Cervicofacial and mediastinal emphysema after balloon eustachian tuboplasty (BET): a retrospective multicenter analysis.

PURPOSE: Balloon Eustachian tuboplasty (BET) is a new treatment modality addressing chronic obstructive dysfunction of the Eustachian tube (ET). So far, BET has been deemed a safe procedure under general anesthesia with only minor adverse effects. However, individual cases of postoperative emphysema have been reported. In the present retrospective multicenter analysis we determined the incidence rate of this potentially life threatening complication after BET. METHODS: In total we collected data from 3,670 BET procedures performed on 2,272 patients in four tertiary care ENT departments. RESULTS: Ten cases of postoperative cervicofacial emphysema were documented, whereas only in 3 of them a pneumomediastinum was developed. None of the affected patients developed at any time serious clinical signs or symptoms besides cutaneous crepitations. A complete resolution and recovery of the emphysema occurred in all patients under antibiotic prophylaxis and abstinence from Valsalva maneuver within the first 2-6 postoperative days. CONCLUSIONS: Possible causes for the development of these postinterventional emphysemas are considered to be mucosal injuries of the ET during manipulations for the correct position of the insertion instrument, through a "kinking" of the balloon catheter or even due to the relative rigid catheter itself, although its form is regarded to be atraumatic. The complication rate of postoperative emphysema was 0.27% (95% CI 0.13-0.50%). The above facts in addition to only minor and transient overall complications after BET reported in literature, can label this procedure as a safe treatment with a low risk profile.

Long-term vestibulocochlear functional outcome following retro-sigmoid approach to resection of vestibular schwannoma.

The objective of this study was to evaluate long-term vestibulocochlear functional outcomes of patients operated for unilateral vestibular schwannoma via the retro-sigmoid approach. Patients who underwent vestibular schwannoma resection via retro-sigmoid approach between 2004 and 2008 at our institution, without prior surgical or radio-surgical therapy were considered to be eligible for this study. Preoperative auditory and vestibular symptoms were assessed retrospectively. Postoperative symptoms were prospectively assessed using a standardised questionnaire, pure tone audiometry, video-oculography, and rotary chair testing. Out of a total of 203 patients, 120 were eligible for this study, of whom 64 responded to follow-up requests and could be enrolled. Serviceable hearing was reported in 42 patients (66 %) preoperatively and was maintained in 18 (43 %) postoperatively. While no significant change in rate of tinnitus and balance impairment between pre- and postoperative periods was detected, vertigo decreased significantly (40 to 28 %, p < 0.001). Postoperative video-oculography demonstrated vestibular paresis in 80 %. Rotary chair testing demonstrated normal or central compensation in 84 %. Absence of central compensation was associated with postoperative balance disturbance (p = 0.035). Increasing tumour size and patient age, also decreasing quality of preoperative hearing were independent factors predictive of a postoperative non-serviceable hearing (p = 0.020, p = 0.039 and p = 0.002, respectively). Resection of vestibular schwannoma via the retro-sigmoid approach is associated with improvement in postoperative vertiginous symptoms. Absence of central compensation leads to increased postoperative balance disturbances. Preservation of serviceable postoperative hearing is associated with good preoperative hearing status, younger age, and smaller tumours.

First results of Endonasal dilatation of the Eustachian tube (EET) in patients with chronic obstructive tube dysfunction.

For years, several surgical and non-surgical therapeutic strategies in Eustachian tube dysfunction have been described. The Endonasal dilatation of the Eustachian tube (EET) utilising a balloon catheter is a feasible option in patients with symptoms of chronic obstructive Eustachian tube dysfunction. However, long-term results in a large series are missing. In a prospective case series, 217 patients (342 cases) with symptoms of chronic Eustachian tube dysfunction underwent uni- or bilateral EET at the ENT Department of the University of Hamburg, Germany, between September 2010 and April 2013. A tube score consisting of the type of tympanogram and the R value of the tubomanometry was used to evaluate pre- and postoperative tube function. All patients underwent follow-up with a post-operative interval of 3-12 months. The mean value of the pre-treatment tube score was 2.23 ± 1.147 and significantly improved to 2.68 ± 1.011 1 year after EET. There was a significant increase in the tube score during follow-up. The co-variables time period, tympanoplasty and pressure range showed a significant impact on the tube score. EET is a minimally invasive and effective treatment of chronic obstructive tube dysfunction. It is a safe procedure without causing significant complications. Nevertheless, long-term results of larger, placebo-controlled multicentre studies are needed to confirm its effectiveness.

