Risk factors for the development of Horner's syndrome following interscalene brachial plexus block using ropivacaine for shoulder arthroscopy: a randomised trial.

BACKGROUND: Horner's syndrome is comprised of a set of symptoms caused by a permanent or transient ipsilateral sympathetic trunk lesion or paralysis. It may occur after numerous pathologies in the cervical region, epidural, spinal anaesthesia, and interscalene, transscalene, supraclavicular, or infraclavicular brachial plexus block. The aim of this randomised, prospective clinical study was to evaluate the effect of the interscalene brachial plexus block (IBPB) technique on the occurrence rate of Horner's syndrome and identify contributing risk factors.

METHODS: 108 randomly selected patients of ASA I-III status were scheduled for elective shoulder arthroscopy. The patients received 20 mL of 0.5% ropivacaine either with ultrasound (US)-guided IBPB (U), peripheral nerve stimulation (PNS)-confirmation IBPB (N), or US-guided, PNS-confirmed IBPB (dual guidance; NU).

RESULTS: We observed that Horner's syndrome developed in 12% of the N group, 6% of the NU group, and 9% of the U group. The differences in the rates were not statistically significant (P = 0.616). Regardless of the technique used to induce IBPB, our study did not demonstrate any particular anthropometric parameter that predisposed the patients to the development of Horner's syndrome. Interestingly, our results showed that NU patients with Horner's syndrome were significantly younger than NU patients without Horner's syndrome.

CONCLUSION: The precision of IBPB by use of the dual guidance technique may reduce the rate of Horner's syndrome. The higher water concentration in the prevertebral spaces of younger patients may create better conditions for the diffusion of ropivacaine, which may result in a statistically significant higher HS rate.