Klaus W. Graetz

Comparison of different registration methods for surgical navigation in cranio-maxillofacial surgery

BACKGROUND Surgical navigation requires registration of the pre-operative image dataset with the patient in the operation theatre. Various marker and marker-free registration techniques are available, each bearing an individual level of precision and clinical practicability. In this study the precision of four different registration methods in a maxillofacial surgical setting is analyzed. MATERIALS AND METHODS A synthetic full size human skull model was registered with its computer tomography-dataset using (a) a dentally mounted occlusal splint, (b) the laser surface scanning, (c) five facial bone implants and (d) a combination of dental splint and two orbital bone implants. The target registration error was computed for 170 landmarks spread over the entire viscero- and neurocranium in 10 repeats using the VectorVision2 (BrainLAB AG, Heimstetten, Germany) navigation system. Statistical and graphical analyses were performed by anatomical region. RESULTS An average precision of 1mm was found for the periorbital region irrespective of registration method (range 0.6-1.1mm). Beyond the mid-face, precision linearly decreases with the distance from the reference markers. The combination of splint with two orbital bone markers significantly improved precision from 1.3 to 0.8mm (p<0.001) on the viscerocranium and 2.3-1.2mm (p<0.001) on the neurocranium. CONCLUSIONS An occlusal splint alone yields poor precision for navigation beyond the mid-face. The precision can be increased by combining an occlusal splint with just two bone implants inserted percutaneously on the lateral orbital rim of each side.

IMRT in oral cavity cancer

BackgroundExcept for early T1,2 N0 stages, the prognosis for patients with oral cavity cancer (OCC) is reported to be worse than for carcinoma in other sites of the head and neck (HNC). The aim of this work was to assess disease outcome in OCC following IMRT.Between January 2002 and January 2007, 346 HNC patients have been treated with curative intensity modulated radiation therapy (IMRT) at the Department of Radiation Oncology, University Hospital Zurich. Fifty eight of these (16%) were referred for postoperative (28) or definitive (30) radiation therapy of OCC.40 of the 58 OCC patients (69%) presented with locally advanced T3/4 or recurred lesions. Doses between 60 and 70 Gy were applied, combined with simultaneous cisplatin based chemotherapy in 78%. Outcome analyses were performed using Kaplan Meier curves.In addition, comparisons were performed between this IMRT OCC cohort and historic in-house cohorts of 33 conventionally irradiated (3DCRT) and 30 surgery only patients treated over the last 10 years.ResultsOCC patients treated with postoperative IMRT showed the highest local control (LC) rate of all assessed treatment sequence subgroups (92% LC at 2 years). Historic postoperative 3DCRT patients and patients treated with surgery alone reached LC rates of ~70–80%. Definitively irradiated patients revealed poorest LC rates with ~30 and 40% following 3DCRT and IMRT, respectively.T1 stage resulted in an expectedly significantly higher LC rate (95%, n = 19, p < 0.05) than T2-4 and recurred stages (LC ~50–60%, n = 102).Analyses according to the diagnosis revealed significantly lower LC in OCC following definitive IMRT than that in pharyngeal tumors treated with definitive IMRT in the same time period (43% vs 82% at 2 years, p < 0.0001), while the LC rate of OCC following postoperative IMRT was as high as in pharyngeal tumors treated with postoperative IMRT (>90% at 2 years).ConclusionPostoperative IMRT of OCC resulted in the highest local control rate of the assessed treatment subgroups. In conclusion, generous indication for IMRT following surgical treatment is recommended in OCC cases with unfavourable features like tight surgical margin, nodal involvement, primary tumor stage >T1N0, or already recurred disease, respectively.Loco-regional outcome of OCC following definitive IMRT remained unsatisfactory, comparable to that following definitive 3DCRT.

Temporomandibular disorders associated with metastases to the temporomandibular joint: a review of the literature and 3 additional cases

INTRODUCTION Metastases involving the oral cavity account for 1% to 8% of all malignancies in the oral cavity Involvement of the temporomandibular joint (TMJ) is uncommon. METHOD AND RESULTS We conducted a review of the literature between 1954 and 2008 regarding metastases to the TMJ. In total, 48 patients were found and in 28 patients a previous history of malignant neoplasm was known. The primary tumor was most commonly found in the breast (34%), followed by the lung (21%). Adenocarcinoma was predominant (72.97%). Three new patients with TMJ pain as a first symptom for a disseminated tumor are also examined here. CONCLUSION Establishing an exact diagnosis of metastatic lesions in the TMJ can provide a diagnostic challenge. Clinicians should include the suspicion of cancer in the differential diagnosis, in particular when patients have a previous history of malignant neoplasm or do not respond to treatment appropriately.

