[Indications of intraoperative ultrasound in head and neck surgery]. / Indikationen für den intraoperativen Ultraschall bei Eingriffen im Kopf-Hals-Bereich.

BACKGROUND: A possible use of B-scan sonography arises from the difficulty in transferring information by means of imaging to the intraoperative situation, which is now possible with navigation systems in complicated surgical procedures in the field of otolaryngology. A solution to this problem offers the intraoperative use of ultrasonography for orientation in soft tissue surgery. PATIENTS AND METHOD: A prospective study involving 115 patients in total entailed scanning with a small part linear and fingertip probe with either 10 and 7.5 MHZ. An ultrasound endoscope featuring a 7.5 MHZ convex probe was used to image endolarygeal processes. RESULTS: Indications included panendoscopies, parotidectomies, submandibulectomies, lymph node exstirpations and abscess incisions. The colour doppler sonography was used in reconstructive surgery involving microvascular transplants. The display of soft tissue tumours provided information about tumour size as well as demarcation or infiltration of neighbouring structures. The fingertip probe and the ultrasound endoscopy served to evaluate areas that were morphologically difficult to access. After clamping the radial artery when harvesting the forearm flap, a sufficient perfusion of the thumb and later the sufficiency of the vascular anastomosis could be verified. CONCLUSION: The intraoperative use of sonography is an inexpensive non-invasive procedure that can be performed by the surgeon himself and allows quick and reliable orientation during difficult operations.

Re-irradiation of head and neck cancer-impact of total dose on outcome.

AIM: To evaluate the outcome of re-irradiation and to define favourable pre-treatment characteristics. PATIENTS AND METHODS: seventy-five patients with locally recurrent head and neck cancer were treated with re-irradiation, either postoperatively or as definitive treatment, with and without chemotherapy. Mean time period between first and second series of irradiation was 19 months. Mean overall dose of re-irradiation was 46 Gy. Median follow-up was 8.7 months. RESULTS: Overall survival, loco-regional disease-free survival and metastasis-free survival after two years were 23%, 24% and 77%, respectively. Higher overall doses of re-irradiation gave a statistically significant better outcome with regard to overall survival (p=0.018). CONCLUSION: For patients with locally recurrent head and neck cancer, re-irradiation is a feasible therapeutic option. The total dose at re-irradiation improves overall survival. Therefore, re-irradiation with curative intent should only be applied if a sufficient total dose of ≥46 Gy can be given.

The influence of the coupling of actuation drivers of implantable hearing systems on the mechanics of the middle ear.

We used multifrequency tympanometry to provide middle ear mechanics after implantation of different implantable hearing aids. A total of 34 patients were included in the investigation; 19 of them were fitted with the Otologics system and 15 with the MED-EL Vibrant Soundbridge system. With the Otologics recipients, measurements were made preoperatively and both two months and at least 12 months postoperatively. Measurements involving the MED-EL patients were taken at least 12 months postoperatively. For all measurements, the non-implanted contralateral side was used as a control. Preoperatively, the resonance frequency of the Otologics patients was 904.3 +/- 218.2 Hz for the implanted side and 907.1 +/- 161.8 Hz for the non-implanted side. Postoperatively, a significant increase (p < 0.01) compared with the preoperative value and the control side was observed after two months: 1111.3 +/- 234.7 Hz, as opposed to 823.8 +/- 274.5 Hz on the contralateral side. After 12 months, the resonance point was restored to approximately the preoperatively measured values: 975 +/- 55.3 Hz (implanted side) and 901.3 +/- 207.1 (control side). The resonance frequency in the Symphonix patients, as measured after at least 12 months (on average, 35 months), was 1006.3 +/- 269.5 Hz on the non-implanted side and 900.1 +/- 249.3 Hz on the implanted side. It is apparent that the resonance frequency on the implanted side was higher than on the control side, although the difference was not significant (p = 0.496). Monitoring following the implantation of active hearing systems is therefore recommended in order that conclusions can be drawn regarding the adequacy of the coupling of the actuation driver to the ossicular chain.

Experimental middle ear surgery in rabbits: a new approach for reconstructing the ossicular chain.

