Neurosurgeon

Craniotomy

A craniotomy simply means an opening into the skull. The standard way to perform a craniotomy is to make a burrhole with a drill and then cut a bone flap through the bone with a different drill, much like using a can opener.

Usually more than one burrhole is used. The patient's head is held in a 3-pin head holder so that there can be absolutely no movement of the head during the delicate parts of the surgery. My emphasis is not only on making the smallest craniotomy necessary - referred to as minimally invasive or keyhole surgery - but also on the cosmetic result. Minimally invasive or keyhole craniotomy doesn't necessarily mean that the surgery is performed through a small hole. Some operations require a large craniotomy... e.g. if there is a large tumour on the surface of the brain immediately beneath the skull. Such a tumour can only be properly removed with a large bone flap.

Minimally invasive surgery means the smallest craniotomy is used that will allow sufficient exposure without compromising the surgery.

There is no point making a tiny craniotomy but not being able to remove the entire tumour because of inadequate exposure. Cosmetic appearance is often underestimated by neurosurgeons. It is understandable that the main concern of the neurosurgeon is to adequately treat the intracranial problem, which is usually a serious condition. Therefore neurosurgeons often argue that the hair will grow back or that visible or palpable burrholes are a small price to pay for a serious disease. However, craniotomies can often be done with minimal change to the patient's appearance. The extent of hair shaving must be tailored for the individual patient and incisions can generally be made behind the hairline. This is a very important part of the pre-operative discussion.

The extent of hair shaving is a particularly important issue to some patients whose recovery is improved if their appearance is kept as normal as possible. I prefer to do a generous hair shave because it makes some aspects of the surgery easier for me, but the shave can be made quite minimal if necessary.

Some people don't care about the extent of head shave, some prefer a complete head shave and others wish to have the least noticeable amount of head shave. Some operations at the front of the skull can be made through an eyebrow incision, which heals amazingly well and with no evidence of scar. My emphasis is also to not leave unsightly bone defects in the skull, particularly on the forehead and temples. But even behind the hairline they can be annoying... e.g. every time the hair is combed. The neurosurgeon also has to be aware that scars or bone defects may become visible in the future if baldness develops.

A bone flap is elevated

If bone defects are made, they can be easily filled in with bone cement or other materials. This type of skull repair is called cranioplasty and is an often overlooked aspect of neurosurgery.

Some operations involve interoperative navigation using computer software and a television screen

Localisation of the pathology More complicated craniotomies may involve navigation assistance to accurately localise a tumour, which also helps minimise the size of incision and craniotomy. Often this involves a preoperative brain MRI (sometimes CT) scan with intraoperative navigation using computer software and a television monitor. This is called stereotactic navigation and provides a complex map of the brain, much like a street directory but in three dimensions.

Awake craniotomy

More complicated techniques involve awake surgery where the patient is not given a general anaesthetic. The scalp can be made totally numb by using local anaesthetic and this is well tolerated.

Usually the patient is given intravenous sedation at the start and end of the operation because they only need to be awake when the brain is exposed. The patient does not need to be fully awake when the craniotomy is being made. Cutting the bone is painless, as is cutting and manipulating the brain.

This is particularly helpful when tumours are in or near "eloquent" areas of brain... i.e. more important areas of the brain where removal would result in an obvious loss of function.

For example, speech function is usually in the left half of the brain. To minimise brain damage and maximise the amount of tumour that can be safely taken, it's helpful to have the patient talk, read and follow commands while a tumour is being removed in that part of the brain. This is one type of brain mapping but another technique is to use an electrical stimulator on the brain which, when applied to the brain, can stop speech and comprehension in the speech areas, cause tingling of the body in the sensory (feeling) areas and produce movement in the motor areas. Electrical stimulation of motor areas can be done with the patient awake or asleep but speech and sensory testing require an awake patient.

Brain exposed in an awake patient

For example, acoustic neuromas are best removed with an electrical stimulator which identifies the facial nerve (the nerve which moves the facial muscles) because this nerve is intimately related to these tumours and can be damaged with their removal. Intraoperative stimulation of the tumour can identify a very thinned out facial nerve by identifying facial muscles twitching in response to stimulation.

Post-operative

Craniotomies are not particularly painful. Expect to wake with a thick bandage on your head, much like a turban. This may stay on for up to three days and helps keep pressure on the wound so there is less swelling. After surgery on the forehead or temple it is common to get bruising and swelling around one or both eyes which settles within two weeks.

The night after surgery is usually spent in the Intensive Care Unit where you can be watched closely. The nurse has to wake you every hour to make observations. You usually have at least one intravenous line and often have an arterial line in your wrist to monitor blood pressure. A catheter in the bladder is generally kept in for the first night.

The next day after surgery involves obtaining a check CT scan to see if there is any blood or complications at the operative site. If the CT scan looks fine you'll be sent to the ward and start Clexane injections into your abdomen to help reduce the risk of blood clot (DVT) in the legs. You will be encouraged to get up and walk on the day after surgery. Patients usually go home after a few days.

