fewer motion artifacts; and (3) symmetrical posture of the patient's head. This headholder is helpful in improving maxillofacial diagnosis by computed tomography if a symmetrical, reproducible posture of the patient's head is to be achieved and motion artifacts could otherwise make the interpretation of the resulting images much more difficult.

Prefabrication of mucosa-lined flaps: a preliminary study in the pig model.

There is a need in reconstructive surgery for flaps lined by nonkeratizing stratified squamous epithelium or mucous membrane. Applications could be found in nasal, oral, genital, and esophageal reconstruction and even in reconstruction of hollow intra-abdominal tubes. Prefabrication of lined flaps has so far been limited to a pretransfer grafting of split-thickness skin. However, in certain situations this does not satisfy the primary requirement of replacing "like with like." Also, the availability of donor sites for harvesting mucosa is limited. The present study involves prefabrication of mucosa-lined flaps without causing donor site morbidity. The study was carried out on six mini-Hartford pigs. Buccal mucosa was harvested from the cheeks; the sheet was divided into several smaller graft pieces of 1 to 2 cm2 area. These graft pieces were then applied to the deep fascia at a distance of 5 to 15 mm from one another, also to galea, and to the undersurface of skin flaps. The grafted area was isolated from the opposing surface with a silicone sheet or Marlex mesh. The grafts were allowed to take and, it was hoped, merge together to form a sheet graft of dimensions greater than those of the original. Two to 7 weeks after the initial grafting, the skin flap was elevated; the mucosal grafts were observed macroscopically for take and surface area and microscopically to confirm that the lining was indeed mucosa. The mucosa took well on both the fascia and galea and also on the undersurface of the skin; it enlarged in size, and the small pieces became confluent to form a single sheet. The increase in surface area varied from 33 percent at 11 days postgrafting to a maximum of 238 percent after 7 weeks. All pigs had positive cultures from the mucosa before implantation but only one developed gross infection leading to partial graft loss.

[Pre-operative diagnosis of complex craniofacial syndromes]. / Präoperative Diagnostik komplexer kraniofazialer Syndrome.

The aim of this study was to evaluate stereolithography as a tool in craniofacial surgery. The indications were classified according to the usefulness of stereolithography for different craniofacial pathologies. Stereolithography models of 21 patients were built; in three cases two models were made. The age of the 7 male and 14 female patients was 17 years on average (range: 15 months-44 years). First a helical volume CT scan of the anatomical region was performed. After transformation of the data set, the models were built by an SLA 250 stereolithography apparatus (3D-Systems, Valencia, Calif., USA), steered by FORM-IT/DCS-Software (University of Zurich, Switzerland). The stereolithography models were constructed by superposition of epoxy resin slices of 0.05 mm thickness, which were polymerized by a helium-cadmium laser. These models were classified according to the indication for stereolithography, the operation performed, the relevance for surgical planning and the usefulness for the fabrication of implants and protheses. In craniofacial syndromes, severe asymmetries of the viscerocranium, large skull defects and before surgical correction of hypertelorism these models provided important additional information for the surgeon. Before complex interventions in these fields the construction of a stereolithography model should be considered. In multiple fractures consolidated in dislocation, the models proved to be less useful.

[A new device for reproducible computed tomography improving diagnosis of maxillofacial pathology]. / Ein neues Gerät für reproduzierbare Computertomographie zur verbesserten Diagnostik kieferchirurgischer pathologischer Befunde.

The aim of this study was the evaluation of a newly developed radiotranslucent headholder (craniostat) in order to improve diagnosis of maxillofacial pathology. In this prospective study, 103 patients with maxillofacial pathology were examined preoperatively with a Philips SR 7000 computed tomograph using this craniostat. The apparatus was applied fixing the patient's head at three points (meatus acusticus externus on both sides and the glabella). The control group consisted of 106 patients with similar pathology who were examined by computed tomography without a headholder. The application of the craniostat resulted in the following advantageous findings: (1) reproducible CT scans, therefore very precise assessment of the course of a disease; (2) fewer motion artifacts; and (3) symmetrical posture of the patient's head. This headholder is helpful in improving maxillofacial diagnosis by computed tomography if a symmetrical, reproducible posture of the patient's head is to be achieved and motion artifacts could otherwise make the interpretation of the resulting images much more difficult.

