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Biomedical subjects

W F Thumfart

Publications and source records attributed to W F Thumfart.

10 recordsLinked to original sources
PubMed1992

An electrohydrothermosation system for application in endolaryngeal and enoral surgery: a technical report.

The use of medical lasers or high-frequency (HF) devices ('electrocautery') allows the dissection of tissue by an application of heat. The main advantage of such techniques is the reduction of intra-operative bleeding. On the other hand, carbonization and coagulation lead to difficulties in the histological investigation of the resected specimen. Electrohydrothermosation (EHT) systems are irrigation-supported HF devices. The cutting or coagulation electrodes are continuously rinsed with distilled water in order to minimize thermal interactions with the tissue. We developed an EHT system for endoscopic head and neck surgery. The system was used to remove defined specimens from pig larynges and tongues experimentally. We compared the results with those obtained by a surgical CO2 laser and found that carbonization and overall tissue damage were less severe with EHT than with laser surgery. This leads to the conclusion that EHT is an improvement of conventional HF surgery and may be an alternative to laser surgery in the head and neck.

Animals↗
PubMed1992

Laser surgery for the treatment of larynx carcinomas: indications, techniques, and preliminary results.

The authors have developed four different types of endolaryngeal laser resections for the treatment of larynx carcinomas. These new techniques are based on traditional concepts employed in partial larynx resections. From 1986 onward, 110 patients with laryngeal cancers were treated by endoscopic laser surgery. One hundred six patients were operated on for cure and 4 for palliation. In 9 cases of T3 tumor, complete removal of the tumor was not possible, requiring total laryngectomy. In all T2 cancers of the glottis and subglottis (n = 36), a total resection was possible. Additional staged neck dissection was performed in 16 cases, and postoperative radiotherapy in 10 cases. Follow-up investigations of the patients treated for cure (n = 106) cover a period of 3 to 42 months (mean, 22 months). These revealed 6 recurrences in the larynx, which were treated by laryngectomy. Recurrences in the cervical nodes were seen in 2 patients following resection of a supraglottic tumor and a subglottic tumor, respectively. Seven patients could not be followed up, 4 patients died of intercurrent disease, and 87 patients are alive and free of tumor. At present the number of recurrences and the rate of survival show no significant difference from those previously reported after conventional surgery. The phonatory function is not always predictable and still remains to be investigated. The authors believe that laser surgery may obviate the need for total laryngectomies in selected cases of laryngeal cancer, especially in T2 tumors. However, T3 tumors should not be treated by endolaryngeal laser surgery.

Carcinoma↗
PubMed1992

Electrophysiologic investigation of lower cranial nerve diseases by means of magnetically stimulated neuromyography of the larynx.

Zoom endoscopic electromyography of the larynx, as introduced in 1979, has contributed greatly to the diagnosis of lower cranial nerve palsies, but in the early stage of a vagus nerve disorder one cannot investigate the nerve conduction from the brain stem to the laryngeal muscles with electrical stimulation. As with the early diagnosis of facial nerve palsies, up to now the intracranial part of the motoric brain nerves could not be stimulated directly. With a new magnetic coil device (Novametrix, Magstim 200) this intracranial stimulation is easily possible in the awake patient with painless magnetic stimuli that induce a muscle action potential into the laryngeal muscles. Hence, an immediate diagnosis is possible. Two coils with mean diameters of 8.5 or 3 cm were used. The stimulator delivered current pulses of peak amplitude up to 5,000 A with rise times of 140 microseconds and 65 microseconds, respectively, that generated peak fields of up to 2 T. In a healthy population, cisternal stimulation of the vagus nerve leads to a muscular response in the vocal muscle after 4 to 6.6 milliseconds (mean 5 milliseconds). Cortical stimulation leads to such a response after 9.5 to 12 milliseconds. Potentials in healthy individuals have been shown to be very uniform. Stimulation in recurrent nerve palsies may show prolongation of these latencies up to 30 milliseconds. The method is limited by the fact that complete neural blocks cannot be overcome by proximal stimulation. We have applied magnetic stimulation to 190 patients with different disorders of the vagus nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

[The temporal bone].

Imaging of the temporal bone by high resolution CT scan has become more and more accurate in recent years. Coronal slices are particularly important. We present the anatomy of four temporal bones embedded in plastic material. Coronal sections with a thickness of 2 mm were taken, radiographed and their density measured. Particular interest was given to the three-dimensional relations as well as to the density of bone of important morphological structures such as the labyrinth, middle ear, facial canal, sigmoid sinus, carotid canal and the mastoid. A low density of bone corresponds to the colour blue, a high density to black. Because of the high resolution of the method it was possible to image small and fine structures such as the auditory ossicles, and the perilymphatic and endolymphatic ducts. A three-dimensional reconstruction may well be possible in the future, and the possibilities of this method are discussed.

Carotid Artery, Internal↗
PubMed1991

[Endoscopically-controlled endonasal orbital decompression in malignant exophthalmos].

