Causes of vestibular schwannoma

Causes of vestibular schwannoma

Causes of vestibular schwannoma

Vestibular schwannoma (VS), also known as acoustic neuroma, is a benign tumour that develops on the vestibulocochlear nerve, which is responsible for transmitting sound and balance information from the inner ear to the brain. The exact cause of VS is poorly understood but is believed to be linked to a genetic mutation or environmental factors.

Chromosome 22

In most cases, VS are sporadic, occurring randomly without a clear cause. However, recent research has shown that a small percentage of cases are associated with a mutation in the tumour suppressor gene on chromosome 22.

The tumour suppressor gene on chromosome 22, also known as NF2 (neurofibromatosis type 2), is crucial in regulating cell growth and division. When a mutation occurs in this gene, it can lead to uncontrolled cell growth and the formation of tumours, including VS (1).

Family history

While 95% of VS occurs sporadically without any known cause, some rare genetic conditions have been linked to an increased risk of developing these tumours. One of these conditions is neurofibromatosis type 2 (NF2), a genetic disorder that causes the growth of tumours on nerves throughout the body, including the vestibular nerve.

NF2 is an inherited condition, meaning that it runs in families. Individuals with a family history of NF2 are at higher risk of developing VS and other nerve tumours. Genetic testing and counselling may be recommended in these cases to assess the risk of developing VS and other associated conditions (2).

Cell phones

Numerous studies have investigated the potential connection between cell phones and VS, but the results have been inconclusive. The World Health Organization’s International Agency for Research on Cancer conducted a comprehensive study on this topic. It concluded that there is no clear evidence to suggest that cell phone use causes VS.

In the COSMOS prospective cohort multinational study, 264,574 participants were followed, accruing to 1,836,479 person-years (3).

The findings suggest that the cumulative amount of mobile phone use is not associated with the risk of VS.

mobile phone
Cell phones do not cause vestibular schwannoma

Prolonged noise exposure

While exposure to loud noises can cause damage to the inner ear and potentially lead to hearing loss, there is no scientific evidence to support the claim that it can cause VS.

In the most extensive case-control study in Norway using 1913 VS patients and 9566 age and sex-matched control, no association between loud noise exposure and the development of VS was found (4).

In another case-control study from Denmark, no association between traffic noise exposure and the development of VS was found(5).

There is no association between prolonged noise exposure and vestibular schwannoma

Childhood exposure to low-dose radiation of the head and neck

There has been ongoing concern regarding the potential link between childhood exposure to low-dose radiation of the head and neck and the development of  VS.

Studies have shown that the majority of VS occur sporadically, with only a tiny percentage being associated with a genetic predisposition or exposure to high-dose radiation, such as that used in specific medical treatments. Low-dose radiation, such as that received during routine medical imaging or from environmental sources, is not believed to impact VS development significantly (6).

The current scientific consensus suggests that childhood exposure to low-dose radiation is not a significant risk factor for the development of VS.

Benign tumours of the parathyroid gland

Benign tumours of the parathyroid gland in the neck, known as parathyroid adenomas, are commonly associated with an overproduction of parathyroid hormone (PTH), leading to hyperparathyroidism. Some studies have suggested a possible association between hyperparathyroidism and an increased risk of developing VS, but further research is needed to confirm this link(7). There is limited evidence linking parathyroid adenomas to the development of VS.

Smoking

Several studies have suggested that cigarette smoking may have a protective effect against the development of VS(8).However, the increased risk of developing other malignancies associated with smoking, such as lung cancer and heart disease, far outweighs any potential benefits for VS. Therefore, it is not advisable to encourage smoking as a means of protection against this specific type of tumour due to the myriad of other health risks associated with smoking. It is important to prioritize overall health and well-being when making lifestyle choices.

Aspirin

Aspirin has been suggested to have a potential protective effect against the development of VS. While there is not enough evidence to recommend aspirin as a therapy for patients with VS currently, studies have shown that aspirin may act as a negative risk factor for the development of sporadic VS. This suggests that aspirin could potentially help prevent the formation of these tumors. Further research is needed to fully understand the mechanisms behind this potential protective benefit and to determine if aspirin could be used as a preventive measure for VS(9).