This experimental animal study aimed at evaluating a new prosthesis to replace the ossicular chain; we developed a new technique for surgical implantation into the middle ear of rabbits. The rabbit middle ear is, owing to the relative anatomical dimensions involved, an ideal environment for implantation procedures involving the ossicles, as the surgical conditions are similar to those of the human middle ear. This study included a total of 34 approximately six-month-old female white rabbits (New Zealand) weighing between 3.2 and 4.4 kg. The implants used were constructed of ceramic materials (titania, TiO(2)) of various pore sizes. Directly prior to implanting the total ossicular reconstruction prostheses (TORPs), as well as at 28, 84 and 300 days after implantation, electric response audiometry was used to determine the hearing thresholds of the animals (bone conduction; click stimulus nHL). An erbium:YAG laser was used to excise the original ossicular chain. Following implantation, we were unable to detect any stenosis of the outer ear canal or perforation of the tympanic membrane. The conductive hearing threshold was in the range of 4.21 +/- 6.68 dB nHL (n = 131). The hearing level showed no significant difference before and after surgery (P < 0.05).

Clinical feasibility test on a minimally invasive laser therapy system in microsurgery of nerves.

The clinical feasibility test described here evaluates the basis for a laser therapy system that enables tumour tissue to be separated from nerves in a minimally invasive manner. It was first investigated whether, using an Er:YAG laser, laser-induced nerve (specifically, facial nerve) responses in the rabbit in vivo can be reliably detected with the hitherto standard monitoring techniques. Peripherally recordable neuromuscular signals (i.e. compound action potentials, CAPs) were used to monitor nerve function and to establish a feedback loop. The first occurrence of laser-evoked CAPs was taken as the criterion for deciding when to switch off the laser. When drawing up criteria governing the control and termination of the laser application, the priority was the maintenance of nerve function. Five needle-electrode arrays specially developed for this purpose, each with a miniature preamplifier, were then placed into the facial musculature instead of single-needle electrodes. The system was tested in vivo under realistic surgical conditions (i.e. facial-nerve surgery in the rabbit). This modified multi-channel electromyography (EMG) system enabled laser-evoked CAPs to be detected that have amplitudes 10 times smaller than those picked up by commercially available systems. This optimization, and the connection of the neuromuscular unit with the Er:YAG laser via the electrode array to create a feedback loop, were designed to make it possible to maintain online control of the laser ablation process in the vicinity of neuronal tissue, thus ensuring that tissue excision is both reliable and does not affect function. Our results open up new possibilities in minimally invasive surgery near neural structures.

Normative auditory brainstem response data for hearing threshold in the rabbit.

In an experimental study, we determined the physiological hearing threshold of the rabbit in order to use these data as normative values for further experimental investigations. The aim was to use different acoustic stimuli (click and tone-pip stimuli) with different frequency spectra for air and bone conduction (BC) in order to obtain further information about the optimal form of stimulus when recording auditory evoked potentials in the rabbit. For the investigation, we used 46 female New Zealand rabbits weighing 3.2-4.4 kg and aged 6 months. The equipment used to record brainstem auditory evoked potentials was the Nicolet Viking IV P System (Nicolet Biomedical, Inc.). In accordance with the experimental set-up, the measurements took place under intubation anesthesia, with a total of four repeat measurements performed on each ear at different times. Tone-pip and click stimuli with varying intensities of stimulus, transmitted via air conduction and BC, were applied. The I-IV waves proved the most stable for both stimulus modalities. They were registrable in 98.7% of cases, whereas only 30.2% of the V waves could be recorded. Values averaged from all measurements made throughout the study yielded a potential threshold of 34.8 dB peak equivalent (p.e.) SPL for the click stimulus, 13.8 dB p.e. SPL for the tone-pip stimulus at 8 kHz and 34.2 dB p.e. SPL for the click stimulus transmitted via BC. With regard to latencies, the results indicated a good reproducibility through different stimuli with acceptable standard deviations. The values for physiological hearing threshold obtained here can serve as normative data in subsequent experimental animal studies.

[Titanium oxide ceramic as an implantation material in otosurgery: animal experimental results and surgical technique]. / Titanoxidkeramik als Implantationsmaterial in der Ohrchirurgie: Tierexperimentelle Ergebnisse zur Operationstechnik.

