The treatment of epidermoids is exclusively surgical where treatment is required. This decision will in all cases be made in consultation with your neurosurgeon who will discuss the rationale for treatment and the potential benefits and risks. Once the decision has been made that treatment is required, the precise nature of the surgery and specifically its location will depend on the location of the epidermoid. In principle, the surgical philosophy is to make a craniotomy (opening of the head) in the best place to allow straightforward and safe access to the epidermoid. The epidermoid is then removed and the relatively soft nature of these tumours means that this is usually achieved in a relatively straightforward manner. However, the nature of an epidermoid is that the contents are contained within a very fine capsule. It is the surgical removal of the contents that is relatively straightforward but it is almost invariably not possible to remove the capsule as it is densely adherent to the brain and attempts to do so would cause harm. Therefore, the surgery is aimed to remove the mass effect (related to the tumour volume) and make no attempt to remove this very fine capsule. The nature of this surgery mean, therefore, that there is a risk of recurrence and routine post-operative management over the years after the surgery is to carry out infrequent but regular imaging to monitor for any re-growth of the epidermoid.
With regard to the risks of the surgery, these relate firstly to the relationship between the tumour and adjacent structures. Any of these neurological structures that are adjacent to the tumour are at risk from the surgery and, therefore, the risk of neurological harm from the surgery relates to the position of the tumour. Thus, a typical site for an epidermoid is in the posterior fossa of the head, near the facial, hearing and sensory (trigeminal) nerves. In such a situation, the risk of the surgery would include the risk of post-operative deafness, numbness and facial weakness. The surgery, therefore, requires considerable skill and expertise in this field and you can be reassured that both Mr Rutherford and Professor King have considerable expertise and experience in this field.
The second risk from the surgery relates to the somewhat irritant nature of the contents of an epidermoid. This irritant quality means that there is a risk of post-operative inflammation of the meninges producing a chemical meningitis. Most people are familiar with meningitis as an infective process where as in this case the inflammation of the meninges is not due to infection but rather due to the chemically irritant nature of the tumour. There are various techniques employed by your surgeon peri-operatively to minimise this risk but the consequences of a chemical meningitis can include disturbance of the normal flow of the fluid in which the brain floats – the cerebrospinal fluid (CSF). If the flow of this fluid is interrupted by the chemical meningitis, it is possible to get post-operative headaches and a build-up of the fluid (hydrocephalus). In the worst cases this can require some form of permanent drainage procedure such as a ventriculoperitoneal shunt.
The surgeons of the Brain and Spine Clinic have developed a range of techniques to minimise the risk of complications peri-operatively,. They have recently re-audited their results to confirm that the risks are indeed very low. This work was presented in a paper entitled "Posterior fossa epidermoid cysts - keeping uncomplicated surgery uncomplicated" at the British Skull Base Society Meeting in Dublin in January 2015.