A stellate ganglion block is performed at the level of C6 using ultrasound guidance. Ten minutes later the patient develops ptosis, miosis, anhidrosis, and nasal stuffiness on the injected side with no other deficit. This finding indicates:

• A Accidental subarachnoid injection requiring emergency airway control
• B Recurrent laryngeal nerve injury from needle trauma
• C Successful spread to the cervicothoracic sympathetic chain ✓
• D Vertebral artery injection with central nervous system toxicity

Explanation

Horner's syndrome (ptosis, miosis, anhidrosis, enophthalmos, nasal congestion) results from blockade of sympathetic fibres to the head and neck and is the expected clinical sign confirming correct placement of a stellate ganglion block. It is used as an endpoint, not a complication. Recurrent laryngeal block would cause hoarseness, vertebral artery injection causes immediate seizures or loss of consciousness, and subarachnoid spread produces a high spinal with apnoea and profound hypotension rather than isolated ocular signs.

Reference: Hadzic's Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia, 3rd ed.

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Written and medically reviewed by the StethoPrep medical team.