Georg Schlöndorff

A new imaging method for intraoperative therapy control in skull-base surgery

AbstractCAS — computer assisted surgery — is a new imaging method supporting skull base surgeons. Support is granted not only for preoperative planning of therapy but also for pathfinding during surgery itself and in the postoperative phase as therapy control. TheCAS-system consists of high technology items such as-a digital image generation system (CT, MR)-a real-time image processing system-a 3 D position recognition system. Robotics are not incorporated in this system but a handguided manipulator houses the surgeons instrument. Accuracy of the method has been experimentally determined to be within 1 mm. Follow up systems are under development to permit microsurgery support as well.

The paranasal sinuses in CT-imaging: Development from birth to age 25

Available data about the size of the different sinuses to date are derived from anatomical or radiological studies. In order to verify or possibly correct the findings of other authors we evaluated the cranial computed tomography (CT)-images of more than 5600 patients. We measured the sex-linked and age-dependent width and length of the four sinuses for both sides in axial sections. For the first time we have a clear picture of the development of the paranasal sinuses for both sexes from birth until the age of 25 years. Our results confirm general ideas concerning the size of the sinuses. Moreover they provide new details, especially about the first occurrence and the course of development in different stages since we found each sinus already present in 1.5% (frontal sinus) to 94% (ethmoid cells) of the newborn of both sexes. Finally, we can state that the periods of expansion are equal in both sexes (ethmoid cells) or last up to 2 or 3 years longer (frontal sinus) in male patients. In agreement the sinuses of both sexes differ between 5.4% (sphenoid sinus) and 17.1% (frontal sinus) in definitive size with statistically significant differences in later ages. The data about sphenoid sinuses deserve special attention since they show a large variability in size (up to 214% in one direction) as well as in shape.

Diagnosis and grading of malignancy in squamous epithelial lesions of the larynx with DNA cytophotometry

For diagnostic purposes 14 histologically benign, 15 dysplastic, and 16 malignant squamous epithelial lesions were subjected to DNA cytophotometry. Results were computed according to an algorithm for DNA diagnosis and grading of malignancy. In cases of unequivocally malignant or benign lesions all DNA diagnoses agreed with the histologic diagnoses. In one case the allegedly faulty DNA diagnosis of cancer was proven to be correct on clinical follow‐up. Within the group of histologically mild to moderate dysplasias the algorithm identified four cases as malignant that were proved to be malignant either in the follow‐up or at another site of the same lesion. With the aid of the DNA malignancy grade two groups of patients with squamous epithelial carcinomas of the larynx could be discerned with a highly significant difference according to their survival times. Cancer 56: 1600‐1604, 1985.

From the expert’s office: localized neural lesions following tonsillectomy

Due to various reasons, localized neural lesions following tonsillectomy are presumably an under-reported complication in the literature. This study was undertaken to compile our experiences including a literature review to disseminate useful insights in the etiology and prognosis of this rare entity. A retrospective chart review of expert reports written by at least one of the authors for malpractice claims in relation to tonsillectomy was undertaken. Additionally, a retrospective analysis of 648 patient documents that had undergone tonsillectomy in 2001 at our institution and a comprehensive literature review were performed. The research was restricted to the item “localized neural lesion”. Seven cases from the expert’s offices, one of our patients who had undergone tonsillectomy at our institution and 122 cases from the literature matched our search criteria. Including our own cases, the glossopharyngeal nerve was affected in 82 patients. Other lesions encompassed injury of the hypoglossal nerve as solitary (15) or combined (5) lesion, recurrent nerve paralysis with (2) or without additional nerve lesions (7), facial nerve paralysis (10) in combination with other nerve lesions (1), and a lingual nerve deficiency as solitary (4) or combined lesion (9). A single report existed for lesion of the phrenic nerve. There were five reported cases with blindness and nine cases with Horner’s syndrome. Albeit rare, localized neural lesions may occur as a troublesome complication following tonsillectomy and/or means to achieve hemostasis. Some of these cases may not result from the dissection itself but injection procedures. Surgical dissection should include careful mouth gag insertion and meticulous dissection to minimize the risk of localized neural complications. A long-term follow-up is recommended for patients with dysgeusia related to glossopharyngeal nerve injury and patients with recurrent nerve dysfunction. Other lesions are much less likely to resolve in the long-term. Localized neural lesions should adequately be included in the informed consent for tonsillectomy as well as for surgical treatment of post-tonsillectomy hemorrhage.

Intraoperative radiotherapy for pre-irradiated head and neck cancer.

