This ambi-spective study enrolled 32 patients who presented to our Institution with Unilateral Vocal cord palsy for a period of 211 years from 2001 to 2021. Patients were grouped depending on duration of symptoms on presentation. Twenty one patients presented within 1 year of symptoms and eleven patients presented after 1 year of symptoms. Detailed history regarding symptom onset, duration, progression, associated symptoms were taken. General Physical Examination and ENT Examination including telelaryngoscopy and flexible laryngoscopy was done. Voice quality analysis in terms of Perceptual analysis of voice quality, acoustic measures of voice quality and Aerodynamic measures of voice quality was done.

Rigid laryngoscopy to rule out other causes of vocal cord of fixation, i.e., post-traumatic causes, crico-arytenoid fixation was done.

Perceptual analysis of voice quality in terms of GRBAS Scale Scoring was done. Grade of hoarseness, Roughness, Breathiness, Asthenia, Strain scale were assessed where each dimension was rated on a 4-point scale (Table 1) 7, 9.

Table 1

0	No perceived abnormality
1	Mild
2	Moderate
3	Severe abnormality

In case of acoustic measures of voice quality, quantitative measures, based on the voice signal (waveform and spectrum) were recorded using a microphone. Few voice characters observed are Fundamental frequency, which is a measure of rate of vibration of vocal folds; Jitter, which is variation/ perturbation in frequency; Shimmer, measures of variation/perturbation in intensity as well as Harmonic to noise ratio 8, 9, 11.

Aerodynamic measure of voice quality includes Maximum phonation time (MPT) which is measured by asking the subject to inhale as deeply as possible and then sustain a steady state vowel sounds “ee / aa” as long as possible. The highest of the 3 values are taken 10, 11, 12, 13, 14.

Quality of life measures in terms of Voice Handicap Index (VHI-10) was taken. Impact of the voice disorder on different aspects of the patient’s quality of life, namely, Physical, Functional and Emotional were assessed based on the scoring system between 0-4 14, 15, 16, 17.

Tele-laryngoscopy using 10 mm, 90 degree rigid laryngoscope or4.3 mm flexible nasopharyngo-laryngoscopy was done.

The Inclusion criteria of the study included patients with Unilateral Vocal cord palsy who were available for regular follow up. The exclusion criteria included cases of post-traumatic vocal fixation, laryngotracheal malignancy, previous vocal cord surgery, multiple cranial nerve palsies, laryngo-tracheal trauma, and failure to follow-up, extrusion of prosthesis.

Intraoperative subjective improvement of voice was assessed for all the cases. Patients were followed up at 2 weeks, 1 months, 3 months and 6 months. Follow up criteria included Tele – rigid/flexible laryngoscopy, Perceptual analysis of voice, MPT and VHI-10.

Surgical technique: Patient is positioned with neck extended at atlanto-occipital joint. A horizontal skin incision is put along the inferior border of thyroid cartilage. Superior and inferior flaps elevated in the sub-platysmal plane, superiorly extending up to the level of hyoid and inferiorly upto lower border of cricoid cartilage. The deep cervical fascia is divided in the midline and the strap muscles are retracted laterally. The thyroid cartilage is visualised. The height and width of the thyroid cartilage were measured using callipers to calculate dimensions of the thyroid window. The thyroid window is incised using a No. 15 surgical blade and window drilled out using a microdrill. Depth of the window is measured using a measuring zig. Silastic block is cut to appropriate size and inserted into the window.Intra-operative feedback about the voice was obtained from the patient and the block is adjusted until the patient was satisfied with his/her voice. The block is fixed using Vicryl 3-0. The wound is closed in three layers.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Out of 32 patients, 26 were males and 6 were females. The age of presentation varied from 19 years to 76 years with the mean age being 47 years. The laterality of the palsy showed preponderance on the left side in majority of patients (R:L :: 4:28). Coming to the etiological factors, out of 4 patients who had Right vocal cord palsy, 3 were iatrogenic, secondary to Thyroid surgery, 1 of idiopathic origin. Out of the 28 patients with Left sided vocal cord palsy, 15 cases were idiopathic in origin, 11 cases iatrogenic, which included 9 cases of post thyroid surgery, 1 case each of skull base surgery and spine surgery, and 2 cases of Mediastinal lesion (Figure 9 ).

On comparing the GRBAS Scoring between the Early subgroup and Late subgroup of patients, there is comparable decrease in scores in both the groups but with better results in early group (Figure 10).

On comparing the results of Maximum phonation time, the Early subgroup has a substantial improvement in duration when compared to the Late group (Figure 11 ).

Similarly with the Voice Handicap Index -10, the early subgroup shows tremendous improvement post surgery when compared to the Late subgroup (Figure 12).

On tele- rigid/ flexible laryngoscopy, patients who underwent late thyroplasty showed varying degrees of compensation, atrophic vocal cord, hanging vocal cord, different levels of approximation with vertical phonetic gap.

Overall results were good in patients who underwent surgery within a year. Though the procedure prevented aspiration, subjective improvement in voice is not satisfactory among the delayed group.

The first attempt at true medialization thyroplasty was done in 1915, by a German surgeon named Erwin Payr (1). Issihiki et al at Kyoto University first described the technique now known as type I thyroplasty in 1974, with a study describing a series of procedures on dogs. Instead of approaching the vocal cords direcly, which causes mucosal scarring, reduced vocal cord compliance and hindered vibration 18, he aimed to change the position and physical property of the vocal cord by actively changing the cartilaginous framework of the larynx. on which the vocal cords were suspended 19.

Type I thyroplasty involves creating a window into ala of anterior thyroid cartilage, and inserting a prosthesis which pushes the paralysed vocal cord medially, allowing it to make contact with the non paralyzed vocal cord and thus restoring its function 20.

Pal et al in their study had stated higher incidence among males, with male:female ratio of 1.50:1 21, whereas it was 2:1 as per study of Baitha et al 22.

Defining a time window for the beginning and end point for synkinetic reinnervation is admittedly difficult, especially when there exists disparity in the cause of denervation, spectrum of anatomic injury and variations in reinnervation patterns. Crumley described a chronic phase of RLN regeneration following complete transection injury, during which regeneration starts to occur and clinical evidence of improvement may be observed within 4 to 5 months post-injury 23.

Friedman et al. hypothesized that with early intervention, the implant material allows the vocal fold to be in a more appropriate resting position during the time window of synkinetic reinnervation. It is possible that synkinetic reinnervation permanently maintains a medialized and more favorably positioned vocal fold 24.

Early medialization of a vocal cord allow better final resting position once synkinetic reinnervation is completed. A paralyzed , but medialized vocal cord may also experience the sensory (vibro-tactile) stimulation from physical contact with the contralateral, mobile vocal cord 23.

Thus in our study, the inferior results of Type-1 Thyroplasty in Delayed Group is mainly due to high patient expectations, different degrees of compensation by the normal vocal cord, primary aetiology, atrophy and sagging of the paralysed vocal cord.

There are certain drawbacks in this study, as this is a small study population, with unequal study group, further study involving greater sample size is required.

When compared to the early subgroup, the results were sub-optimal among the delayed subgroup, hence concluding that Early Thyroplasty yields better results.