Two-Year Survival Analysis of 50 Consecutive Head and Neck Cancer Patients Treated with Transoral Robotic Surgery in a Single European Centre.

BACKGROUND: To date, this prospective cohort study is the largest of its kind from a single European academic tertiary care center to report 2-year survival outcomes for head and neck squamous cell carcinoma treated primarily with transoral robotic-assisted resection. PATIENTS AND METHODS: Fifty consecutive, appropriately staged patients were enrolled prospectively, and underwent transoral robotic surgery (TORS) between September 2011 and August 2013. Overall, 24 patients had a T1 primary tumor, 23 had a T2 primary tumor, 2 had a T3 primary tumor, and 1 had a T4a primary tumor. Eighteen patients had overall stage I-II disease, and 32 patients had stage III-IV disease. Following transoral robotic resection of their primaries and appropriate neck dissection(s) as indicated, adjuvant treatment could be spared for 20 patients; another 5 patients refused the recommended adjuvant treatment. Seventeen patients received 60 Gy adjuvant radiotherapy and 8 patients underwent 66 Gy adjuvant chemoradiotherapy. RESULTS: At the time of the last follow-up visit (median 27 months), overall survival was 94 %, with two disease-specific deaths and one unrelated death (heart attack). The 2-year disease-free and recurrence-free survival rates were 88 and 80 %, respectively; however, the local recurrence rate was only 10 % after 2 years. CONCLUSION: Using TORS as their primary modality, 40 % of patients did not need adjuvant treatment and showed similar survival rates to that of conventional surgery or primary chemoradiotherapy. In another 34 % of patients, adjuvant chemotherapy could be spared and adjuvant radiotherapy could be reduced by 10 Gy compared with primary chemoradiotherapy of 70 Gy. Further studies are warranted with respect to long-term survival.

Reduced dosage of bevacizumab in treatment of vestibular schwannomas in patients with neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is a tumor suppressor syndrome associated with vestibular schwannomas and other benign tumors of the central nervous system. Bevacizumab is used for treatment of progressive vestibular schwannomas, with the intent to reduce tumor size or preserve/improve hearing. Prolonged treatment can cause side effects such as hypertension and proteinuria, which can be cause for discontinuation of therapy. We report on 3 patients who were treated with bevacizumab for 66-76 months, with dose reductions that minimized side effects while sustaining the clinical effect of the antiangiogenic therapy. After dose reduction from 5 mg/kg bi- or tri-weekly to 2.5 mg bi- or tri-weekly, all patients appeared clinically stable and radiographic and audiologic follow-up showed sustained response. In conclusion, in some NF2 patients, dose reduction of bevacizumab seems to be an effective option for managing side effects.

A comparison of hearing results following stapedotomy under local versus general anesthesia.

Advances in operative technique, instrumentation, and prosthesis design in otosclerosis surgery continue since Shea performed the first successful surgery. This is the first analysis to specifically compare post-operative hearing outcomes following stapedotomy surgery performed under local versus general anesthesia. Hearing outcomes were further stratified by comparing conventional perforator and Er:YAG laser ablation perforation techniques. Pre- and post-operative audiograms were retrospectively analyzed together with the method of anesthesia and the perforation technique for all patients with otosclerosis who underwent stapedotomy between 1998 and 2007. Pre-operative individual standard audiometry frequency thresholds (IFTs), air (AC) and bone conduction pure tone averages (PTA), and air bone gaps (ABG) were compared against post-operative results. Differences between pre- and post-operative PTAs and ABGs were compared between patients who received stapedotomy under local versus general anesthesia, as well as for patients who underwent conventional versus Er:YAG laser ablation perforations. Eighty-six patients were identified of which 24 % (n = 21) received local and 76 % (n = 65) received general anesthesia. Post-operative audiograms were available for 84 and 48 patients, respectively. Significant improvements were seen across all groups for standard 4-frequency AC-PTA and ABG and for IFTs up to 3 kHz. No significant difference was seen for IFTs between 4 and 6 kHz. A significant decline in post-operative hearing thresholds was seen at 8 kHz. Significant improvements in PTA and ABG were seen for all groups. There was a trend toward general compared to local anesthesia post-operative hearing results furthermore in combination with conventional perforation technique then with laser technique.

Endonasal dilatation of the Eustachian tube (EET) in children: feasibility and the role of tubomanometry (Estève) in outcomes measurement.

