A thorough history is essential but may not be possible in acute situations involving BVFI. In most cases establishing the diagnosis is relatively straightforward as there is usually an obvious cause such as recent thyroidectomy or trauma. Where doubt exists, a comprehensive history followed by examination and diagnostic tests is indicated.

The history should identify any previous surgery to the central nervous system (CNS), head, neck and thorax. Any recent intubation either for medical or surgical reasons should be noted. Examination including fibre-optic laryngoscopy with or without stroboscopy in the clinic setting should be performed and if possible recorded on image-capturing software for future comparison. Thereafter, depending on the history and preliminary examination findings, further imaging studies and specific laboratory tests should be considered [18].

A fine cut computer tomogram (CT) scan from the brainstem to the arch of the aorta is essential to rule out any lesion that may either be infiltrating or compressing the vagus nerve or the RLNs. The use of CT in diagnosing BVFI when the diagnosis is uncertain is becoming more common. Magnetic resonance imaging (MRI) of the CNS if such pathology is suspected should be performed as in the case of demyelinating diseases. The use of ultrasound has become more popular in assessing not only the neck but also the vocal folds for complete paralysis but has not been as accurate in diagnosing paresis [19].

Pulmonary function tests are helpful in assessing the extent of airway compromise. Peak inspiratory and expiratory flow (PIF, PEF), airflow resistance and the flow-volume curves are indicated in diagnosing the extent of central airway compromise. PEF has been shown to be more useful (compared to PIF) in comparing post-operative improvement [13, 14, 20, 21].

LEMG is an electrophysiological method of assessing the electrical activity in muscle (details in Chap. 1). Since its introduction by Weddel et al. [22] and its development thereafter by Faaborg-Andersen et al., it has become an increasingly important diagnostic and prognostic tool, although a recent meta-analysis showed that over 40% of patients with findings predictive of recovery did not in fact recover [23]. LEMG has the ability to diagnose neuropathic conditions and distinguish between a neurological cause for BVFI and mechanical immobility. In this regard, visual observation alone may be inadequate, and the use of vocal dynamic studies and videostroboscopy has been shown to be wrong in almost a third of cases after LEMG [24].

Where possible, voice analysis should be performed pre- and post-operatively. Phonation can be assessed by measuring maximum phonation time and phonation quotient for aerodynamic parameters. Acoustic evaluation measuring mean vocal intensity and high-resolution frequency analysis allows for the categorisation of intensity according to frequency which can be used to distinguish the spectrum ranging from no sound, noise, harmonics and fundamental frequency [7].

Where the diagnosis of BVFI is uncertain, especially in the case of joint fixation, a rigid microlaryngoscopy and testing the passive mobility of the arytenoids under general anaesthesia are recommended. EMG studies help in this regard although both fixation and paralysis can occur simultaneously or even affect different cords in the same setting.

In many cases of acute stridor, patients respond positively to medical treatment. The use of high-dose intravenous steroids and nebulised adrenaline with high flow oxygen or helium-oxygen mixture (heliox) has been shown to be effective. Over time, they compensate well enough to breathe comfortably. Patients should be encouraged to perform, within reason, some physical activity to optimise their respiratory reserve and help overcome the increased inspiratory airway resistance.

The use of antibiotics where a bacterial infection is highly suspected is acceptable, and some practitioners also encourage the use of antireflux agents such as proton pump inhibitors (PPIs) to reduce any laryngopharyngeal reflux (LPR) and its concomitant inflammation to the narrowed glottis.

Short-term intubation either nasotracheally with fibre-optic guidance or orotracheally is helpful in the very short term. The use of adjuncts in managing the acute airway prior to intubation such as a trans-tracheal catheter or cricothyroid needle is well described in the literature. In general, intubated patients should either have a tracheotomy, a reversible lateralisation procedure or a trial of extubation with maximal medical therapy if the acute event precipitating respiratory compromise and life threatening stridor has been effectively treated.

The surgical management of patients with BVFI can be broadly divided into two groups, i.e. tracheotomy and all ‘other procedures’. This categorisation may be simplistic but in essence distinguishes the philosophy surrounding surgical management. ‘Other procedures’ offer a variety of possibilities to treat BVFI—both temporary (reversible) and permanent.