In 6 patients with endocrine ophthalmopathy, indications, surgical technique and results of the endoscopic controlled endonasal orbital decompression are described in comparison to the common surgical procedures. When medical and radiation therapy fail, indications for decompression are a) loss of visual acuity or visual field defects, b) increasing strabismus, c) severe keratopathy due to eyelid retraction. The endoscopic-controlled endonasal surgical decompression technique is proceeded in three steps. First, an endonasal ethmoidectomy with resection of the middle turbinate is performed and the medial wall of the maxillary sinus is widely opened. Second, the medial and inferior wall of the orbital walls are removed, preserving the infraorbital nerve. In the last step, the periorbital area is incised and the orbital fat herniates. The advantages of this procedure consist in the absence of exterior scars and the known morbidity of a Caldwell-Luc antrotomy. The results were documented by computed tomographic scans (CT), magnetic resonance imaging (MRI), Hertel measurements, evaluation of ocular motility and ophthalmoscopy. An average of 3-4 mm improvement in Hertel-measurements could be reached. All patients had a postoperative improvement of visual acuity. 2 patients developed more significant diplopia postoperatively, whereas in all other patients ocular motility either improved or rested unaffected. Therefore, the endoscopic controlled endonasal procedure allows to obtain comparable results to the common extranasal and transantral procedures without the disadvantages of the latter.

Aged↗
PubMed1990

[Endolaryngeal laser surgery in the treatment of laryngeal cancers. The current Cologne concept].

Tumors can be resected in two different ways using endolaryngeal laser surgery. 1. After taking a biopsy from the lesion for histological purposes, the remaining tumor is completely vaporized. This method is only to be used in the treatment of premalignant lesions, as it does not allow a clear histological examination of the boundaries of such lesions. 2. The laser is used as a "scalpel", allowing a complete resection of laryngeal tumors in one block and a histological assessment of the margins. In the treatment of carcinoma in situ and severe dysplasia, we perform a laser-decortication of one or both vocal cords, leaving the vocal muscle intact (endolaryngeal laser-resection type I). Limited carcinomas of one vocal cord undergo a cordectomy, leaving the anterior commissure behind (endolaryngeal laser-resection type II). Extended and bilateral vocal cord carcinomas are treated by an extended cordectomy, which can comprise resection of one of the arytenoid cartilages if necessary (endolaryngeal laser-resection type III). Vocal cord carcinoma with extension to one or both false cords (stage T2) require a complete resection of one or both vocal and false cords in combination with an arytaenoidectomy, if necessary. The resection comprises the inner perichondrium of the thyroid and cricoid cartilages as well as the cricothyroid membrane (endolaryngeal laser-resection type IV, endolaryngeal exenteration).

Follow-Up Studies↗
PubMed1990

[Preliminary results of endolaryngeal laser resections of laryngeal cancers].

From 1986 to 1988 ninety four patients with carcinoma of the larynx were treated by endoscopic laser surgery. Follow-up ranges from 3 to 39 months with a mean value of 23 months. Ninety patients were operated on with curative intent and 4 with palliative intent. In 7 cases of T3 tumors a complete removal of the tumor was not possible, so that a total laryngectomy could not be avoided. In all cases of T2 cancers of the glottic and subglottic level a definite resection was possible. Follow-up investigations showed 3 recurrences in the larynx so far. These were treated by laryngectomy. Recurrences in the cervical nodes were seen in two patients following resection of a supraglottic and a subglottic tumor. The authors believe that laser surgery may obviate the need for total laryngectomies in certain stages of laryngeal cancer, especially in T2 tumors. T3 tumors should not be treated by endolaryngeal laser surgery. At present, the number of recurrences and the rate of survival show no significant difference to those after conventional surgery. The phonatory function is not always predictable, and still needs to be investigated.

Adult↗
PubMed1990

[Comparative studies of the stability of nerve anastomoses using CO2 laser adaptation compared with conventional technics].

Despite sophisticated microsurgical techniques for nerve repair, neural anastomoses often dehisce, especially under pronounced traction on the nerve endings. We investigated the resistance to traction of several neural anastomoses made by different techniques, including the laser. Neural anastomoses constructed or fixed by a CO2 laser beam were considered with special interest. The forces required to disrupt the different anastomoses were monitored by a dynamometer, and the whole procedure was recorded in slow motion on video. Improved results cannot be achieved with the laser techniques available today: indeed neural anastomoses were less resistant to traction after CO2 laser coagulation. Anastomoses constructed by means of epineural sutures showed much the best resistance to traction.

Anastomosis, Surgical↗
PubMed1988

[Prevention and therapy of synechia following laser resection of laryngeal tumors].

Laser resection of vocal cord carcinomas often requires the exstirpation of the ventral commissure and exposure of the thyroid cartilage to ensure complete excision of the tumour. The appearance of synechia near the commissure is a frequent complication of such operations. Even intensive conservative postoperative treatment does not effectively combat this complication. A newly developed operative technique is presented for the prevention and/or treatment of such synechia or granulation after endolaryngeal laser surgery. The method is also documented photographically.

Aprotinin↗