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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 18  |  Issue : 2  |  Page : 140-144

Tympanometric findings in children with cerebral palsy in a tertiary health centre in Nigeria


1 Department of Otorhinolaryngology, Aminu Kano Teaching Hospital, Kano, Nigeria
2 Department of Otorhinolaryngology, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
3 Department of Paediatrics, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
4 Department of Paediatrics, Aminu Kano Teaching Hospital, Kano, Nigeria

Date of Submission17-Oct-2020
Date of Decision17-Sep-2021
Date of Acceptance03-Nov-2021
Date of Web Publication10-Dec-2021

Correspondence Address:
Dr. Yasir Nuhu Jibril
Department of Otorhinolaryngology, Aminu Kano Teaching Hospital, Kano
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njbcs.njbcs_31_20

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  Abstract 


Context: Cerebral palsy (CP) is one of the commonly occurring physical disabilities, beginning in early childhood and persisting through the lifespan. Hearing impairment is a common problem in children with CP. The type of the hearing loss is mostly sensorineural, but conductive hearing loss from middle ear disease is a possibility. Aim: The aim was to assess the tympanometric findings in children with CP. Materials and Methods: This was a cross-sectional study conducted amongst children with CP and matched (age and gender) controls in Kano, Nigeria. Ethical approval was obtained from the institution's Ethics Committee. Simple random sampling was used to enrol 330 participants. Consent was obtained and a structured questionnaire was used to collect data on the history, ear examination and tympanometric findings. The data collected were analysed using Statistical Product and Service Solutions version 21. Results: One hundred and sixty-five children with CP and the same number of matched controls participated in the study. The mean age of CP patients and controls was 4.49 ± 2.85 and 4.40 ± 2.92 years, respectively. Abnormal tympanograms were found in 51 (30.9%) of the children with CP as against 19 (11.5%) in the controls. Abnormal acoustic reflex was found in 28.5% of the cases compared to 12.1% in the control group. There was a statistically significant difference between the tympanometric findings of patients with CP and that of the controls (P = 0.0001). Conclusions: This study found a high prevalence of abnormal tympanograms in children with CP compared to controls.

Keywords: Cerebral palsy, children, hearing assessment, tympanometry


How to cite this article:
Jibril YN, Abdullahi H, Adamu A, Sabo UA, Shamsu KA, Salisu AD. Tympanometric findings in children with cerebral palsy in a tertiary health centre in Nigeria. Niger J Basic Clin Sci 2021;18:140-4

How to cite this URL:
Jibril YN, Abdullahi H, Adamu A, Sabo UA, Shamsu KA, Salisu AD. Tympanometric findings in children with cerebral palsy in a tertiary health centre in Nigeria. Niger J Basic Clin Sci [serial online] 2021 [cited 2022 Jun 25];18:140-4. Available from: https://www.njbcs.net/text.asp?2021/18/2/140/332191




  Introduction Top


Cerebral palsy (CP) is a motor disorder that results from a non-progressive insult to the developing brain. It is a clinical presentation of a wide variety of cortical or subcortical insults occurring during the 1st year of life.[1] It is a common disorder that occurs in paediatric age group and prematurity remains the most common aetiology.[2] Patients with CP could have multiple neurological disabilities ranging from seizure disorder, mental retardation, feeding difficulties, visual problems and hearing impairment.[2] The presence of one or more of these disabilities has a negative impact on health status and quality of life of these patients. Furthermore, hearing loss even a mild type has been shown to affect speech and language development in CP patients.[3]

Hearing impairment is a common problem in children with CP.[4] A study conducted in Germany reported hearing impairment in 4%–25% of children with CP.[5] Another study reported hearing loss as high as 60% in children with CP.[6] The nature of the hearing loss is mostly sensorineural, but conductive hearing loss from the middle ear pathology could also occur.[7]

Various subjective and objective tests have been used to assess the auditory function and middle ear parameters in patients with CP. However, subjective tests are unreliable in children with CP, as it may be difficult for the patients with motor and cognitive impairment to follow the instructions of the test. As such, objective assessment has been recommended.[8] Amongst these tests, tympanometry is an audiometric test that evaluates the middle ear parameters and acoustic reflex, and it does not require input from the patient. Tympanometry and acoustic reflex have been shown to be useful in the audiological assessment of children with CP.[7] Aside from providing insight into the status of the middle ear system, tympanometry results also provide important information regarding the possible source of abnormal otoacoustic emissions (OAEs).[9] Acoustic reflex threshold as a component of tympanometry can also be useful in differentiating whether a hearing loss is caused by a lesion in the cochlea, the auditory nerve or brainstem.[10] Therefore, this study was aimed at assessing the tympanometric findings amongst children with CP in Kano, Nigeria.


