The difference between lumbar anesthesia and epidural anesthesia needle

There are three layers of dura, arachnoid and soft spinal membrane in the spinal cavity. The space between the periosteum of the vertebral body and the dura mater is the epidural space. The subarachnoid space lies between the arachnoid membrane and the soft spinal membrane covering the spinal cord.

Lumbar anesthesia, also known as subarachnoid block anesthesia, is administered in the subarachnoid space. There are cerebrospinal fluid and spinal cord in this space, so the dose is relatively small. The blocked part is below the anesthesia plane, which is commonly referred to as lower body anesthesia, and the sensation and movement below the anesthesia plane are blocked.

Epidural block anesthesia is the administration of drugs in the epidural space, which is loose connective tissue, blood vessels and lymphatic vessels. The spinal nerve roots can be blocked by the administration of drugs in the epidural space. The range of block is segmental, that is, the sensory and motor nerves in the plane innervated by one or several spinal segments according to the space of administration. Postoperative patient-controlled analgesia (PCA) is usually performed with an epidural catheter.

In adults, the spinal cord is usually dispersed into the cauda equina and suspended in the cerebrospinal fluid below the first level of the lumbar spine, and puncture is not easy to damage the spinal cord. Therefore, lumbar anesthesia is usually applicable to the parts below the first level of the lumbar spine, and the operation applicable to lumbar anesthesia is also applicable to the epidural. Since the epidural is not connected to the intracranial brain, it is theoretically applicable to any operation except craniocerebral surgery. But in practice, it's usually below the chest, and high epidurals require more technique and a greater risk of problems. Lumbar anesthesia and epidural anesthesia can be performed simultaneously, known as combined lumbo-epidural block anesthesia, to provide more sustained and extensive surgical analgesia and anesthetic effects.