The Effects of Horner's Syndrome Developing After Interscalene Brachial Plexus Block on Autonomic Nervous Activity

The Effects of Difference in Pupil Size Between Bilateral Eyes on Cardiac Sympathetic Nervous Activity Following Interscalene Brachial Plexus Block

Status

Completed

Phases

Unknown

Study type

Observational

Source

ClinicalTrials.gov

Registry ID

NCT03514342

Enrollment

Registered

2018-05-02

Start date

2018-06-18

Completion date

2019-07-01

Last updated

2021-06-18

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Brachial Plexus Block, Horner Syndrome, Autonomic Imbalance

Keywords

Heart rate variability, Mesopic pupil size

Brief summary

This study evaluates the effects of Horner's syndrome on cardiac autonomic nervous activity after interscalene brachial plexus block. Cardiac autonomic nervous activity and bilateral pupil diameters will be measured in a scotopic light condition, 30 minutes after interscalene brachial plexus block under ultrasound guidance and 15 minutes after the subsequent sitting position.

Detailed description

Stellate ganglia provide sympathetic fibers to the heart. Ipsilateral stellate ganglion block accompanied by interscalene brachial plexus block causes Horner's syndrome presenting with miosis, ptosis, and anhidrosis. The extent of Horner's syndrome can be represented by the difference in pupil diameter between bilateral eyes. Cardiac autonomic nervous activity affected by stellate ganglion block can be measured by calculation of heart rate variability parameters.

Interventions

PROCEDUREInterscalene brachial plexus block

Under ultrasound guidance, the 5th to 7th cervical nerve roots are identified between anterior and middle scalene muscles and subsequently blocked.

DRUG0.75% ropivacaine

Placement of 25 to 30 ml of 0.75% ropivacaine around the 5th to 7th cervical nerve roots

Study design

Observational model

COHORT

Time perspective

PROSPECTIVE

Eligibility

Sex/Gender

ALL

Age

20 Years to 60 Years

Healthy volunteers

Inclusion criteria

* American Society of Anesthesiologists physical status 1 * Arthroscopic shoulder surgery under interscalene brachial plexus block

Exclusion criteria

* Coagulopathy * Infection at the site of brachial plexus block * Peripheral neuropathy or neurologic sequelae on the operative limb * Allergy to local anesthetics or history of allergic shock * Psychiatric diseases * Patient refusal * Difficulty communicating with medical personnel * Arrhythmias * Ischemic heart disease * Hypertension * Diabetes mellitus * Thyroid dysfunction * Conduction abnormalities on electrocardiogram * Electrolyte imbalance * Medications affecting cardiac conduction * Contralateral vocal cord palsy * Contralateral hemidiaphragmatic paresis or paralysis * Contralateral pneumothorax or hemothorax

Design outcomes

Primary

Measure	Time frame	Description
Post-sitting sympathetic nervous activity	15 minutes after the sitting position following interscalene brachial plexus block	Natural-log transformed low frequency power of heart rate variability calculated using R wave to R wave intervals obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block

Secondary

Countries

South Korea

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026

Measure	Time frame	Description
Post-sitting ipsilateral pupil diameter	15 minutes after the sitting position following interscalene brachial plexus block	Ipsilateral pupil diameter measured under a mesopic condition 15 minutes after the sitting position following interscalene brachial plexus block
Post-sitting contralateral pupil diameter	15 minutes after the sitting position following interscalene brachial plexus block	Contralateral pupil diameter measured under a mesopic condition 15 minutes after the sitting position following interscalene brachial plexus block
Post-anesthetic ipsilateral pupil diameter	30 minutes after interscalene brachial plexus block	Ipsilateral pupil diameter measured under a mesopic condition 30 minutes after interscalene brachial plexus block
Post-anesthetic contralateral pupil diameter	30 minutes after interscalene brachial plexus block	Contralateral pupil diameter measured under a mesopic condition 30 minutes after interscalene brachial plexus block
Pre-anesthetic ipsilateral pupil diameter	15 minutes after baseline acclimation	Ipsilateral pupil diameter measured under a mesopic condition 15 minutes after baseline acclimation
Post-sitting parasympathetic nervous activity	15 minutes after the sitting position following interscalene brachial plexus block	Natural-log transformed high frequency power of heart rate variability calculated using R wave to R wave intervals obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block
Post-sitting sympathovagal balance	15 minutes after the sitting position following interscalene brachial plexus block	Low-to-high frequency power ratio of heart rate variability obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block
Post-sitting overall variability of autonomic nervous system	15 minutes after the sitting position following interscalene brachial plexus block	Natural-log transformed total power of heart rate variability obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block
Post-anesthetic sympathetic nervous activity	Between 25 and 30 minutes after interscalene brachial plexus block	Natural-log transformed low frequency power of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block
Pre-anesthetic contralateral pupil diameter	15 minutes after baseline acclimation	Contralateral pupil diameter measured under a mesopic condition 15 minutes after baseline acclimation
Post-anesthetic sympathovagal balance	Between 25 and 30 minutes after interscalene brachial plexus block	Low-to-high frequency power ratio of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block
Post-anesthetic overall variability of autonomic nervous system	Between 25 and 30 minutes after interscalene brachial plexus block	Natural-log transformed total power of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block
Pre-anesthetic sympathetic nervous activity	15 minutes after baseline acclimiation	Natural-log transformed low frequency power of heart rate variability 15 minutes after baseline acclimation
Pre-anesthetic parasympathetic nervous activity	15 minutes after baseline acclimiation	Natural-log transformed high frequency power of heart rate variability 15 minutes after baseline acclimation
Pre-anesthetic sympathovagal balance	15 minutes after baseline acclimiation	Low-to-high frequency power ratio of heart rate variability 15 minutes after baseline acclimation
Pre-anesthetic overall variability of autonomic nervous system	15 minutes after baseline acclimation	Natural-log transformed total power of heart rate variability 15 minutes after baseline acclimation
Sensory blockade	30 minutes after interscalene brachial plexus block	C5 to T1 dermatomal blockade of the shoulder graded from 0 to 2 (0 = no cold sensation, 1 = reduced cold sensation, and 2 = normal cold sensation) by applying ice to the shoulder
Motor blockade	30 minutes after interscalene brachial plexus block	Motor blockade of the radial, ulnar, median, musculocutaneous, and axillary nerves graded from 0 to 2 (0 = no block 1 = partial block, and 2 = complete block)
Post-anesthetic parasympathetic nervous activity	Between 25 and 30 minutes after interscalene brachial plexus block	Natural-log transformed high frequency power of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block