October 2014

Unilateral Hearing Loss


History & Examination

  • 30 y/o previously healthy female presents with a 1 year history of progressive left-sided hearing loss and tinnitus.
  • Her past medical history and surgical history are unremarkable.
  • Physical examination reveals difficulty with tandem gait and nystagmus, but no dysmetria.
  • A limited post-contrast study of the IAC and an audiogram are obtained.

Diagnostic Studies

  • Word recognition scores in the right ear is 100% at 55 dB and 84% at 75 dB
  • PTA
    • 22 dB (air) and 18 dB (bone) –right
    • 42 dB (air) and 32 dB (bone) - left
  • Summary -moderate to severe sensorineural hearing loss for the left ear

T1-Weighted with contrast

T2-BFFE

Audiogram

 
1. If this patient elects for surgical intervention, which approach are you most likely to utilize?
2. In this clinical setting, if performing surgery, which cranial nerves are you most likely to monitor with intraoperative electrophysiologic assessment (if any)?
3. In addition to a unilateral vestibular schwannoma, which of the following findings would help support a clinical diagnosis of NF2 in this patient?
4. When treating vestibular schwannomas with radiosurgery, what dose is typically prescribed to the 50% isodoseline that conforms to the margin?
5. To which class does this patient belong (left ear) based on the AAO-HNS scale?
6. Which of the following describes you?
7. I practice in one of the following locations.
8. Please add any suggestions or comments regarding this case:
  • I practice in Jamaica.

Didactic

  • The utility of radiosurgery (utilizing a 50% isodose margin dose of 12-13 Gy ) and possiblity for short-term observation was discussed with the patient, but she declined and wished to proceed with surgery.
  • In this case, due to the patient’s hearing status (Class B-AAO-0HNS) a retrosigmoid craniotomy was performed for approach to and resection of the tumor.  VII and VIII (BAER) were monitored during surgery.
  • At surgery, a complete resection was performed with preservation of House Brackman Grade 1 Function. Despite preservation of the cochlear nerve, BAERs were lost and the patient had Class D hearing function postoperatively.

References

  • House JW, Brackmann D E Facial nerve grading system.Otolaryngol Head Neck Surg 1985;93:146–7.
  • MonsellE, BalkanyT, Gates G, Goldenberg RA, MeyerhoffWL, House JW. Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma (vestibular schwannoma). Otolaryngol Head Neck Surg.1995;113:179-180
  • Kondziolka D, et al. The newly diagnosed vestibular schwannoma: radiosurgery, resection, or observation Neurosurg Focus 2012; 33: E8.