Viruses

While viruses have been shown to be a cause of approximately 15% of all cancers, no direct relationship has been established between viruses and VS. Research on the possible viral involvement in VS is limited, and further studies are needed to determine any potential links between viruses and this type of tumour. (10).

References

1. Coy S, Rashid R, Stemmer-Rachamimov A, Santagata S. An update on the CNS manifestations of neurofibromatosis type 2. Acta Neuropathol. 2020 Apr;139(4):643-665. doi: 10.1007/s00401-019-02029-5. Epub 2019 Jun 4. Erratum in: Acta Neuropathol. 2019 Aug 20;: PMID: 31161239; PMCID: PMC7038792.

2. Durham AR, Tooker EL, Patel NS, Gurgel RK. Epidemiology and Risk Factors for Development of Sporadic Vestibular Schwannoma. Otolaryngol Clin North Am. 2023 Jun;56(3):413-420. doi: 10.1016/j.otc.2023.02.003. Epub 2023 Apr 3. PMID: 37019771.

3.M, Schüz J, Toledano MB, Vermeulen R, Auvinen A, Harbo Poulsen A, Deltour I, Smith RB, Heller J, Kromhout H, Huss A, Johansen C, Tettamanti G, Elliott P. Mobile phone use and brain tumour risk – COSMOS, a prospective cohort study. Environ Int. 2024 Mar;185:108552. doi: 10.1016/j.envint.2024.108552. Epub 2024 Mar 2. PMID: 38458118.

4. Aarhus L, Kjærheim K, Heikkinen S, Martinsen JI, Pukkala E, Selander J, Sjöström M, Skare Ø, Straif K, Mehlum IS. Occupational Noise Exposure and Vestibular Schwannoma: A Case-Control Study in Sweden. Am J Epidemiol. 2020 Nov 2;189(11):1342-1347. doi: 10.1093/aje/kwaa091. PMID: 32440685.

5. Roswall N, Stangerup SE, Cayé-Thomasen P, Schüz J, Johansen C, Jensen SS, Raaschou-Nielsen O, Sørensen M. Residential traffic noise exposure and vestibular schwannoma – a Danish case-control study. Acta Oncol. 2017 Oct;56(10):1310-1316. doi: 10.1080/0284186X.2017.1337925. Epub 2017 Jun 13. PMID: 28609173.

6. Schneider AB, Ron E, Lubin J, Stovall M, Shore-Freedman E, Tolentino J, Collins BJ. Acoustic neuromas following childhood radiation treatment for benign conditions of the head and neck. Neuro Oncol. 2008 Feb;10(1):73-8. doi: 10.1215/15228517-2007-047. Epub 2007 Dec 13. PMID: 18079359; PMCID: PMC2600840.

7. Phatharaporn Kiatpanabhikul, ODP561 Unilateral Vestibular Schwannoma as the Presentation and Aggravation to be Severe Primary Hyperparathyroidism, Journal of the Endocrine Society, Volume 6, Issue Supplement_1, November-December 2022, Pages A876–A877.

8. Benson VS, Green J, Pirie K, Beral V. Cigarette smoking and risk of acoustic neuromas and pituitary tumours in the Million Women Study. Br J Cancer. 2010 May 25;102(11):1654-6. doi: 10.1038/sj.bjc.6605695. Epub 2010 May 11. PMID: 20461083; PMCID: PMC2883161.

9. Ignacio KHD, Espiritu AI, Diestro JDB, Chan KI, Dmytriw AA, Omar AT 2nd. Efficacy of aspirin for sporadic vestibular schwannoma: a meta-analysis. Neurol Sci. 2021 Dec;42(12):5101-5106. doi: 10.1007/s10072-021-05193-3. Epub 2021 Mar 26. PMID: 33772351.

10. Plummer M, de Martel C, Vignat J, Ferlay J, Bray F, Franceschi S. Global burden of cancers attributable to infections in 2012: a synthetic analysis. Lancet Glob Health. 2016 Sep;4(9):e609-16. doi: 10.1016/S2214-109X(16)30143-7. Epub 2016 Jul 25. PMID: 27470177.