Medical Contraindications for Spinal Anesthesia
Spinal anesthesia is a technique used to induce temporary loss of sensation in the lower abdomen, pelvis, and/or lower extremities, primarily for surgeries involving those areas. The procedure involves injecting a local anesthetic into the subarachnoid space, numbing the nerves in the lower part of the body 1. While spinal anesthesia is generally safe, it is not suitable for all patients. Certain medical conditions and circumstances can make the use of spinal anesthesia dangerous or ineffective. Understanding these contraindications is crucial for minimizing risks and ensuring patient safety.
Absolute contraindications are medical conditions in which spinal anesthesia should never be administered due to the high risk of serious complications. First, if there is an active infection, such as cellulitis, abscess, or sepsis, at the planned injection site, spinal anesthesia can spread the infection into the central nervous system, leading to serious conditions such as meningitis or sepsis. Second, patients with bleeding disorders (like hemophilia or thrombocytopenia) or those on anticoagulant therapy (such as warfarin or heparin) face a high risk of developing spinal hematomas. A spinal hematoma can compress the spinal cord, leading to permanent neurological damage or paralysis. In addition, in patients with extreme blood loss or dehydration, spinal anesthesia can cause profound hypotension. The sudden drop in blood pressure may not be easily reversible in these patients, making it dangerous to proceed. Finally, conditions that increase intracranial pressure, such as brain tumors, trauma, or intracranial bleeding, are contraindications because spinal anesthesia can exacerbate the pressure shift, leading to brain herniation, a life-threatening condition 2,3. All anesthesiologists must examine patients for these contraindications before attempting spinal anesthesia.
Relative contraindications are situations where the risks of spinal anesthesia are higher, but the decision to proceed may be made on a case-by-case basis, depending on the individual patient’s health status and the necessity of the procedure. First, conditions such as multiple sclerosis, peripheral neuropathies, or spinal cord diseases are relative contraindications. Although spinal anesthesia may be safely administered in some cases, there is a potential risk of exacerbating the underlying neurological condition or causing new deficits 4,5. In addition, in patients with severe aortic stenosis, spinal anesthesia may lead to a sudden drop in systemic vascular resistance and blood pressure, which can significantly reduce cardiac output. This can result in life-threatening complications such as myocardial infarction or cardiac arrest. Furthermore, patients with hemodynamic instability 6 or severely uncontrolled hypertension may experience extreme fluctuations in blood pressure related to spinal anesthesia. The sudden drop in blood pressure can compromise vital organ perfusion, especially in the brain and heart. Finally, patients with conditions such as scoliosis or a history of spinal surgery may have altered anatomy, making it difficult to correctly place the spinal needle. This can increase the risk of complications, such as failed anesthesia or nerve damage 7,8.
Spinal anesthesia is a highly effective technique, but it is not appropriate for every patient. Understanding absolute and relative contraindications for spinal anesthesia is essential for every anesthesia provider.
References
1. Spinal and epidural anesthesia: MedlinePlus Medical Encyclopedia. Available at: https://medlineplus.gov/ency/article/007413.htm.
2. Spinal Anesthesia – NYSORA. Available at: https://www.nysora.com/techniques/spinal-anesthesia-2/.
3. Spinal Anesthesia – StatPearls – NCBI Bookshelf. Available at: https://www.ncbi.nlm.nih.gov/books/NBK537299/.
4. Horlocker, T. T. Regional anaesthesia in the patient with pre-existing neurological dysfunction. in Anaesthesia, Pain, Intensive Care and Emergency A.P.I.C.E. (2007). doi:10.1007/978-88-470-0571-6_29
5. Regional Anesthesia in the Patient with Preexisting Neurologic Disease – NYSORA. Available at: https://www.nysora.com/topics/foundations-of-regional-anesthesia/patient-management/regional-anesthesia-patient-preexisting-neurologic-disease/.
6. Lopes, L., Marialva, J. & Cardoso, H. Spinal Anesthesia in Hemodynamic Instability: A Case Report. Cureus (2023). doi:10.7759/cureus.33821
7. Contraindications for spinal anesthesia. Available at: https://www.vinmec.com/eng/article/contraindications-for-spinal-anesthesia-en.
8. Spinal Anesthesia – NYSORA. Available at: https://www.nysora.com/techniques/spinal-anesthesia-2/.