[Fronto-orbital correction and frontal sinus development]. / Frontoorbitale Korrekturen und Stirnhöhlenentwicklung.

The development of frontal sinuses following bilateral fronto-orbital advancement is a topic of controversial discussion in the literature. In a retrospective study on 33 patients (15 girls and 18 boys) the development of the frontal sinus was examined radiologically. Only patients with a minimum age of 6 years and with at least 1 year of postoperative follow-up were included. The radiological reference for the frontal sinus development consisted of pneumatisation at or above the level of the supraorbital rims, as projected in postero-anterior cephalograms. According to these criteria a frontal sinus development was seen in 72.7% of our patients. There was no statistically proven correlation between sinus development and the sex of the patient, age at surgery or the amount of advancement. With the exception of severe cases of Crouzon's disease we usually expect normal development of the frontal sinus following bilateral fronto-orbital correction.

[Cranial development and growth following treatment of craniosynostosis skull deformities]. / Wachstumsverhalten nach Schädelkorrekturen bei Kraniosynostosen.

Craniofacial development may be potentially implicated after vault corrections in cases of craniosynostosis. The aim of this prospective study was the investigation of the surgical effect on calvaria growth, correlating the percentiles of a group of patients before and after craniosynostosis correction in relation to the normal percentiles of growth. The patient population consisted of 71 children; the postoperative follow-up time in 57 patients was more than 12 months. Of the children followed up, 36 were male and 21 female. Thirty-six cases involved untreated non-syndromic craniosynostosis; the remaining 21 were syndrome cases. The patient ages ranged from 16 to 27 months. In 11 cases correction of an occipital craniosynostosis was carried out. The fronto-occipital circumference was registered in accordance with Prader's percentile table. The operative method included a fronto-parietal craniotomy, the temporary removal and shaping of the fronto-orbital band and a vault cranioplasty. During follow-up 13 patients treated with fronto-orbital advancement in cases of isolated craniosynostosis remained in the registered percentile curve. In 13 patients a change to a lower percentile curve was confirmed; 1 patient changed to a higher curve. In cases of syndromic craniosynostosis 10 patients remained in the post-operatively registered percentile curve; 8 patients changed to a lower and 1 patient to a higher percentile curve. No growth restriction of the reshaped calvaria after surgical correction of craniosynostosis was observed. No significant difference was found in the potential calvaria growth between syndromic and isolated craniosynostosis.

[The occipital correction in plagiocephaly and scaphocephaly]. / Okzipitale Korrektur bei Skapho- und Plagiozephalie.

The operation technique and the results after occipital correction in children with plagiocephaly and scaphocephaly are reported. The indication for the intervention is provided by aesthetic and functional considerations. The outcome is very good; the growth of the skull follows the same range of percentiles as preoperatively and normal mental development is seen.

Distraction osteogenesis for lengthening of the hard palate: Part I. A possible new treatment concept for velopharyngeal incompetence. Experimental study in dogs.

Many procedures have been described to correct velopharyngeal incompetence. Significant complications can occur, and the results may not be satisfactory. If the short soft palate has satisfactory muscle function and if it could be moved toward the posterior pharyngeal wall by distraction osteogenesis of the hard palate, an entirely new concept of treatment for velopharyngeal incompetence would be available. The object of the present study was to explore the possibility of osteogenesis occurring in the hard palate in dogs after gradual distraction (callus distraction). Six adult, mix-bred dogs were anesthetized, and the palatal mucosa was elevated. A midpalatal transverse osteotomy and two lateral osteotomies were performed. Tantalum bone markers for cephalometric analysis were placed, and an individually fabricated, orthodontic-like distraction device with an expansion screw in the sagittal direction was inserted. The device was stabilized on the premolars and fixed to the palatal bone with titanium miniscrews. Gradual distraction began after a latency period of 10 to 18 days. The rate of the distraction varied from 0.25 to 0.75 mm per day. The device was left in place for 6 to 8 weeks after expansion to allow for bony consolidation. Assessment was by direct examination, cephalograms, computed tomography, and histology with bone labeling. Impressions of the jaws were taken preoperatively and after device removal to examine plaster cast changes in the dental occlusion. Cephalometric and computed tomographic scan analysis demonstrated a distraction of up to 8 mm. All gaps were filled with de novo osteogenesis. Comparison of the plaster casts revealed no change in the occlusion. At 1 month after distraction, the computed tomographic scan showed the first signs of ossification of the experimental gap from the anterior and posterior bone ends. After 4.5 months ossification was almost complete with a small translucent zone in the middle of the experimental gap. After 7 months ossification was complete.

