Impact of a Modified Restoration of Tensor Veli Palatini on Hearing and Middle Ear Function in Cleft Palate Children—a Retrospective Study

Background:

Many children with cleft palate also exhibit hearing loss and middle ear dysfunction, which could last for years. There are still arguments on how to treat this problem. This study aimed to evaluate the impact of a modified restoration of tensor veli palatine (TVP) on hearing and middle ear function in the cleft palate children.

Methods:

This retrospective study was completed using records of the cleft palate children who received surgery in Peking Union Medical College Hospital from May 2013 to December 2020. They were divided into 2 groups: Group 1: children who received cleft palate surgery without specific restoration of TVP; Group 2: children who received palate surgery with a specific TVP restoration technique. Perioperative information was collected. The conductive auditory brainstem response and the 226-Hz tympanometry before and after the cleft surgery were compared intragroup and intergroup.

Results:

Totally 42 children were included in this study, 21 children in each group. There were no significant differences considering clinical characteristics between the 2 groups. The modified TVP restoration didn’t increase operation time or complication compared with no TVP restoration. Statistically, neither the auditory brainstem response air conduction hearing thresholds nor the 226-Hz tympanometry results had significant differences between the 2 groups after the surgery.

Conclusions:

This modified restoration of TVP was not time-consuming and did not increase complications. The beneficial effect of the modified TVP restoration on the hearing or the middle ear function of cleft palate children was uncertain around 6 months after surgery compared with no restoration.

Many children with cleft palate exhibit hearing loss and middle ear dysfunction. The incidence could be high to around 90% in early childhood and gradually decreases as age increases.1–3 The degree of hearing loss is mostly mild to moderate. The middle ear dysfunction mainly manifests as otitis media with effusion, and it may aggravate the hearing loss. Hearing loss and middle ear dysfunction could relive in most children in their teenage.3 However, in some children, these problems could persist into adulthood.4 Several factors, including dysfunction of the palatal muscles, abnormalities and dysfunction of the eustachian tube (ET), and the abnormal anatomy of skull base, are considered to be associated with the audiological and otological problems in these children.5,6 Considering the short-term effect of ventilation tube insertion and the accompanying complications,7,8 some surgeons believed that correcting the anomalies of the palatal muscles, especially restoring the integrities of tensor veli palatini (TVP) and levator veli palatini (LVP), could improve the long-term outcome.9,10 In particular, the contraction of TVP is believed to have an important role in the opening of the ET. However, there are few studies illustrating the effect of TVP restoration on the improvement of hearing and middle ear function, while some literatures studied the restoration of palatal muscles as a whole.11–14 Besides the listed background above, tube insertion in infancy had not been carried out in our hospital until 2019 for the limited local condition. For the concern of hearing loss and middle ear dysfunction, we developed a modified TVP restoration during palate repair. This retrospective study was attempted to study the possible effect of the modified restoration of TVP on hearing and middle ear function in children with cleft palates.

METHODS

Study Design and Patients

From May 2013 to December 2020, children who received primary cleft palate repair surgery at Peking Union Medical College Hospital were selected for this study. The inclusion criteria were the children who received audiological and otological examinations before and after the surgery. The exclusion criteria were the children with confirmed hereditary general diseases or associated syndromes and the children who received any kind of audiological or otological therapy before the postoperative examination. Both preoperative and postoperative clinical records of these children were reviewed. Clinical characteristics include age, gender, extent of cleft palate, and the time interval between the audiological and otological examination and surgery. The extent of cleft palate was classified according to the Veau classification.15 Children were divided into 2 groups: Group 1: children who received palate surgery with no special restoration of TVP; Group 2: children who received palate surgery with a modified TVP restoration. The children were assigned to each group mainly by time sequence. The modified TVP restoration was adopted from 2013 to 2016. At other times, no TVP restoration was done.

Surgical Methods

All the palate surgeries were performed in our center by a senior surgeon under general anesthesia. Mucosa incision and suturing were done referring to Langenbeck’s technique in both groups. For muscle construction, LVP was restored in both groups. Different methods of TVP repair were carried out in 2 groups. Children in group 1 received no special restoration of TVP. Children in group 2 received a modified TVP restoration. This modified TVP restoration was developed by the senior surgeon in this study (Fig. 1). The conception was based on the normal anatomy of TVP. The idea was similar to what was proposed by Bütow in 1991.16 The techniques were as follows: After the TVP was identified, its tendinous fibers were released but still connected to the pterygoid process without breaking the hamulus or cutting off the tendinous fibers. If the tension was too strong during suturing, the tensor tendon was partly dissected laterally, meanwhile maintaining the continuity of the muscle. Then, the LVP, the TVP, together with the palatine aponeurosis, and the nasal mucosa from the 2 sides were sutured in the middle line. Bilateral TVP was drawn close to each other to intensify the tension of this muscle. The TVP may not be joined to the contralateral one directly (Fig. 2).

FIGURE 1.

Illustration of the modified restoration of tensor veli palatini. (A) Tensor veli palatini before restoration. (B) Tensor veli palatini after restoration. E indicates Eustachian tube; H, hamulus; L: levator veli palatini; T, tensor veli palatini; U, uvula.