BACKGROUND: For the experimental animal study to evaluate a new ossicular chain replacement prosthesis, we developed a new technique for surgical implantation into the middle ear of rabbits. The selection of the species was based on its similarity to human middle ear anatomy and the favored, standardized, microsurgical approach to the middle ear cavity. METHOD: For the study we included a total of 34 approximately 6-month-old female white rabbits (New Zealand) with a weight of 3.2 to 4.4 kg. The implants used were constructed of ceramic materials TiO(2) (titania) with different pore size. Directly before the implantation of the TORPs, as well as at 28, 84 and 300 days after implantation, electric response audiometry was used to determine the hearing thresholds of the animals (bone conduction click stimulus nHL). The Erbium Yag-Laser was used to cut out the originally ossicular chain. RESULTS: After implantation we could not detect any stenosis of the outer ear canal or perforation of the tympanic membrane. The conductive hearing threshold was in the range of 4.21 +/- 6.68 dB nHL (n = 131). The hearing level showed no significant difference before and after surgery (p > 0.05). CONCLUSIONS: The laser surgery is a very safe procedure for prosthesis implantation in the middle ear of rabbits..

Intraoperative computed tomography in otorhinolaryngology.

CONCLUSIONS: Intraoperative CT surgery provides the surgeon with additional information about the altered surgical site in difficult anatomical situations. The skull base and lamina papyracea may be revealed by means of intraoperative CT, which may be beneficial in endonasal sinus surgery involving difficult surgical sites, although individual ethmoid cells cannot be assessed owing to blood artefacts. This provides the surgeon with valuable information that may facilitate the procedure considerably. In soft-tissue surgery it is advisable to apply a contrast agent in order to achieve good soft-tissue contrast, thus allowing the tumour to be adequately distinguished from benign tissue. The intraoperative application of CT is a fairly time-consuming procedure, partly owing to the preparation time (set-up of the appliance; 10-min warming-up phase) and partly due to the length of time required to calculate each image (15 s). OBJECTIVE: CT is a well-established imaging method for the assessment of osseous and soft-tissue structures in the head and neck region. Saving information and transferring it to the intraoperative site may, however, be problematic. Computer-assisted navigation systems are now able to assist difficult surgical procedures in the field of otolaryngology. To investigate the indications for intraoperative CT, we used it in various surgical procedures in the head and neck region. MATERIAL AND METHODS: Intraoperative CT was applied using the Tomoscan M in 46 cases in order to demonstrate the surgical benefit of the following procedures: endonasal surgical procedures on the paranasal sinuses (maxillary and ethmoidal sinusitis, anterior fracture of the sphenoidal sinus); tumour removal by means of laser surgery (carcinomas of the hypopharynx and larynx); and cochlear implantation (to verify the electrode position). After positioning the patient on the CT table, the workstation was set up in the operating theatre. If necessary, the gantry could be moved over the patient's head without repositioning the patient. RESULTS: Intraoperative CT was used to assist in the exposure of the skull base and lamina papyracea in endonasal surgery of the paranasal sinuses. Individual ethmoidal sinuses could not be evaluated owing to blood artefacts. Intraoperative imaging proved particularly helpful in revision surgery for chronic sinusitis in cases with missing anatomical landmarks owing to previous surgeries, where there is an increased risk of inflicting damage to the skull base or orbita. The resection margins can be determined in craniofacial resections. In soft-tissue procedures, such as tumour removal by means of laser surgery, it proved possible to visualize the resection borders of malignant tumours. Assessment of the electrode position in cochlear implantation is particularly useful in revision cases and in cases of cochlear obliteration.

[Unusual metastasis of hypernephroma in the maxillary sinus]. / Ungewöhnliche Metastasierung eines Hypernephroms in den Sinus maxillaris.

BACKGROUND: Metastases of infraclavicular malignancies to the nose and paranasal sinuses are characterized by their untypical symptoms and late clinical manifestation. Metastases of renal carcinoma on paranasal cavities may be highly vasculared and can cause profuse bleeding. PATIENT: We report a rare case of a 60-year-old man who suffered from a large metastatic hypernephroma to the right maxillary sinus. Intermittent epistaxis and pain were the first symptoms. The patient had undergone a tumor nephrectomy six months previously. The endonasal biopsy of the vascular tumor caused abundant bleeding which required surgical treatment. RESULTS: The solitary metastasis was resected by a maxillectomy with closure of the large cavity with a microvascular latissimus dorsi flap. Additionally, a conservative treatment of interleukin-2 and alpha-interferon was administered. CONCLUSIONS: In case of a solitary metastasis of a renal carcinoma, a radical resection should be considered to improve the prognosis. The possibility of extensive perfusion should be taken into account when taking a biopsy of the lesion in order to be prepared for managing bleeding.