Spinal Anaesthesia Home A-Z Health Information A-Z Health Library Spinal Anaesthesia Overview Spinal anaesthesia is a type of local anaesthesia in which an anaesthetic is injected within the cerebrospinal fluid around the vertebrae in the lower spine; it numbs specific regions of the body by blocking nerve signals near the spinal cord. As spinal anaesthesia causes loss of sensation (i.e., eliminates pain) and muscle movement and reduction in the activity of the sympathetic nervous system (which controls blood pressure, heart rate, and blood vessel constriction), it is effective for lower body procedures, such as orthopaedic surgeries (e.g., hip and knee replacement), abdominal surgeries (e.g., caesarean section and hernia repair surgery), and urological procedures (bladder surgery). Key Benefits Spinal anaesthesia improves patient outcomes has the following key benefits:Avoidance of risks associated with general anaesthesia: Spinal anaesthesia is associated with low risk of nausea, vomiting, sore throat, and memory problems such as mental confusion.Enhanced safety: Conscious patients do not require airway management, which reduces the risk of complications like aspiration, breathing difficulties, or adverse reactions to general anaesthetics.Effective pain control: This technique provides excellent pain relief, especially in the lower half of the body, making it ideal for labour, childbirth, and lower-body surgeries.Minimal systemic effects: As this technique avoids the use of systemic (affecting the entire body) sedatives or narcotics, it does not cause drowsiness or respiratory depression.Faster recovery: Better blood flow reduces the risk of clots in the legs or lungs; bowel function returns sooner, helping patients get moving earlier.Haemodynamic stability: This technique reduce the surgical stress response, which leads to better blood pressure control during surgery (and hence smoother surgery).Pain relief for cancer: Local anaesthetics or opioid medications can be used for ongoing pain in advanced cancers affecting the abdomen or lower body, often as part of palliative care. How is the procedure performed? Spinal anaesthesia is administered after careful planning; the following steps are performed (following the preoperative stage):Checking the spinal anatomy: This is done to allow for safe needle placement and drug delivery to ensure reduced risk of complications, such as spinal cord injury, nerve damage, or failed anaesthesia.Drug administration: A small amount of local anaesthetic is directly injected via a needle into the cerebrospinal fluid (CSF) in the subarachnoid space (the space surrounding the spinal cord) in the lower back. This results in the rapid numbing of the target region (1 to 5 minutes for numbing).Monitoring: Vital signs like blood pressure, heart rate, and oxygen saturation are continuously monitored and complications like low blood pressure (hypotension) and slow heartbeat (bradycardia)—which may require treatment—are looked out for.Onset of anaesthesia: Numbing is checked using a pinprick test or cold swab.Post-procedure steps: After the completion of the procedure, patients are positioned flat on their back to allow even distribution of the anaesthetic and reduce the risk of a spinal headache. Risks/Potential side effects As with general anaesthesia, the risks associated with spinal anaesthesia may be common or rare depending on the root cause or the patient’s medical history or genetics:Common risksLow blood pressure (hypotension): The anaesthetic can block certain nerves that control the body's "fight-or-flight" response and blood pressure, leading to dizziness, nausea, fainting, or, in severe cases, cardiovascular collapse.Spinal headache (post-dural puncture headache): A severe headache caused by leakage of cerebrospinal fluid (CSF) through the puncture site. It may also cause stiffness in the neck, nausea, and sensitivity to light.Nausea and vomiting: These are the result of low blood pressure or irritation of internal organ nerves.Back pain: This is caused due to local tissue trauma or muscle spasm at the injection site.Difficulty urinating (Urinary retention): Temporary bladder control issues can occur due to nerve signal disruption.Rare but serious risks:High or total spinal block: This is caused by the excessive spread of the anaesthetic into higher spinal levels, potentially affecting breathing muscles or brainstem function. Symptoms include difficulty in breathing, low blood pressure, slow heartbeat, or loss of consciousness.Nerve or spinal cord injury: This may result from direct needle trauma, blood clots pressing on the spinal cord, or reduced blood flow. Symptoms include persistent numbness, weakness, tingling, or, in extremely rare cases, paralysis.Infection: This could include meningitis (infection of the brain and spinal cord covering) or a brain abscess. Symptoms include severe back pain, fever, memory problems, confusion, or seizures.Bleeding (Spinal hematoma): This is caused due to accidental puncture of the blood vessels during anaesthesia, especially in patients with blood-clotting disorders or on blood thinners. Symptoms include back pain, numbness, paralysis, or loss of bladder/bowel control.Allergic reactions: These are caused when the patient is sensitive to the anaesthetic drug or preservatives used. Symptoms include rash, itching, or anaphylaxis (a severe, potentially life-threatening allergic reaction).If spinal anaesthesia does not work as expected, the doctors may choose to go with general anaesthesia for the procedure to ensure adequate pain control. 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