|Year : 2021 | Volume
| Issue : 3 | Page : 158-162
Assessment of hearing loss in temporal bone fractures
M Abhishek, Revathishree Kaleeswaran, K Srinivasan
Department of Otorhinolaryngology and Head and Neck Surgery, Saveetha Medical College and Hospital, Chennai, Tamil Nadu, India
|Date of Submission||26-Aug-2020|
|Date of Decision||02-Mar-2021|
|Date of Acceptance||03-Oct-2021|
|Date of Web Publication||16-Dec-2021|
Dr. Revathishree Kaleeswaran
Saveetha Medical College and Hospital, Thandalam, Chennai - 602 105, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Introduction: Thirty percent to seventy percent of skull fractures in adult head trauma patients is due to temporal bone fractures and is caused due to road traffic accidents (RTAs). Temporal bone fractures are more commonly associated with hearing loss. Objective: The objective of this study is to assess the type and the amount of hearing loss in temporal bone fractures. Methodology: A 3-month retrospective study was conducted at the department of ear, nose, and throat in a tertiary care center. Fifty patients, diagnosed as cases of temporal bone fractures with hearing loss were included in the study. The patients with temporal bone fractures were categorized into two groups-otic-capsule sparing (OCS) and otic-capsule violating (OCV) fractures, and hearing loss was evaluated with Pure tone audiogram (PTA). Results: OCS fractures were more common (64%) than OCV. Conductive type of hearing loss was commonly associated with OCS, whereas sensorineural hearing loss was more common in OCV fractures. The average degree of hearing loss ranged from 20 to 68 db. The correlation was statistically significant for temporal bone fractures (OCS and OCV) with respect to hearing loss (P < 0.00001). Other complications such as external auditory canal filled with blood, perforation of tympanic membrane, and hemotympanum were also observed in our study. Conclusion: Temporal bone fractures are most commonly due to RTAs and are frequently associated with severe brain injury. Classifying temporal bone fractures as OCS and OCV fractures correlates well with the severity of hearing loss, and conductive hearing loss was the most common type hearing loss.
Keywords: Hearing loss, otic capsule sparing, otic capsule violating, temporal bone fracture
|How to cite this article:|
Abhishek M, Kaleeswaran R, Srinivasan K. Assessment of hearing loss in temporal bone fractures. Indian J Otol 2021;27:158-62
| Introduction|| |
Thirty percent to seventy percent of skull fractures in adult head trauma patients is due to temporal bone fractures and is caused due to road traffic accidents (RTAs).,, Temporal bones are paired structures present on the lateral aspect of the skull. The anatomy of temporal bone is quite complex, as it contains several important structures such as the middle and inner ear, the vestibulocochlear nerve, the facial nerve, the internal carotid artery, the jugular vein and contributes to the middle and posterior cranial fossae and forms the base of skull. The temporal bone consists of four parts: the mastoid process, squamous, petrous, and the tympanic part.
Conventionally, temporal bone fractures are classified as transverse, longitudinal, or mixed type of fractures, depending on the relationship between the long axis of the fracture and the petrous apex., This classification was based on the cadaveric studies done in the 1950s., Recent studies have shown a much better way of classifying temporal bone fractures as optic-capsule sparing (OCS) and optic-capsule violating (OCV) fractures. This type of classification has more relevance with the prognosis of hearing loss and other complications., In 1994, Kelly suggested the terms “OCS” and “OCV” as an alternative nomenclature for classifying temporal bone fractures. Honeybrook and Zayas also proposed a similar approach for classifying temporal bone fractures.,
Since temporal bone encloses a myriad of important structures, devastating complications arise. Sensorineural hearing loss (SNHL), conductive hearing loss (CHL), balance dysfunction, facial nerve paralysis, perilymphatic fistulas, cerebrospinal fluid (CSF) leak, and vascular injury are some complications of temporal bone fractures, or it can be asymptomatic., SNHL occurs when there is damage to the internal ear or the vestibulocochlear nerve, whereas CHL occurs when ossicular chain disruption occurs or when there is damage to the tympanic membrane. CHL is more common with longitudinal/OCS fractures of temporal bone, while transverse/OCV fractures have a greater propensity to cause SNHL.,, Injury to facial nerve is more common in OCV fractures.
About 10%–25% of longitudinal fractures and 38%–50% of transverse fractures tend to cause facial nerve injury., In 11%–25% of temporal bone fractures, CSF leak has been noticed.,,, Due to CSF leak, blood in the ear or tympanic membrane perforation, CHL is more common., SNHL is commonly associated with transverse fractures of temporal bone and can be due to perilymphatic fistula, labyrinthine concussions, fracture of the labyrinth, or due to brain stem injuries.