BACKGROUND AND PURPOSE Radiotherapy of recurrent head and neck tumours is limited in dose due to pre-treatment up to normal tissue tolerance doses. Surgery alone is limited by the problems related to pre-surgery, post-radiation fibrosis, and infiltration of tumours into nerves and vessels too closely to be completely removed. Our aim was to evaluate the possible role of intraoperative radiotherapy (IORT) in such tumours treated with palliative intent. METHODS In the last 10 years, we performed 113 intraoperative irradiations in a total of 84 pre-irradiated patients with head and neck cancer. The patient data were evaluated with regard to palliative effect, complications of treatment, recurrence and survival after IORT. RESULTS Palliation of symptoms, as assessed by clinical evaluation, was achieved in 88% of symptomatic patients, often just by removal of large exophytic or exulcerating tumours, with IORT preventing their immediate recurrence after surgery. The complication rate did not exceed that expected after surgery alone. The median survival after IORT was 6.8 months, with a median time to local tumour recurrence or progression of 3.7 months. CONCLUSION Intraoperative irradiation can be used as a palliative treatment option in pre-treated head and neck tumours with satisfactory results. With large and infiltrating tumours, however, recurrences or tumour progression occur close to the IORT portals, thus rendering this method unsuitable for achieving long-term control in such extended tumours.

CAS — a Navigation Support for Surgery

Computer Assisted Surgery (CAS) is a new navigation support for skull base surgeons. The combination of 3D coordinate measurement techniques, voxel processing methods and pseudo-3D image presentation supports preoperative planning of therapy, pathfinding during the operation itself and postoperative therapy control. For this purpose, the surgeon employs a hand-guided electro-mechanical 3D coordinate digitizer to locate points of interest within the operative field. The coordinates measured this way are correlated with a voxel model of the object gained by a preceding CT examination. With a prototype system the accuracy of this method has proven to be better than ±1 mm. The system has been successfully applied in more than 100 ENT operations and ten neurosurgical procedures. A similiar system was tested two times in the field of radiotherapy for the computer assisted placement of afterloading probes.

The Computer-Assisted Localizer, a Navigational Help in Microneurosurgery

The computer-assisted-localizer (CAL) achieves a direct linkage between preoperative radiological images and individual intraoperative anatomical findings. Experiences with our system demonstrate that CAL improves the intraoperative orientation and facilitates the neurosurgical procedure. The system described here consists of a mechanical articulated robot arm with six degrees of freedom and a three-dimensional image processor. After calibration, the displayed image dynamically pointed out the exact intraoperative localization in three perpendicular sectional views. Meanwhile, CAL was successfully used in 73 selected microneurosurgical procedures.

Complications of midline-open tracheotomy in adults

Percutaneous tracheotomy is progressively replacing open tracheotomy as a consequence of promising results of comparative studies. However, this comparison has four considerable weaknesses: 1) selected indications (high‐risk patients excluded for percutaneous tracheotomy); 2) varying spectra of complications included in different studies; 3) varying operative settings (experienced surgeons exclusively, surgeons in training, or both); and 4) missing differentiation between different surgical techniques. Our study was performed to collect complete datasets of unselected patients who all underwent a tracheotomy in a uniform technique in an academic teaching hospital setting.

Intra-operative radiotherapy--5 years of experience in the palliative treatment of recurrent and advanced head and neck cancers.

Recurrent and advanced cancer in the head and neck region is usually associated with limited therapeutic concepts and a dismal prognosis. Efforts mainly focus on palliative treatment in order to improve the patients quality of life. From May 1989 to December 1994, a total of 120 intra-operative radiotherapy (IORT) procedures with high-energy electron beams (mean energy: 7 MeV: mean dose: 20 Gy) were performed in 95 patients. Therapy was usually performed under endotracheal anaesthesia (84%). There were 91 cases (75.8%) of recurrence in the lymph nodes of the neck and 14 cases (11.7%) of local recurrence. 15 patients (12.5%) received IORT as part of the initial treatment. Considering the palliative nature of IORT in these patients, only an R2 resection (gross residual tumour) was achieved in 71.7%. Local tumour control was nonetheless possible in 17% (R2 resection) to 64% (complete R0 resection), with a mean 11-month follow-up period for survivors (mean for deceased patients: 8 months). Regarding palliative criteria, IORT proved to be feasible since patients profited from short hospitalisation (median: 10 days), a low complication rate (27 instances; e.g. tracheostomy: 11; necrosis: 8, or fistula: 3) and, in part, a substantial reduction of pain (73.8%). Most of them regained physical and psychic integrity for weeks to months and were able to take part in social life during the final stage of their disease.