Despite the many advances in endoscopic microsurgery for BVFI, tracheostomy continues to be the time-tested procedure for both temporary and permanent BVFI. It is understandably much cheaper as it requires no special equipment as is seen with laser microlaryngeal surgery. It provides a safe airway and can be removed if the patient regains cord function in the future. Indeed many of the historical procedures for BVFI were performed with a tracheostomy tube already in place and depending on the level of success—removed accordingly. In the acute setting, there may be little choice but to tracheotomise the patient. However, many patients are loathed to having a tracheotomy and would forsake voice quality over a surgical airway [25]. Tracheotomy is not without risks either both in the early perioperative period and thereafter and patients should be counselled where possible on the risks and benefits appropriately [26].

Broadly speaking, all other procedures aimed at surgical management of BVFI aim to mainly widen the glottic chink with the exception of procedures that aim to restore the innervation of the intrinsic muscles of the larynx—primarily its only abductor, i.e. the PCA. Theoretically, reinnervation would be the ideal procedure as it does not compromise voice quality over airway size unlike glottis-expansion procedures that have a lesser or greater degree of voice compromise. In some patients who have either had fixation due to radiation or BVFI due to cerebral events, swallow and ensuing aspiration can also be an important factor surrounding decision-making vis-a-vis glottis-expansion surgery.

Deteriorating respiratory function/exercise tolerance with inspiratory stridor at rest and increase in inspiratory resistance (>2.5 kPa x s/L) are indications for surgical intervention. Some patients are prone to recurrent attacks of upper respiratory tract infections which have a significant effect on the already narrow glottic chink precipitating acute stridor. These patients should be considered for surgical intervention early and pre-emptively. When a diagnosis is made for idiopathic or neurogenic BVFI, it is reasonable to wait up to even a year before performing surgery. LEMG can be used to assess the presence of electrical intramuscular activity although its prognostic success is debatable [27–29]. In cases where bilateral ankylosis (fixation) is suspected initially on the history and confirmed with LEMG and assessment of joint mobility in the operating theatre, treatment options fall broadly into two categories. The first involves surgical procedures attempting mobilisation of the cricoarytenoid (CA) joint. This is performed in cases of joint subluxation or dislocation. The second category consists of the exact same procedures performed in cases of neurogenic pathology requiring glottis-expansion surgery. Posterior glottic stenosis, anterior synechiae and laryngeal, thyroid and pharyngeal malignancy are other causes of BVFI, and their respective treatment options are outside the scope of this chapter.

BVFI may not be permanent. Some surgeons advocate waiting between 6 months and 1 year to see if cord function returns prior to undertaking any procedure that may result in a permanent change to the larynx anatomically or physiologically. Temporary BVFI is most commonly seen from thyroid surgery, and resolution is seen between 40 and 86% [29, 30]. Management options for patients suspected of having temporary BVFI include intubation for acute and short-lived palsies, tracheotomy and reversible lateral fixation suture techniques—category 3. First described by Ejnell, this procedure has been modified by Lichtenberger and involves a specially designed endolaryngeal needle holder which brings two sutures from within the larynx above and below the vocal process out into a small opening in the neck where it is secured over the thyroid cartilage or the extralaryngeal muscles [31–33]. Other modifications on this technique obviating the need for the specially designed needle holder and jet ventilation have been described [34, 35] with equally good results.

Category 1 and 2 procedures include posterior cordotomy, arytenoidectomy, cordectomy (submucosal and posterior) and permanent/definitive lateralisation (with CO₂ ablation of the thyroarytenoid muscles and arytenoid cartilage) as described by Lichternberger.

Dennis and Kashima [36, 37] first described this procedure which involves making a transverse cordotomy anterior to the vocal process using a CO₂ laser. This was combined with division of the conus elasticus (releasing the glottic sphincter) and retraction of the remaining thyroarytenoid muscle anteriorly increasing both the posterior glottic airway and anterior vocal fold (phonatory) mass. Cicatrisation (and granuloma formation) following this procedure has been commonly encountered requiring repetition and/or further resection of either the true cord anteriorly or the vocal process and/or varying extents of the arytenoid posteriorly [36, 38]. Usually a single-sided procedure is sufficient, but occasionally a bilateral procedure is required.