Studies on endonasal dilatation of the Eustachian tube (EET) utilizing a balloon catheter have shown encouraging results over the last years. This retrospective analysis presents our outcomes with EET in children with chronic obstructive dysfunction of the Eustachian tube, as well as the role of tubomanometry (TMM, Estève) as a diagnostic tool in the pre- and postoperative assessment of the Eustachian tube (ET) dysfunction. The data of 33 children, having undergone EET between September 2010 and March 2014, were retrospectively evaluated. They were assessed using tubomanometry before and after the EET. The R-data as the rate of Eustachian tube function in tubomanometry (TMM) were pre- and postoperatively matched with the clinical outcomes. Moreover, the patients' complaints before and after the procedure were analyzed. We did not see any EET-related complications in children. Most patients noticed a relief of their complaints. In the same time, tubomanometry was not able to show improved tube function or favorable postoperative changes in the R-data. Ear-related symptoms (e.g. otorrhea, otalgia, hearing loss) have been improved. EET is a feasible method in adults as well as in children to treat chronic tube dysfunction. However, tubomanometry does not seem to be the adequate tool to evaluate the tube function and thus the success rate of EET in children with chronic dysfunction of the Eustachian tube.

Reduction of thermocoagulative injury via use of a picosecond infrared laser (PIRL) in laryngeal tissues.

The carbon dioxide (CO2) laser is routinely used in glottic microsurgery for the treatment of benign and malignant disease, despite significant collateral thermal damage secondary to photothermal vaporization without thermal confinement. Subsequent tissue response to thermal injury involves excess collagen deposition resulting in scarring and functional impairment. To minimize collateral thermal injury, short-pulse laser systems such as the microsecond pulsed erbium:yttrium-aluminium-garnet (Er:YAG) laser and picosecond infrared laser (PIRL) have been developed. This study compares incisions made in ex vivo human laryngeal tissues by CO2 and Er:YAG lasers versus PIRL using light microscopy, environmental scanning electron microscopy (ESEM), and infrared thermography (IRT). In comparison to the CO2 and Er:YAG lasers, PIRL incisions showed significantly decreased mean epithelial (59.70 µm) and subepithelial (22.15 µm) damage zones (p < 0.05). Cutting gaps were significantly narrower for PIRL (133.70 µm) compared to Er:YAG and CO2 lasers (p < 0.05), which were more than 5 times larger. ESEM revealed intact collagen fibers along PIRL cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 and Er:YAG laser incisions. IRT demonstrated median temperature rise of 4.1 K in PIRL vocal fold incisions, significantly less than for Er:YAG laser cuts (171.85 K; p < 0.001). This study has shown increased cutting precision and reduced lateral thermal damage zones for PIRL ablation in comparison to conventional CO2 and Er:YAG lasers in human glottis and supraglottic tissues.

Role of panendoscopy in identifying and managing risk of head and neck squamous cell carcinoma in routine follow-up: a retrospective clinical evaluation.

We discuss the clinical effectiveness and predictive value of routine panendoscopy for surveillance and follow-up of head and neck squamous cell carcinoma (HNSCC). Retrospective comparative study. Department of Otolaryngology-Head and Neck Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Two hundred and four HNSCC patients (follow-up between 2004 and 2007) were retrospectively evaluated. During follow-up, panendoscopy was performed routinely once a year. To avoid unnecessary procedures, we evaluated the value of radiological and clinical parameters in follow-up. On comparing normal-computerized tomography (CT) vs. abnormal CT results, a 13-fold higher frequency of recurrence (odds ratio 12.74; 95% CI 4.22, 38.48; p < 0.001) was found. Additionally, patient medical history, clinical investigation, and recurrence pattern were significant parameters when detecting a possible recurrence. Panendoscopy could have been avoided in 40% of patients with HNSCC (173/432). A follow-up schedule avoiding routine panendoscopy in HNSCC follow-up when the combination of diagnostic parameters is satisfactory does not influence the sensitivity or specificity of the test.

Use of a microsecond Er:YAG laser in laryngeal surgery reduces collateral thermal injury in comparison to superpulsed CO2 laser.

