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sufentanil or clonidine, as initial labour analgesia, was without side effects and allowed a
'mobile epidural’; at the doses studied it produced modest analgesia following Caesarean
section (Roelants, 2006 Level II). The addition of epidural clonidine to bupivacaine reduced
hourly patient‐controlled epidural bupivacaine requirements during labour (Ross et al,
2009 Level I).
Intra‐articular administration of neostigmine produced a useful analgesic effect in the
postoperative period and was not associated with an increase in the incidence of adverse
effects (Habib & Gan, 2006 Level I).
Studies investigating the efficacy of adding neostigmine to the local anaesthetics used for
brachial plexus block and intravenous regional anaesthesia reported conflicting results
indicating the need for further studies (Habib & Gan, 2006 Level I).

5.3.6 Magnesium
The long‐term effects of perineural or neuraxial magnesium have not been clarified.
In patients undergoing orthopaedic surgery, supplementation of spinal anaesthesia with
combined intrathecal and epidural magnesium sulphate significantly reduced patients'
postoperative morphine requirements (Arcioni et al, 2007 Level II). Addition of magnesium
sulphate to lignocaine IVRA improved intra‐ and postoperative analgesia and tolerance of the
tourniquet (Turan et al, 2005 Level II; Kashefi et al, 2008 Level II). While the addition of magnesium
to intrathecal bupivacaine prolonged the times for block regression and first request for
analgesia after knee arthroscopy, time to ambulation was longer in the magnesium group
(Dayioglu et al, 2009 Level II).
Intra‐articular magnesium combined with bupivacaine resulted in better pain relief than either CHAPTER 5
drug given alone or placebo (Elsharnouby et al, 2008 Level II).

5.3.7 Botulinum toxin A
Following direct IM injection, botulinum toxin acts to irreversibly bind to the acetylcholine
receptor and induce a chemical denervation with resultant muscular paralysis. The extent and
duration of paralysis depends on the dose administered. Systemic weakness may follow high
cumulative doses. Reinnervation may occur over a period of weeks to months.
In treating pain and related muscle spasm in multiple sclerosis, data on the use of botulinum
toxin are conflicting and of low quality (Shakespeare et al, 2003). Similarly, the current evidence
does not support the use of botulinum toxin injection in trigger points for myofascial pain
(Ho & Tan, 2007 Level I). In subacute and chronic neck disorders IM botulinum toxin injections
have similar effects to saline in improving pain (pooled mean difference: ‐0.39; CI ‐1.25 to
0.47) (Peloso et al, 2007 Level I); although there is benefit in cervical dystonia (Simpson et al,
2008 Level I).

Key messages
1. Intrathecal clonidine improves duration of analgesia and anaesthesia when used as an
adjunct to intrathecal local anaesthetics (N) (Level I).

2. Clonidine improves duration of analgesia and anaesthesia when used as an adjunct to local
anaesthetics for peribulbar, peripheral nerve and plexus blocks (N) (Level I).
3. Intrathecal neostigmine marginally improves perioperative and peripartum analgesia in
combination with other spinal medications but is associated with significant side effects (S)
(Level I).

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