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Poorly Diagnostic Findings

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Acoustic neuroma: Likelihood Ratios

Introduction: None written.

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Tags: Neoplasm Otolaryngology Tag this Diagnosis.

Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Overall	0.02%	This is based on a retrospective analysis of 46,000 MRI done for other reasons, which identified 8 acoustic neuromas. The prevalence of "incidental" acoustic neuroma. Lin D; Hegarty JL; Fischbein NJ; Jackler RK Arch Otolaryngol Head Neck Surg 2005 Mar;131(3):241-4. Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, USA. PMID 15781765
Neurofibromatosis Type 2	100%	Eventually, close to 100% of NF Type 2 patients will develop bilateral acoustic neuromas. Neurologist. 2006 Mar;12(2):86-93. Neurofibromatosis types 1 and 2. Yohay K. Division of Child Neurology and Pediatrics, Johns Hopkins University, Baltimore, Maryland 21287, USA. kyohay@jhmi.edu PMID: 16534445
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The likelihood ratios of findings for Acoustic neuroma are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Hearing loss, asymmetric		Sensitivity = 95%
In this study, 5% of patients with an acoustic neuroma had normal or symmetric hearing. Abnormal hearing was defined as an interaural difference of > or =15 dB at a single frequency or > or =10 dB at two or more frequencies, and an interaural speech reception threshold difference of > or =20 dB, or a speech discrimination score of > or =20% Study: Am J Otol. 1998 Mar;19(2):212-8. Acoustic neuromas presenting with normal or symmetrical hearing: factors associated with diagnosis and outcome. Lustig LR, Rifkin S, Jackler RK, Pitts LH. Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, USA. PMID 9520059
[ + ] Auditory Brainstem Response test (ABR)		Sensitivity = 85%
Abnormal ABR, measured by CN V latency This test can be helpful both in diagnosing acoustic neuromas and also in identifying such tumors that are amenable to resection with salvage of hearing Note: In the following study based on 51 patients with acoustic neuromas the sensitivity was higher for extracranial tumors (24/25 = 96%) than for intracranial tumors (10/15) = 67% Study: The sensitivity of auditory brainstem response testing in small acoustic neuromas. Wilson DF; Hodgson RS; Gustafson MF; Hogue S; Mills L Laryngoscope 1992 Sep;102(9):961-4. Portland Ear Medical Group, Ore. 97209. PMID 1518359

Findings With Unspecified Accuracy
Finding	Result	+LR	-LR
[ + ] MRI with Gadolinium Contrast		No accuracy specified.
MRI with gadolinium with milimeter sections through the internal auditory meatus can be used to detect tumors as small as 1 to 2 mm in diameter Study: no study specified.
[ + ] Vertigo		No accuracy specified.
Study: no study specified.
[ + ] Cranial Nerve V abnormalities		No accuracy specified.
facial hypoesthesia or paresthesia Study: no study specified.
[ + ] Cranial Nerve VII abnormalities		No accuracy specified.
Includes: Facial nerve motor weakness as measured by House-Brackman Scale Loss of sensation in posterior superior aspect of external ear canal Study: no study specified.
[ + ] Headache		No accuracy specified.
Study: no study specified.