Annals of Otology. Rhinology & Laryngology 119(9):628-630. © 2010Annals PublishingCompany.All rights reserved. Dislocation of Stapes With Footplate Fracture Caused by Indirect Trauma Ryoji Kagoya, MD; Ken Ito, MD; Akinori Kashio, MD; Shotaro Karino, MD; Tatsuya Yamasoba, MD We report the first case of isolated stapedial dislocation caused by indirect head trauma, and present imaging and surgical findings in the case of a 25-year-old woman who suffered hearing loss and dizziness after head trauma caused by a traffic accident. The pure tone average was 60 dB, with an air-bone gap of 50 dB. The stapedial reflex was positive with the probe on the affected ear. Computed tomography scans revealed a longitudinal fracture of the temporal bone and a dislocated stapedial superstructure in the tympanic cavity, adhering to the tympanic membrane. During surgery, it was found that the stapes was broken at the base of the posterior crus and at the anterior one third of the footplate and that the stapedial superstructure was dislocated outward and downward, with the anterior one third of the footplate adhering to the tympanic membrane. The stapedial tendon was connected to the superstructure. Ossicular chain reconstruction was performed with success. In the present case, two mechanisms may have acted together: 1) an increase in perilymphatic pressure that caused the footplate to fracture, and 2) a distorting force that broke the posterior crus, disconnecting the incudostapedial joint, and finally dislocating the stapedial superstructure together with the anterior part of the footplate. Key Words: footplate fracture, indirect trauma, stapes dislocation. adherent to the posteroinferior quadrant of the tympanic membrane (Fig 1). Pure tone audiometry revealed a conductive hearing loss. Her pure tone average was 60 dB, with an air-bone gap of 50 dB. A tympanogram showed type Ad, and the stapedial reflex was positively recorded on the left with right- INTRODUCTION Head trauma can cause ossicular chain disruption.' The incudostapedial joint is the most fragile part of the chain. Dislocation of the incus is the second most frequent injury. Fracture of the stapedial crura can also occur, but the stapedial footplate rarely fractures.e" An isolated dislocation of the stapes combined with a fracture as a result of indirect trauma has not yet been reported. Here, we present a very rare case of stapedial footplate fracture in which the superstructure with part of the footplate was dislocated and adhered to the tympanic membrane. This is the first report of isolated stapedial dislocation caused by indirect head trauma. CASE REPORT A 25-year-old woman was hit by a car while riding a bicycle and suffered a left temporal bone fracture, cerebrospinal fluid otorrhea, cerebral contusion, and acute subdural hematoma. She noticed a left-sided hearing loss immediately after the accident. She also experienced dizziness with changes of head position, which gradually subsided over 2 months. She was referred to our clinic for examination 11 months after the accident. Fig 1. Preoperative findings of tympanic membrane. White arrowhead - dislocated stapes (anterior part of footplate) adherent to tympanic membrane; black arrow - fracture in external auditory canal. A fracture of the left external auditory canal was observed, and a bony fragment was presumed to be From the Department of Otolaryngology, Faculty of Medicine, University of Tokyo (all authors), and the Department of Otolaryngology,Facultyof Medicine, Teikyo University (Ito),Tokyo, Japan. Correspondence: Ken Ito, MD, Deptof Otolaryngology, Teikyo University, 2-11-1 Kaga,Itabashi-ku, Tokyo 173-8605, Japan. 628 Kagoya et al, Traumatic Dislocation ofStapes 629 Fig 2. Endoscopic findings during surgery. A) White arrowhead - anteriorpart of footplate adherent to tympanic membrane; black arrowhead - stapedial tendon.B) Black arrowhead - anteriorthird of oval window, in which footplate is missing owing to fracture and dislocation. sided stimuli. No nystagmus or fistula sign was seen. Her caloric responses were normal. Facial palsy was not observed. Her past medical history other than the accident, as well as her family history, was unremarkable. High-resolution computed tomography scans revealed a longitudinal fracture of the temporal bone traversing the left mastoid air cells to the posterior wall of the external