Vestibular schwannoma diagnosis [Neurosurgery Wiki]

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====== Vestibular schwannoma diagnosis ======

  * **Audiometry:** High-frequency sensorineural hearing loss
  * **MRI with gadolinium contrast:** Gold standard; shows enhancing mass in the internal auditory canal or CPA
  * **ABR (Auditory Brainstem Response):** May show delay in wave V latency

In the 1980s tests for cerebrospinal fluid protein, vestibular testing, and arteriography have been supplanted by modern audiometry with acoustic reflex testing, brain stem evoked responses, and computed tomography (CT). The various types of plain radiography are confirmed as an extremely useful screening modality. CT is insufficiently sensitive to serve as a primary screening procedure, but is a valuable confirmatory test
((Hart RG, Davenport J. Diagnosis of acoustic neuroma. Neurosurgery. 1981
Oct;9(4):450-63. Review. PubMed PMID: 7029342.
)).

Vestibular schwannoma (VS) usually present the widening of [[internal auditory canal]] (IAC), and these bony changes are typically limited to IAC, not extend to [[temporal bone]]
((Park SJ, Yang NR, Seo EK. Vestibular schwannoma atypically invading temporal
bone. J Korean Neurosurg Soc. 2015 Apr;57(4):292-4. doi:
10.3340/jkns.2015.57.4.292. Epub 2015 Apr 24. PubMed PMID: 25932298; PubMed
Central PMCID: PMC4414775.
)).

====Audiologic evaluation====

Evaluation—should include [[pure tone audiometry]] and [[speech discrimination test]] (50/50 is considered serviceable hearing with 50 Db pure tone hearing and 50% speech discrimination).
----
The most common chief complaint in patients diagnosed with CPA tumors was asymmetrical [[hearing loss]], with most frequent accompanying symptoms being [[tinnitus]] in patients with [[vestibular schwannoma]] (VS) and [[dizziness]] in those with other types of CPA tumor. The most frequent patterns of hearing loss were the descending type in patients with VS and the flat type in patients with non-VS tumors (p < 0.05). Pure tone thresholds tended to increase more in patients with VS than non-VS tumors according to tumor size, and pure tone averages were significantly higher in patients with VS than non-VS tumors of 11-25 mm in size (p < 0.05)
((Kim SH, Lee SH, Choi SK, Lim YJ, Na SY, Yeo SG. Audiologic evaluation of
vestibular schwannoma and other cerebellopontine angle tumors. Acta Otolaryngol. 
2016 Feb;136(2):149-53. doi: 10.3109/00016489.2015.1100326. Epub 2015 Oct 19.
PubMed PMID: 26479426.
)).

====Neurological examination====
===Trigeminal nerve dysfunction===
Trigeminal nerve, and facial nerve dysfunction are common preoperative findings.

Examination may show [[hypoesthesia]] in the most
superficial part of the external auditory canal. In a
population of 46 patients tested by a Schirmer test before radiosurgery, Tamura et al found that 41% of patients
experienced some lacrimal deficit on the side of the
tumor.
more common at the time of presentation than facial
weakness (about 10% of patients). A decrease in the
corneal reflex generally occurs earlier and more
commonly than documented facial hypoesthesia. Even
though approximately 50–70% of individuals with large
tumors have facial hypoesthesia on neurological
examination, they are often unaware of it, and it is rarely
the presenting symptom.

===Facial nerve dysfunction===

[[House-Brackmann score]].

The HBS produced comparable results between different observers in patients with normal or only mildly impaired facial nerve function. Interobserver variability increased depending on the severity of facial nerve paresis. The results suggest that the HBS does not promote uniformity of reporting and comparison of outcomes in patients with moderate or severe facial nerve paresis
((Scheller C, Wienke A, Tatagiba M, Gharabaghi A, Ramina KF, Scheller K, Prell
J, Zenk J, Ganslandt O, Bischoff B, Matthies C, Westermaier T, Antoniadis G,
Pedro MT, Rohde V, von Eckardstein K, Kretschmer T, Kornhuber M, Barker FG 2nd,
Strauss C. Interobserver variability of the House-Brackmann facial nerve grading 
system for the analysis of a randomized multi-center phase III trial. Acta
Neurochir (Wien). 2017 Apr;159(4):733-738. doi: 10.1007/s00701-017-3109-0. Epub
2017 Feb 10. PubMed PMID: 28188418.
)).

===== CT scan =====

see [[Vestibular schwannoma CT scan]]


===== MRI =====

see [[Vestibular schwannoma magnetic resonance imaging]]