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Postoperative problems with chewing and talking

For many craniotomies the temporalis muscle needs to be incised. This muscle is important for closing the jaw. The muscle is repaired at the end of the operation and once healed will function normally. However, it is important that you complete the exercises below to ensure that your jaw does not become stiff after the operation. You may find that opening your mouth, chewing food and doing the exercises are uncomfortable. However, this will ease the more you exercise your jaw. It is recommended doing the exercises at least 10 times a day. They should only take a few minutes so doing them just prior to meals and at coffee break times will remind you. As healing time for a muscle is approximately six weeks, it is recommended you continue these exercises for at least this time. If pain or stiffness persists after six weeks, continue the exercises until there is no pain and you can move your jaw freely.

Exercises

Ensure that you complete each exercise slowly and carefully.

1. Open your mouth as widely as possible and hold open for five seconds. Do this 10 times.

2. Open your mouth a small amount and move your jaw from side to side. Do this 10 times.

3. Open your mouth widely and move your jaw from side to side. Do this 10 times.

4. Make exaggerated chewing movements, as if chewing toffee, for 30 seconds. It is recommended chewing up to five sticks of chewing gum at the one time; this will really exercise the jaw muscle.

If you have any further questions please talk to the speech pathologist or physiotherapist on the ward.

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Risks of cranial surgery

Infection
This may simply be an infection of the scalp which requires some dressings, removal of a stitch and/or antibiotics. Deeper infection can affect the bone, which may need to be removed and a plastic plate inserted after about six months. Deeper still, infection may affect the CSF (cerebrospinal fluid) around the brain, which is called meningitis, and requires hospitalisation and intravenous antibiotics.

Bleeding
Postoperative bleeding is the greatest concern that we have following cranial surgery. When an operation is completed, there is no bleeding and it is then safe to close. However, delayed bleeding can occur, most often within the first 24 hours after surgery. This may occur if the blood pressure gets too high, if the patient is on blood thinning drugs (which should have been stopped preoperatively), if the patient gets agitated or for no obvious reason. Postoperative bleeding can be an emergency with the patient becoming unconscious or developing a deficit such as arm and leg weakness. This will usually require an urgent trip back to theatre to prevent a permanent deficit (or stroke).

Stroke
Injury may occur to the brain or to a major blood vessel supplying the brain, resulting in a stroke. This means that a part of the brain will not work normally. Often this improves, but may be permanent - e.g. impaired speech, weakness of an arm and leg.

Epilepsy
The condition that requires surgery (e.g. a tumour) or the surgery itself may result in seizures or fits arising from a part of the brain. This is called epilepsy. This can usually be prevented by the use of a drug, often Dilantin (also called phenytoin), used before and after surgery. If epilepsy continues after surgery, it can usually be treated with drugs. For many (but not all) operations on the brain, a patient may be advised to not drive for three months because of the small risk of postoperative epilepsy. If epilepsy does occur before or after surgery, the patient will not be allowed to drive until the epilepsy has been completely controlled - that is, no seizures for usually at least a year or possibly two

Cerebrospinal Fluid (CSF) leak
The brain and spinal cord are surrounded by CSF, which looks like water and is salty. When the head is closed at surgery, the outermost layer of the meninges (= the three outer coats of the brain and spinal cord), called the dura, is closed. CSF can leak through the dura and then through the skin and this will need to be fixed, otherwise there is a risk of meningitis. Just like a leak in the roof, there only needs to be a small hole to let water through and this can sometimes be troublesome to repair, but is virtually always correctable. Repair may require a simple skin stitch, a spinal drain tube inserted in the low back to drain the CSF via another route, or a trip back to theatre. Occasionally a CSF leak can be less obvious by leaking through the nose or ear - e.g. if there has been a skull opening into the paranasal sinuses or into the ear canals.

Deep Vein Thrombosis (DVT)
DVT means a blood clot developing in the leg. The patient may notice a painful swelling of the calf but a DVT may not be noticed. This clot may dislodge and travel to the lungs and heart to block the circulation, which is known as a pulmonary embolus (PE). A PE can be fatal and usually occurs about 1-2 weeks after surgery, or 1-2 weeks after a patient has commenced being confined to bed. Increased risks for DVT and PE are bed rest, prolonged surgery, obesity, cancer, past DVT, paralysed leg/s and heart failure. To prevent DVT, the patient is encouraged to get out of bed as soon as possible, usually the day after surgery. Before this, the patient can wiggle the toes and move the legs around in bed as soon as wakening from the anaesthetic. Prior to surgery, the patient will have elastic stockings put on. While in surgery the patient has leg pumps to improve the circulation. After surgery, blood thinning injections are commenced - I like to use Clexane injections into the stomach each morning until discharge from hospital.

Death
Death on the operating table is very rare. Death can occur with any surgery and usually occurs after the operation. The most common reasons are myocardial infarct (heart attack) due to the stress of the surgery, a rare reaction to a drug (anaphylaxis) or pulmonary embolus. I mention the risk of death or paralysis (stroke) to any patient having an operation, no matter how minor the procedure.

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