Spinal or epidural anaesthesia is used in some patients for some surgeries on the lower half of the body (below the waist). These anaesthetics are performed using an injection in the back and cause temporary loss of feeling or numbness in the lower body, often along with temporary leg weakness. These techniques are sometimes called “half-body anaesthesia”.
The majority of patients having half-body anaesthesia are given a spinal anaesthetic, which is most often given as a single injection. Occasionally the anaesthetist may use a technique where a very small plastic catheter is inserted in the back - this allows anaesthesia to be topped-up for long procedures.
Injections in the back can also be used along with a general anaesthetic to give pain relief afterwards. These injections are carried out when you are awake before your general anaesthetic. The anaesthetist may advise a single spinal injection for this or may perform an epidural, inserting a plastic catheter for pain relief afterwards.
Can I have half-body anaesthesia?
Operations suitable for spinal anaesthesia may include:
- Orthopaedic surgery on the leg
- Vascular (blood vessel) surgery on the leg
- Some gynaecology or male genital surgery
- Some operations on the bladder and prostate
- Some operations on the anus, rectum or saddle area
- Some open groin hernia operations
Some patients cannot have spinal anaesthesia due to some medical conditions, certain medications or severe back problems. However some other patients have health problems or are having operations where a spinal has clear advantages. Your anaesthetist and sometimes your surgeon will tell you if a spinal anaesthetic is a good idea in your case.
You are likely to have an opportunity to discuss this at your clinic appointments before your surgery. The anaesthetist looking after you will also talk with you before your operation.
What will happen if I have a spinal anaesthetic?
Patients having a spinal anaesthetic get the same level of care as any other patient having an anaesthetic. When you come to the operating theatre suite you will have safety and consent checks, monitoring will be attached and the anaesthetist will site an intravenous line.
The theatre team will help you get into the correct position for the spinal injection - sometimes this is sitting, sometimes lying on your side. In either position you will be asked to curl up as best you can. The team will help you and explain to you what to do.
The anaesthetist performing the injection will wash your back with a sterilising solution, cover your back with a drape and then inject some local anaesthetic under the skin. The spinal injection itself should not be painful. You will be asked to tell the anaesthetist if you have any pain or discomfort during the injection. You will be asked to remain very still during the injection. The needle is removed immediately after the injection.
After the injection you will be helped to get in position for surgery. Often patients are aware of some leg weakness soon after the spinal - this is normal. Many patients also experience a warm sensation in their legs.
After a few minutes the anaesthetist may ask you to move your legs or check sensation with touch or temperature. Surgery will only begin when the anaesthetist is happy that the spinal is working normally.
You will be screened from the operation site. It is common for patients to have some sense of being positioned and some patients tell us that they know ‘something is going on’ at times during the operation. This is normal, not something to worry about!
After the surgery is completed you will have a period of bed test until the spinal wears off, after around 4 hours. Some patients experience transient tingling or ‘pins and needles’ as the spinal wears off.
When you are told it is time to get out of bed, it is important that a member of staff is with you - legs can be weaker than you think or your blood pressure can fall when you first stand up making you feel faint. It is very important to take your time and to make sure a trained member of staff is there with you.
What if I have an epidural?
Most of our epidurals are put in for pain relief after surgery. The technique is much the same as a spinal injection, above, with the addition of some extra time to insert the epidural catheter and put dressings on to fix the catheter in place. The anaesthetist may sometimes choose to do a test injection before giving your general anaesthetic.
Afterwards, on the ward, you may be able to sit in a chair or even to stand or walk with the epidural in place. This is because the dosages are much less than with a spinal anaesthetic. The medical and nursing staff will give you instructions about this and will assist you at all times. As with spinal anaesthesia it is very important not to get out of bed alone.
How long does it take to perform a spinal or epidural? How long does it last?
Most spinal anaesthetics are performed in only a few minutes, however where there is difficulty in positioning you correctly, if you are obese or if you have some back problems already (this is common in older patients) then it can take a little longer. The team will be talking to you throughout telling you what is happening.
A few extra minutes are also needed for a spinal or epidural catheter technique.
Spinal anaesthesia can last from 1-3 hours depending on the drug and dose used, and can take another 2-4 hours to wear off.
An epidural or postoperative pain relief can be used for up to 3-4 days if this is clinically appropriate.
What if I don’t want to be awake? What if I don’t want a spinal?
Some patients who may benefit from spinal anaesthesia do not want to be awake during their surgery. Most patients can safely be given some sedation during the operation. The dose can be adjusted between feeling calm and slightly drowsy to being very sleepy, however this is not the same as a general anaesthetic - many patients drift in and out of sleep - but many patients having sedation have little or no memory of the surgery and are very satisfied with the experience.
Sometimes a patient is offered or advised to have a spinal or epidural but does not want to go ahead with this. We would not proceed without your consent - you can always say no. If your doctors judge that a spinal or epidural is very much in your best interests we would, of course, have a full discussion with you about risks and benefits before asking for your final decision.
If you have particular concerns about being awake or any other aspect of a spinal anaesthetic you should tell the anaesthetist - talking through fears or concerns is always a good idea and will help you make the right choices.
What are the advantages of a spinal?
Compared to having a general anaesthetic a spinal has no effect on the lungs or the breathing and has less risk of chest problems afterwards.
Pain relief during and immediately afterwards is very good or complete, avoiding the need for strong painkillers which themselves have side effects.
There is less sickness and vomiting afterwards and patients eat and drink earlier.
Could I still need a general anaesthetic?
If the anaesthetist cannot get the spinal in, or if it is ineffective, you will need a general anaesthetic. This is unusual.
Very occasionally surgery takes much longer than anticipated and the spinal begins to wear off. The anaesthetist will give you a general anaesthetic or deep sedation if that happens.
Are there risks or side-effects?
Blood pressure often falls transiently in patients with a spinal or epidural. This is why patients are monitored carefully. The anaesthetist or ward staff will treat this and most patients experience no symptoms.
If a painkiller is used as part of the spinal or epidural technique, itching is common. If this is severe, treatment can be given.
Some patients experience difficulty passing urine, or incontinence, after a spinal. If necessary you will have a urinary catheter until the anaesthetic wears off when your bladder function will return to normal.
During insertion of a spinal or epidural, some patients have pain down the leg, in the bottom or to one side of the body. If you experience any pain during insertion you must immediately tell the anaesthetist. Some discomfort or a pushing sensation at the injection site is normal.
Around 1 in 200 patients (much less in older age groups) experience a headache a few days after a spinal or epidural. This headache can be worse when you sit or stand up and is relieved by lying flat. Hearing may be muffled. Other types of headaches are quite common after surgery but if you get a postural heachache you should speak to us.
Around 1 in 1000 patients may get bruising of a nerve causing temporary numbness, tingling or even weakness in one area of the leg or bottom. This can take up to six weeks to resolve completely.
Permanent nerve damage is rare (approximately 1 in 50,000 spinals and epidurals). This is roughly the same chance as having the most severe complications of a general anaesthetic.
Contributed by Department of Anaesthesia.
