Gelfoam-Induced Acute Cauda Equina Syndrome Following L3–L5 Decompression and Instrumented Fusion: A Case Report

In the complex architecture of the human spine, surgeons often rely on small, absorbable sponges to stop bleeding during delicate operations. These sponges, made from a porous gelatin material, are designed to soak up blood and tissue fluid, helping the body form a clot naturally. Once the bleeding stops, the sponge is meant to dissolve away over a few weeks, leaving no trace behind. Because they are effective and generally safe, these materials are a standard tool in spinal surgery, used to protect the nerves while the surgeon works on the bones. However, the space inside the spine is incredibly tight, packed with bundles of nerves that control movement and sensation in the legs and bladder. When a surgeon removes bone to relieve pressure on these nerves, they create a narrow tunnel where even a tiny amount of extra material can cause significant problems. The medical community has long known that if these sponges swell too much, they can press on the nerves, but the timing and speed of such an event were thought to be slow and predictable.

A recent case report from a hospital in China challenges this assumption, describing a situation where a standard surgical sponge caused a sudden and severe neurological crisis within just two hours of surgery. The story begins with a seventy-one-year-old man who had suffered from leg pain and difficulty walking for four years. His condition had not improved with physical therapy or medication, so doctors decided to perform a surgery to remove bone and ligaments pressing on his spinal nerves at the lower back. The operation involved removing parts of three vertebrae and installing metal screws and rods to stabilize the spine. During the procedure, the surgeon noticed some minor bleeding on the surface of the protective covering of the spinal cord. To stop this, a single, intact sheet of the gelatin sponge was placed directly over the nerves. The sheet was not soaked in a special liquid to remove air, nor was it cut into smaller pieces; it was left as a large, dry mat.

When the patient woke up from anesthesia, he initially seemed fine. But just two hours later, his right leg suddenly became weak. He could not lift his knee, move his ankle, or wiggle his toes. The weakness was so severe that the muscles in his leg were barely able to move against gravity. Doctors quickly realized this was not a normal postoperative ache but a sign of acute compression on the bundle of nerves at the base of the spine. A scan of his lower back showed that the metal screws were in the correct position and there were no broken bones pushing inward, but there was a strange mass pressing against the nerves. Because the patient had a catheter in place to drain his bladder during the surgery, the doctors could not tell if he was unable to urinate, which is a classic warning sign of this type of nerve compression. This hidden symptom, combined with the sudden weakness, made the situation tricky to diagnose immediately.

The medical team performed an emergency scan using magnetic resonance imaging, which revealed the true cause: the gelatin sponge had absorbed fluid from the surgical site and swelled up like a balloon, forming a solid mass that squeezed the nerves tightly. The sponge had expanded so quickly that it filled the narrow space where the nerves travel, cutting off their function. The patient was taken back to the operating room immediately. When the surgeons opened the incision, they found the sponge had turned into a large, gelatinous lump that wrapped around the nerves from the third to the fifth vertebrae. They carefully removed the entire mass and the surrounding blood clots. Once the pressure was released, the patient's condition began to improve almost immediately. Within twelve hours, his leg strength had returned enough for him to move his muscles moderately, and by six weeks later, he was walking without any assistance.

This case highlights a specific and dangerous way that a routine surgical tool can fail. The researchers found that the speed of the damage was due to how the sponge was used. Because the sheet was left whole and dry, it trapped air inside its pores. When it touched the wet environment of the spine, it sucked in fluid rapidly, expanding with great force in a space that could not stretch. In previous reports, similar problems happened slowly over ten to fourteen days as the sponge absorbed fluid gradually and caused inflammation. In this instance, the damage happened in a matter of hours, driven purely by the physical swelling of the material rather than a slow immune reaction. The presence of the urinary catheter also played a role by hiding the usual sign of bladder trouble, which might have otherwise alerted doctors to the problem sooner.

The authors of the report suggest that to prevent this from happening again, surgeons should change how they use these sponges. They recommend that the material should never be left as a large, intact sheet in the spinal canal. Instead, it should be cut into tiny pieces, soaked thoroughly to remove all trapped air, and squeezed dry before use. Most importantly, any leftover sponge should be removed completely once the bleeding stops, rather than being left behind to dissolve. The report concludes that when a patient experiences sudden leg weakness after spine surgery, doctors must look for this type of swelling immediately, even if the patient has a catheter and cannot show signs of bladder retention. By recognizing the speed of the threat and acting quickly to remove the swelling material, the severe damage to the nerves can often be reversed, allowing the patient to recover their ability to walk.