1 General introduction 27 The use of ‘sitz baths’ is believed to help by improving hygiene and decreasing the IAS-tone mediated through sensory perianal skin receptors getting stimulated by warm water. The decrease in spasm and pain relief is attributed to this ‘thermosphincteric reflex’ through the activation of non-adrenergic and non-cholinergic neural release of nitric oxide.77,78 Gupta79 found a significant relief in anal burning and higher satisfaction score, but no significant pain relief and wound healing. It is advised to use the sitz bath only to cover the perineum and lower pelvis (with max.400C), and not whole baths because this could lead to vasodilatation and a decrease of circulation in the perineal area.80 Guideline recommendations differ on this subject. Sitz baths are recommended in international clinical guidelines,8,81 but not in the Dutch guideline.82 The use of ointments is aimed at reducing elevated sphincter tone and consequently increase the anodermal vascular blood flow, for which nitro-glycerine as well as calcium channel blockers may be prescribed.5,81 Topical glyceryl dinitrate, is a nitrogen donor that works by increasing nitric oxide, which induces relaxation of the IAS. Glycerine nitrate is better than placebo in healing CAF, however recurrence occurred in around 50% of those initially cured.7 Calcium channel blockers (diltiazem) achieve healing rates of 80.4%,83 but sideeffects e.g., mainly pruritis may occur. Recurrence of 60% was found in patients within 2 years after end of therapy.84 Both treatments have been shown effective although glyceryl nitrate has more side effects including headache.81 Botulinum toxin can be considered as an alternative or as a step-up approach when standard conservative therapy fails.81,82 Botulinum toxin is an exotoxin produced by the bacterium clostridium botulinum. Botulinum toxin blocks nerve conduction by preventing acetylcholine release from the presynaptic nerve endings resulting in temporary muscle paralysis and to improve local vascularity.85 Botulinum toxin is considered as a minimal invasive procedure with minor adverse effects which can be performed in an outpatient setting, however the recurrence rates vary between 1850%.7,86,87 Posterior tibial nerve stimulation Posterior tibial nerve stimulation is an office-based device to deliver retrograde electrostimulation to the sacral nerve. The tibial nerve is a mixed nerve containing L4–S3 fibers and originates from the same spinal segments as the innervations to
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