Hoarseness and Throat Discomfort After Quadratus Lumborum Block: Two Case Reports
For people with severe lower back pain, a quadratus lumborum block (QLB) is a trusted, safe option for relief. But what if this procedure—performed on the lower spine—caused unexpected issues like a hoarse voice or a “something’s stuck in my throat” feeling? Two new cases suggest it might, and researchers are now exploring why.
The transmuscular quadratus lumborum block (TQLB) eases pain by targeting sympathetic nerves in the thoracic paravertebral space (the area alongside the spine). It’s considered safer than older methods, but until now, no one had linked it to voice or throat problems. That changed when a team from the Catholic University of Korea and Ajou University College of Medicine reported two patients who developed these symptoms after TQLB.
Case 1: A 42-Year-Old Man with Lower Back and Groin Pain
The man arrived at the clinic with acute lower back and inguinal (groin) pain, scoring a 7 out of 10 on the numeric rating scale (NRS, where 0 = no pain, 10 = worst pain). Doctors performed TQLB on both sides at the L4 lumbar level, injecting 20 mL of 0.375% ropivacaine (a local anesthetic) mixed with epinephrine (to slow absorption). His pain dropped to a 1—but soon after, he noticed his voice was hoarse. He also felt constant discomfort when trying to clear his throat, though he had no trouble breathing, coughing, or taking deep breaths. Ultrasound ruled out diaphragm paralysis, and he had no other red flags like small pupils (miosis), drooping eyelids (ptosis), or low blood pressure. He mentioned a “swollen feeling” in his left arm, but tests showed no nerve damage. The hoarseness resolved on its own within 4 hours.
Case 2: A 40-Year-Old Woman with Acute Low Back Pain
The woman had a nearly identical experience. Doctors did bilateral L4 TQLB with the same medication. An hour later, she felt itching and odd sensations on her left torso (T4-L2) and right side (T11-L1). Three hours after the injection, she reported mild hoarseness and a “foreign body” feeling in her throat—just like the first patient. Again, no diaphragm paralysis, miosis, or ptosis. Her symptoms faded in 2 hours without treatment.
Why Would a Lumbar Block Affect the Throat?
Hoarseness after nerve blocks is almost always linked to neck (cervical) procedures, where the recurrent laryngeal nerve (which controls the vocal cords) might be accidentally blocked. But these cases were done on the lower spine—so how did the issue reach the throat?
Researchers point to two key findings:
- Upward Spread: TQLB injections often move cephalad (upward) into the thoracic paravertebral space (near the upper spine). Studies in Anesthesiology and Surgical and Radiologic Anatomy confirm this flow.
- Fascial “Pump”: The deep fascia (connective tissue) where TQLB is injected has a “pumping” action from muscle movement, which can actively push the anesthetic higher. This was highlighted in a 2018 study in Regional Anesthesia and Pain Medicine.
The Likely Mechanism: Sympathetic Nerve Blockade
The team suspects the anesthetic reached the high thoracic paravertebral space, where it blocked sympathetic nerves that control blood flow to the larynx (voice box). Anatomically, the vocal cords and laryngeal mucosa get blood from the superior laryngeal and thyroid arteries—nerves for these vessels come from the superior cervical sympathetic ganglion, which connects to the T1-T2 spinal levels. Blocking these nerves could widen (dilate) the laryngeal blood vessels, causing temporary congestion and edema (swelling) in the mucosa. That swelling would make the vocal cords vibrate differently (hoarseness) and create a “phlegmy” or “stuck” feeling—exactly what the patients described.
While recurrent laryngeal nerve blockade is another possible cause, the team says edema is more likely because symptoms were mild, short-lived, and resolved without intervention.
What This Means for Patients and Clinicians
The cases are rare—only two reported so far—and symptoms were brief. But they highlight a new potential side effect of TQLB. For clinicians, it’s a reminder to ask patients about throat or voice changes even after lumbar procedures. For patients, it’s reassurance that if these symptoms happen, they’re likely temporary.
The study, published in the Chinese Medical Journal in 2021, was led by Jihyun Chung, Seunguk Bang, and colleagues from the Catholic University of Korea and Ajou University College of Medicine in South Korea. All patients gave written consent for their cases to be shared, with steps taken to protect their privacy.
More research is needed to confirm the mechanism—but these cases add a critical piece to our understanding of TQLB. They show why even “routine” procedures deserve close monitoring.
For the full study, visit the Chinese Medical Journal or use the DOI: doi.org/10.1097/CM9.0000000000001352
Was this helpful?
0 / 0