Matthias Echternach

Does the timing of tracheal intubation based on neuromuscular monitoring decrease laryngeal injury? A randomized, prospective, controlled trial

Vocal cord injuries (VCI) and postoperative hoarseness (PH) are common complications after general anesthesia. Poor muscle relaxation at the moment of tracheal intubation may result in VCI. There is a large interindividual variation in neuromuscular depression after administration of neuromuscular blocking drugs. Therefore, the optimal individual timing of tracheal intubation based on neuromuscular monitoring (monitoring) may decrease VCI. In this prospective trial, 60 patients were randomized into 2 groups: Monitoring group: tracheal intubation at maximum block based on monitoring after atracurium 0.5 mg/kg and 2-min group: tracheal intubation 2 min after injection of atracurium 0.5 mg/kg. Intubating conditions were evaluated with the Copenhagen score. VCI were examined by stroboscopy before and 24 and 72 h after surgery. PH was assessed at 24, 48, and 72 h after surgery by a standardized interview. Excellent intubating conditions were significantly increased in the monitoring group compared with the 2-min group: 8 versus 2 patients, respectively (P = 0.036). The incidence of PH between the study groups was comparable: 7 (monitoring) versus 8 patients (2-min) (P = 0.860). Similar findings were observed for VCI: 9 versus 5 patients; respectively (P = 0.268); type of VCI: thickening of the vocal cords: 8 (monitoring) versus 5 (2-min) patients (P = 0.423), hematomas: 2 patients in each group (not significant). The present study demonstrated that neuromuscular monitoring improved endotracheal intubating conditions. However, tracheal intubation at maximum intensity of neuromuscular block was not associated with a decrease in vocal cord injuries.

Laryngeal Complications After Thyroidectomy: Is It Always the Surgeon?

HYPOTHESIS Laryngeal dysfunction after thyroidectomy is a common complication. However, few data are available to differentiate whether these complications result from injury to the recurrent nerve or to the vocal folds from intubation. SETTING University medical center. PATIENTS Seven hundred sixty-one patients who underwent surgery to the thyroid gland from 1990 to 2002. Of these patients, 8.4% underwent a revision thyroidectomy. INTERVENTION Preoperative and postoperative laryngostroboscopic examination. MAIN OUTCOME MEASURE Laryngostroboscopic evaluation of laryngeal complications. RESULTS The overall rate of laryngeal complications was 42.0% (320 patients). Complications from an injury to the vocal folds occurred in 31.3% of patients. Weakness or paresis of the recurrent nerve was initially present in 6.6% and was related to the nerves at risk. This rate was higher in revision thyroidectomies than in primary surgical interventions (6.2% vs 11.6%; P = .04). The rate of laryngeal injuries was higher in patients older than 65 years (39.8% vs 30.8%; P = .03). CONCLUSIONS These data suggest that laryngeal complications after thyroidectomies are primarily caused by injury to the vocal folds from intubation and to a lesser extent by injury to the laryngeal nerve. We recommend documentation of informed consent, especially for patients who use their voice professionally, such as singers, actors, or teachers.

Dynamic magnetic resonance imaging of swallowing and laryngeal motion using parallel imaging at 3 T

OBJECT To evaluate the feasibility of an optimized MRI protocol based on high field imaging at 3 T in combination with accelerated data acquisition by parallel imaging for the analysis of oropharyngeal and laryngeal function. MATERIALS AND METHODS Fast 2D gradient echo (GRE) MRI with different spatial resolutions (1.7x2.7 and 1.1x1.5 mm2) and image update rates (4 and 10 frames per second) was employed to assess pharyngeal movements and visualize swallowing via tracking of an oral contrast bolus (blueberry juice). In a study with 10 normal volunteers, image quality was semi-quantitatively graded by three independent observers with respect to the delineation of anatomical detail and depiction of oropharynx and larynx function. Additionally, the feasibility of the technique for the visualization of pathological pre- and post-surgical oropharynx and larynx function was evaluated in a patient with inspiratory stridor. RESULTS Image grading demonstrated the feasibility of dynamic MRI for the assessment of normal oropharynx and larynx anatomy and function. Superior image quality (P<.05) was found for data acquisition with four frames per second and higher spatial resolution. In the patient, dynamic MRI detected pathological hypermobility of the epiglottis resulting in airway obstruction. Additional post-surgical MRI for one clinical case revealed morphological changes of the epiglottis and improved function, i.e., absence of airway obstruction and normal swallowing. CONCLUSION Results of the volunteer study demonstrated the feasibility of dynamic MRI at 3 T for the visualization of the oropharynx and larynx function during breathing, movements of the tongue and swallowing. Future studies are necessary to evaluate its clinical value compared to existing modalities based on endoscopy or radiographic techniques.

Vocal tract and register changes analysed by real-time MRI in male professional singers—a pilot study

Changes of vocal tract shape accompanying changes of vocal register and pitch in singing have remained an unclear field. Dynamic real-time magnetic resonance imaging (MRI) was applied to two professional classical singers (a tenor and a baritone) in this pilot study. The singers sang ascending scales from B3 to G#4 on the vowel /a/, keeping the modal register throughout or shifting to falsetto register for the highest pitches. The results show that these singers made few and minor modifications of vocal tract shape when they changed from modal to falsetto and some clear modifications when they kept the register. In this case the baritone increased his tongue dorsum height, widened his jaw opening, and decreased his jaw protrusion, while the tenor merely lifted his uvula. The method used seems promising and should be applied to a greater number of singer subjects in the future.

