Stellate ganglion block has been used for the diagnosis and treatment of conditions involving chronic pain. The incidence of various complications during or after stellate ganglion block has been recognized and the commonest of these are brachial plexus, phrenic nerve or recurrent laryngeal nerve block, intra-arterial or intravenous injection, and pneumothorax and subarachnoid injection . Airway obstruction due to retropharyngeal or cervicomediastinal haematomas is a rare complication following stellate ganglion block and is often not mentioned in textbooks. Only our previous case report  has been indexed in the English language literature. However, another 21 reported cases of this complication that have been reported in the Japanese literature have not been indexed in MEDLINE. We report another similar case and seek to increase the awareness of the life-threatening complication of stellate ganglion block.
Our patient was a 60-yr-old male who presented with neck-shoulder pain. His medical history included diabetes mellitus and obesity. He had received nine sequential stellate ganglion blocks, without complications, and his pain was improving. The tenth block was performed using an anterior paratracheal approach. The needle (23 G, 2.5 cm) was inserted until the tip reached the transverse process of the seventh cervical vertebra. After negative aspiration, mepivacaine 1% 8 mL was injected, the needle was withdrawn and digital pressure was applied to the insertion point for 5 min. One hour later the only complication was Horner's syndrome. The patient was then permitted to leave the outpatient clinic to go home. However, 2.5 h after the stellate ganglion block, the patient became hoarse and after another 1 h had to lie down complaining of dyspnoea and neck pain. His wife then brought him to the Emergency Department of our hospital. On examination, he was afebrile, with a blood pressure of 153/100 mmHg, a heart rate of 70 beats min−1 and a respiratory rate of 25 breaths min−1; electrocardiography revealed no abnormalities. There was no evidence of any pneumothorax. The swelling and tenderness in the anterior region of the neck increased. An otorhinolaryngologist examined the patient, but was unable to make a diagnosis. Since the patient's wife mentioned that her husband had undergone a stellate ganglion block that morning, the anaesthetist was called and by the time he arrived the patient's dyspnoea was quite severe. Endotracheal intubation was attempted but the usual anatomical landmarks could not be seen at laryngoscopy; the soft tissues were grossly oedematous and intubation proved impossible. The otorhinolaryngologist performed an emergency tracheotomy that relieved the dyspnoea significantly. Lateral neck radiography subsequently showed a large haematoma in the neck (Fig. 1). Laboratory data revealed an association between the haematoma and a decrease in haemoglobin concentration (10.8 g dL−1). Thus, the cause of the patient's difficulties was a haematoma resulting from the stellate ganglion block. Although surgery under general anaesthesia was undertaken to evacuate the haematoma, little blood could be evacuated and precise identification of the vessels responsible was not possible. The stoma was closed 37 days after the tracheotomy. The patient was discharged from the hospital with no further complications.
When a vessel in the neck is injured as a result of stellate ganglion block, sequelae are not typical. Minor haematomas may develop, but usually they resolve spontaneously . Development of a large haematoma in the neck to the point airway obstruction occurs is exceedingly uncommon. The exact mechanism of severe dyspnoea due to the haematoma remains unclear. It was thought that the needle might have ruptured a small retropharyngeal blood vessel, so accounting for the substantial duration for the blood to collect and form a space-occupying mass of significant size. This would explain the delay in the onset of symptoms following stellate ganglion block. The primary cause of airway obstruction may have been laryngeal oedema secondary to venous and lymphatic obstruction by the haematoma . Direct compression of the trachea by the haematoma is unlikely to be a feasible mechanism of airway obstruction because a normal trachea is rigid and largely resistant to compression.
This complication may give rise to difficulties in diagnosis. A history of recent stellate ganglion block is therefore extremely useful information. Symptoms can vary with the degree of bleeding and may initially present as neck pain, swelling in the neck, dyspnoea and pharyngeal discomfort. However, early symptoms are frequently non-specific . Computed tomography and lateral neck radiography represent useful investigations in differential diagnosis of dyspnoea as a complication of stellate ganglion block.
If the patient displays any adverse signs following stellate ganglion block, close monitoring should be maintained in hospital until they resolve. When the patient presents with mild dyspnoea, the airway must be monitored and preparations made for possible endotracheal intubation or tracheotomy. Endotracheal intubation may be sufficient in less severe cases, but in severe cases the trachea is extremely difficult to intubate even using small endotracheal tubes. Tracheostomy should be performed when endotracheal intubation is unsuccessful or considered dangerous.
Unfortunately, we were unable to identify useful precautions for the prevention for this complication. Fortunately, our patients undergo stellate ganglion block without complications and rarely display adverse symptoms immediately following the procedure. The onset of initial signs following stellate ganglion block can range in time from 2 to 3 h, which means that diagnosis and treatment are often delayed. It is therefore important that not only physicians, but also patients undergoing stellate ganglion block should be informed about this complication.
In conclusion, retropharyngeal or cervicomediastinal haematomas following stellate ganglion block are a rare but life-threatening complication. Prompt recognition and treatment is therefore vital.
Department of Anesthesiology; Dokkyo University School of Medicine; Mibu, Tochigi, Japan
1. Buckley FP. Regional anesthesia with local anesthetics. In: Loeser JD, ed. Bonica's Management of Pain,
3rd edn. Tokyo, Japan: Lippincott Williams & Wilkins, 2001: 1893-1966.
2. Mishio T, Matsumoto T, Okuda Y, Kitajima T. Delayed severe airway obstruction due to hematoma following stellate ganglion block. Reg Anesth Pain Med
3. Kapral S, Krafft P, Gosch M, Fleishmann D, Christian W. Ultrasound imaging for stellate ganglion block: direct visualization of puncture site and local anesthetic spread. A pilot study. Reg Anesth
4. Kua JSW, Tan IKS. Airway obstruction following internal jugular vein cannulation. Anaesthesia