Volume 1, Issue 4 , Pages 286-288, December 2006
An infant case of delayed conductive hearing loss following head trauma
Article Outline
Summary
We present here a rare infant case of delayed traumatic conductive hearing loss. A 12-year-old boy, who had suffered head trauma 6 years previously, visited our hospital complaining of progressive left hearing loss. A horizontal fracture line was observed in the posterior–superior quadrant of the left bony external auditory canal. Pure-tone audiometry revealed combined hearing loss with increasing air-bone gap in the middle- and low-tone ranges compared with 3 years previously. Exploratory tympanotomy revealed that the head of the malleus was fixed to the bony wall of the epitympanum, and the patient's hearing was successfully improved by ossiculoplasty.
Keywords: Traumatic conductive hearing loss, Ossicular fixation, Exploratory tympanotomy
1. Introduction
Conductive hearing loss is a frequent complication of temporal bone injury and is mainly due to ossicular dislocation. It usually occurs instantly at the time of trauma, but can in rare cases occur more than a year after trauma.
We demonstrate here a rare infant case of delayed conductive hearing loss following head trauma suffered in a traffic accident, which occurred more than 3 years after trauma. Exploratory tympanotomy revealed that the head of the malleus was fixed to the bony wall of the epitympanum, and the patient's hearing was successfully improved by ossiculoplasty.
2. Case report
A 12-year-old boy visited our hospital complaining of left hearing loss. He had suffered head trauma in a traffic accident 6 years previously, and high-tone sensorineural hearing loss in the left ear was noted at the previous hospital. He complained that the loss of hearing in his left ear had gradually progressed after the trauma and desired further evaluation of it. He had suffered no facial paralysis and no vertigo since the traffic accident.
At initial examination, otoscopic view of the left ear revealed a horizontal fracture line in the posterior–superior quadrant of the bony external auditory canal (Fig. 1). The tympanic membrane appeared intact. Pure-tone audiometry revealed combined hearing loss with an air-bone gap in the middle- and low-tone ranges (Fig. 2A). Compared with the previous audiogram of the left ear, obtained 3 years after the trauma, the air-bone gap in the middle- and low-tone ranges was increased without progression of sensorineural hearing loss (Fig. 2B). There was no auditory brainstem response to stimulation of the left ear with a sound pressure of 90
dB. Tympanometry of the left ear revealed type A findings. Neither stapedial reflex nor symptoms of fistula of the left ear were observed. Computed tomography (CT) examination revealed no ossicular dislocation, and no soft tissue around the ossicles (Fig. 3).
Fig. 1.
Otoscopic view of the left ear. A horizontal fracture line in the posterior–superior quadrant of the bony external auditory canal was observed.
Fig. 2.
Audiograms on initial examination (A), 3 years before the initial examination (B), and after the operation (C).
Fig. 3.
CT scan of the left temporal bone.
To obtain the correct diagnosis and to treat the conductive hearing loss of the left ear, exploratory tympanotomy was performed under general anesthesia. Malleus handle was fixed. Lateral tympanotomy revealed that the incudostapedial joint was not dislocated (Fig. 4A). Even after resection of scutum, the malleus and incus were still fixed. The incus was easily removed, so fixation of the head of the malleus to the bony wall of epitympanum was suspected. The malleus was cut at its neck, and its handle recovered mobility. The head of the malleus was fixed at its inner side to the bony wall of the epitympanum and removed. The stapes appeared intact. The ossicular chain was reconstructed by interposition of the modified incus between the handle of the malleus and the superstructure of the stapes (Fig. 4B). The patient had an uneventful postoperative course and was discharged on postoperative day 9 in good condition. Although his high-tone sensorineural hearing loss persisted, the air-bone gap in the middle- and low-tone ranges was decreased and his hearing was improved postoperatively (Fig. 2C).
Fig. 4.
Surgical findings. The incudostapedial joint was not dislocated, but was almost fixed (A). The ossicular chain was reconstructed by interposition of the modified incus between the handle of the malleus and the superstructure of the stapes (B).
3. Discussion
Posttraumatic hearing loss is caused by interruption of the ossicular chain as a result of direct or indirect trauma and usually occurs instantly at the time of trauma. The patient presented here exhibited delayed progressive conductive hearing loss due to ossicular fixation after head trauma, though it is rare for ossicular fixation to occur after indirect trauma. Wennmo et al. reported only 1 case of posttraumatic ossicular fixation among 72 cases of temporal bone fracture [1].
Wennmo et al. suggested that posttraumatic ossicular fixation is caused by new formation of bone between the walls of the middle ear and the region around the fracture line [1]. This theory is reasonable for the present case. Hough noted that delayed complications of middle ear trauma include hyperostosis, secondary inflammatory disease, and tympanosclerosis [2]. Our patient had no hyperostosis and no inflammation of the middle ear. The findings in this case suggest that posttraumatic conductive hearing loss may occur several years after trauma, and that long-term follow up is correspondingly necessary in cases of middle ear trauma.
Does et al. noted that the malleus is firmly attached to the eardrum and to the anterior and posterior malleolar ligaments, but that the incus lacks anchorage by ligaments and is predisposed to dislocation [3]. They also suggested that there are frequent changes in and around the incudomalleal joint (such as subluxation and adhesions in the epitympanum), and that if inspection of the middle ear discloses an intact ossicular chain, exploration of the epitympanum must follow. Thus, if posttraumatic conductive hearing loss occurs without ossicular dislocation, fixation of the malleus, and especially of its head, should be considered.
The usefulness of high-resolution CT for all aspects of temporal bone study has been demonstrated [4]. Meriot et al. suggested that both axial and coronal images are needed for evaluation of a dislocated malleus or incus [5]. Our patient presented no ossicular dislocation on axial CT examination. In cases without dislocation of malleus and incus, exploratory tympanotomy is necessary for correct diagnosis, and will be beneficial for patients with posttraumatic conductive hearing loss.
References
- . Fractures of the temporal bone-chain incongruencies. Am. J. Otolaryngol. 1993;14:38–42
- . Otologic trauma. In: Paparella MM, Shumrick DA editor. Otolaryngology. vol. 2:Philadelphia: WB Saunders Co.; 1980;p. 1656–1679
- . Posttraumatic conductive hearing loss. Arch. Otolaryngol. 1965;82:331–339
- Computerized tomographic evaluation of the middle ear and mastoid for posttraumatic hearing loss. Ann. Otol. Rhinol. Laryngol. 1985;94:263–266
- CT appearances of ossicular injuries. Radiographics. 1997;17:1445–1454
PII: S1871-4048(06)00085-2
doi:10.1016/j.pedex.2006.08.003
© 2006 Elsevier Ireland Ltd. All rights reserved.
Volume 1, Issue 4 , Pages 286-288, December 2006
