2025 Proffered Presentations
S275: AGE-RELATED VARIATION IN ACCESS TO THE POROUS ACOUSTICUS IN PEDIATRIC PATIENTS
Sam Tenhoeve, BS1; Michael T Bounajem, MD1; Diwas Gautam, BS1; Allison Liang, MD1; Michael Levy, MD2; Douglas Brockmeyer, MD1; William T Couldwell, MD, PhD1; Robert C Rennert, MD1; 1University of Utah; 2University of California San Diego
Introduction: Lesions within the cerebellopontine angle and specifically those entering the porous acousticus (PA) are rare but do occur in pediatric patients. Special consideration must be made to access this region given the variation in the pediatric skull base throughout development, however, thorough description of this area has not yet been conducted.
Methods: A retrospective analysis was conducted to identify pediatric patients with high resolution imaging from a single institution. Patients with skull base fractures, tumors, hydrocephalus, craniofacial dysmorphology, or other causes for skull base deformation were excluded. Patients were divided into 5 groups: category 1: 0-3 years old, 2: 4-7 years old, 3: 8-11 years old, 4: 12-15 years old, and 5: 16-18 years old. Measurements included anterior petrous distance (APD; distance from the petroclival suture to the anterior margin of the PA), and the posterior petrous distance (PPD; distance from the anterior aspect of the sigmoid sinus to the posterior margin of the PA). Relevant angles included the anterior petro-auditory angle (APA; angle between the APD and a line parallel to the anterior border of the internal acoustic canal (IAC)), posterior petro-auditory angle (PPA; angle between the PPD and a line parallel to the posterior border of the IAC), and the internal auditory angle (IAA; angle between the trajectory of the IAC and a horizontal line across the patient’s head).
Results: A total of 50 patients (10 per category) were included. The average age in category 1 was 1.49 years old, with an average APD of 10.6±2.12 mm, average PPD of 19.9±6.43 mm, average APA of 125º, average PPA of 63.7º, and average IAA of 28.9º. The average age in category 2 was 5.4 years old, with an average APD of 13.3±1.6 mm, average PPD of 24.5±2.98 mm, average APA of 129º, average PPA of 58.9º, and average IAA of 25.6º. The average age in category 3 was 9.4 years old, with an average APD of 14.3±2.23 mm, average PPD of 25.2±2.27 mm, average APA of 134º, average PPA of 58.4º, and average IAA of 27.1º. The average age in category 4 was 13.2 years old, with an average APD of 13.9±1.69 mm, average PPD of 25.3±2.55 mm, average APA of 129º, average PPA of 61.3º, and average IAA of 22.4º. The average age in category 5 was 16.5 years old, with an average APD of 14.3±2.45 mm, average PPD of 26.1±4.08 mm, average APA of 129º, average PPA of 61.5º, and average IAA of 23.8º.
Conclusions: Average APD and PPD demonstrated gradual increase with age, while IAA generally decreased with increasing age. APA and PPA did not demonstrate an obvious linear relationship with age. Temporal bone changes with development relevant to surgical approaches to the IAC include an elongation of the petrous face (both anterior and posterior to the IAC), and a progressively more acute angle of the IAC relative to the coronal plane. Together, these changes increase the surgical depth and decrease visualization of the mid-to-distal IAC from a standard posterolateral approach without additional bony removal.