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Acoustic tumours (fwd)

Larry Lundy llundy at VOYAGER.NET
Tue May 14 06:53:57 EST 1996


Ms Bailey,

You raise many relevant points for the management of acoustic neuromas. In
a young woman with a non hearing ear who now has evidence of trigeminal
nerve compression (loss of feeling on that side of her face) and 3 cm tumor
by MRI, it is very likely an acoustic neuroma. There are many excellent
centers that treat these tumors in high volumes. I can give you some
information from our group, with approximately 400 acoustic neuromas over
the last 10 years, though I cannot make a direct comparison with other
centers.

The treatment of choice in her situation is a translabyrinthine resection
of the tumor with intraoperative electromyographic monitoring of the facial
and trigeminal nerve. Stereotactic radiotherapy is reserved for the
medically infirm, elderly patients, or patients who absolutely refuse
surgery. About 15-30% of patients with stereotactic radiotherapy will
experience facial paralysis, and when followed for a few years, 10 - 20%
will demonstrate further tumor growth (recall that stereotactic
radiotherapy does not remove or "dissolve" the tumor, and practically
speaking only halts its growth, though we don't know for how long). The
National Institute of Health Consensus statement notes that surgery is the
treatment of choice. (Acoustic Neuroma. NIH Consens Dev Conf Consens
Statement 9 (4), 1991).

The advent of intraoperative facial nerve monitoring has significantly
improved the final facial nerve function, as about 75% of patients (all
sizes of tumors included) will have normal or near normal (House-Brackman
grade 1 or 2) facial nerve function post operatively (Kartush, JM, Lundy L:
Facial nerve outcome in acoustic neuroma surgery. Otolaryngol Clin North Am
25: 623-647). The translabyrinthine approach offers the significant
advantage of positive identification of the facial nerve laterally,
especially in a tumor of this size. In our own experience of about 400
cases, when intraoperative monitoring is used, over 95% will have normal or
near normal facial nerve function. Other factors also come into play, as
discussed in the paper referenced.

Unfortunately, when a tumor has reached this size and the hearing is lost
preoperatively, there is no chance at restoring hearing. This is one reason
the translabyrinthine approach is chosen, since hearing is already lost,
and this approach has lower morbidity (facial nerve function, cerebellar
function, headaches, etc). Hearing preservation, not restoration, is
attainable if the tumor is small and is diagnosed and operated on early
enough, usually by a middle fossa craniectomy approach.

Incidentally, I see no medical reason to wait 4-6 months for surgery.

There are some good general reference materials recently.
        Acoustic Neuroma I & II, April & June 1992, Otolaryngologic Clinics
of North America
        NIH Consensus Statement, noted above
        Neurotology (textbook), Jackler & Brackman, Mosby publisher, 1994
        Acoustic Neuroma Association, a support/information group, who has
a web page also
                http://neurosurgery.mgh.harvard.edu/ana/
        Otology Online, web page
                http://ww.ears.com

I know this is kind of a cursory overview, and there is much more
information, as well as unresolved issues, but I hope this is of some
benefit.

Larry Lundy, MD
Michigan Ear Institute
llundy at voyager.net





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