Endolymphatic sac tumor – immediate postoperative radiosurgery of surgical bed

SKULL BASE REGION	Cerebellopontine angle/petrous bone
HISTOPATHOLOGY	Endolymphatic sac tumor
PRIOR SURGICAL RESECTION	Yes
PERTINENT LABORATORY FINDINGS	N/A

Case description

The patient is a 74-year-old female with a known history of an endolymphatic sac tumor (ELST) involving the left cerebellopontine angle (CPA) and temporal bone leading to hearing loss, which was previously resected about 4 years earlier at another institution. Gross total resection (GTR) was achieved, but her perioperative course was complicated by a temporal stroke and aphasia, requiring long-term rehabilitation and speech therapy. She presented to our care with a new left facial weakness. Follow-up brain magnetic resonance imaging (MRI) showed local tumor recurrence in the left CPA, with extension to the petrosal bone ( Figure 7.33.1 ). Repeat surgical resection of the recurrent tumor was recommended, and the patient agreed to proceed. Immediately prior to the surgery, her facial weakness had already progressed to a complete facial palsy. Due to tumor invasion and complete facial palsy, a complete mastoidectomy/petrosectomy was performed. The specimen confirmed ELST recurrence without any new histopathological changes, and postoperative MRI confirmed GTR ( Figure 7.33.2 ). Postoperatively, the patient remained neurologically stable, with left complete facial palsy and hearing loss. Given tumor recurrence despite initial GTR, stereotactic radiosurgery (SRS) of the surgical bed was recommended immediately after the second surgery. The patient received 20 Gy in 5 fractions on the TomoTherapy unit. ( Figure 7.33.3 ).