Contralateral Hearing Loss in Temporal Bone Fractures: A Potential Association with Combined Intracranial Injury

Temporal bone (TB) fractures are frequently accompanied by intracranial injury. This study aimed to analyze combined intracranial injuries in relation to functional changes in the inner ear, including those of the contralateral ear, in patients with TB fractures. Ninety-four patients (mean age: 35.6 ± 18.7 years, M : F=67 : 27) diagnosed with unilateral TB fracture were included. Bone conduction (BC) threshold, word recognition score (WRS), and changes in vestibular function were compared based on intracranial injuries, focusing on the contralateral side. Various types of intracranial injuries were observed (67.9%). Among these, a significant association between traumatic brain injury (TBI) and otic capsule-violating fractures was noted. The BC threshold on the fractured side significantly deteriorated in patients with TBI. Additionally, a significantly worse BC threshold was confirmed on the contralateral side in patients with TBI, intracranial hemorrhage (ICH), and contrecoup injury. The follow-up BC threshold did not improve or differ, regardless of high-dose steroid administration. The initial WRS and canal paresis in the bithermal caloric test were not significantly different in the presence of each intracranial injury. Concurrent fluctuations in the pressure of the cerebrospinal fluid space and perilymphatic space were speculated to be the potential underlying mechanisms. A significantly worse BC threshold was confirmed on the contralateral side of patients with TBI, contrecoup injury, ICH, and on fracture sides of patients with TBI.