Despite causing significant thermocoagulative insult, use of the carbon dioxide (CO2) laser is considered gold standard in surgery for early stage larynx carcinoma. Limited attention has been paid to the use of the erbium:yttrium-aluminium-garnet (Er:YAG) laser in laryngeal surgery as a means to reduce thermal tissue injury. The objective of this study is to compare the extent of thermal injury and precision of vocal fold incisions made using microsecond Er:YAG and superpulsed CO2 lasers. In the optics laboratory ex vivo porcine vocal folds were incised using Er:YAG and CO2 lasers. Lateral epithelial and subepithelial thermal damage zones and cutting gap widths were histologically determined. Environmental scanning electron microscopy (ESEM) images were examined for signs of carbonization. Temperature rise during Er:YAG laser incisions was determined using infrared thermography (IRT). In comparison to the CO2 laser, Er:YAG laser incisions showed significantly decreased epithelial (236.44 µm) and subepithelial (72.91 µm) damage zones (p < 0.001). Cutting gaps were significantly narrower for CO2 (878.72 µm) compared to Er:YAG (1090.78 µm; p = 0.027) laser. ESEM revealed intact collagen fibres along Er:YAG laser cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 laser incisions. IRT demonstrated absolute temperature rise below 70 °C for Er:YAG laser incisions. This study has demonstrated significantly reduced lateral thermal damage zones with wider basal cutting gaps for vocal fold incisions made using Er:YAG laser in comparison to those made using CO2 laser.

Investigation of noise levels generated by otologic drills.

Drilling during temporal bone surgery may result in temporary or permanent noise-induced hearing loss or tinnitus. This has practical implications for both the patient and the surgeon. Different surgical drill devices, routinely used in temporal bone surgery, are examined referring to their emitted sound levels and sound transport. Two surgical drills were used on a brass tubing and a steel wire to simulate sound generation during temporal bone surgery. Overview measurements were performed on human cadaver in a medical laboratory. A set-up in a silent chamber was chosen to exclude external sound sources. The noise emissions and the vibration generated by a silver diamond bur and a cutting drill (Rose bur) were registered when used on a brass tubing and a solid steel wire with sound level meter and a non-contact laser vibrometer. The highest sound rate generated by the diamond burr did not exceed 63 dB(A) when used on a solid steel wire, whereas the cutting burr emitted 76 dB(A). Both drills produced lower sound levels on the brass tubing. Again the cutting burr topped the diamond burr with 68 dB(A) against 56 dB(A). The sound emission did not exceed 76 dB(A) outside a radius 4 cm around the drill location. In conclusion, sound emission generated by different surgical burs routinely used in temporal bone surgery is lower than expected. Still, within a small radius around those burs high sound pressure levels may be induced into surrounding structures such as ossicles, labyrinth, and cochlear. Still damage is feasible when using surgical drills for a longer time period close to sensitive structures.

The endoscopic approach to the neck: a review of the literature, and overview of the various techniques.

BACKGROUND: The endoscopic surgical approach to the neck has reached the head and neck surgeons' view with a certain delay, compared to other fields of endoscopic procedures. This may be attributed to the tight work space and plenty of vital structures in the operating field. Since study groups described first attempts with endoscopic or video assisted removals of thyroid glands in the late nineties, selective neck dissections on animal models or cadaveric dissections were performed in 2003. METHOD: The review consists of a Medline Search regarding the terms of endoscopic, video- assisted neck dissections, excision of neck lesions, thyroidectomy and submandibular resection and minimal access surgery. The three main procedures (selective neck dissection, submandibular resection and thyroidectomy) are described and reviewed in the following test. RESULTS: Various techniques have been performed successfully and led to good clinical results. The studies described in literature other than for thyroidectomy often do not exceed the level of small series or case-reports. CONCLUSION: With a good proof of indication gasless lifting techniques, video assisted endoscopical techniques and subcutaneous approaches with gas filling procedures are feasible in neck surgery. All methods depending on the surgeons' experience describe no significantly extended operation times, a better and faster wound-healing and an optimized cosmetic outcome, compared to open approaches. Surgeons should always be aware of the limitations of the minimal invasive techniques regarding the complications or modifications during neck dissection/thyroidectomy.

The value of digital volume tomography in assessing the position of cochlear implant arrays in temporal bone specimens.

