Flaccid Leg Paralysis Caused by a Thoracic Epidural Catheterization: A Case Report
A 44-year-old woman (height, 162 cm; weight, 51 kg) was admitted to the Department of Surgery at this hospital for an extended right hemicolectomy due to colonic intussusceptions caused by cecal lipoma. Upon admission, the patient's vital signs were normal, and the patient had no history of any other diseases. Epidural catheterization was performed to achieve postoperative pain controls. As the patient was nervous and uncooperative, an epidural block was performed after general anesthesia. The median approach was used, and the epidural space was located using an 18-gauge Tuohy needle and the loss of resistance to air technique between the T12 and L1 spinous processes. On the first needle insertion attempt, increased resistance was felt as the needle entered the ligamentum flavum, followed by loss of resistance with injection of air as the needle was advanced to a depth of about 4 cm from the skin. After confirming that there was no cerebrospinal fluid (CSF), a 20-gauge epidural catheter (Perifix epidural catheterization set; B. Braun Melsungen AG, Melsungen, Germany) was inserted 5 cm further into the epidural space, and the catheter was placed with little resistance. An epinephrine injection was not conducted as the epidural catheter was being mislocated in the blood vessel. After the successful placement of the epidural catheter, a total volume of 20 mg of 0.5% levobupivacaine (Chirocaine; Abbott Korea Ltd., Seoul, Korea) and fentanyl (Fentanyl Citrate; Guju Pharm Co. Ltd., Seoul, Korea) 50 µg was administered, and a patient-controlled analgesia pump ambulatory infusion pump (Woo Young Medical Co. Ltd., Seoul, Korea) was connected to the epidural catheter. The pump was programmed to deliver 300 mg of 0.5% levobupivacaine with morphine (Highmol; BCworld Pharm Co. Ltd., Seoul, Korea) 20 mg, alfentanyl (Alfentanil; Hana Pharm Co. Ltd., Seoul, Korea) 6 mg, ondansetron (Onsetron; BoRyung Pharm, Seoul, Korea) 8 mg, and normal saline 47 mL at a rate of 2 mL/h.\nAlthough the patient's postoperative vital signs were stable, she complained of feeling weakness, hypesthesia, and numbness of the lower left limb after gaining her conscious. The epidural pump infusion was thus discontinued, and the epidural catheter was removed as the symptoms persisted the following day. On postoperative day 9, the neurologic assessment that was performed in accordance with the consultation with the Department of Rehabilitation Medicine revealed decreased touch, pain, and temperature sensations as well as preservation of vibration sensation and proprioception in the dermatomes from T11 to S4-5, on the lower left limb. Although manual muscle testing showed that the muscle strengths of the upper and right lower extremities were normal, the muscle strength in the left lower extremities decreased to 4/5 in the hip flexors and extensors, 2/5 in the knee flexors, 4/5 in the knee extensors, and 0/5 in the ankle dorsiflexors and plantar flexors. The ankle jerk of both sides and the knee jerk on the left side also decreased, and Babinski reflex and ankle clonus were not observed on both sides. Although digital rectal examinations revealed that the construction of the anal sphincter had slightly diminished, the patient did not complain of changes in her bladder and bowel functions. No symptom of infection (e.g., fever) was seen, and no abnormal findings were reported according to the hematology, including blood test and liver function and urinalysis test.\nOn the 9th postoperative day, the magnetic resonance imaging (MRI) of thoracolumbar spine was performed. It revealed well-defined intramedullary linear high-signal-intensity lesion at the sagittal T2-weighted images and low-signal-intensity lesion at the T1-weighted images, in the left spinal cord between T9 and the L1 vertebral level. Also, the T1-enhanced images showed minimal enhancements in the spinal cord between T9 and the L1 vertebral level, and diffuse enhancements in the spinal cord below the T12 vertebral level and in the cauda equina (, ).\nElectrodiagnostic examination was performed on postoperative day 22. Although the sensory-nerve conduction study of the lower extremities on both sides was normal, and the motor nerve conduction study of right peroneal and tibial nerves was normal, the amplitude of the compound motor action potentials in the left peroneal and tibial nerve decreased, and the latency of the left tibial nerve was delayed. The somatosensory-evoked potentials of both tibial nerves and the motor-evoked potentials of the lower right extremities were within the normal range while the motor-evoked potentials recorded in the left abductor hallucis muscle and tibialis anterior muscle were not evoked. Electromyography showed a finding of denervation below the L4 myotome, and consequently, electrodiagnostic examination demonstrated a finding that was consistent with the lumbosacral radiculopathy below L4 nerve roots on the left side (, ).\nIn review of the clinical findings, according to the outcomes of the imaging studies and electrodiagnostic examinations, it was supposed that the intrinsic spinal cord lesion caused by the epidural catheterization was accompanied by nerve roots injuries below L4 on the left side. The follow-up MRI of the thoracolumbar spine that was performed nine weeks later did not show new lesions, and the high-signal-intensity lesions on the previous T2-weighted images and the enhanced lesions on the T1-enhanced images were found to have decreased considerably. In addition, the nerve conduction study that was performed at postoperative week 10, revealed that the amplitude of the compound motor action potentials in the left peroneal nerve and tibial nerve increased as compared with that in the previous outcome. The motor-evoked potentials of the left abductor hallucis muscle and the left tibialis anterior muscle were evoked, and that the motor unit action potentials of the left tibialis anterior muscle which were not seen in the electromyography were being observed, demonstrating improvement of the lumbosacral radiculopathy below L4 nerve root on the left side.\nAfter a period of about three months, with the muscle strengths of the hip flexor, extensor, and knee extensor, have recovered to normal levels, and those of the ankle dorsiflexor and plantar flexor, which have recovered to 2/5. The patient, who can now walk independently using an ankle-foot orthosis, is already getting strengthening exercises on lower muscular extremities in left side and gait trainings. Moreover, the patient is complaining of neuropathic pain in the left hip and dorsum of foot. A physical agent modalities and pharmacologic treatments are offered for pain control.