  Materials and Methods Top


This was a cross-sectional study conducted amongst 165 CP patients attending the paediatric neurology clinic and ENT clinic of Aminu Kano Teaching Hospital, Kano; 165 age- and gender-matched controls were selected from healthy children attending a private school in the same community. Ethical clearance was obtained from the Research and Ethics Committee of the hospital with reference number: NHREC/21/08/2008/AKTH/EC/2160. Informed consent was obtained from the parents of the participants before enrolment into the study. Subjects included were children with CP 1–12 years of age, who were recruited from the paediatric neurology clinic of the institution. For the controls, apparently healthy schoolchildren, from Crèche to Primary 6 within the age range of 1–12 years whose parents consented to the study, were selected from a school at the same locality with the hospital. Excluded criteria for the cases and controls were as follows: children that were too ill, those with ear deformity or ear disease, those with recurrent upper respiratory tract infection, those with history of use of ototoxic medication or those whose parents do not give consent to participate in the study. Participants were selected using simple random sampling until the required sample size was reached. The study was conducted over a period of 1 year (April 2018–March 2019). A specially designed questionnaire was used to collect the information about the sociodemographic variables and relevant clinical details. All study participants underwent detailed ENT examination. Those with ear wax were de-waxed appropriately.

All cases and controls that satisfied the inclusion criteria had tympanometry testing done using a calibrated tympanometer (Otopront Tymp, Serial No. 1521, 226 Hz, manufactured by Happersberger Otopront, Germany, last calibration May 2017). Modified Jerger's nomenclature[11] was used to classify the tympanometric findings into Types A, As, Ad, B and C. Type A represented normal finding. Types B and Type C tympanograms were used to represent middle ear effusion and Eustachian tube dysfunction, while Types As and Ad were considered an abnormal variant of Type A tympanogram, respectively.

Acoustic reflexes were also recorded from the tympanometry machine from the ipsilateral ear by delivering a sound of 85–105 dB to the test ear at 500, 1000, 2000 and 4000 Hz. Appearance of a well-defined amplitude in at least three of the test frequencies was considered normal and was denoted as 'AR present', while appearance of the amplitude in only two of the test frequencies or an absence of response following stimulation was considered an abnormal response and was denoted as 'AR absent'.

The data were analysed using Statistical Products and Service Solution version 21 for Windows (IBM Inc., Chicago, Illinois, USA). The data were summarised and presented as quantitative and qualitative variables. Quantitative variables were presented as mean and standard deviation, while qualitative variables were expressed as frequencies and percentages, and Chi-squared test was used to establish the association between categorical variables in which P ≤ 0.05 was considered statistically significant.


  Results Top


Three hundred and thirty children (165 children with CP and 165 controls) participated in the study. The mean age of the participants was 4.49 ± 2.85 years amongst the cases and 4.40 ± 2.92 years amongst the control group. The sociodemographic variables of the children with CP and the controls are shown in [Table 1].
Table 1: Sociodemographic variables of the 330 participants

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The relevant clinical history amongst patients with CP is shown in [Table 2], which revealed that majority of the children with CP (96.4%) were born at term. One hundred and two (61.8%) of them were diagnosed with CP at <1 year of age. Most of the children with CP (70%) were delivered in the hospital, while few were delivered at home (29.7%).
Table 2: Relevant clinical history amongst 165 patients with cerebral palsy

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Out of the 330 ears examined amongst the cases, Type A tympanogram was seen in 210 (63.6%), Type B in 77 (23.3%), Type C in 26 (7.9%), Type As in 11 (3.3%) and finally Type Ad in 6 (1.8%). Similarly, amongst the control group, Type A tympanogram was seen in 289 (87.6%), Type B in 18 (5.5%), Type C in 16 (4.8%), Type As in 3 (0.9%) and finally Type Ad in 4 (1.2%). [Table 3] shows the distribution of the various tympanograms amongst patients with CP and controls with respect to the side of ear, respectively. [Figure 1] shows a sample of tympanometry result of patients with CP.
Table 3: Tympanogram findings in 330 ears of children with cerebral palsy and 330 ears of the controls

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Figure 1: Normal Type A tympanogram

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Overall, Type A tympanogram (in one or both ears) was present in 114 (69.1%) of the cases, while 51 (30.9%) of them had abnormal tympanogram (Type As, Ad, B and C) in one or both ears. The distribution of normal and abnormal tympanograms amongst the controls is shown in [Table 4]. A statistically significant difference was found between type of tympanogram amongst the patients with CP and the control group (P = 0.0001), with abnormal tympanogram seen more in children with CP than in the control group. Acoustic reflex was normal in 118 (71.5%) and abnormal in 47 (28.5%) of the CP patients examined, while the distribution of normal and abnormal acoustic reflexes amongst the controls is shown in [Table 4]. A statistically significant difference was found between the acoustic reflex of the cases and that of the controls (P = 0.0002). Most of the CP patients with abnormal tympanogram had abnormal acoustic reflex. Out of 51 CP patients with abnormal tympanograms, 40 had abnormal acoustic reflex.
Table 4: Comparison of tympanometric findings amongst cases and controls