OBJECTIVES: Radiological evaluation of the position of cochlear implant (CI) devices is an upcoming method for quality control after CI surgery. First, results of imaging of the middle and inner ear with digital volume tomography (DVT) show considerable advantages such as exceptional image quality, thin slice thickness, and low radiation dose. The aim of this study was to evaluate whether DVT is an appropriate method for postoperative imaging of CI patients and to identify the exact position of the implant array within the cochlear by multiple measurements. DESIGN: Thirteen formalin-fixed temporal bone specimens were implanted with a CI array and scanned in DVT. To determine the exact electrode position, these specimens were ground and stained for microscopic measurements. The measurements on grindings acted as a referee and were compared with the measurements in DVT scans. The statistical analysis between the two measurement protocols was performed using the Bland-Altman method. RESULTS: Best achievable agreement between DVT scans and histological reference was shown. Mean differences between DVT and grindings from -1.55 to -65.40 microm were calculated. All means are within the region of accuracy. General positioning of the implant into the cochlea could be verified in all specimens. The exact position of the implanted array within the cochlear scalae could be recognized correctly in 11 of 13 cases in DVT. It was possible to identify shiftings between the tympanic and vestibular scalae in all cases. CONCLUSION: DVT seems to be a convenient technique for postoperative position control after cochlear implantation.

Balloon Eustachian Tuboplasty (BET) in Children: A Retrospective Multicenter Analysis.

OBJECTIVE: Generation of pilot data for planning of prospective BET-studies for treatment of dilatory Eustachian tube (ET) dysfunction in children. STUDY DESIGN: Retrospective multicenter analysis. SETTING: Nine ENT departments at tertiary care teaching hospitals. PATIENTS: 4-12-year-old children with chronic otitis media with effusion (COME) for more than 3 months or more than 3 episodes of acute otitis media during the last year, having failed standard surgical therapy at least once. INTERVENTION: BET with or without paracentesis, ventilation tube insertion, or tympanoplasty. MAIN OUTCOME MEASURES: Tympanic membrane appearance, tympanometry, and hearing threshold. RESULTS: Two hundred ninety-nine ETs of 167 children were treated. Mean age was 9.1 years (95% confidence interval [95% CI]: 8.7-9.4 yr). In 249 ears (83.3%), COME and/or retraction of the tympanic membrane were the indication for BET. Median hearing threshold was 20 dB HL (95% CI: 0-46 dB). One hundred fifty-five ears (51.8%, 95% CI: 46.1-57.4%) showed a tympanogram type B. Treatment consisted of BET without other interventions ("BET-only") in 70 children, 128 ears. Median length of follow-up for 158 (94.6%) children was 2.6 months (95% CI: 0.3-16.1 mo). After treatment, the tympanic membrane appeared normal in 196 ears (65.6%, 95% CI: 60.0-70.8%, p < 0.001). Median hearing threshold improved to 10 dB HL (95% CI: 0-45 dB, p < 0.001). Tympanograms shifted toward type A and C (type A: 39.1%, 95% CI: 33.7-44.7, p < 0.001). These improvements were also observed in subgroup analyses of "BET-only" treatment and the indication of "COME" respectively. CONCLUSION: BET is improving a variety of dilatory ET dysfunction-related ear diseases in children. This study provides detailed data for design and planning of prospective studies on BET in children.

Picosecond Infrared Laser (PIRL) Application in Stapes Surgery-First Experience in Human Temporal Bones.

OBJECTIVE: Using a contact-free laser technique for stapedotomy reduces the risk of mechanical damage of the stapes footplate. However, the risk of inner ear dysfunction due to thermal, acoustic, or direct damage has still not been solved. The objective of this study was to describe the first experiences in footplate perforation in cadaver tissue performed by the novel Picosecond-Infrared-Laser (PIRL), allowing a tissue preserving ablation. PATIENTS AND INTERVENTION: Three human cadaver stapes were perforated using a fiber-coupled PIRL. The results were compared with footplate perforations performed with clinically applied Er:YAG laser. Therefore, two different laser energies for the Er:YAG laser (30 and 60 mJ) were used for footplate perforation of three human cadaver stapes each. MAIN OUTCOME MEASURE: Comparisons were made using histology and environmental scanning electron microscopy (ESEM) analysis. RESULTS: The perforations performed by the PIRL (total energy: 640-1070 mJ) revealed a precise cutting edge with an intact trabecular bone structure and no considerable signs of coagulation. Using the Er:YAG-Laser with a pulse energy of 30 mJ (total energy: 450-600 mJ), a perforation only in the center of the ablation zone was possible, whereas with a pulse energy of 60 mJ (total energy: of 195-260 mJ) the whole ablation zone was perforated. For both energies, the cutting edge appeared irregular with trabecular structure of the bone only be conjecturable and signs of superficial carbonization. CONCLUSION: The microscopic results following stapes footplate perforation suggest a superiority of the PIRL in comparison to the Er:YAG laser regarding the precision and tissue preserving ablation.