Professional Opera Tenors' Vocal Tract Configurations in Registers

Objective: Tenor singers may reach their top pitch range either by shifting from modal to falsetto register or by using their so-called ‘voix mixte’. Material and Methods: In this study, dynamic real-time MRI of 8 frames per second was used to analyze the vocal tract profile in 10 professional opera tenors, who sang an ascending scale from C4 (262 Hz) to A4 (440 Hz) on the vowel /a/. The scale included their register transition and the singers applied both register techniques in different takes. Results: Modal to falsetto register changes were associated with only minor vocal tract modifications, including elevation and tilting of the larynx and a lifted tongue dorsum. Transitions to voix mixte, by contrast, were associated with major vocal tract modifications. Under these conditions, the subjects widened their pharynges, their lip and jaw openings, and increased their jaw protrusion. These modifications were stronger in more ‘heavy’ tenors than in more ‘light’ tenors. The acoustic consequences of these articulatory changes are discussed.

High-speed imaging and electroglottography measurements of the open quotient in untrained male voices' register transitions.

Vocal fold oscillation patterns in vocal register transitions are still unclarified. The vocal fold oscillations and the open quotient were analyzed with high-speed digital imaging (HSDI) and electroglottography (EGG) in 18 male untrained subjects singing a glissando from modal to the falsetto register. Results reveal that the open quotient changed with register in both HSDI and EGG. The in-class correlations for different HSDI and EGG determinations of the open quotient were high. However, we found only weak interclass correlations between both methods. In 10 subjects, irregularities of vocal fold vibration occurred during the register transition. Our results confirm previous observations that falsetto register is associated with a higher open quotient compared with modal register. These data suggest furthermore that irregularities typically observed in audio and electroglottographic signals during register transitions are caused by irregularities in vocal fold vibration.

Polydimethylsiloxane particles for permanent injection laryngoplasty

Objectives: Polydimethylsiloxane (PDMS) particles are a nonresorbable material that allows for permanent vocal fold augmentation. This study investigated morbidity and voice quality in patients treated for unilateral vocal fold paralysis by injection of PDMS particles. Methods: Fourteen patients who had neurogenic unilateral vocal fold paralysis of different causes were included in this prospective study. Each patient underwent videostroboscopic assessment before and after operation. Friedrichs dysphonia index (DI), a score system combining subjective and objective parameters, was used to describe voice quality. A DI of 0 reflects a normal voice, and a DI of 3 stands for complete aphonia. The PDMS particles were injected into the paraglottic space by microlaryngoscopy under general anesthesia. Results: The median follow-up was 4.1 months. There was no complication attributable to the injection of PDMS particles. The mean DI was 2.8 before operation. After the operation, voice quality improved significantly in each patient, as reflected by a mean postinjection DI of 1.4. Conclusions: Particles of PDMS provide a relatively safe and minimally invasive option for permanent vocal fold augmentation. The functional results in terms of voice improvement are comparable to those obtained with other techniques, including thyroplasty. In the European Community, PDMS particles are officially approved for use in the human larynx.

Rhino-orbital-cerebral mucormycosis and aspergillosis: differential diagnosis and treatment

In immunocompromised patients, symptoms and the pathogen spectrum of sinusitis are frequently atypical. If progressive loss of vision occurs, an infection of the anterior skull base or nasal sinuses should be considered. We report on four patients with orbit-associated symptoms. CT-imaging revealed bony defects in sinus borders to orbits or endocranium. In all the cases immediate surgical drainage was performed because complications following sinusitis were suspected. Histopathological diagnosis revealed two cases of aspergillosis and mucormycosis. The possibility of opportunistic infections by saprophytic fungi must be taken into account in immunocompromised patients, as they may endanger both vision and survival. Immediate diagnosis and therapy are essential. Nowadays, therapeutic success can be achieved due to advances in antimicrobial therapy, hyperbaric oxygen therapy and treatment of the underlying disease. Radical procedures like orbital exenteration must be considered in all cases. The current state of diagnostics, therapy and prognosis is discussed based on these case reports and the recent literature.

Vocal tract configurations in male alto register functions.

PURPOSE Professional male altos (countertenors) mostly use a register function, which is considered to be derived from falsetto. However, the sound produced differs in professional altos compared with the modal register or falsetto of untrained voices. The aim of this study was to analyze differences of the vocal tract shapes in male alto register functions. MATERIAL AND METHODS Dynamic real-time magnetic resonance imaging of eight frames per second was used to analyze the vocal tract profile in seven professional male altos who sang on the vowel /a/, an ascending and descending scale from G3 (196 Hz) to E4 (330 Hz). The scale included their register transition from modal register to stage (counter) falsetto and naïve falsetto. RESULTS Register transitions from modal register to stage falsetto were associated with increased lip opening, jaw retraction, elevation and back positioning of the tongue, pharynx narrowing, uvula elevation, drop of larynx height, and tilting of the larynx. Differences between stage and naïve falsetto were found mostly with regard to lip opening and pharynx width. CONCLUSIONS The differences between the vocal tract configurations might have an impact on the acoustic characteristics observed in professional male alto register functions.

Vocal fold vibrations at high soprano fundamental frequencies

Human voice production at very high fundamental frequencies is not yet understood in detail. It was hypothesized that these frequencies are produced by turbulences, vocal tract/vocal fold interactions, or vocal fold oscillations without closure. Hitherto it has been impossible to visually analyze the vocal mechanism due to technical limitations. Latest high-speed technology, which captures 20,000 frames/s, using transnasal endoscopy was applied. Up to 1568 Hz human vocal folds do exhibit oscillations with complete closure. Therefore, the recent results suggest that human voice production at very high F0s up to 1568 Hz is not caused by turbulence, but rather by airflow modulation from vocal fold oscillations.