The purpose of this article is to analyze the type and the amount of hearing loss due to temporal bone fracture by its gender distribution, the cause of injury, presentations, and hearing loss due to the fractures and the outcomes.
| Methodology|| |
This is a retrospective study, conducted at the department of otorhinolaryngology, in a tertiary care center, for a time period of 3 months, from January 1, 2020, to March 31, 2020. Fifty consecutive patients who satisfied the inclusion and exclusion criteria were studied. All the patients of the otorhinolaryngology, neurosurgery, and the emergency departments and who were diagnosed as a case of temporal bone fractures with complaint of hard of hearing were included in the study. Computed tomography (CT)/high-resolution computed tomography (HRCT) findings were included in this study. Patients with previous history of ear problems, severe injury to the brain parenchyma, and other severe comorbid illnesses were excluded from this study. Details of history, which elicited the cause and mode of injury, Puretone Audio Gram (PTA) findings were taken from hospital data base. To quantify the degree and type of hearing loss, air conduction threshold, bone conduction threshold, and air bone gap were assessed in PTA. The results were tabulated and statistically analyzed using Microsoft Excel spreadsheet. The Chi-square test was done for comparison. A probability value (P) < 0.05 was considered statistically significant. Ethical approval for this study SMC/IEC/2020/03/302 was provided by the Institutional Ethical Committee, Saveetha Medical College and hospital,Thandalam,Chennai,Tamilnadu,India on 17 March 2020.
| Results|| |
Fifty patients with temporal bone fractures were diagnosed using CT scan between January 2020 and March 2020.
In our study, 27 (54%) were male and 23 (46%) were female. Mean age was 38.6 years, and the age ranged from 20 to 70 years [Figure 1] and [Table 1].
In our study, RTA accounted for 52% (26) as cause of temporal bone fracture accidental fall accounted for 22% (11) of the fractures, blunt trauma 16% (8), and other causes accounted for 10% (5) of the fractures [Figure 2].
According to the newer classification system of temporal bone fractures, 33 (66%) cases were found to be OCS and 17 (34%) cases were OCV type. When classified according to the traditional system, 32 (64%) of the fractures were longitudinal, 12 (24%) were transverse, and 6 (12%) were mixed fractures [Table 2].
Of the 50 patients with hearing loss, 34 (68%) cases had CHL and 16 (32%) cases had mixed hearing loss. Minimal, mild, moderate, and moderately severe hearing loss was observed in 3 (6%), 20 (40%), 15 (30%), and 12 (24%) patients, respectively [Table 3].
In our study, out of 34 CHL patients, 31 (91.1%) had OCS type of fractures and 3 (8.9%) had OCV type of fractures. 2 (12.5%) out of 16 cases of mixed hearing loss had OCS fractures and 14 (87.5%) of 16 cases had OCV type of fractures. This correlation is statistically significant as P < 0.050 (P = 0.00001) [Table 4].
|Table 4: Correlation of the classification of temporal bone fractures with hearing loss|
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When the fractures were classified according to the traditional method, of the same 34 CHL patients, 25 (73.5%) had longitudinal fractures, 6 (17.6%) had transverse, and 3 (8.9%) had mixed fractures. In the SNHL category, 10 (62.5%) had transverse fractures, 5 (31.25%) had longitudinal, and 1 (6.25%) had mixed type of fractures.
At the time of trauma, upon ENT examination, 25 patients (50%) had external auditory canal (EAC) filled with blood, and their tympanic membrane was not visible, 18 (36%) had hemotympanum, 3 (6%) had perforation of tympanic membrane, and 4 (8%) had normal tympanic membrane [Figure 3] and [Table 5].
Ear fullness due to the presence of blood in the EAC was found in 25 patients (50%), of which 13 (52%) patients had longitudinal fractures, 9 (36%) had transverse and 3 (12%) patients had mixed type of fractures.
| Discussion|| |
Across the globe, head injury remains to be the major source of morbidity and mortality. This can be attributed to the difficulties faced by our country's authorities to reduce the incidence of RTAs. Perhaps, with better trauma care facilities or by building a separate trauma care unit may serve as the long-term solution in the management of RTAs.
