Intrathecal block

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. 

This technique is used in obstetrics and genito-urinary surgery and is also known as intrathecal block. 

Techniques range from inhltraiion of anac-sthctic around a single nerve (e.g. dental anaesthesia) to epidural and spinal anaesthesia. In. spinal anaesthesia (intrathecal block) a drug is injected into the ccrebrospina) fluid in the subarachnoid space. In epidural anaesthesia the anaesthetic is injected outside the dura. Spinal anaesthesia is technically far easier to produce than cpidural anaesthesia, but the latter technique virtually eliminates the postanaesihetic complications such as headache. 

Gellerfors M, Lundin H, Svensen CH. Rotational vertigo and nystagmus rapidly after an intrathecal block with bupivacaine and fentanyl. Br J Anaesth 2012 109(3) 467-. ... 

Morgan RJ, Steller PH. 1994. Acute paraplegia following intrathecal phenol block in the presence of occult epidural malignancy. Anaesthesia 49 142-144. 

Iwashita, T., Shimizu, T. Imipramine inhibits intrathecal substance P induced behavior and blocks spinal cord substance P receptors in mice, Brain Res. 1992, 581, 59-66. 

Xu, X. J., Dalsgaard, C. J., Wiesenfeld-Hallin, Z. Intrathecal CP-96,345 blocks reflex facilitation induced in rats by substance P and C-fiber-conditioning stimulation, Eur. J. Pharmacol. 1992, 216, 337-344. 

Glucocorticoids given intrathecally can cause a rise in cerebrospinal fluid protein and carry the risk of arachnoiditis (SED-8, 820). Chemical meningitis has been reported after two intrathecal injections of methylpredni-solone acetate (450) and after lumbar facet joint block (SEDA-17, 450). Intraspinal injections of hydrocortisone for multiple sclerosis apparently led in one case to a cauda equina syndrome, with subsequent ulceromutilating acro-pathy (SEDA-17, 450). Intra-discal injections of triamcinolone acetonide in a number of French cases led to disk or epidural calcification, sometimes symptomless (SEDA-17, 450). 

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). 

Cridland RA, Henry IL (1988b) Intrathecal administration of substance P in the rat spinal transection or morphine blocks the behavioirral responses but not the facilitation of the tail flick reflex. Neurosd Lett 84 203-208... 

Different combinations of fentanyl, bupivacaine, and clonidine were investigated in a multicenter (6 sites) trial of 78 women undergoing elective cesarean section under spinal block (30). In some cases, this appeared to imply intrathecal administration, and in others combined intrathecal and epidural administration. Patients received hyperbaric bupivacaine alone, or with 75 pg of clonidine, or with 75 pg of clonidine and 12.5 pg of fentanyl. There were no reported hemodjmamic differences between the groups, but sedation and pruritus were significantly more common in those who received fentanyl, occurring in 65% and 25% of... 

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. 

Prolonged profonnd motor block occnrred in two patients using patient-controUed epidnral analgesia with 0.1% ropivacaine subseqnent to spinal bnpivacaine for cesarean section (136). One of them developed pressnre sores on both heels. The authors hjq)othesized that epidural ropivacaine may interact with intrathecal bnpivacaine to prolong its effects and advised cantion when this combination is used, as unexpected motor block can ensne. 

---