A clinical study of the efferent auditory system in patients with normal hearing who have acute tinnitus.

OBJECTIVE: Etiological diagnosis and treatment of tinnitus still remain challenging in clinical practice. The aim of this study was to determine the potential contribution of a defective cochlear efferent innervation to the onset of tinnitus in patients with normal hearing. STUDY DESIGN: Prospective randomized controlled study. SETTING: Otorhinolaryngology department of a general hospital. PATIENTS: The patient group consisted of 18 normal-hearing adults (7 men, 11 women) with acute tinnitus (bilateral in 3 patients). INTERVENTIONS: Tympanogram, stapedial muscle reflex, pure tone audiometry, tinnitus pitch matching, spontaneous otoacoustic emissions, and distortion product otoacoustic emissions (DPOAEs) in the absence and presence of contralateral suppression by white noise. MAIN OUTCOME MEASURE: DPOAEs suppression amplitudes recorded from tinnitus and nontinnitus ears of the patients' group were compared with each other and with a control group. RESULTS: The contralateral application of white noise induced the enhancement of DPOAE amplitudes in some patients. The suppression of DPOAE amplitudes by contralateral white noise did not reach statistically significant levels in either ear (with or without tinnitus). On the contrary, under the same conditions, our control group demonstrated statistically significant reduction of DPOAE amplitudes at all frequencies. CONCLUSION: Patients with normal hearing acuity who have acute tinnitus seem to have a less effective functioning of the cochlear efferent system because the application of contralateral noise enhanced the DPOAEs or suppressed them less intensely than it did in a control group. Further studies may establish the clinical applications for the diagnosis of changes in efferent function, in the subjective evaluation, patient etiological grouping, treatment, or prognosis of tinnitus.

Acute haemorrhage in patients with advanced head and neck cancer: value of endovascular therapy as palliative treatment option.

AIMS: Acute or subacute haemorrhage is one of the most frightening complications in patients suffering from advanced head and neck cancer. Few articles report experience with superselective endovascular therapy for this purpose. Is endovascular therapy underestimated in the field of palliative head and neck cancer therapy? This study set out to investigate this question. PATIENTS AND METHODS: A review was undertaken of the clinical courses of seven patients (six men, one woman) suffering from incurable, advanced head and neck cancer (four pharyngeal, two laryngeal, one neck) and treated with superselective endovascular strategies as an emergency procedure for acute bleeding. RESULTS: All patients were successfully treated without evidence of neurological complication. Patients reached a median survival of 20 weeks (range eight-168 weeks). Following endovascular treatment all patients were discharged from the hospital within several days. Three patients survived almost free of symptoms for several weeks and were able to stay at home with their families until their death. CONCLUSION: We conclude that in the field of palliative care, superselective endovascular therapy deserves to be considered alongside standard treatment options for the management of acute haemorrhage from advanced head and neck cancer.

In-vitro investigations evaluating the detection spectrum of cervical lymph nodes via handheld gamma probe.

BACKGROUND: Currently the significance of the sentinel node (SN) biopsy also for head and neck cancer is discussed intensively. Based on the complex anatomic structures of this region with a low distance between primary and sentinel node as well as approximately 300 lymph nodes an intensive discussion of the methodical basis of sentinel node detection seems to be essential. Thus it was the aim of the present study to examine the detection spectrum of a gamma probe for identification of cervical lymph nodes using an in vitro model to describe and objectify the particularities of measurement existing in the head and neck region. MATERIAL/METHODS: In an in vitro model the detection spectrum of a gamma probe is examined in 29 different series of measurements (variation of the specimen filled with 99m pertechnetat regarding activity, position, collimator distance, tissue sheath). RESULTS: The presented in vitro model reflects the clinical problem of narrow intranodal activity of neighbouring lymph nodes and reveals a direct relation between the number of radiation sources and their isolated evidence. Using muscle tissue with a thickness of 0.4 cm, two two-rowed radiation sources, the more powerful is placed 1.5 cm behind the other specimen, with a lateral difference of 3 cm, can be resolved only with a maximal detector distance of 1 cm. Not the difference of the tissue but the thickness of the tissue is decisive for detection. CONCLUSION: Especially for pharyngeal and laryngeal lymph nodes a transcutaneous measurement reflecting the exact localisation of hot nodes in the area of the deep jugular lymph nodes is not possible with increasing tissue thickness. The described results require a critical discussion of the different detection techniques varying among the different working groups of this field.