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  Discussion Top


Tympanometry is useful in the audiological assessment of children with CP. Hearing loss amongst such patients can be due to middle ear pathologies with different types of tympanogram reported.[7] Several studies have reported the use of impedance audiometry to determine tympanometric finding in CP patients and other neurological diseases.[3],[12],[13] Aside from providing insight into the status of the middle ear system, tympanometry also provides important information regarding the possible source of OAEs.[9] Acoustic reflex thresholds (one of the components of tympanometry) can also be useful in differentiating whether a hearing loss is caused by a lesion in the cochlear or auditory nerve. For hearing losses ranging from mild to severe, the acoustic reflex threshold is more likely to be elevated or absent in ears with neural pathology than in those with cochlear damage. The pattern of acoustic reflex thresholds for ipsilateral and contralateral stimulation across both ears can aid in the diagnosis of brainstem lesions affecting the reflex pathways.[10]

In this study, about 30.9% of the patients with CP had abnormal tympanograms indicating impaired middle ear function. The abnormal middle ear function may be related to stiffness of Eustachian tube muscles similar to characteristic generalised muscle hypertonia and stiffness of CP patients. It is therefore likely that the presence of CP affects the outcome of tympanometry. The prevalence of abnormal middle ear function obtained amongst children with CP in this study differs from a study in India,[3] where a prevalence of abnormal tympanometry was reported to be 45%. It also differs from a study conducted in Egypt,[12] where abnormal tympanometry result was found in 52% of the cases. Similarly, the finding also differs from another study,[7] where the prevalence of middle ear pathology amongst patients with CP was found to be 78.6%. Furthermore, an abnormal tympanometry was reported in 40% of the cases from a study conducted in Brazil.[13] The high percentage of abnormal tympanograms in their study could be as a result of age differences or nature of the study. The retrospective nature of their studies[3],[12],[13] and non-exclusion of other comorbidities such as upper respiratory infections and congenital anomalies may have increased the percentage of those with abnormal tympanograms in their study. Similarly, patients in this study were older compared to some of the patients in their studies. Younger children tend to have wider and more horizontal Eustachian tube leading to frequent Eustachian tube dysfunction from repeated respiratory tract infections.[14]

This study found abnormal tympanograms in 11.5% of the controls. This value differs from that obtained in another study,[7] where the prevalence of abnormal tympanometry amongst the healthy control group was found to be as high as 40.2%. A high percentage of abnormal tympanograms in the control group of their study may be due to non-exclusion of individuals with upper respiratory tract infection, which invariably causes abnormal tympanograms.[15]

In this study, the prevalence of abnormal tympanogram was significantly higher in patients with CP than the controls. The implication of this is that middle ear pathology could be one of the causes of hearing loss in children with CP, therefore, it is important to include tympanometry in the evaluation of these children so as not to miss a treatable form of hearing loss. The hearing loss reported by parents of children with CP was 46.7%. This percentage may not only be the usual sensorineural hearing loss, likely some may have conductive hearing loss from middle ear pathology.

Acoustic reflex is useful in the screening of hearing loss, especially in paediatric population, and has a high accuracy rate of 97% for identifying hearing impairment in children with CP.[16] This study found abnormal acoustic reflex in 28.5% of the patients with CP compared to 12.1% in the controls. A statistically significant difference was found between the acoustic reflex of the cases and that of the controls (P = 0.0002). This is similar to the findings of Emmer and Silman where they reported that acoustic reflex threshold for patients with CP was remarkably distinct from that of participants without CP.[17] The significance of our finding is that the presence of CP likely affected the outcome of acoustic reflex, therefore, acoustic reflex screening test should be included in evaluation of CP patients. CP can affect the outcome of acoustic reflex in different ways: (1) in CP patients with cochlear or auditory nerve damage, the afferent pathway of acoustic reflex is affected and the reflex is abnormal. (2) In CP patients with middle ear disease or facial nerve paralysis proximal to the nerve to stapedius, the efferent pathway of acoustic reflex is affected and the reflex is abnormal. (3) In CP patients with infarct at cochlear nucleus in the brainstem or facial nerve motor nucleus in the pons, both the afferent and efferent pathways of acoustic reflex are affected and the reflex is abnormal. Exact differentiation between these conditions requires further investigations such as computed tomographic scan, magnetic resonance imaging and auditory brainstem response, which are some of the limitations of this study.

The strength of this study lies in the assessment of tympanometric findings in randomly selected CP patients and matched controls using a well-calibrated Otopront tympanometre. However, some of the limitations of this study include inability to perform pure-tone audiometry due to the fact that younger children amongst the study participants may not obey the instructions of the procedure. Moreover, a couple of number of CP patients in this study had mental retardation which hinder the use of pure-tone audiometric assessment in these patients.


  Conclusion Top


This study found a high prevalence of abnormal tympanograms in children with CP compared to controls. Therefore, there is a need to include tympanometry as a routine in the screening and evaluation of children with CP, so as not to miss a treatable middle ear pathology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Revai K, Patel JA, Grady JJ, Chonmaitree T. Tympanometric findings in young children during upper respiratory tract infections with and without acute otitis media. Pediatr Infect Dis J 2008;27:292-5.  Back to cited text no. 15
    
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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