Epidural space

The epidural space surrounds the dura mater of the spinal cord. It is bounded by the pedicles of the vertebral arches and by the anterior and posterior ligaments connecting the bony vertebral column. The epidural space contains nerve roots, fat, and blood vessels. 

Epidermal Growth Factor (EGF) Receptor Family Epidermal Growth Factor Receptor 2 (ErbB2) Epidural (Space)... 

Spinal cord I Epidural space Arachnoid space... 

A conduction block is a type of regional anesthesia produced by injection of a local anesthetic drug into or near a nerve trunk. Examples of a conduction block include an epidural block (injection of a local anesthetic into the space surrounding the dura of the spinal cord) a trails sacral (caudal) block (injection of a local anesthetic into the epidural space at the level of the sacrococcygeal notch) and brachial plexus block (injection of a local anesdietic into the brachial plexus). Epidural, especially, and trailssacral blocks are often used in obstetrics. A brachial plexus block may be used for surgery of the arm or hand. 

Epidural analgesia is frequently used for lower extremity procedures and pain (e.g., knee surgery, labor pain, and some abdominal procedures). Intermittent bolus or continuous infusion of preservative-free opioids (morphine, hydromorphone, or fentanyl) and local anesthetics (bupivacaine) may be used for epidural analgesia. Opiates given by this route may cause pruritus that is relieved by naloxone. Adverse effects including respiratory depression, hypotension, and urinary retention may occur. When epidural routes are used in narcotic-dependent patients, systemic analgesics must also be used to prevent withdrawal since the opioid is not absorbed and remains in the epidural space. Doses of opioids used in epidural analgesia are 10 times less than intravenous doses, and intrathecal doses are 10 times less than epidural doses (i.e., 10 mg of IV morphine is equivalent to 1 mg epidural morphine and 0.1 mg of intrathecally administered morphine).45... 

Epidural anesthesia is administered by injecting local anesthetic into the epidural space. Located outside the spinal cord on its dorsal surface, the epidural space contains fat and is highly vascular. Therefore, this form of anesthesia can be performed safely at any level of the spinal cord. Furthermore, a catheter may be placed into the epidural space, allowing for continuous infusions or repeated bolus administrations of anesthetic. 

An important difference between epidural anesthesia and spinal anesthesia is that agents injected into the epidural space may readily enter the blood due to the presence of a rich venous plexus... 

Intrathecal (IT) Into the subarachnoid space between two of the membranes (meninges) separating the spinal cord from the vertebral column. This route is used for drugs that do not penetrate the blood-brain barrier, but which are required for their central action (e.g., antibiotics). Drugs can also be injected spinally (into the epidural space) for local anaesthesia or analgesia. 

Administration DepoDur s not intended for intrathecal, IV, or IM administration. Administration of DepoDt/r into the thoracic epidural space or higher has not been evaluated and therefore is not recommended. DepoDt/r may be administered via needle or catheter at the lumbar level. DepoDwr may be administered undiluted or may be diluted up to 5 mL total volume with preservative-free 0.9% normal saline. Do not use an in-line filter during administration of DepoDur. 

Some simple but powerful solutions have come from this industrial model of quality assurance. For example, just the removal of concentrated potassium chloride solutions from hospital wards can prevent a toxic dose of potassium from being accidentally injected intravenously. Making the color of the tubing different may prevent epidural lines and IV lines being interchanged so that medication intended to go into a vein does not go into the epidural space,or vice versa. 

Local anaesthetics can be applied topically, deposited around peripheral nerves, or infiltrated into tissues. Central neural blockade can be produced by injection into the subarachnoid or epidural spaces. Less common uses are for intravenous regional anaesthesia and attenuation of cardiovascular responses to tracheal intubation. The membrane-stabilising effect of local anaesthetics has been utilised in the treatment of myocardial arrhythmias. 

Epidural A form of intraspinal analgesia where the agent is injected into the epidural space that surrounds the dura mater, which is the membrane that contains the cerebo-spinal fluid directly outside the spinal cord. 

Central neural blockade. The anesthetic is injected within the spaces surrounding the spinal cord10 (Fig. 12-2). Specifically, the term epidural nerve blockade refers to injection of the drug into the epidural space—that is, the space between the bony vertebral column and the dura mater. A variation of epidural administration known as a caudal block is sometimes performed by injecting the local anesthetic into the lumbar epidural space via the sacral hiatus (see Fig. 12-2). Spinal nerve blockade refers to injection within the subarachnoid space— that is, the space between the arachnoid membrane and the pia mater. Spinal blockade is also referred to as intrathecal anesthesia because the drug is injected within the tissue sheaths surrounding the spinal cord (intrathecal means within a sheath see Chapter 2). 

