EDITORIAL (BY INVITATION)
Awake craniotomy for vestibular schwannoma
Received: 25 May 2017 /Accepted: 31 May 2017 /Published online: 14 June 2017
Springer-Verlag GmbH Austria 2017
BThis will never work^.
Cardiologist Spencer King (later to become president of
the American College of Cardiology) commenting in
1977 on Andreas Gruentzig’sposterBExperimental per-
cutaneous dilatation of coronary artery stenoses^.
During my years as a resident, laminectomy for cervical
spondylosis with myelopathy was done in local anaesthesia in
several departments in Norway. A few leading surgeons had
once witnessed a single case where a patient woke up from
general anaesthesia being tetraplegic. They concluded that it
would be less risky if the procedure was done on awake pa-
tients, who, admittedly, sometimes reported Lhermitte phe-
nomena if an instrument was introduced into a narrowed spi-
nal canal. The practice was forwarded to us residents, but it
has since been abandoned. The concept of reducing the risk of
neurological damage by keeping patients awake during neu-
rosurgery, however, has not.
Awake craniotomy has become common practice in sur-
gery for low grade gliomas involving eloquent areas.
Integrating cortical mapping, functional magnetic resonance
imaging and neuronavigation enable us to do resections adja-
cent to critical areas [3, 7]. Provided careful preoperative and
perioperative counselling is given, the procedure is feasible in
many patients . Recently, even aneurysm surgery has been
done in local anaesthesia . The authors reported that the
procedure was tolerated, and that neurophysiological and
clinical monitoring led to clip repositioning in several patients
who might otherwise have developed deficits.
In the present issue of Acta Neurochirurgica, Shinoura and
colleagues  report, as a first, awake craniotomy for a series
of eight patients operated on for vestibular schwannoma. They
managed to save some hearing in all, and even improved it in
one patient. There were no new facial deficits. The authors
demonstrate that because they could communicate with the
patient, deficits in facial function and hearing could be detect-
ed early during surgery and thereby prevented because the
patient could communicate. If a deficit occurred, the surgeons
paused resection and either continued if the deficit resolved or
terminated it if it persisted. Hence they managed to preserve
function. Although this is commendable, there are concerns.
First, surgery for large vestibular schwannoma is time-con-
suming. The mean operating time was 6 h. Even if the patients
were asleep during opening and closure, they were kept awake
in head fixation and park-bench position for several hours.
This burden has to be considerable, whatever precautions are
made. Second, the surgeons chose a very conservative resec-
tion policy, performing subtotal resection in most cases. This
may call for close follow-up and many of these patients may
be expected to experience a regrowth of their tumour, requir-
ing additional treatment . One may assume that the smaller
the remnant, the less risk of recurrence. The strategy of doing
near-total resection, leaving a very thin tumour remnant on the
facial nerve is gaining increasing support, as this may lead to
better facial nerve outcomes; the remnant grows slowly or not
at all, and radiosurgery may stop further growth [2, 8, 10].
Near-total resection may, however, increase the risk of dam-
age to the cochlear nerve.
The authors argue that radiosurgery may produce long-
term hearing loss, and that their own strategy of performing
subtotal resection on awake patients may lead to better out-
comes. This is debatable. Subtotal resection may lead to
* Morten Lund-Johansen
Haukeland University Hospital, Bergen, Norway
Acta Neurochir (2017) 159:1587–1588