auditory canal and a bow-shaped bone fragment, presumably the dislocated stapedial superstructure, in the tympanic cavity. Five months after her first visit to our clinic, an exploratory tympanotomy was performed, followed by tympanoplasty. The findings during surgery were as follows (Fig 2). The incudostapedial joint was disrupted. The stapes was broken at the base of the posterior crus and at the anterior one third of the footplate and was dislocated. The anterior third of the oval window, in which the footplate was missing, was covered with connective tissue, and no perilymph fistula was seen. The stapedial superstructure was found dislocated outward and downward, and the anterior third of the footplate was adherent to the tympanic membrane. The stapedial tendon was connected to the superstructure, and its integrity, ie, contraction, was confirmed with a facial nerve stimulator. A small cartilage plate was harvested from the tragus and placed between the oval window and the long crus of the incus (type IV tympanoplasty; Fig 3). The postoperative pure tone average recovered to 23 dB, with an air-bone gap of 10 dB. DISCUSSION Fig 3. Microscopic view after ossiculoplasty. Small arrowhead - tip of long processof incus;large arrowhead - columellaconsisting of cartilage; arrow - preserved stapedial superstructure. The ossicular chain can be disrupted by an indirect force due to head trauma, but fractures of the ossicles are less common. There have been only a few reports of stapedial footplate fractures.es Elbrond and Aastrup'' reported 11 cases of isolated stapedial fracture, among which only 1 was a stapedial footplate fracture. Moreover, there has been no report of stapedial dislocation. The Table2-6 summarizes previous footplate fractures caused by indirect force. The stapes is fixed to the oval window by the annular ligament. Therefore, the crura, rather than the footplate, can easily be broken when a strong force due to head trauma distorts the temporal bone. Since 630 Kagoya et al, Traumatic Dislocation oj Stapes FRACTURES OF STAPEDIAL FOOTPLATE CAUSED BY INDIRECT EXTERNAL FORCE Authors Year Sade1964 Azem and Caldarelli1973 Elbrond and Aastrups 1973 Whinney et al4 1996 Whitehead1999 Whitehead1999 Whitehead" 1999 Present report N/A - no information available. Cause Age (y) Gender 54 40 N/A M F N/A Traffic accident Sneezing 43 28 40 50 26 M M F F Valsalva's maneuver during diving Suppression of sneezing Sneezing while carrying weight Parturition Traffic accident F N/A the skull bone of children is more deformable than that of adults, allowing distortion by indirect force to reach the stapes more easily, traumatic fracture of the stapedial arch is more common in children.s-? On the other hand, the footplate seems to be susceptible to barotrauma, ie, an abrupt increase in middle ear pressure or perilymphatic (inner ear) pressure, and all cases reported to date have involved adults, although in 1 case, the age was not specified (see Fracture oj Stapedial Arch Dislocation ofStapes Both crura No Posterior crus No No Posterior crus No Posterior crus No No No No No No No Yes Table). In our case, two mechanisms may have acted together: 1) an increase in perilymphatic pressure causing the footplate to fracture, since a strong force affecting the brain can raise the cerebrospinal fluid pressure, which in tum increases the pressure of the inner ear fluid; and 2) a distorting force that broke the posterior crus, disconnecting the incudostapedial joint, and finally dislocating the stapedial superstructure with the anterior part of the footplate. REFERENCES 1. Hough JV. Stuart WD. Middle ear injuries in skull trauma. Laryngoscope 1968;78:899-937. 2. Sade J. Traumatic fractures of the stapes. Arch OtolaryngoI1964;80:258-62. 3. Azem K. Caldarelli DO. Sudden conductive hearing loss following sneezing. Arch Otolaryngol 1973;97:413-4. 4. Whinney OJ, Parikh AA, Brookes GB. Barotraumatic fracture of the stapes footplate. Am J Otol 1996;17:697-9. 5. Whitehead E. Sudden sensorineural hearing loss with fracture of the stapes footplate following sneezing and parturition. Clin Otolaryngol Allied Sci 1999;24:462-4. 6. Elbrond O. Aastrup JE. Isolated fractures of the stapedial arch. Acta Otolaryngol 1973;75:357-8. 7. Singh S. Salib RJ. Oates J. Traumatic fracture of the stapes suprastructure following minor head injury. J Laryngol OtoI2002;116:457-9.