HSC Section 8_April 2017

Otolaryngology–Head and Neck Surgery 154(1)

Table 2. Initial and Follow-up Audiometric Outcomes Based on Fracture Pattern. a

All

OCS

OCV

P Value

Fracture

60

56 (93) 30 (54)

4 (7)

—

Abnormal audio

34 (57)

4 (100)

.1258

Type of hearing loss Conductive

14 (41)

14 (47)

— —

.1261

Sensorineural

3 (9) 3 (9)

3 (10)

1.000

Mixed

1 (3)

2 (50) 2 (50) b

.0307

12 (40) b

Unclassified

14 (41)

1.000

Hearing loss severity Mild

23 (68)

22 (73)

1 (25)

.0889

Moderate

3 (9)

3 (10)

—

1.000

Severe

4 (12) 4 (12)

1 (3)

3 (75)

.0026

4 (13) c

Unclassified

—

1.000 1.000

Follow-up audio available

25 (42)

23 (41)

2 (50)

Improvement from abnormal to normal on follow-up d

13 of 20 (65) 10 of 12 (83)

13 of 18 (72) 10 of 12 (83)

0 of 2 (0)

.1105

Conductive losses

—

Other types

3 of 8 (38)

3 of 6 (50)

0 of 2 (0)

Abbreviations: OCS, otic capsule–sparing; OCV, otic capsule–violating. a Values presented as n (%). b Otoacoustic emissions or due to lack of bone lines. c Otoacoustic emissions. d Improvements occurred at a mean of 46 6 15.9 days.

In this study, most fractures were unilateral and OCS ( Table 1 ). In adult population reports, 9% to 20% of tem- poral bone fractures are bilateral. 2 The bilateral prevalence is lower here (3%). In the same vein, the prevalence of all skull base and maxillofacial fractures seems to be lower in children than adults. 1,3,12 Though speculation, this may be related to greater skull flexibility and impact absorption in children. 3 Pediatric craniofacial anatomy is fundamentally different, with developing paranasal sinuses and prominent buccal fat pads. Varying fracture rates between pediatric and adult populations may also relate to a different mechan- ism of injury pattern in children. 12 The mechanism of injury distribution in this study was similar to that seen in prior pediatric skull base trauma liter- ature, with falls as the leading cause ( Figure 3 ). 1,3,6 A majority of patients in this study were Caucasian males, reflecting a possible tendency for males to engage in more active and reckless behavior ( Table 1 ). Motor vehicle acci- dents are still the leading cause of adult temporal bone frac- tures, but that prevalence is decreasing. 2,3,13 It has been postulated that this decrease may be related to stricter safety regulations involving airbags and seatbelts. 1 There may be a similar and stronger effect in the pediatric population given rigorous standards for car seats and child restraint devices. Similar to this study, a previous work showed that most hearing losses associated with OCS fractures were conduc- tive. 6 Whereas a majority of OCV fracture-associated hear- ing losses were classified as sensorineural in a prior study, we found that most classifiable losses in OCV fractures are mixed ( Table 2 , Figure 4 ). 6 The difference here may be

Figure 4. Severity and type of hearing loss (HL) based on fracture pattern. OCS, otic capsule–sparing; OCV, otic capsule–violating.

severe, mixed hearing losses. Although OCS fractures are often associated with no measureable hearing loss, those that are tend to be associated with mild, conductive losses. Hearing losses, especially conductive losses, associated with OCS fractures tend to resolve over the course of about 6 weeks ( Table 2 ).

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