This literature reports RTAs to be the major cause of head injury,,,, which in our case, is confirmed by 54% of cases were due to RTAs. During our study period, the emergency department of our hospital had reported a total of 648 head injury cases, of which 50 (7.7%) patients had temporal bone fracture. Our study showed a less incidence of temporal bone fractures than a study done by Maradi and Somanath (19.1%).
In our study, 27 patients (54%) were male and 23 (46%) were female, with a male: female ratio of 1.17:1. Our study shows similar findings to Basavaraju et al. in gender distribution. Like their study, our study shows that temporal bone fractures are more common in male patients. The distribution of age and gender for our study is similar to the other larger studies that have been previously published.,,,
All the 50 patients, who were included in this study, had complained of hearing loss. Of these 50 patients, 34 (68%) had CHL and 16 (32%) had mixed hearing loss SNHL. This shows that CHL is more in temporal bone fractures. This could possibly be due to the presence of blood in the EAC, ossicular disruption, or tympanic membrane perforation., The incidence of CHL was significantly higher than SNHL in a similar study conducted by Amin et al. and Basavaraju et al., which indicates that CHL is the more common. Profound SNHL was found to be more prevalent in the transverse fractures of temporal bone. This is because of the involvement of otic capsule in such fractures.,
In our study, the severity of hearing loss was minimal in 6%, mild in 40%, moderate in 30%, and moderately severe in 24%. In a similar study conducted by Barber, it is noticeable that out of 42 patients, 10 had mild, 4 had moderate, and 8 had moderately severe hearing loss., Maradi and Somanath in a similar study noted that the severity of hearing loss was minimal in 40%, mild in 26.7%, moderate in 15.6%, and moderately severe in 13.3%.
In this study, we classified temporal bone fractures in both traditional and new systems of classification. When classified according to the alternative nomenclature proposed by Kelly, we observed of the 50 cases, 33 (66%) were OCS, and 17 (34%) were OCV fractures. There was a correlation between fractures when classified as OCS/OCV and hearing loss (P < 0.00001). We found that the severity of hearing loss was higher in patients with OCS fractures. We also found that the incidence of CHL was significantly higher in OCS fractures (91.1%) and mixed hearing loss in OCV fractures (87.5%). Maradi and Somanath observed in their study that patients with OCV fractures were at 25% higher risk of developing SNHL than those who have OCS fractures. The incidence of CHL in patients with OCS fractures was higher in their study. Similar results were observed in a study done by Little and Kesser.,
We observed that of the 50 cases, 32 (64%) were longitudinal fractures, 12 (24%) were transverse, and 6 (12%) were mixed type of fractures. Ishman and Friedland in their study on 155 fractures reported 99 (64%) were longitudinal, 36 (23%) were transverse, and 20 (13%) were mixed. Little and Kesser, when retrospectively reviewed 30 temporal bone fractures, noticed that 15 (50%) patients had longitudinal fractures, 8 (27%) patients had transverse, and 7 (23%) patients had mixed fractures.,
In our study, the incidence of facial nerve paralysis was found to be 14% (7 cases). Of the 7 patients, 5 cases (71.4%) noticed paralysis within 48 h (immediate facial palsy) and 2 cases (28.57%) noticed paralysis after 48 h (delayed facial palsy). It is noticeable that the incidence of facial nerve paralysis is more common in patients with OCV fractures (6 cases), whereas in OCS fractures, it was 1 case. This could be because of the invasion of the labyrinth which is seen in OCV fractures.,,,
Tympanic membrane perforations were seen in three patients (6%). Among these, 2 (66.7%) had small-sized perforation while 1 (33.3%) had medium-sized perforation.
Hemotympanum was observed in 18 cases (36%) in our study. The incidence of hemotympanum was similar in a study conducted by Maradi and Somanath (18 cases, 40%).
Limitations of the study
The limitations of the study include small sample size, presence of wax in the ear canal before trauma, and pre-existing hearing loss which is not documented.
| Conclusion|| |
RTAs continue to be the most common cause of head injury globally. Temporal bone fractures occur as a result of high-intensity trauma. Temporal bone fractures can be easily diagnosed using a HRCT. Traditional classification of temporal bone fractures as longitudinal, transverse, or mixed lack the detail and precision and correlate poorly with the clinical findings such a facial nerve paralysis and CSF leak. Far better ways of classifying these fractures are based on the involvement of otic capsule as, OCS and OCV fractures. They demonstrated a far better correlation with respect to hearing loss. Hearing loss was the most common complication associated with temporal bone fracture. Out of which CHL was more common than mixed loss and mixed loss was most commonly associated with OCV fractures.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]