FIGURE 2.

Clinical photograph of the modified approach with both levator veli palatini and tensor veli palatini construction. (A) Dissection of the tendon of tensor veli palatini from the hard palate plate. (B) Suturing the bilateral tensor veli palatini and levator veli palatini together at the midline. L indicates levator veli palatini; P, hard palate; T, tensor veli palatini; V, vomer.

Audiological and Otological Testing Methods

Auditory brainstem response (ABR) and 226-Hz tympanometry were used to test the children’s audiological and otological status. They were carried out in 2 separate sound-treated rooms. Before the test, all the children were sedated with 10% chloral hydrate.

The equipment used for ABR was Smart EP (Intelligent Hearing System Corp.). The stimuli were clicks with alternating polarity. The stimulus repetition interval time was 50 ms. The bandpass filter was set at 30-3000 Hz. The intensity of stimulus started from 25 dB with a step of 5 dB. The air conduction hearing thresholds were used in this study. Results over 25 dB nHL were assigned as abnormal.

MADSEN OTOflex 100 (Otometrics, Denmark) with a 226-Hz probe tone frequency was used to assess the middle ear function. The air pressure in the closed external meatus was changed from +200 mm daPa to −400 mm daPa with a pressure change rate of 50 daPa/s. The results of 226-Hz tympanometry were classified based on the Liden/Jerger classification system.17 Type B was considered as abnormal in this study.

Statistical Analysis

All analyses were performed in IBM SPSS Statistics for Windows, version 24 (IBM Corp.). The distributions of gender and Veau cleft classification between the 2 groups were compared by χ² test. The distributions of age at the surgery, the time interval of surgery, and perioperative examination between the 2 groups were compared by Mann-Whitney U test. Intergrouply, the differences in the ABR air conduction hearing thresholds were compared by the Mann-Whitney U test. The difference of the 226-Hz tympanometry results was compared by χ² test. Intragroup, the possible effect of palatoplasty on the ABR air conduction hearing thresholds and the 226-Hz tympanometry results before and after the surgery are compared using McNemar test. The 2-sided P value was set at 0.05.

RESULTS

Forty-two cases of cleft palate were included in this study, 21 cases in each group.( Supplemental Digital Content 1, Table 1 http://links.lww.com/SCS/E716) summarizes the age distribution at surgery, gender, the extent of the cleft, and the time interval between surgery and perioperative examination. The distribution of age at the time of surgery, gender, the extent of cleft, time interval of surgery, and perioperative examination showed no significant differences between the 2 groups (P=0.738, 0.227, 0.112, 0.699, and 0.676, respectively).

Considering the surgical outcome and complications using the modified TVP restoration, all children had an uneventful recovery and were discharged from the hospital 1 or 2 days after surgery. No more complications, including postoperative bleeding, oronasal or palatal fistula, were found compared with no TVP restoration group.

The results of ABR air conduction hearing thresholds and 226-Hz tympanometry of the 2 groups were recorded by ears. Totally 84 ears in 42 children were studied. In 226-Hz tympanometry, 1 child had only the left ear results both preoperation and postoperation. There was missing data in the results of 226-Hz tympanometry perioperation. The baseline results of ABR and 226-Hz tympanometry had no significant difference before surgery in the 2 groups (P=0.205 and 0.232). After cleft surgery, the ABR air conduction hearing thresholds and the results of 226-Hz tympanometry also had no significant difference considering different TVP management (P=0.415 and 0.081). Intragroup, the ABR air conduction hearing thresholds got better after palate surgery in both groups (P=0.007 and 0.005). The 226-Hz tympanometry results of both groups showed no improvement after either repair technique (P=1.000 and 0.607, respectively). The ABR air conduction hearing thresholds and the 226-Hz tympanometry results of both groups before and after palate repair are summarized in Figure 3 and Supplementary Digital Content 1, Table 2 http://links.lww.com/SCS/E716

FIGURE 3.

ABR air conduction hearing thresholds in 2 groups preoperation and postoperation. The horizontal axis represents the hearing thresholds in dBnHL. The vertical axis represents the number of ears in each hearing level. ABR indicates auditory brainstem response; TVP, tensor veli palatini.

DISCUSSION

More than half of the children with cleft palate would suffer from audiological and/or otological problems.18 We confirmed this in our own patient cohort.19 Considering the audiological and otological problems, different opinions regarding the problem exist. When the hearing loss is not serious, or the middle ear effusion is not present, some centers advocate the “wait and see” protocol, whereas some implement more aggressive protocols.20,21 When the hearing loss is serious, or the middle ear effusion is confirmed, most of the centers would apply certain interventions. Still, some centers applied more conservative protocols.8 Although studies confirmed that ventilation tube insertion does provide an appreciable benefit with regard to short-term hearing gain, all our children did not receive this approach as a routine otological intervention due to the limited conditions in our hospital. Also, this approach may cause the following associated complications: perforations, otorrhea, eardrum atrophy, granulation tissue, and tympanosclerosis.7 A long-term effective approach without obvious complications is pursued by surgeons, including us. By observing our own patient cohort, irrespective of the palatal technique, we found the hearing loss got better, but tympanometry results showed no significant improvement as a whole group around 1 year after surgery.22 Whether the type of palatoplasty is an independent influence factor influencing hearing and/or middle ear function is still under study.11,12,23–25 Based on these, this study reviewed a modified TVP restoration to find out whether it was beneficial to hearing and middle ear function of cleft palate children.