In theory, epidural and spinal blocks can be done at any level of the cord, but they are usually administered at the L3-4 or L4-5 vertebral interspace (i.e., caudal to the L-2 vertebral body, which is the point where the spinal cord ends). Epidural anesthesia is somewhat easier to perform than spinal blockade because the epidural space is larger and more accessible than the subarachnoid space. However, spinal anesthesia is... 

Epidural anesthesia is administered by injecting local anesthetic into the epidural space (the space bounded by the ligamentum flavum) posteriorly, the spinal periosteum laterally, and dura anteriorly. Epidural anesthesia can be performed in the sacral hiatus (caudal anesthesia) or in the lumbar, thoracic, or cervical regions of the spine. 

Functional disturbances within the spinal cord are caused by the venous congestion due to arteriali-zation and elevated pressure of the medullary veins (Aminoff et al. 1974). In addition, venous outlets are insufficient and thus reinforcing impairment of the venous circulation and chronic spinal hypoxia. In particular, Merland and coworkers (1980) introduced the concept of blocked venous drainage into the epidural space. 

Kirihara et al. (2003) compared neurotoxicity of intrathecal and epidural lidocaine in rats. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital (30 mg/kg i.p.) and 1.5% halothane. A catheter of stretched polyethylene tubing PE-10 was introduced into the subarachnoid or epidural space using an aseptic technique. Catheters were passed through the L4-L5 intervertebral space and advanced 1.3 cm in the caudal direction. Rats were allowed 4 days to rest for recovery from the operation. 

Horner s syndrome has been reported after lumbar epidural block in two other patients who were having lumbar epidural anesthesia for chronic pain treatment (144). The authors suggested that this complication had probably occurred through anatomical changes in the epidural space, leading to a high degree of sympathetic blockade. 

Nitrous oxide can diffuse into any cavity that has air inserted or left in situ. Intraoperative subdural tension pneumocephalus arising during neurosurgery has been described (27). Air injected into the epidural space can cause symptomatic pressure effects if nitrous oxide diffuses into the air pocket. 

Budd K, Brown PM, Robson PJ. The treatment of chronic pain by the use of meptazinol administered into the epidural space. Postgrad Med J 1983 59(Suppl 1) 68-71. 

Relatively hydrophilic dmgs such as methotrexate (log P = -0.5) which do not cross the blood-brain barrier in significant amounts, have been infused intrathecally to treat meningeal leukaemia, and baclofen (log P =-1.0) to treat spinal cord spasticity. High lumbar CSF concentrates are achieved as a result. Figure 9.56 shows the anatomy of the epidural space and routes of dmg transport. The spinal CSF has a small volume (70 cm ) and a relatively slow clearance (20-40 cm h ) for hydrophilic dmgs. 

Wittern C, Hendrickson D A, Trumble T et al 1998 Complications associated with administration of detomidine into the caudal epidural space in a horse. Journal of the American Veterinary Medical Association 213 516-518... 

The drug is injected into the epidural space between the vertebrae and spinal cord. This numbs the nerves leading to the uterus and the pelvic area and leads to pain relief during labor. Epidural anesthesia may sometimes cau.se headaches. 

A cyst that is located in the posterior or lateral epidural space in the spinal canal and that is lined only by fibrous tissue resembling dura and lacking arachnoid membrane is a meningeal cyst or diverticulum (see Table 20.12). A subdural or subarachnoid cyst that has a thinner wall than the epidural cyst and that protrudes toward brain or spinal cord is an arachnoid cyst. Reactivity for vimen-tin, progesterone receptors, and EMA is common. This inununoreactivity resembles that of arachnoid granulations and meningiomas. Other cysts have variable thickness and are more difficult to categorize. 

Peripheral nerve block anesthesia involves injecting the drug near the nerves close to the area to be anesthetized. Epidural anesthesia results when the local anesthetic is injected into the epidural space between a lumbar and sacral vertebra. Several drugs can safely produce useful levels of anesthesia for obstetrics as well as postoperative pain. Another method of utilizing local anesthetics is to inject solutions into subarachnoid spaces (e.g., the spaces between certain vertebrae). 

The concentration of local anesthetic used determines the type of nerve fibers blocked The highest concentrations are used when sympathetic, somatic sensory, and somatic motor blockade are required. Intermediate concentrations allow somatic sensory anesthesia without muscle relaxation. Low concentrations will block only preganglionic sympathetic fibers. A significant difference between epidural and spinal anesthesia is that the dose of local anesthetic used can produce high concentrations in blood following absorption from the epidural space. 

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