Acoustic neuroma on left; five years post-gamma knife radiosurgery on right. Source: pennmedicine.com

It’s possible for an acoustic neuroma that’s surgically removed to grow back.

The question then becomes, What are the odds that an acoustic neuroma will recur if it’s surgically removed?

An acoustic neuroma is a benign tumor that arises in the inner ear canal: a proliferation of the Schwann cells – hence its alternate name of vestibular Schwannoma.

There are two studies looking at the recurrence rate of a surgically removed acoustic neuroma.

The first one is published in Laryngoscope (Sept. 1995) and gives data for these tumors treated via total translabyrinthine removal.

“Review of the patient records of the House Ear Clinic revealed five recurrent tumors,” says the paper, “for an approximate incidence of 0.3%.”

A questionnaire was sent out to 857 patients with AN removal who were at least nine years post-surgery; none had recurrences.

Of the five noted recurrences, the average time span between first removal and recurrence was about 10 years. It’s not known what was different about these cases that resulted in a regrowth of the acoustic neuroma.

The next study comes from the Annals of Otology, Rhinology and Otolaryngology (March 2012).

The study authors looked at the regrowth rate involving three removal methods: translabyrinthine, retrosigmoid and middle cranial fossa.

An analysis was done of 2,400 cases from the Gruppo Otologico in Italy from 1983 to 2010.

Regrowth rate of removed acoustic neuroma
by the following methods:

• 0.05 percent for translabyrinthine
• 0.7 percent for retrosigmoid
• 1.8 percent for middle cranial fossa

The study authors believe that regrowth of the acoustic neuromas may have been triggered by microscopic deposits left on crucial areas such as the preserved cochlear nerve, facial nerve or fundus of the internal auditory canal.

Sources:
onlinelibrary.wiley.com/doi/abs/10.1288/00005537-199509000-00016
journals.sagepub.com/doi/abs/10.1177/000348941212100303