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Spinal Anaesthesia

What is a spinal anaesthetic?

For some operations, local anaesthetic medicine is injected through a needle into the middle of your lower back. This can numb the nerves supplying the lower part/half of your body for one to four hours and sometimes longer. During this time it will be difficult or impossible to move your legs as normal. Other medicine may be injected at the same time that prolongs pain relief for many hours. The medicine works by blocking the pain signals from reaching your brain. During your spinal anaesthetic you may be fully awake, sedated or also be given a general anaesthetic. Your anaesthetist will discuss this with you before the operation.

What are some advantages of a spinal anaesthetic?

  • Less risk of a chest infection after surgery
  • Less effect on the lungs and breathing
  • Excellent pain relief immediately after surgery
  • Less need for strong pain-relieving medicines, and their side effects, including nausea, confusion, drowsiness, and constipation
  • Less sickness and vomiting
  • Quicker return to drinking and eating after surgery
  • Less risk of becoming confused after the operation, especially if you are an older person
  • Improved bowel recovery after bowel surgery
  • Improved blood flow after vascular surgery
  • If you are having a caesarean section birth, you will be able to see your baby
    as soon as they are born, the baby will only get incredibly small amounts of any medications given and your partner can be with you.

What happens during the procedure?

Before the procedure commences, a ‘drip’ (also known as a cannula, intravenous fluids or IV) is always put into one of your veins, usually in your hand or lower arm. You will normally have the spinal injection into your back either sitting, or lying on your side, on the trolley or operating table. The anaesthetist and the team will explain what they want you to do. Just like an operation, the injections are done in a very clean (sterile) way. Local anaesthetic is given into the skin to reduce the pain of the spinal needle.

When the anaesthetist is inserting the spinal needle, they will ask you to stay as still as possible and to tell them if you feel any discomfort, tingling or shock sensations. It can take more than one attempt to get the needle in the right place. If you find this difficult, tell your anaesthetist as there are things they can do to help, including switching to a different kind of anaesthetic.

With a spinal anaesthetic a single injection of anaesthetic medicines, is given into the spinal space by a very thin needle where the medication mixes with the spinal fluid. It also blocks the movement signals which mean that you will be unable to move your legs while it is working. This type of anaesthesia is quick to work (usually within 5–10 minutes).

You may notice a warm tingling sensation as the spinal anaesthetic starts to take effect. The anaesthetist will not let the operation begin until they are satisfied that the area is numb. While you will be pain free during an operation, you may feel movement and pressure sensations around the area of the operation.

Your anaesthetist will position you in this way for your spinal

What are the risks of spinal anaesthesia?

Common risks and complications:

  • Failure of the spinal
  • Nausea, vomiting, itching and  shivering
  • Low blood pressure: this can make you feel faint, dizzy or sick
  • Problems in passing urine: you may require a catheter to be placed in your bladder
  • Pain during the injection: immediately tell your anaesthetist if you feel pain in places other than where the needle is. The pain might be in your legs or bottom and might be due to the needle touching a nerve
  • Headache and/or backache
  • Pain, bruising and/or bleeding at the injection site
  • Prolonged numbness or tingling.

Uncommon risks and complications:

  • Severe headache: Please inform your doctor immediately if you have a severe and persistent headache after spinal anaesthesia
  • Temporary nerve damage:
    temporary loss of sensation, pins and needles and sometimes muscle weakness in the lower body
  • Allergic reaction to the medication, requiring further treatment
  • Existing medical problems getting worse

Rare risks and complications:

  • Permanent nerve damage with possible paralysis
  • Severe breathing difficulty: the block may go higher than planned and affect breathing by paralysing the breathing muscles
  • Infection around injection site which may cause meningitis and/ or epidural abscess, requiring antibiotics and further treatment
  • Blood clot with spinal cord damage
  • Serious allergic reaction or shock to the medication, requiring further treatment
  • Equipment failure (e.g. breakage of needles or catheters possibly requiring surgery to remove them)
  • Local anaesthetic toxicity, requiring further medication and treatment
  • Seizures may occur, requiring further medication and treatment
  • Heart attack or stroke could occur due to the strain on the heart
  • Death and cardiac arrest as a result of this anaesthesia are rare.

It is important to note that an anaesthesiologist is specifically trained to manage the above-mentioned complications.

NB: PLEASE INFORM YOUR ANAESTHETIST IF YOU ARE ON BLOOD THINNING MEDICATION, HAVE A BLEEDING DISORDER OR HAVE ANY FORM OF NEUROLOGICAL DISEASE.

The above infographic describes what is meant by common, uncommon and rare risks

What can you expect after the spinal anaesthetic?

The numbness/weakness may take several hours to wear off. It is very important that during this time you do not attempt to walk unless approved by your doctor/ clinician. You will be unsteady on your feet. Ask for help from the nurse to help you walk. Do not attempt to walk by yourself. As sensation returns, you may experience some tingling in the skin. At this point, you may become aware of some pain from the operation site. Ask for more pain relief before the pain becomes too obvious. Within the first 2 weeks after a spinal, if you have any numbness, weakness, headache or severe back pain contact the anaesthetist/your GP/emergency department.

This information page has been adapted from the information pamphlets used by the Royal College of Anaesthesiologists in the United Kingdom ( https://www.rcoa.ac.uk/patients ) and the Government of Queensland, Australia.