Background: Horner's syndrome (HS) - a combination of miosis, ptosis, anhidrosis, enophthalmus and vasodilation presenting as bloodshot conjunctiva caused by a block of the upper thoracic sympathetic pathways - is a rare complication of epidural anaesthesia. The incidence is increased in labouring women compared to other patient groups.
Case report: A 33-year old primigravida underwent induction of labour at 40 weeks following spontaneous rupture of membranes without uterine contractions. Labour was augmented with an oxytocin infusion and an epidural inserted for analgesia. The epidural was sited at L3/4 using a loss of resistance to saline technique with the patient in the sitting position. Through a 16G Tuohy needle, a 20G catheter was advanced 4cm into the epidural space. After negative aspiration, a test dose of 10ml low dose mixture (LDM) of 0.1% bupivacaine containing fentanyl 2mcg/ml was administered. This was followed by another 10ml of LDM after 5 min. The epidural worked better on the left side with a block to sensation for cold to T4 on the left and to T6 on the right, but pain control was satisfactiory. An hour later, the lady realised that her left eye was red and felt different. On neurological examination, a ptosis, miosis, enophthalmus and bloodshot conjunctiva were noticable. No other neurological symptoms could be found. The block was still T4 to cold on the left and T6 to cold on the right. Systolic bloodpressure had dropped from initially well above 100mmHg to 85mmHg. Symptoms resembled left sided HS. The epidural catheter was drawn back to 2.5cm. Use of the epidural catheter was continued under close monitoring of the parturient. Symptoms of HS resolved over the next two hours.
Discussion: It remains unclear why HS is more frequent in parturients with epidural analgesia. During pregnancy the epidural space is smaller due to engorged epidural veins and epidural pressure is additionally increaded during uterine contractions, possibly leading to higher blocks .
1. Barbara R, Tome R, Barua A, et al. Obstet Gynecol Surv. 2011;66(2):114-9.
Learning points: It is of key importance that the obstetric anaesthetist is aware of the rare occurence of HS after lumbar epidural analgesia. The condition is in most cases benign and correct diagnosis can prevent expensive further workup. However, HS can precede hypotension and possibly cardiac shock due to high sympathetic block. Therefore close monitoring is required.