Carcinoma cuniculatum: a rare entity in the oral cavity.

Background:Carcinoma cuniculatum, a well-differentiated squamous cell carcinoma, is a rare neoplasm with a low risk of metastasis. Methods and Results:A 74-year-old female patient is presented with a carcinoma cuniculatum of the right maxilla, a very rare variant of squamous cell carcinoma that usually occurs in the skin of the lower extremities, in particular, in the skin of the plantar surface of foot. It is described by an invasive growth pattern, but metastases to regional lymph nodes are rare. In the oral cavity, only very few cases have been published. Conclusion:The correct diagnosis of this entity with the knowledge that it is a variant of a low-grade carcinoma with low risk of metastasis is important, so that elective neck dissection must not be obligate.

Follow up after IMRT in oral cavity cancer: update.

PurposeExcept for early stages (T1/2 N0), the prognosis for patients with oral cavity cancer (OCC) is known to be worse than for those with pharyngeal carcinoma. While definitive intensity modulated radiation therapy (IMRT)-chemotherapy affords loco-regional control rates (LRC) of approximately 80% in advanced pharyngeal cancer, corresponding rates are reported to be much lower for OCC. The aim of this work was to evaluate loco-regional disease control and overall survival (OAS) in a relatively large OCC patient cohort treated in the IMRT era.Methods and materialsBetween October 2002 and June 2011, 160 OCC patients were treated with curative intention IMRT at our department. 122 patients (76%) were referred with primary disease and 38 patients (24%) with a recurrent OCC at least 3 months after surgery alone. Definitive IMRT was performed in 44/160 patients (28%), whilst 116 patients underwent previous surgery. Simultaneous systemic therapy was administered in 72%.ResultsPatients with postoperative IMRT (+/−systemic therapy) with R0-1 status (n = 99) reached significantly higher LRC/OAS rates than patients following IMRT for macroscopic disease (n = 61), with 84%/80% versus 38%/33% at 3 years, respectively (p < 0.0001). This was found in patients treated for initial, as well as recurrent, disease. Less than 2% persisting grade 3/4 late effects were observed.ConclusionsIMRT for R0-1 situations translated into a highly significant superior LRC and OAS compared to the IMRT cohort treated for macroscopic disease. Treatment was well tolerated.

Craniofacial landmarks in young children: how reliable are measurements based on 3-dimensional imaging?

Introduction Different approaches for 3-dimensional (3D) data acquisition of the facial surface are common nowadays. Meticulous evaluation has proven their level of precision and accuracy. However, the question remains as to which level of craniofacial landmarks, especially in young children, are reliable if identified in 3D images. Potential sources of error, aside from the systems technology itself, need to be identified and addressed. Reliable and unreliable landmarks have to be identified. Materials and Methods The 3dMDface System was used in a clinical setting to evaluate the intraobserver repeatability of 27 craniofacial landmarks in 7 young children between 6 and 18 months of age with a total of 1134 measurements. Results The handling of the system was mostly unproblematic. The mean 3D repeatability error was 0.82 mm, with a range of 0.26 mm to 2.40 mm, depending on the landmark. Single landmarks that have been shown to be relatively imprecise in 3D analysis could still provide highly accurate data if only 1 of the 3 spatial planes was relevant. There were no statistical differences from 1 patient to another. Conclusions Reliability in craniofacial measurements can be achieved by such 3D soft-tissue imaging techniques as the 3dMDface System, but one must always be aware that the degree of precision is strictly dependent on the landmark and axis in question. For further clinical investigations, the degree of reliability for each landmark evaluated must be addressed and taken into account.

Comparison of different flow-reducing bag-valve ventilation devices regarding respiratory mechanics and gastric inflation in an unprotected airway model

