|
|
| Line 1: |
Line 1: |
| __NOTOC__ | | __NOTOC__ |
| {{Acoustic neuroma}} | | {{Acoustic neuroma}} |
| {{CMG}} | | {{CMG}}{{AE}}{{Simrat}} |
| ==Overview== | | ==Overview== |
| | | The incidence of acoustic neuroma is approximately 1 per 100,000 individuals worldwide. The prevalence of acoustic neuroma is approximately 2,500 new cases per 100,000 individuals. Women are more commonly affected with acoustic neuroma than men.Most cases of acoustic neuroma develop in individuals between the ages of 30 and 60. |
| ==Epidemiology and Demographics==
| | ==Epidemiology and Demographic== |
| | | Acoustic neuroma account for 7-8% of all primary intracranial tumours 2 and 75-90% of cerebellopontine angle masses 1-2,8. Bilateral vestibular schwannomas are highly suggestive of neurofibromatosis type 2 (NF2), although bilateral tumours are encountered in the familial form of acoustic schwannomas in the absence of other stigmata of NF2 |
| The true incidence of Acoustic neuromas has been difficult to estimate.<ref>Ho SY, Kveton JF. Acoustic neuroma assessment and management. Otolaryngol Clin North Am 2002;35:393-404</ref> <ref>Tos M, Charabi S, Thomsen J. Clincial experience with vestibular schwannomas: epidemiology, symptomatology, diagnosis, and surgical results. Eur Arch Otorhinolaryngol 1998;255:1-6.</ref> The incidence has been reported to range from 1 to 20 per million per year.<ref> Howitz MF, Johansen C, Tos M, Charabi S, Olsen JH. Incidence of Vestibular Schwannoma in Denmark, 1977-1995. Am J Otol 2000;21:690-694</ref> <ref>Tos M, Charabi S, Thomsen J. Clincial experience with vestibular schwannomas: epidemiology, symptomatology, diagnosis, and surgical results. Eur Arch Otorhinolaryngol 1998;255:1-6.</ref> <ref>Tos M, Stangerup SE, Cayé-Thomasen P, Tos T, Thomsen J. What is the real incidence of vestibular schwannoma? Arch Otolaryngol Head Neck Surg 2004;130:216-220</ref> A study of acoustic neuromas in a review of 24,000 brain MRIs reported a prevalence of 0.07%. When comparing the clinical incidence | | ===Prevalence=== |
| of acoustic neuromas to the prevalence of occult acoustic neuromas ascertained from histopathological studies of temporal bones, it can be concluded that the vast majority of tumors that exist are never clinically manifested.<ref>Thomsen J, Tos M. Acoustic neuroma: clinical aspects, audiovestibular assessment, diagnostic delay, and growth rate. Am J Otol 1990;11:12-19.</ref> <ref>Rosenberg SI. Natural history of acoustic neuromas. Laryngoscope 2000;110:497-508.</ref> Acoustic neuromas are most commonly diagnosed between the ages of 30 and 68.<ref>Strasnick B, Glasscock ME, Haynes D, McMenomey SO, Minor LB. The natural history of untreated acoustic neuromas. Laryngoscope1994;104:1115-1119.</ref> <ref>Hart RG, Davenport J. Diagnosis of acoustic neuroma. Neurosurgery 1981;9:450-463.</ref> Reported cases of acoustic neuroma in childhood are rare and in such patients other evidence of NF2 should be investigated. In a study of 146 cases of acoustic neuromas, the median age of cases was 52 years.<ref>Edwards CG, Schwartzbaum JA, Lönn S, Ahlbom A, Feychting M. Exposure to loud noise and risk of acoustic neuroma. Am J Epidemiol 2006;163:327-333.</ref> In a second study of 793 cases of Acoustic neuroma, the median age of the cases was 54 years. The sex ratio (females/males) for acoustic neuromas has been reported to be >1 <ref>Inskip PD, Tarone RE, Hatch EE, et al. Sociodemographic indicators and risk of brain tumours. Int J Epidemiol 2003;32:225-233.</ref> <ref>Howitz MF, Johansen C, Tos M, Charabi S, Olsen JH. Incidence of Vestibular Schwannoma in Denmark, 1977-1995. Am J Otol 2000;21:690-694.</ref> <ref>Chandler CL, Ramsden RT. Acoustic schwannoma. Br J Hosp Med 1993;49:336-343.</ref> <ref>Spoelhof GD. When to suspect acoustic neuroma. Am Fam Physician 1995;52:1768-1774.</ref>
| | Acoustic neuromas are estimated to affect 1 in 100,000 people in the general population. |
| However, data from the Central Brain Tumor Registry of the United States (CBTRUS) do not support a female/male difference<ref>Propp JM, McCarthy BJ, Davis FG, Preston-Martin S. Descriptive epidemiology of vestibular schwannomas. Neuro-oncol 2006;8:1-11.</ref> Nevertheless,some of the studies that analyzed Swedish data, the sex ratio (females/males) of acoustic neuromas in the Nordic counties has been shown to be >1. This sex ratio may indicate that hormones play a role in the etiology of acoustic neuromas<ref>Schlehofer B, Blettner M, Wahrendorf J. Association between brain tumors and menopausal status. J Natl Cancer Inst 1992;84:1346-1349</ref> <ref>Howitz MF, Johansen C, Tos M, Charabi S, Olsen JH. Incidence of Vestibular Schwannoma in Denmark, 1977-1995. Am J Otol 2000;21:690-694.</ref> The tumor has been reported to be higher in whites than in non-whites<ref>Propp JM, McCarthy BJ, Davis FG, Preston-Martin S. Descriptive epidemiology of vestibular schwannomas. Neuro-oncol 2006;8:1-11.</ref> as well as being uncommon in individuals of African ancestry<ref>Chandler CL, Ramsden RT. Acoustic schwannoma. Br J Hosp Med 1993;49:336-343..</ref> According to some studies the incidence of acoustic neuromas has been
| | ===Incidence=== |
| increasing. This may be due to several factors. Steady improvements in
| | Approximately 2,500 new cases are diagnosed each year. Researchers believe that the incidence of acoustic neuroma has risen in the last several years, due to the greater frequency in which small tumors are recognized. |
| diagnosis, such as the introduction of auditory brainstem response, CT, and MRI could
| | ===Gender=== |
| explain part of the increased incidence. Increased awareness among physicians
| | Acoustic neuromas affect women more often than men. Although quite rare, they can develop in children. |
| and patients of the symptoms of acoustic neuromas may have caused an increase in the
| | ===Age=== |
| reporting of the tumor. Changes in classification or coding may also explain some
| | Most cases of acoustic neuroma develop in individuals between the ages of 30 and 60. |
| of the trend, whereby registries may have misclassified nonvestibular schwannomas as
| |
| acoustic neuromas. Or, there may be a true increase in the incidence of these
| |
| tumors. The trend may also lend support to the emerging hypotheses regarding an
| |
| environmental cause of these tumors. Established and hypothesized risk factors have been
| |
| reported extensively in the literature and include ionizing radiation exposure, cellular
| |
| telephone use, specific occupations, a possible hormonal cause, and loud noise exposure.
