Stellate ganglion block is an innovative procedure that can be used in the management of a variety of chronic pain conditions including CRPS, phantom pain, facial pain, and postherpetic neuralgia. More recently it has been used in the management of post-traumatic stress disorder and hot flushes. Covid infection has demonstrated the ability to cause post-acute sympathetically-mediated autonomic dysfunction affecting sleep, resting heart rate, orthostatic intolerance and dyspnea. Dysautonomia is believed to be the main aetiology of long Covid symptoms and suggests that SGB may be an effective intervention for this condition, with the potential to change the course of the long covid.
Stellate ganglion block is an innovative procedure that can be used in the management of a variety of chronic pain conditions including CRPS, phantom pain, facial pain and postherpetic neuralgia. More recently it has been used in the management of post-traumatic stress disorder, cardiac arrhythmias and hot flashes associated with cancer treatment and menopause. Mechanisms for the durable central nervous system effects of the SGB in these conditions are unclear, delaying its broad acceptance as a valid treatment.
Covid infection has demonstrated the ability to cause post-acute sympathetically-mediated autonomic dysfunction affecting sleep, resting heart rate, orthostatic intolerance and dyspnea. Dysautonomia is believed to be the main aetiology of long Covid symptoms and suggests that SGB may be an effective intervention for this condition, with the potential to change the course of the long covid.
Ultrasound technique has added a new dimension to this procedure, making it very safe and accurate. Ultrasound allows the needle to be safely guided around the nerves and blood vessels in the neck as it is placed next to the Stellate Ganglion. Under x-ray (fluoroscopic) guidance, only bones are visible, and nerves are not visible at all, therefore the position of the stellate ganglion can only be approximated.
It is important to note that in some cases injection treatment may not provide the desired results or the pain relief may not be sustained.
At Pain, Spa Dr Krishna is very experienced in interventional treatments. Dr Krishna always performs stellate ganglion block under ultrasound guidance, for greater accuracy and improved safety. Ultrasound provides the added advantage of visualizing the surrounding structures including muscles, nerves and blood vessels.
The stellate ganglion is part of the sympathetic nervous system that is located in your neck, on either side of your voice box. A stellate ganglion block is an injection of a local anaesthetic around these nerves. We perform this injection under real-time ultrasound guidance. The sympathetic nervous system controls the “fight or flight” response and blocking this with local anaesthetic tends to dampen this system. It also controls the blood flow to the various organs in the body, including the brain. In other words, SGB can regulate cerebral blood flow. Impaired CBF is associated with dysautonomia syndromes that share symptoms with long covid, namely myalgic encephalitis/chronic fatigue syndrome (ME/CFS) and postural orthostatic tachycardia syndrome (POTS).
It is believed/hypothesized that a regional sympathetically mediated process is involved in the maintenance of their long covid symptoms. This supports the theory that dysautonomia underlies the pathophysiology of at least a subset of long covid. The autonomic nervous system provides complex bidirectional communication between the immune system and the nervous system.
Alterations in autonomic processes regulating homeostasis are appropriate during acute infection, but persistent sympathetic hyperactivity may result in neuronal adaptation that manifests as persistent dysautonomia similar to that seen in complex regional pain syndrome (CRPS)—in which an acute tissue injury produces long-standing vasomotor dysfunction, neurogenic inflammation, and aberrant neuroplasticity in the affected body region. While CRPS is usually associated with a limb, long covid seems to predominantly affect the brain. We believe that SGB-induced sympathectomy produces its beneficial effects in long covid by attenuating chronic sympathetic hyperresponsiveness, improving cerebral and regional blood flow, and recalibrating the autonomic nervous system toward pre-COVID homeostasis.
Cerebral blood flow (CBF) in humans is affected by a variety of inputs and regulated by sympathetic fibres extending from the cervical sympathetic chain. Impaired CBF is associated with dysautonomia syndromes that share symptoms with long covid, namely myalgic encephalitis/chronic fatigue syndrome (ME/CFS) and postural orthostatic tachycardia syndrome (POTS). Compared to healthy controls, ME/ CFS patients ubiquitously display reduced CBF and impaired cognitive function during orthostatic testing.
