Every so often I take a look at new research and I've come across this - interesting hypothesis - got me wondering how many of us have suffered with a cold sore at sometime during their lifetime - is there the link they think there may be? I don't think I agree with the 'increase in symptoms only if the enlarge' idea... Personally I had cold sores now and again in my youth - haven't had one for years...
Herpes and acoustic neuromas: Is there a cause and effect to observe?Craig G. Burkhart *
University of Toledo College of Medicine, Toledo, OH, USA
Ohio University College of Osteopathic Medicine at Athens, 5600 Monroe Street, Suite 106B, Sylvania, OH 43560, USA
a r t i c l e i n f o
Article history:
Received 8 January 2010
Accepted 17 January 2010
Available online xxxx
s u m m a r y
Acoustic neuromas are a result of damage to the affected nerve function and can potentially press surrounding
tissues. Although some sources suggest that observation is the treatment of choice for only
those over 65 years of age and those unable to tolerate undergoing surgery or radiosurgery, most affected
individuals should strongly consider not doing any aggressive therapies. Herpes has already been shown
to mimic acoustic neuroma clinically, but growing evidence suggests that it is likely the cause of most
cases of this entity.
2010 Elsevier Ltd. All rights reserved.
Acoustic neuroma, or vestibular schwannoma, is a benign tumors
located on the eighth cranial nerve. The nerve is insulated
by layers of specialized cells called Schwann cells, and it is the multiplication
and thickening of these cells which forms the tumor.
This nerve traverses from the inner ear to the brain and the growth
can be situated anywhere on this path. Acoustic neuromas do not
metastasize, but damages the affected nerve function and can
potentially press surrounding structures.
The present options for treatment of acoustic neuromas
include:
1. Surgery (partial or total tumor removal) with three basic
approaches (translabyrinthine, retrosigmoid/sub-occipital,
middle fossa).
2. Radiation therapy (including stereotactic, gamma knife, cyberknife,
linear accelerator, fractionated radiation therapy).
3. Observation.
In America, observation is the treatment of choice for only two
categories of patients: those over 65 years of age, and those medically
unable to tolerate undergoing surgery or radiosurgery [1]. Indeed,
the 1991 Consensus Conference of the National Institutes of
Health recommended surgical excision as the treatment of choice
for symptomatic acoustic neuromas. Aggressive treatment has
been promoted by authors who have drawn an overpessimistic
prognosis by suggesting that they ‘‘eventually cause clinically significant
problems, then death if not treated [2].†In truth, most tumors
cause few symptoms besides depressed unilateral hearing
loss; of note, both surgery and radiotherapy cause total loss of
hearing of the affected nerve as well as potentially significant other
risks.
Observation is the standard in many countries including Japan
and Canada [3,4]. Moreover, observation is suggested as appropriate
therapy by the Acoustic Neuroma Association, the American
Hearing Research Foundation, and meta-analysis with suggested
treatment algorithm [5].
Although some countries are more surgically oriented, observation
should be a strong consideration in all patients regardless of
age or ability to withstand surgery. The reasoning for observation
begins by realizing that acoustic neuromas are benign tumors
and only produce symptoms, besides decreased hearing, if they enlarge.
On point, most acoustic neuromas grow very slowly. In one
study, 85% of patients had no change in tumor size after over 4
years of follow up [6]. Bederson et al. [7] actually reported 6% of
acoustic neuromas decrease in size with time.
Acoustic neuromas are much more common than reported, as
0.8–2.7% of cadavers reveal asymptomatic intracanalicular acoustic
neuromas [8,9] Thus, most afflicted individuals do not have surgery
or radiation therapy, as these individuals just assume that
they have ‘a bad ear,’ and live with it.
As stated above, acoustic neuromas represent an injury-like response
of Schwann cells. Of interest, herpes may be a major cause
of this defect. To begin with, herpes can actively multiply within
Schwann cells [10]. Herpes has already been shown to mimic
acoustic neuroma on MRI [11] The virus commonly reactivates
upon injury to the acoustic nerve, such as with nerve resection
[12,13]. Just as the herpes virus has been implicated with Ramsay
Hunt syndrome and Bell’s palsy, it has been suggested to be the
cause of delayed facial palsy with surgery to acoustic neuromas
[13]. Herpes virus has been found within the parenchyma of virtually
all organs of the body as well as within the dorsal root ganglia
throughout the spinal column of all humans [14]. In a symbiotic
relationship, the body retains the virus because it offers its human
host oncolytic, immune-stimulating, and anti-tumor properties
[14]. Although the herpes virus can act as a pathogen causing serious
disease, such as acoustic neuroma, the virus also offers benefits.
Thus, the body stores the virus in several locations within
the host, whereby they can exist in a latent site or reproduce and
substances on demand by initiating factors [14].
Unless a neuroma grows producing other symptoms due to
compression, the risks of surgery seem way out of proportion to
any perceived benefits. As stated by Flint [15], ‘‘delaying surgery
until required by symptoms or tumor growth does not result in
more morbidity.†Additionally, better treatments may be on the
horizon, including chalcone derivatives and anti-herpetic
prophylaxis.
0306-9877/$ - see front matter 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.mehy.2010.01.010
* Address: Ohio University College of Osteopathic Medicine at Athens, 5600
Monroe Street, Suite 106B, Sylvania, OH 43560, USA. Tel.: +1 419 885 3403; fax: +1
419 885 3401.
E-mail address: cgbakb@aol.com.
Medical Hypotheses xxx (2010) xxx–xxx
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www.elsevier.com/locate/mehyARTICLE IN PRESS
Please cite this article in press as: Burkhart CG. Herpes and acoustic neuromas: Is there a cause and effect to observe?. Med Hypotheses (2010),
doi:10.1016/j.mehy.2010.01.010