| |
| | |
| <div><div><div><div>'''Average annual incidence rates, overall and by gender and race, CBTRUS (1995–1999) and LACCSP (1995–1998)'''</div></div></div></div><div>
| |
| {| cellspacing="3" cellpadding="2"
| |
| |-
| |
| | align="center" |
| |
| | align="center" |
| |
| | align="center" |
| |
| | align="center" | '''Gender'''
| |
| | |
| ----
| |
| | align="center" | '''Race'''
| |
| | |
| ----
| |
| |-
| |
| | '''Type of Tumor'''
| |
| | align="center" | '''Total Number of Tumors (N)'''
| |
| | align="center" | '''Overall Rate (CI)'''
| |
| | align="center" | '''Male'''
| |
| | align="center" | '''Female'''
| |
| | align="center" | '''White'''
| |
| | align="center" | '''Nonwhite'''
| |
| |-
| |
| | colspan="7" rowspan="1" | ''CBTRUS, 1995–1999''
| |
| |-
| |
| | rowspan="1" colspan="1" | Nerve sheath
| |
| | align="center" rowspan="1" colspan="1" | 2,811
| |
| | align="center" rowspan="1" colspan="1" | 1.08 (1.04–1.12)
| |
| | align="center" rowspan="1" colspan="1" | 1.10 (1.04–1.16)
| |
| | align="center" rowspan="1" colspan="1" | 1.07 (1.02–1.13)
| |
| | align="center" rowspan="1" colspan="1" | 1.13 (1.08–1.17)
| |
| | align="center" rowspan="1" colspan="1" | 0.56 (0.48–0.63)
| |
| |-
| |
| | rowspan="1" colspan="1" | Vestibular schwannoma
| |
| | align="center" rowspan="1" colspan="1" | 1,424
| |
| | align="center" rowspan="1" colspan="1" | 0.55 (0.52–0.58)
| |
| | align="center" rowspan="1" colspan="1" | 0.56 (0.52–0.60)
| |
| | align="center" rowspan="1" colspan="1" | 0.55 (0.51–0.58)
| |
| | align="center" rowspan="1" colspan="1" | 0.58 (0.55–0.61)
| |
| | align="center" rowspan="1" colspan="1" | 0.23 (0.18–0.28)
| |
| |-
| |
| | colspan="7" rowspan="1" | ''LACCSP, 1995–1998''
| |
| |-
| |
| | rowspan="1" colspan="1" | Nerve sheath
| |
| | align="center" rowspan="1" colspan="1" | 352
| |
| | align="center" rowspan="1" colspan="1" | 1.11 (0.99–1.22)
| |
| | align="center" rowspan="1" colspan="1" | 1.15 (0.97–1.32)
| |
| | align="center" rowspan="1" colspan="1" | 1.07 (0.91–1.23)
| |
| | align="center" rowspan="1" colspan="1" | 1.21 (1.08–1.36)
| |
| | align="center" rowspan="1" colspan="1" | 0.68 (0.50–0.87)
| |
| |-
| |
| | rowspan="1" colspan="1" | Vestibular schwannoma
| |
| | align="center" rowspan="1" colspan="1" | 256
| |
| | align="center" rowspan="1" colspan="1" | 0.82 (0.71–0.92)
| |
| | align="center" rowspan="1" colspan="1" | 0.83 (0.68–0.99)
| |
| | align="center" rowspan="1" colspan="1" | (0.66–0.94)0.80
| |
| | align="center" rowspan="1" colspan="1" | 0.89 (0.77–1.01)
| |
| | align="center" rowspan="1" colspan="1" | 0.51 (0.36–0.67)
| |
| |}
| |
| </div><div><div>Rates are per 100,000 person-years and are age adjusted to the year 2000 U.S. standard population.</div><div>Abbreviations: CBTRUS, Central Brain Tumor Registry of the United States; CI, confidence interval; LACCSP, Los Angeles County Cancer Surveillance Program.</div></div>
| |
| | |
| ==References==
| |
| {{reflist|2}}
| |
| | |
| {{WikiDoc Help Menu}}
| |
| {{WikiDoc Sources}}
| |