ET dysfunction, otitis media with effusion, and hearing loss are believed to be the common pattern of the development of audiological and otological problems in children with cleft palate.9,26 In terms of anatomy, the ET’s open function is related to TVP to a great extent.26 Ghadiali et al found that the loss of TVP muscle tone and stiffness resulted in a significant decrease in ET opening pressure, increased ET compliance, and reduced ET viscoelasticity.27 Heidsieck et al suggested TVP is the primary opener of ET, while LVP only takes synergistic assistance.26 Restoration of TVP would be more effective than the restoration of only LVP when considering the ET function. In fact, several surgical techniques were attempted to restore this particular muscle. However, the actual effect on the middle ear function of those modified techniques has not been confirmed widely.11,16,28 In the present study, we also attempted to restore the function of TVP to improve the ET function. Here, the TVP was elevated and released from the maxillary tuberosity, the medial side of the medial plate of the sphenoid bone pterygoid process, and the posterior edge of the palatine bone. All these were TVP’s insertion points.26 After dissection, together with the palatine aponeurosis, the TVPs from 2 sides were tensed toward the midline and sutured to each other. Our suture sling is similar to what was reported by Bütow et al.16 However, Bütow and colleagues retained a part of oral mucosa with the tensor tendon, while we did not. In addition, the dissection of the tensor tendon is more complete. The anterior part of the tensor tendon turned medially with more reliability in our technique. The pterygoid hamulus must not be broken so that the tendon of TVP could slide around the pterygoid hamulus as a free pulley system. In this manner, the integrity and stiffness of TVP are preserved, which is beneficial to muscle function. Furthermore, the muscle tension is increased, which could contribute to the opening of the ET.

Unfortunately, the result of our study indicates no significant improvement compared with no restoration of the TVP technique. Intergrouply, no difference was found either with ABR hearing threshold or 226-Hz tympanogram. The previous studies9,11,12,14,29–32 showed the special restoration of palatal muscles may or may not be beneficial to the hearing and the middle ear function. At least, it would not deteriorate the results. The benefit would not be clear until around 6 years.9,29 Although our results were not satisfactory, it may also be consistent with reality. The benefit of TVP restoration is not definite 6 months after surgery. It would not be clear in toddlers. Longer follow-up is required. Reasons for the results in this could be explained as follows. First, the middle ear function and hearing are affected not only by palatal muscles, but also affected by others, like ET and skull base anatomy. The ET is wide and almost horizontal in infants and toddlers. The abnormal function of ET is common during this time frame. The abnormal results of tympanogram in cleft children may mainly be affected by the abnormal ET function. As the ET matures, the ET functions more efficiently, and the benefit of restoration of TVP becomes clear progressively. In this study, the TVP restoration group has a tendency to improve considering the 226-Hz tympanogram compared with no TVP restoration. The normal proportion increased more in TVP restoration, although the difference was not significant(P=0.081). Considering the short-term follow-up in this study, a longer follow-up may show more clear results. Second, the effect of the reconstruction of the tensor velar palatine in this group may not be reliable. Using a flexible suture that can continuously narrow the tensor velar palatine muscle after suturing the severed ends of both sides is a revision of our future work.

In both groups, the ABR air conduction hearing thresholds improved after palate repair significantly. This improvement in ABR also appeared in our last study.22 The ABR could be used for hearing screening in children who could not give accurate subjective feedback. It is mainly focused on cochlear and brain pathways for hearing. The cleft palate repair probably had an effect on the middle ear. The improvement in ABR air conduction hearing thresholds could be the change in the middle ear’s acoustic impedance after cleft palate repair, which may interfere with the sonic energy transmitted to the cochlea.33 However, this change in the middle ear’s acoustic impedance did not show in tympanometry.

Limitations

There are several limitations of this study. First, this is a retrospective analysis. Children are not assigned to each group randomly. The restoration of TVP was mainly carried out from 2013 to 2016. Since 2017, this technique was not applied as we did not find very obvious improvement compared with no restoration clinically. Second, there was no comparison between this restoration of TVP and another commonly used Furlow technique. Several studies suggested Furlow technique may do better for audiology and otology compared with Langenbeck technique.10 A comparison between this restoration and Furlow technique could give more comprehensive information. Future research with more complete data and organized distribution in each group would provide a better understanding of the effect of this modified restoration.

CONCLUSIONS

In this study, we reviewed 2 different surgical techniques for cleft palate repair. The modified preservation and restoration of TVP during palate repair didn’t show significant improvement for the hearing level and middle ear condition compared with no restoration; only a better tendency in 226-HZ tympanometry was found considering the short-term follow-up in this study. Prolonged follow-up may further verify the effect of TVP restoration.

Supplementary Material

scs-34-e259-s001.docx ^{(16.9KB, docx)}