Distraction osteogenesis for lengthening of the hard palate: Part II. Histological study of the hard and soft palate after distraction.

To correct velopharyngeal incompetence, a new treatment concept was proposed in Distraction Osteogenesis for Lengthening of the Hard Palate: Part I (using lengthening of the hard and soft palate by distraction osteogenesis). Cephalometry and computed tomography showed successful elongation of the posterior hard palate with gradual calcification. Here the sequential use of fluorochrome markers (oxytetracycline, xylenol orange, DCAF [2,4-bis-N-N'-dicarboxymethyl aminomethyl fluorescein], and alizarin complexone) during the distraction and retention period is reported together with the histologic investigations using light and laser scan microscopy without prior demineralization. The experimental gap showed de novo osteogenesis in all dogs. The new bone was always in continuity with the original anterior and posterior palatal bone margins. It either bridged the experimental gap fully or left a small central zone of fibrous tissue, in which eventual ossification occurred. Several distinct zones could be distinguished: A small central zone was found with parallel strains of collagen fibers, oriented longitudinally in the direction of the distraction. Next to this zone a layer of undifferentiated mesenchymal precursor cells was seen in direct contact to newly formed bone. The next zone was coarse woven bone, showing a transition to mature lamellar bone through remodeling. No evidence of endochondral bone formation was found, i.e., all dogs showed exclusively intramembranous bone formation. The soft tissues showed no signs of alteration: in particular, there was no necrosis or scar formation. The soft tissues were not thinned but appeared to have followed the longitudinal displacement. In conclusion, gradual distraction osteogenesis of the hard palate could be a possible method for lengthening the palate to treat velopharyngeal incompetence.

Mandibular osteomyelitis: evaluation and staging in 18 patients, using magnetic resonance imaging, computed tomography and conventional radiographs.

Over a period of 3 years, 18 patients with mandibular osteomyelitis were prospectively investigated by conventional radiograph, computed tomography (CT) and in 6 cases by magnetic resonance imaging (MRI). The diagnosis was based on histology in 17 patients operated upon.

[The measurement of orbital volume in reconstruction of the orbital walls]. / L'orbitovolumetria nella ricostruzione delle pareti orbitarie.

Before reconstruction of the orbital walls and other surgical procedures involving the orbits leading to a modification of pathologically altered orbital volumes, it is useful to measure these volumes in order to allow a more precise correction. Orbital volumetric studies on 22 patients and 6 dry skulls were performed using high resolution computer tomography. Fourteen patients presented enophthalmos of various origin, 3 patients fibrous dysplasia involving the orbits and 5 patients showed orbital pathology. In 10 patients with unilateral post-traumatic enophthalmos an increase of the bony orbital volume of 20.1% in the average was found corresponding to an enophthalmos of 3.5 mm in the average. Correlation between the severity of the enophthalmos and the increase in orbital volume was found. Enophthalmos could not be correlated to the intraorbital fat volume, especially no atrophy of orbital fat could be demonstrated in these patients. Normal orbital volume measurements of patients and dry skulls were compared to those found in the literature. Planning of the surgery was therefore facilitated before correction of enophthalmos, reconstruction of bony orbital contour after tumor-resection and in patients with fibrous dysplasia. Results suggest that the bony enlargement, followed by a change in soft-tissue shape and position is the usual cause of posttraumatic enophthalmos. Changes in volume of soft-tissues themselves are less significant.