Syncope Risk in Cervical Nerve Treatments for Pain

A 41-year-old woman undergoing a pulsed radiofrequency procedure for chronic neck pain and headaches experienced a delayed episode of vasovagal syncope, a sudden drop in consciousness and heart rate, nearly 20 hours after treatment. This case, documented by researchers Kurnia Hendra Wijaya and Buyung Hartiyo Laksono, highlights a rare but serious potential complication of a common pain management technique, particularly for patients with overlapping conditions like vertigo and tinnitus.

A Detailed Case of Delayed Syncope

The patient had a complex history including chronic cervical radiculopathy from a herniated disc, tension-type headaches, cluster headaches, chronic spontaneous vertigo, and newly diagnosed hypertension. She underwent a bilateral procedure where pulsed radiofrequency energy was applied to the lesser and greater occipital nerves and the C3 and C4 dorsal root ganglia. This minimally invasive technique uses short bursts of radiofrequency energy to modulate nerve activity without causing permanent damage, often used for chronic head and neck pain.

The procedure itself, performed under light sedation with propofol and midazolam, was completed without issue. Approximately 20 hours later, however, the patient developed an acute decrease in consciousness. Her Glasgow Coma Scale score dropped to 12 (indicating a significant impairment), and her heart rate profile was consistent with a reflex vasovagal event—a sudden drop in heart rate and blood pressure leading to fainting. She gradually recovered consciousness over seven hours, reaching a full score of 15 with no lasting neurological deficits.

The Pathophysiology: Nerve Stimulation and a Heart Reflex

The researchers propose a specific mechanism for this delayed event. The occipital nerves and upper cervical dorsal root ganglia are intricately connected to the trigeminocervical complex, a network of neurons in the brainstem that processes sensory information from the head and neck. Stimulating these nerves can send afferent signals into this complex.

In some susceptible individuals, this input can activate the Bezold–Jarisch reflex. This reflex originates in the heart; when certain cardiac receptors are stimulated, they signal the brainstem to lower heart rate and blood pressure, potentially causing vasovagal syncope. The patient’s history of vertigo and autonomic dysregulation (like hypertension) may have increased her susceptibility. This connection illustrates how treatments targeting cervical nerves can have systemic, autonomic consequences.

Clinical Outcomes: Pain Relief Despite Complications

A noteworthy aspect of this case is the treatment outcome. Despite the syncope episode, a comparison of symptoms before and after the procedure showed clear improvement in several areas. The patient reported reduced cervical paraesthesia (abnormal sensations), vertigo, and tinnitus. Her cluster-type headache symptoms also improved.

This positive effect on tinnitus and vertigo is clinically significant. It suggests that modulating upper cervical nerve activity (C3, C4) and occipital nerves can influence auditory and vestibular pathways, possibly by reducing aberrant sensory input or central hyperactivity. This aligns with models of tinnitus where cervical spine dysfunction contributes to the condition. The tension-type headache, however, persisted at a similar intensity, indicating a more complex or separate mechanism for that particular pain.

Practical Implications for Patient Safety

This single case report, detailed in Journal of Anesthesiology and Clinical Research, does not change the overall safety profile of pulsed radiofrequency, which remains a low-risk procedure. However, it identifies a rare but clinically important adverse event that requires awareness.

The authors recommend specific safety measures:

• Multimodal Monitoring: Careful monitoring of vital signs during and after the procedure.
• Adequate Hydration: Ensuring the patient is well-hydrated before and after treatment to support blood pressure stability.
• Titrated Sedation: Using minimal, carefully adjusted sedation to avoid masking early signs of discomfort or autonomic imbalance.
• Structured Observation: Implementing a structured post-procedural observation period, potentially extending beyond immediate recovery, to catch delayed events like this one.

For patients considering such procedures, particularly those with a history of vertigo, autonomic dysfunction, or sound sensitivity conditions like hyperacusis, this information is valuable for informed consent and shared decision-making.

Connecting Cervical Treatment to Hearing Health

The improvement in this patient’s tinnitus following cervical nerve treatment reinforces a growing understanding of the neck’s role in auditory disorders. Cervical spine issues can contribute to tinnitus through shared neural pathways and central sensitization. This case adds a practical observation to that theoretical framework. It also suggests that treatments aimed at cervical pain may have serendipitous benefits for some forms of tinnitus, much like how targeting jaw muscle tension can relieve bruxism-related tinnitus.

Furthermore, the overlap of symptoms—vertigo, headache, tinnitus, cervical pain—in this patient underscores the need for holistic assessment in hearing health. Diagnosing and treating these conditions often requires looking beyond the ear, as explored in articles on pediatric vestibular disorders and the complex factors in misophonia treatment.

The full case report, “Vasovagal syncope following pulsed radiofrequency of the cervical dorsal root ganglia and occipital nerves: a case report,” provides detailed clinical reasoning and is available via its DOI link. While pulsed radiofrequency remains a valuable tool, this research reminds clinicians and patients that even minimally invasive neuromodulation can have unexpected autonomic effects, warranting vigilance and comprehensive care.