ABSTRACT
Early diagnosis of vestibular schwannoma (VS) has increased in recent years because
of increased longevity and availability of magnetic resonance imaging (MRI). Initial
conservative radiological surveillance is often requested by patients and physicians
to establish whether these tumors are growing before embarking on intervention. Initial
observation of at least 1 year in all small VS was therefore recommended by some authors.
We evaluated our prospective skull base database of VSs that were managed with initial
radiological surveillance to establish when this policy should be abandoned and what
predicts future growth. Fifty-four consecutive patients with VS in our institution
who were managed by initial yearly MRI scanning were studied. The MRI data were collected
prospectively and analyzed by Kodak CareStream viewing software where VS maximum diameters
in three perpendicular planes and volume were calculated. One patient was excluded
from the analysis as he had only one MRI follow-up. The median age of the 53 patients
was 59 years (range, 26 to 86 years), 25 were males and 28 were females, and 33 were
under 65 years of age; 18 VSs were extracanalicular, 18 were intracanalicular, and
17 extended both inside and outside the canal; 21 VSs were 1.2 cm3 or less, 22 were 1.2 to 4 cm3, and the rest were >4 cm3. Using volumetric analysis, 29.72% of conservatively managed VS grew by at least
2 mm per year, and 70.82% did not grow in 5 years. Age, gender, symptoms, and side
did not predict future growth. However, growth in the first year was a strong predictor
of future growth (p < 0.001) and initial volume was also a strong predictor of future growth (p < 0.05). Twenty-nine percent of observed VSs grew by at least 2 mm per year in the
first 5 years of surveillance. As the growth rate is slow, initial radiological surveillance
is justified in elderly patients and patients with small VSs and nonserviceable hearing.
Growth in the first year was a strong predictor of future growth. The reported treatment
effect should be interpreted in the light of 70.24% of VSs that either shrink or do
not change in the first 5 years.
KEYWORDS
MRI - microsurgery - radiosurgery - schwannoma - vestibular
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Sam EljamelM.D. F.R.C.S. (Ed.,Ir.,S.N.)
Consultant Neurosurgeon, Ninewells Hospital and Medical School
Dundee, DD1 9SY, UK
eMail: sameljamel@doctors.net.uk