The evidence for use of SGB in the management of Long Covid is limited. A case series was published by Luke Liu and Deborah Duricka in the Journal of neuroimmunology in 2022. This case series describes the improvement of long covid symptoms after local anaesthetic blockade of the cervical sympathetic chain bilaterally in two patients suggesting that a regional sympathetically mediated process is involved in the maintenance of their long covid symptoms. This supports the theory that dysautonomia underlies the pathophysiology of at least a subset of long covid patients. Stellate ganglion block has been used for nearly a century to treat a variety of sympathetically mediated medical conditions. Its safety profile is well established. Its application in treating long covid is novel but promising. The lack of effective treatments for long covid makes the SGB an attractive therapeutic modality that deserves further investigation.
We would initially recommend a right-sided SGB under Ultrasound guidance. If symptoms do not improve significantly in the next few days, we would recommend a repeat injection on the left side under Ultrasound guidance. In the recent case series published by Luke Liu and Deborah Duricka, SGB was performed initially on the right side and then repeated on the left side after 24-48 hours.
Ultrasound imaging (sonography) uses high-frequency sound waves to view inside the body. Ultrasound shows all the surrounding soft tissue structures including muscles, tendons, ligaments, and nerves, whereas x-rays show only the bones. Because ultrasound images are captured in real-time, they can also show the movement of the body’s internal organs as well as blood flowing through the blood vessels. Unlike X-ray imaging, there is no ionizing radiation exposure associated with ultrasound imaging. Under ultrasound guidance, the needle tip can be visualized in real-time whilst being advanced close to the stellate ganglion. This is not possible under x-ray guidance.
Using ultrasound guidance to safely perform an SGB takes special training and considerable skill which many doctors do not have. Dr. Krishna is an expert in performing ultrasound-guided procedures and has successfully performed several SGBs using this technology.
Multiple approaches have been used to localize the stellate ganglia. These include blind technique, plain fluoroscopic guidance and use of ultrasound. Traditionally these blocks have been performed either by using surface landmarks or by using a fluoroscopy-guided technique. Computerized tomography (CT) and magnetic resonance imaging (MRI) approaches have been described, these techniques are not practical in daily clinical practice. Recently, however, there has been a growing interest in using an ultrasound-guided technique because of the many advantages that this technique might offer.
At Pain Spa, we always use ultrasound guidance for performing stellate ganglion block. Dr Krishna has performed hundreds of SGB injections without any complications.
Ultrasound-guided SGB can improve the safety of the procedure by direct visualization of the related anatomical structures and, accordingly, the risk of vascular and soft tissue injury may be minimized. In addition, ultrasound guidance will allow direct monitoring of the spread of the injectate and hence may minimize complications such as recurrent laryngeal nerve (RLN) palsy and intrathecal, epidural or intravascular spread.
The procedure is usually done on an outpatient basis. Stellate ganglion block injection is performed under ultrasound guidance to ensure the accuracy of needle placement. Patients need to be aware that the outcome of the procedure is variable and they may not receive the desired benefits. Similarly, they must be aware of the transient nature of the therapeutic benefits and that there may need repeat injections.
For pain procedures generally, a mixture of local anaesthetic and steroids is injected. However, for long covid treatment, only a local anaesthetic is injected around the stellate ganglion. Injection of local anaesthetic near the stellate ganglion can block the activity of the entire cervical sympathetic chain, as evidenced by the physiological signs of a successful block collectively known as “Horner’s Syndrome”.
Complications are rare, particularly if the injections are performed using a precise needle-positioning technique. Possible complications include bruising, infection, hematoma, nerve injury and reaction to the injectate. Infection can be avoided with appropriate aseptic precautions. Severe allergic reactions to local anaesthetics are uncommon. These local reactions last for 24 to 48 hours and are relieved by the application of ice packs. A post-procedural flare-up of symptoms may occasionally occur and tend to settle with time.
It is important to know that stellate ganglion block can be associated with several serious complications as the stellate ganglion is located near various vital structures. These complications include:
SGB in long covid is a novel treatment, especially as the management options are pretty limited. However, it is certainly not a ‘magic bullet’ that a lot of patients are searching for. In experienced hands, it is an extremely safe procedure and worth trying if other management options have not helped.