Acoustic neuromas are benign, slow-growing tumours that arise from the sheath of the vestibular nerve.1
Pathologically, they are vestibular schwannomas. Overall, they represent about 6% of all intracranial tumours.1
Most frequently, they present with unilateral hearing impairment.1
If left untreated, the continued growth will usually cause compression of the brainstem and fourth ventricle with resultant raised intracranial pressure.1
However, symptoms at presentation can be very varied, and may not even include hearing impairment.1
Due to their complex relations and anatomy, surgery for acoustic neuromas is a highly specialised matter. The fact that they are benign and usually slow-growing means that surgery is usually elective. These characteristics enable patients to travel to specialist centres for treatment.
Several tools exist to aid the surgeon, one of which is the facial nerve monitor. The Clinical Effectiveness Guidelines consider the use of this instrument mandatory. In our study, all neurosurgeons reported using facial nerve monitoring.
The majority of units had 1 or 2 designated super-specialist neurosurgeons and most of these worked in conjunction with a specialist neuro-otolaryngologist – a teamwork approach that is considered essential by the guidelines.
A learning curve has been described in acoustic neuroma surgery with a plateau being reached between 20 and 100 cases ().2–6
Annual reported caseload was 2–30, with most in the range of 15–25 cases per annum. It is important that those undertaking vestibular schwannoma surgery are operating on enough cases to gain the initial experience required, and to maintain their competency in this procedure subsequently. This does then raise a question as to what would be considered a minimum annual caseload. However, this is likely to be different between an established acoustic neuroma surgeon and a trainee.
Learning curve for surgical practice
Of note, surgeons operating on more than 10 tumours per annum all complied fully with the guidelines for good practise, as did their units. Eight out of 15 surgeons operating on 5–10 tumours per year would not have complied due to lack of ENT collaboration and the consequence of this also limiting their choice of surgical approach.
Examining the pattern of practice within units we found that where 3 or 4 surgeons were operating, there was a tendency for the caseload to be sufficient for only 1 or 2 surgeons and insufficient for their colleagues. This suggests a case for further sub-specialisation to reduce the number of operating surgeons and hence increase their operative caseload for these tumours. It may be reasonable to suggest that the number of operating surgeons in each unit should be determined by the caseload of that unit, so that patient demands are satisfied and surgical skills are maintained.
As a result of this survey, neurosurgeons in a number of units have reported changes in their pattern of practice.
The response rate for this survey was extremely pleasing, and suggests openness amongst neurosurgeons in the UK and Ireland to audit of their practice and the consequent benefits to patients of this. This is something that is becoming increasingly important as we seek to improve patient care.
Acoustic neuroma surgery requires a comprehensive approach by different specialist teams working together. Clinical Effectiveness Guidelines for the management of acoustic neuromas have been published by a multidisciplinary working party. This study highlights many areas of excellence in clinical practice, but also the need for change and improvement. The challenge is now for neurosurgeons in the UK and Ireland to examine their practice and make any necessary adjustments.