Modifications of Kashima’s technique involving resection rather than purely incising the true and false vocal cords to further increase the laryngeal aperture have been shown in various series to have better results in managing the airway but as stated before may have a detrimental effect on the voice [39, 40]. The cordectomy therefore can be used in a broader sense as a procedure (usually with CO₂ laser) involving resection of greater amounts of the true cord and false cords with or without a degree of resection of the vocal process of the arytenoid as well. Submucosal resection of the phonatory (anterior) part of the true cord with closure of the mucosa with fibrin glue was also shown to be effective not only for respiration but also phonation [41]. Failures of this procedure like cordotomy include cicatrisation, granulation or, in the case of more extensive cordectomy, a resulting scar replacing the cord—the ‘pseudocord’ which can retract medially [42–46].

Kleinsasser’s introduction of endoscopic techniques and special instruments in the latter half of the last century revolutionised laryngeal surgery and with it the management of BVFI. Initially, arytenoidectomy as described by Thornell was performed under temporary tracheostomy and utilising electrocautery. An obturator was inserted between the cords and removed in the second stage 3–4 weeks later. Things have progressed since with the utilisation of the CO₂ laser by Eskew (in dogs), Lim (in humans) and Ossoff [47–49] to dissect and either resect or ablate the arytenoid. The first description to preserve the mucosal flap overlying the arytenoid and seal the bed using fibrin glue was described by Sato [50]. The main concerns in this technique include frequent transient aspiration along with scarring and granuloma formation as seen in cordectomy and cordotomy. Cricoid chondritis can also occur especially in patients who have had prior radiation treatment to the neck.

A modification of Ossoff’s technique has been shown by Remacle et al. to have a stable and lasting effect on airway patency with preservation of laryngeal competence and socially acceptable voice quality [51]. This procedure is a subtotal CO₂ laser arytenoidectomy. It is performed under general anaesthesia with a laser safe orotracheal tube or a tracheostomy tube in an already tracheotomised patent. The use of modern CO₂ laser systems has improved energy delivery, reducing thermal damage and allowing for computerised calculation of power delivery. This scanner software modification to some CO₂ lasers allows the beam to travel across the target in a circle, straight or curved line depending on the shape desired. Various lengths (0.5–3.5 mm) and penetration depths (0.2–2.0 mm) are programmable. The procedure is performed in superpulse mode at a computer adjusted power setting of approximately 10 W using scanner mode with a depth of penetration of two hundred microns and beam length of 2 mm usually. The technique begins at the tip of the vocal process extending laterally to involve sectioning of the ventricular fold up to the rim of the arytenoid and inferiorly to the conus elasticus. A coronal section of the arytenoid body is performed with preservation of the aryepiglottic fold laterally and mucosa of the medial aspect of the arytenoid. A 1–2 mm thin cartilaginous shell of the posterior body of the arytenoid is left in situ along with its remaining mucosa attached behind and medial to it (Fig. 13.1a–d). The muscular process is preserved while the rest of the arytenoid is excised after dislocating the CA joint (Fig. 13.2). Slow-setting fibrin glue (to avoid irritation and post-operative cough) is applied in the resection bed and helps reduce haematoma and granulation post-operatively. Antibiotic prophylaxis is administered perioperatively. Patients are usually discharged on a short course of antibiotics, inhaled steroids and PPIs. Overall, the results from subtotal arytenoidectomy according to Remacle et al. [7] have been very good. All tracheotomised patients were decannulated; voice quality was minimally affected with some reduction in maximum phonation time, but mean conversational vocal intensity was not notably modified over time. Another advantage of subtotal arytenoidectomy is the preservation of the posterior aspect of the arytenoid frame and mucosa. This prevents inward collapse of the mucosa and helps reduce aspiration. Hence, removal of only the intraluminal portion of the arytenoid with resection and cutting through the conus elastics at the level of the tip of the vocal process releases the cricoarytenoid ligament (vocal ligament) allowing for passive glottal opening [52]. Results in a series published by Remacle et al. (Table 13.2) showed significant improvement in the mean ratio of PEF/PIF highlighting sustained respiratory improvement.