Image Quiz

Lower-Extremity Muscle Weakness After Removal of an Epidural Catheter Used for Anesthesia and Analgesia Following Total Knee Arthroplasty (continued)

Answer: Epidural hematoma.


Fig. 1		 Fig. 1 Sagittal magnetic resonance images showing an epidural hematoma in the posterior epidural space (arrows), from the T12 level to the L3 level, with inhomogeneously moderate high signal intensity on the T1-weighted (a) and the T2-weighted (b) image. There is anterior displacement of the conus medullaris.

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The patient was taken to the operating room approximately thirty-two hours after the symptoms began, and an emergent laminectomy at the level of the hematoma was performed. Two laminae (L1 and L2) were resected without disturbing the facets, and the vertebral canal was explored. An extensive clot had formed and was compressing the dura and its contents. The hematoma was meticulously evacuated, but no actively bleeding vessels were identified. The wound was closed. In the recovery room, a bolus dose of 1000 µg of methylprednisolone (Solu-Medrol; Pfizer Hellas, Athens, Greece) was administered to the patient over the course of one hour. No additional doses of methylprednisolone were given.

Subsequently, the patient remained in bed for two days and was evaluated regularly, but his neurological status did not improve during that time. The third day after the laminectomy, the patient started to show neurological improvement, with increased muscle strength in the anterior and posterior tibial muscles. Improvement continued, and, on the eighth day after the laminectomy, the patient could move his legs freely in bed. On the twelfth day after the laminectomy, he could stand alone and take a few steps with a walker and, according to the grading scale of the British Medical Research Council, muscle strength was rated as 4 for both iliopsoas muscles, 5 for the right quadriceps and 4 for the left quadriceps, and 4 for the anterior and posterior tibial muscles in both legs. The patient was discharged from the hospital to a rehabilitation center on the twelfth day after the laminectomy and was reevaluated three weeks later (thirty-three days after the laminectomy). At that time, he had no residual neurological deficit, and the range of motion in the involved knee ranged from full extension to 95° of flexion. No further special coagulation studies were performed.

The patient underwent the usual follow-up for a patient who had undergone joint replacement. At one year after knee replacement, the patient had normal muscle strength, and the range of motion in the knee ranged from full extension to 100° of flexion. At the time of the two-year postoperative followup, the results were similar to those obtained at one year.

Discussion

The rate of bleeding complications associated with epidural anesthesia is estimated to range from 1 in every 150,000 to 1 in every 1,000,000 patients. Although rare, this complication may be catastrophic as it can result in a severe neurologic deficit, such as paraplegia. Vandermeulen et al. identified two major risk factors. The first factor is difficult or traumatic insertion or removal of the catheter (including multiple punctures), and the second is abnormalities of the coagulation mechanism. These abnormalities can be due to conditions that existed preoperatively (such as thrombocytopenia, chronic renal failure, or chronic liver disease) or can be caused by anticoagulant medications that are administered to the patient to prevent deep venous thrombosis. As reported in the literature, administration of heparin or low-molecular-weight heparin is a recognized factor for the development of an epidural hematoma, especially when the epidural catheter was introduced with notable difficulty. Intake of salicylates may be associated with an increased risk of epidural bleeding and subsequent hematoma, but heparin and low-molecular-weight heparin are even more strongly associated with that risk. In our review of the literature, we did not find a case of epidural hematoma in a patient receiving Coumadin (warfarin) who had an international normalized ratio of ≤2.0. The source of the hematoma is believed to be an injured epidural artery or a vein from the epidural venous plexus. It is well known that anticoagulant treatment is associated with hematoma formation. Although there are certain instructions regarding the administration of anticoagulants and the removal of the spinal catheters, the possibility of hematoma formation cannot be excluded. Early diagnosis and treatment of a hematoma is crucial to avoid permanent neurologic deficits. A high index of suspicion should be maintained and careful and repeated clinical examinations are necessary to assess symptoms, especially if there is gradual worsening. Magnetic resonance imaging is the preferred modality to confirm compression of the spinal cord and nerve roots. Immediate laminectomy and surgical evacuation of the hematoma is indicated to decompress the spinal cord. The surgeon must be aware that, even when early action has been taken, the outcome may not be optimal.

Although the literature contains many case reports of epidural hematoma after removal of an epidural catheter, we are aware of only one report describing an epidural hematoma that occurred after spinal anesthesia in total knee arthroplasty. In that report, the epidural hematoma occurred immediately after surgery and sensorimotor disturbances were present before removal of the catheter. Nonoperative treatment was chosen, and sensorimotor recovery was complete six months after surgery.

In our patient, the hematoma occurred after removal of the epidural catheter three days after the operation. In our opinion, there was not an obvious reason to explain the formation of the epidural hematoma. Insertion of the catheter was not difficult, and it was removed twelve hours after the last administration of low-molecular-weight heparin in accordance with recommendations for safe removal of catheters. We think the likely cause for the hematoma formation was an arterial or venous injury that occurred in the vertebral canal during removal of the catheter. Surgical decompression of the spinal canal with laminectomy and evacuation of the hematoma was the chosen course of action, and the patient fully recovered. Fortunately, the delay in diagnosis for this patient did not have serious consequences.

Although rare, hematoma formation should be suspected when a patient presents with symptoms suggesting spinal cord compression after epidural or spinal anesthesia and the administration of low-molecular-weight heparin. Immediate intervention to evacuate the hematoma and decompress the vertebral canal must be undertaken to optimize neurological recovery.

Reference

1. Varitimidis SE, Paterakis K, Dailiana ZH, Hantes M, Georgopoulou S. Epidural hematoma secondary to removal of an epidural catheter after a total knee replacement. A Case Report. J Bone Joint Surg Am. 2007;89:2048-50.