Subarachnoid block

Miscellaneous Tuberculous meningitis with subarachnoid block or impending block when accompanied by appropriate antituberculous chemotherapy in trichinosis with neurologic or myocardial involvement. 

Phenylephrine hydrochloride (Neo-Synephrine) is a pure a-agonist that is occasionally used for subarachnoid block and is marketed with procaine for use in dentistry. It has little direct cardiac effect. 

Lignocaine injections are indicated for production of local or regional anaesthesia by infiltration techniques such as percutaneous injection, peripheral nerve block, spinal or subarachnoid block. 

Local segmental pain (Compression of post, root) Iff Remote pain through spinothalmic tract Subarachnoid block (Bupivacaine)... 

Dasgupta D, Garasia M, Gupta KC, Satoskar RS. Randomised double-blind study of centbucridine and lignocaine for subarachnoid block. Indian J Med Res 1983 77 512-16. 

The accidental transformation of epidural to subarachnoid block can be dramatic, and tracheal intubation and ventilatory support may be necessary (102). Severe hypotension can result after inadvertent intrathecal local anesthesia (SEDA-21, 131). In women in labor, fetal bradycardia can occur. Postdural puncture headache can also be a sign of catheter migration. 

Wajima Z, Shitara T, Inoue T, Ogawa R. Severe hghtning pain after subarachnoid block in a patient with neuropathic pain of central origin which drug is best to treat the pain Clin J Pain 2000 16(3) 265-9. 

Subarachnoid block The injection is into the subarachnoid space in the third or fourth lumbar space. 

Spanish American sugar and acetone slow-acting antirheumatic drugs subarachnoid block/bleed short arm cast solid ankle cushion heel... 

Spinal anaesthesia (spinal block or sub-arachnoid block) is used to administer the injection into the subarachnoid space. Several local anaesthetics are used for spinal anaesthesia such as procaine, lidocaine, tetracaine, and bupivacaine. Vasoconstrictors such as adrenaline (0.1-0.2 mg) and phenylephrine (0.5-2 mg) can be added to subarachnoid blocks to decrease vascular uptake and prolong diuation of action. 

Local anesthetics are used for topical anesthesia, local infiltration, peripheral nerve block, paravertebral anesthesia, intravenous block also known as regional anesthesia, epidural block, and spinal i.e. subarachnoid blockade. The local anesthetics may be divided into two main groups, the esters and the amide-type agents. 

Local anesthetics have poorly understood effects on inflammation at sites of injury, and these anti-inflammatory effects may contribute to improved pain control in some chronic pain syndromes. At the concentrations used in spinal anesthesia, local anesthetics can inhibit transmission via substance P (neurokinin-1), NMDA, and AMPA receptors in the secondary afferent neurons (Figure 26-1). These effects may contribute to the analgesia achieved by subarachnoid administration. Local anesthetics can also be shown to block a variety of other ion channels, including nicotinic acetylcholine channels in the spinal cord. However, there is no convincing evidence that this mechanism is important in the acute clinical effects of these drugs. High concentrations of local anesthetics in the subarachnoid space can interfere with intra-axonal transport and calcium homeostasis, contributing to potential spinal toxicity. 

Schematic diagram of the typical sites of injection of local anesthetics in and around the spinal canal. When local anesthetics are injected extradurally, it is known as epidural (or caudal) blockade. Injections around peripheral nerves are known as perineural blocks (eg, paravertebral block). Finally, injection into the subarachnoid space (ie, cerebrospinal fluid), is known as spinal blockade.

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... 

Spinal nerve block Administration of local anesthesia into the spinal canal between the arachnoid membrane and the pia mater (i.e., the subarachnoid space). 

Anesthesia of the lower extremities and abdomen may be induced by the introduction of anesthetic drugs into the subarachnoid space (Figure 23.6). The drug most often used for this purpose is bupivacaine. The latency period plus the duration of the maximal cephalad level for both plain and hyperbaric bupivacaine lasts from 10 to 60 min. A bupivacaine solution is made hyperbaric by the addition of 5 to 8% glucose. The distribution of bupivacaine in the cerebrospinal fluid (CSF) is affected by gravity and is therefore influenced by the patient s position. With a dose of 15 mg of plain 0.5% bupivacaine, a half-life of about 3 h is achieved. The addition of epinephrine to bupivacaine prolongs the duration of block. 

Kiiker W, Thiex R, Block F (1999) Hyperacute perimesencephalic subarachnoid hemorrhage demonstration of blood extravasation with MRI. J Comput Assist Tomogr 23 521-523 Kwa VH, Franke CL, Verbeeten B Jr et al (1998) Silent intracerebral microhemorrhages in patients with ischemic stroke. Ann Neurol 44 372-377... 

Subarachnoid (intrathecal) block (spinal anaesthesia). By using a solution of appropriate specific gravity and tilting the patient the drug can be kept at an appropriate level. Sympathetic nerve blockade causes hypotension. Headache due to CSF leakage is virtually eliminated by using very narrow atraumatic penal point needles. 

A 68-year-old man was given 0.5% bupivacaine 4 ml or spinal anesthesia, and 5 minutes later complained of nausea and developed hypotension, loss of consciousness, and a tonic-clonic seizure. He had first-degree heart block 4 minutes after subarachnoid injection, followed 1 minute later by third-degree heart block, and then asystole. He was successfully resuscitated. Proposed theories included a reflex bradycardia resulting from reduced venous return and/or unopposed... 

A 76-year-old man undergoing trabeculectomy developed bilateral amaurosis after a peribulbar block with 6 ml of a mixture of 2% lidocaine, 0.5% bupivacaine, and hyaluronidase (318). The authors thought it unlikely that the optic nerve sheath had been penetrated and suggested that local spread to the optic nerves via the subarachnoid or subdural space had been responsible. 

The authors concluded that the local anesthetic may have passed down a fistulous track into the subarachnoid space, producing spinal block. 

Spinal anesthesia is carried out by injecting the anesthetic agent into the subarachnoid. space in the spinal cord. The anesthetic acts mainly on the nerve fibers and blocks the pain regions of the body served by the sections of the spinal cord affected. 

The calcium channel blocking drugs may prove to be very useful in the treatment of patients following acute stroke. In particular, nimodipine has been found to have selective actions on cerebral vascular smooth muscle without affecting systemic arterial pressure [16]. After intravenous administration, nimodipine increases hemispheric cerebral blood flow in patients with acute ischaemic stroke [235]. A placebo-controlled double-blind trial has shown that nimodipine significantly decreases the occurrence of severe neurologic deficits from spasm alone in patients who have had subarachnoid haemorrhage [236],... 

---