SKULL BASE REGION | Cerebellopontine angle/internal auditory canal |
HISTOPATHOLOGY | Schwannoma |
PRIOR SURGICAL RESECTION | Yes |
PERTINENT LABORATORY FINDINGS | Pretreatment audiogram: Class B hearing with word recognition scores at 65% and pure tone average of 40 dB in the left ear; normal right hearing |
Case description
The patient was a 33-year-old woman who noted difficulty with balance and progressive left-sided facial numbness and hearing loss over several months. She underwent a brain magnetic resonance imaging (MRI) with gadolinium contrast, revealing an exceptionally large enhancing tumor in the cerebellopontine angle (CPA) ( Figure 8.39.1 ). There was associated mass effect on the pons and cerebellum with parenchymal distortion but without edema or hydrocephalus. An audiogram showed mild-to-moderate sensorineural hearing loss, with word recognition at 65% ( Figure 8.39.2 ). Neurological examination revealed mild numbness in the left V2 distribution and slight imbalance with tandem walking. She had no history of vertigo or facial weakness.
![](https://radiologykey.com/wp-content/uploads/2024/04/f39-01-9780323874373.jpg)
![](https://radiologykey.com/wp-content/uploads/2024/04/f39-02-9780323874373.jpg)
Due to the size and symptomatic nature of the lesion, as well as her young age, she underwent a left retrosigmoid craniotomy for aggressive, but subtotal, resection to preserve the facial nerve. Hearing could not be preserved. The tumor was confirmed to be a vestibular schwannoma (VS). Postoperative facial nerve function was House-Brackman (HB) grade II but returned to normal by the 3-month follow-up. She experienced altered taste involving the left tongue, as well as left nasal and ocular dryness, signifying nervus intermedius dysfunction, all of which improved at 3 months. Postoperative MRI revealed a 6-mm plaque of tumor along the facial nerve ( Figure 8.39.3 ). This residual tumor subsequently demonstrated growth at 3.5 years ( Figure 8.39.4 ), necessitating treatment with Gamma Knife radiosurgery (GKRS) ( Figure 8.39.5 ).
Radiosurgery Machine | Gamma Knife – Perfexion |
Radiosurgery Dose (Gy) |
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Number of Fractions | 1 |
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