OBJECTIVE Gastric inflation (GI) is a significant issue when ventilation is performed on unprotected airways. DESIGN Experimental analysis on the respiratory effects of hose extended bag-valve ventilation devices designed to reduce inspiratory pressure and flow. SETTING Laboratory with lung/oesophageal sphincter simulator and pressure-flow-volume analyser. Lung compliance: 300ml/kPa, airway resistance: 0.5kPa/l/s. Lower oesophageal sphincter pressure (LOSP): 0.5kPa. INTERVENTIONS Bag-valve ventilation of lung simulator. Twelve academic dental staff members used four devices: Ambu Mark III attached to either a reservoir bag (R) or a pressure relief valve (SV), SMART BAG (SB), and Easy Grip (EG) as control. RESULTS After Bonferroni correction (p-level of significance 0.0083) for multiple comparisons, no evidence of difference between inspiratory tidal volumes (TVIN) administered by use of R (median 137ml) and SB (149ml) was found. Differences in TVIN were only detected between R and SV (188ml) (p=0.002). Only a trend towards TVIN differences between SB and R in comparison to EG (195ml) was found (p=0.009). Distributions of peak pressures differed when R (median 0.7kPa) and SV (1.0kPa) (p=0.006) or SB (0.7kPa) and SV (p=0.002) were compared. Peak inspiratory flow rates differed between EG (median 59l/min) and R (32l/min) as well as SB (42l/min) and between SB and SV (50l/min) (all with p=0.001). GI was lowest by use of R (median 103ml) compared to all other devices (EG: 518ml, SV: 394ml, SB: 271ml) (p=0.001). The areas under the pressure/flow over time curves were larger during SB compared to R ventilation. Mean airway pressures were significantly lower by use of R (0.1kPa) compared to SB (0.3kPa) (p<0.008). CONCLUSION Lowering GI by pressure-flow reduction may result in lower TV depending on the device used. Lowest GI resulted from R ventilation. This may be explained by the specific pressure/time or flow/time patterns achieved by use of this device.

Outcome in recurrent head neck cancer treated with salvage-IMRT.

BackgroundRecurrent head neck cancer (rHNC) is a known unfavourable prognostic condition.The purpose of this work was to analyse our rHNC subgroup treated with salvage-intensity modulated radiation therapy (IMRT) for curable recurrence after initial surgery alone.PatientsBetween 4/2003–9/2008, 44 patients with squamous cell rHNC were referred for IMRT, mean/median 33/21 (3–144) months after initial surgery. None had prior head neck radiation. 41% underwent definitive, 59% postoperative IMRT (66–72.6 Gy). 70% had simultaneous chemotherapy.MethodsRetrospective analysis of the outcome following salvage IMRT in rHNC patients was performed.ResultsAfter mean/median 25/21 months (3–67), 22/44 (50%) patients were alive with no disease; 4 (9%) were alive with disease. 18 patients (41%) died of disease. Kaplan Meier 2-year disease specific survival (DSS), disease free survival (DFS), local and nodal control rates of the cohort were 59/49/56 and 68%, respectively.Known risk factors (advanced initial pTN, marginal initial resection, multiple recurrences) showed no significant outcome differences. Risk factors and the presence of macroscopic recurrence gross tumor volume (rGTV) in oral cavity patients vs others resulted in statistically significantly lower DSS (30 vs 70% at 2 years, p = 0.03). With respect to the assessed unfavourable outcome following salvage treatment, numbers needed to treat to avoid one recurrence with initial postoperative IMRT have, in addition, been calculated.ConclusionA low salvage rate of only ~50% at 2 years was found. Calculated numbers of patients needed to treat with postoperative radiation after initial surgery, in order to avoid recurrence and tumor-specific death, suggest a rather generous use of adjuvant irradiation, usually with simultaneous chemotherapy.

A simple technique for sterility and patient accessibility during intraoperative three-dimensional (3D) imaging

a h a s c t n ntraoperative three-dimensional imaging is becoming rouine for some operations,1 can be amalgamated with reoperative data, and of course be combined with computerssisted surgery.2,3 As well as the obvious medical benefits of mmediate control of surgical procedures, cost analysis has hown benefits in diagnosis related groups.4 Because of the omplex three-dimensional anatomy of the facial skeleton, ombined with limited surgical access, one could expect it to ave distinct advantages in craniomaxillofacial surgery. To acquire data from three-dimensional images, C-arms r cone beam computed tomographic (CB-CT) images must otate around the patient. In the head and neck region, this nevitably means that machine parts routinely pass through on-sterile regions before coming close to the surgical field,

Demodicidosis: an uncommon erythema after cranio-maxillofacial surgery.

Demodex mites are commonly found in the healthy population, but the pathogenesis of demodicidosis has still not been clarified, though it is usually found in cases of immune deficiency. A 45-year-old man presented with an unusual outbreak of erythema and swelling 6 months after resection and chemoradiotherapy for a squamous cell carcinoma of the anterior floor of the mouth. The cheek was biopsied and histological examination showed demodicidosis. In cases of erythema with a normal blood cell count and no history of allergy, particularly in patients with reduced immunity, demodicidosis should be considered as a diagnosis and should be confirmed by examination of a biopsy specimen.