A Rare Hyperextension Injury in Thoracic Spine Presenting with Delayed Paraplegia
A 91-year-old female patient visited our hospital. She was in good condition and walked very well for her age. While she was getting on a bus, she lost her footing and fell backwards onto the ground. She was unable to walk because of severe back pain, but the initial physical examination did not show neurologic deficit. She did not complain of sensory decrease and the lower extremity motor grade was more than grade 4 on both lower legs. The initial plain radiographic study showed a fracture at the anterosuperior portion of the thoracic eleventh (T11) vertebral body (). Also, we suspected oblique fractures at the spinous processes of T9 and T10 vertebrae, and therefore conducted computed tomography (CT) to confirm fracture characteristics as we diagnosed (). The L2 vertebral body fracture was diagnosed as an old compression fracture. Because the fracture involved the posterior column, which are spinous process fractures, magnetic resonance imaging (MRI) was required. On MRI, acute benign fracture was shown at the anterosuperior portion of the T11 vertebral body with hemorrhage of the fracture site (). Hemorrhage within the disc was also seen at the T10 to T11 space. The posterior column including spinous process and interspinous ligament had high signal intensity on T2-weight MRI. The ALL was disrupted with the bony fragment attached. Although the interspinous ligament showed a high signal, the signal intensity within the spinal cord was not increased.\nConsidering the patient's age and the absence of neurologic deficit at the initial phase, conservative management was chosen. Also, bony lesion, vertebral body and spinous process fractures, were more prominent than soft tissue lesions, and we expected only bony union. On day two of hospitalization, we applied thoraco-lumbo-sacral orthosis and started standing physical therapy including tilt table. On seventh day, follow-up plain radiographic showed slightly reduced the fracture site of the T11 vertebra (). Until day 19, she could stand for 20 minutes but couldn't walk by herself. She did not complain of any neurologic change until then.\nOn day 20 of hospitalization, she complained of lower extremity weakness, and general lower extremity motor grade was decreased to grade 1 or 2. Sensory functions may have also been slightly decreased. She said the symptoms gradually aggravated over the last three days and she couldn't remember any significant event before the appearance of the neurologic deficit. Knee jerk and ankle jerk of both lower legs were accelerated. Ankle clonus and babinski sign were positive. We immediately conducted a follow-up plain X-ray and MRI (). The fracture was not more displaced compared to previous imaging, but the intervertebral disc of T10 to T11 space was extruded with superior migration, compressing the spinal cord with compressive myelopathy.\nWe immediately did surgical decompression (spinous process resection and total laminectomy from T9 to T12), pedicle screws instrumentation and then fusion of T9 to T12 with morcellized allograft (freeze-dried human allograft) and demineralzation bone matrix (). Operation finding showed the dura of the spinal cord was intact. We couldn't remove the herniated disc for fear of further spinal cord injury. Three days after operation we started again standing physical therapy. Three months following surgery, she regained lower extremity motor strength to the grade 4. She could walk with a walker.