When this technique is used for labor, a small amount of narcotic is usually given. The fact that the medication is given so close to the spinal cord means that a much smaller amount can be given when compared to giving narcotics intravenously. This means that side effects are less likely.

However, the use of narcotics alone in this manner still only provides analgesia (reduction in pain) and not anesthesia (numbness, lack of pain). This is a disadvantage when compared to an epidural - which provides a higher level of pain relief due to the fact that local anesthetics are usually used with the epidural. To get around this, sometimes a small amount of local anesthetic is also given intrathecally which provides some level of anesthesia (although still not as much as with an epidural).

There are some other disadvantages to an intrathecal. The placement of medications into the intrathecal space requires placement of a needle (click here to see a picture of the spinal needle) through a membrane called the dura, which surrounds the fluid in the space. After this puncture, these is a chance of a headache (a so-called post-dural puncture headache, also known as a "spinal" headache). Although this headache is not likely to be life threatening and is treatable, it can very annoying. It is estimated to occur in about 1-2% of laboring patients that receive intrathecals.

Another drawback is that once the medication is placed, the effect of the medication is time-limited - it does wear off. This is unlike an epidural where a catheter is placed in the body to allow continuous application of medication or administration of additional medication as needed. Of course, an intrathecal could always be repeated but this involves another needle stick for the patient.

Pros:

• Easier to place than an epidural
• Medications take effect faster than with an epidural
• Small amount of medication means that side effects are less likely
• Absence of or small amount of local anesthetic means that muscle weakness is less likely
• Less chance of low blood pressure than with other techniques
• There also is some evidence in the anesthesia and obstetrical literature that suggests that there is a smaller risk of caesarean section, prolonged labor, and forceps delivery when intrathecal is utilized versus when an epidural is utilized
• Can be combined with an epidural to gain advantages of both - the so called "walking epidural"

Cons:

• Patient may have spinal headache afterwards
• Other possible complications include nausea, vomiting, pruritis (itching) and urinary retention
• More serious complications such as epidural hematoma and respiratory depression are fortunately very rare
• Time limited technique - the medication will wear off and may need to be repeated